1770 lines
66 KiB
ReStructuredText
1770 lines
66 KiB
ReStructuredText
*********************
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Command Line Options
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*********************
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.. _string-options-ref:
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Note that unless an option is listed as **CLI ONLY** the option is also
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supported by x265_param_parse(). The CLI uses getopt to parse the
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command line options so the short or long versions may be used and the
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long options may be truncated to the shortest unambiguous abbreviation.
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Users of the API must pass x265_param_parse() the full option name.
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Preset and tune have special implications. The API user must call
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x265_param_default_preset() with the preset and tune parameters they
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wish to use, prior to calling x265_param_parse() to set any additional
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fields. The CLI does this for the user implicitly, so all CLI options
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are applied after the user's preset and tune choices, regardless of the
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order of the arguments on the command line.
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If there is an extra command line argument (not an option or an option
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value) the CLI will treat it as the input filename. This effectively
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makes the :option:`--input` specifier optional for the input file. If
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there are two extra arguments, the second is treated as the output
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bitstream filename, making :option:`--output` also optional if the input
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filename was implied. This makes :command:`x265 in.y4m out.hevc` a valid
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command line. If there are more than two extra arguments, the CLI will
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consider this an error and abort.
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Generally, when an option expects a string value from a list of strings
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the user may specify the integer ordinal of the value they desire. ie:
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:option:`--log-level` 3 is equivalent to :option:`--log-level` debug.
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Executable Options
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==================
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.. option:: --help, -h
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Display help text
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**CLI ONLY**
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.. option:: --version, -V
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Display version details
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**CLI ONLY**
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Command line executable return codes::
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0. encode successful
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1. unable to parse command line
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2. unable to open encoder
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3. unable to generate stream headers
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4. encoder abort
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5. unable to open csv file
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Logging/Statistic Options
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=========================
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.. option:: --log-level <integer|string>
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Logging level. Debug level enables per-frame QP, metric, and bitrate
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logging. If a CSV file is being generated, frame level makes the log
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be per-frame rather than per-encode. Full level enables hash and
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weight logging. -1 disables all logging, except certain fatal
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errors, and can be specified by the string "none".
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0. error
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1. warning
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2. info **(default)**
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3. debug
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4. full
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.. option:: --no-progress
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Disable periodic progress reports from the CLI
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**CLI ONLY**
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.. option:: --csv <filename>
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Writes encoding results to a comma separated value log file. Creates
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the file if it doesnt already exist. If :option:`--csv-log-level` is 0,
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it adds one line per run. If :option:`--csv-log-level` is greater than
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0, it writes one line per frame. Default none
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Several frame performance statistics are available when
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:option:`--csv-log-level` is greater than or equal to 2:
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**DecideWait ms** number of milliseconds the frame encoder had to
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wait, since the previous frame was retrieved by the API thread,
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before a new frame has been given to it. This is the latency
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introduced by slicetype decisions (lookahead).
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**Row0Wait ms** number of milliseconds since the frame encoder
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received a frame to encode before its first row of CTUs is allowed
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to begin compression. This is the latency introduced by reference
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frames making reconstructed and filtered rows available.
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**Wall time ms** number of milliseconds between the first CTU
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being ready to be compressed and the entire frame being compressed
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and the output NALs being completed.
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**Ref Wait Wall ms** number of milliseconds between the first
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reference row being available and the last reference row becoming
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available.
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**Total CTU time ms** the total time (measured in milliseconds)
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spent by worker threads compressing and filtering CTUs for this
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frame.
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**Stall Time ms** the number of milliseconds of the reported wall
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time that were spent with zero worker threads, aka all compression
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was completely stalled.
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**Avg WPP** the average number of worker threads working on this
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frame, at any given time. This value is sampled at the completion of
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each CTU. This shows the effectiveness of Wavefront Parallel
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Processing.
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**Row Blocks** the number of times a worker thread had to abandon
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the row of CTUs it was encoding because the row above it was not far
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enough ahead for the necessary reference data to be available. This
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is more of a problem for P frames where some blocks are much more
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expensive than others.
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**CLI ONLY**
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.. option:: --csv-log-level <integer>
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CSV logging level. Default 0
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0. summary
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1. frame level logging
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2. frame level logging with performance statistics
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**CLI ONLY**
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.. option:: --ssim, --no-ssim
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Calculate and report Structural Similarity values. It is
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recommended to use :option:`--tune` ssim if you are measuring ssim,
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else the results should not be used for comparison purposes.
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Default disabled
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.. option:: --psnr, --no-psnr
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Calculate and report Peak Signal to Noise Ratio. It is recommended
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to use :option:`--tune` psnr if you are measuring PSNR, else the
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results should not be used for comparison purposes. Default
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disabled
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Performance Options
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===================
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.. option:: --asm <integer:false:string>, --no-asm
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x265 will use all detected CPU SIMD architectures by default. You can
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disable all assembly by using :option:`--no-asm` or you can specify
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a comma separated list of SIMD architectures to use, matching these
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strings: MMX2, SSE, SSE2, SSE3, SSSE3, SSE4, SSE4.1, SSE4.2, AVX, XOP, FMA4, AVX2, FMA3
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Some higher architectures imply lower ones being present, this is
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handled implicitly.
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One may also directly supply the CPU capability bitmap as an integer.
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Note that by specifying this option you are overriding x265's CPU
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detection and it is possible to do this wrong. You can cause encoder
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crashes by specifying SIMD architectures which are not supported on
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your CPU.
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Default: auto-detected SIMD architectures
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.. option:: --frame-threads, -F <integer>
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Number of concurrently encoded frames. Using a single frame thread
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gives a slight improvement in compression, since the entire reference
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frames are always available for motion compensation, but it has
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severe performance implications. Default is an autodetected count
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based on the number of CPU cores and whether WPP is enabled or not.
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Over-allocation of frame threads will not improve performance, it
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will generally just increase memory use.
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**Values:** any value between 0 and 16. Default is 0, auto-detect
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.. option:: --pools <string>, --numa-pools <string>
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Comma seperated list of threads per NUMA node. If "none", then no worker
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pools are created and only frame parallelism is possible. If NULL or ""
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(default) x265 will use all available threads on each NUMA node::
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'+' is a special value indicating all cores detected on the node
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'*' is a special value indicating all cores detected on the node and all remaining nodes
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'-' is a special value indicating no cores on the node, same as '0'
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example strings for a 4-node system::
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"" - default, unspecified, all numa nodes are used for thread pools
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"*" - same as default
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"none" - no thread pools are created, only frame parallelism possible
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"-" - same as "none"
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"10" - allocate one pool, using up to 10 cores on node 0
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"-,+" - allocate one pool, using all cores on node 1
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"+,-,+" - allocate one pool, using only cores on nodes 0 and 2
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"+,-,+,-" - allocate one pool, using only cores on nodes 0 and 2
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"-,*" - allocate one pool, using all cores on nodes 1, 2 and 3
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"8,8,8,8" - allocate four pools with up to 8 threads in each pool
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"8,+,+,+" - allocate two pools, the first with 8 threads on node 0, and the second with all cores on node 1,2,3
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A thread pool dedicated to a given NUMA node is enabled only when the
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number of threads to be created on that NUMA node is explicitly mentioned
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in that corresponding position with the --pools option. Else, all threads
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are spawned from a single pool. The total number of threads will be
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determined by the number of threads assigned to the enabled NUMA nodes for
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that pool. The worker threads are be given affinity to all the enabled
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NUMA nodes for that pool and may migrate between them, unless explicitly
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specified as described above.
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In the case that any threadpool has more than 64 threads, the threadpool
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may be broken down into multiple pools of 64 threads each; on 32-bit
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machines, this number is 32. All pools are given affinity to the NUMA
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nodes on which the original pool had affinity. For performance reasons,
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the last thread pool is spawned only if it has more than 32 threads for
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64-bit machines, or 16 for 32-bit machines. If the total number of threads
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in the system doesn't obey this constraint, we may spawn fewer threads
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than cores which has been emperically shown to be better for performance.
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If the four pool features: :option:`--wpp`, :option:`--pmode`,
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:option:`--pme` and :option:`--lookahead-slices` are all disabled,
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then :option:`--pools` is ignored and no thread pools are created.
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If "none" is specified, then all four of the thread pool features are
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implicitly disabled.
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Frame encoders are distributed between the available thread pools,
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and the encoder will never generate more thread pools than
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:option:`--frame-threads`. The pools are used for WPP and for
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distributed analysis and motion search.
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On Windows, the native APIs offer sufficient functionality to
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discover the NUMA topology and enforce the thread affinity that
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libx265 needs (so long as you have not chosen to target XP or
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Vista), but on POSIX systems it relies on libnuma for this
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functionality. If your target POSIX system is single socket, then
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building without libnuma is a perfectly reasonable option, as it
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will have no effect on the runtime behavior. On a multiple-socket
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system, a POSIX build of libx265 without libnuma will be less work
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efficient. See :ref:`thread pools <pools>` for more detail.
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Default "", one pool is created across all available NUMA nodes, with
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one thread allocated per detected hardware thread
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(logical CPU cores). In the case that the total number of threads is more
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than the maximum size that ATOMIC operations can handle (32 for 32-bit
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compiles, and 64 for 64-bit compiles), multiple thread pools may be
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spawned subject to the performance constraint described above.
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Note that the string value will need to be escaped or quoted to
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protect against shell expansion on many platforms
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.. option:: --wpp, --no-wpp
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Enable Wavefront Parallel Processing. The encoder may begin encoding
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a row as soon as the row above it is at least two CTUs ahead in the
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encode process. This gives a 3-5x gain in parallelism for about 1%
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overhead in compression efficiency.
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This feature is implicitly disabled when no thread pool is present.
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Default: Enabled
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.. option:: --pmode, --no-pmode
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Parallel mode decision, or distributed mode analysis. When enabled
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the encoder will distribute the analysis work of each CU (merge,
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inter, intra) across multiple worker threads. Only recommended if
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x265 is not already saturating the CPU cores. In RD levels 3 and 4
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it will be most effective if --rect is enabled. At RD levels 5 and
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6 there is generally always enough work to distribute to warrant the
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overhead, assuming your CPUs are not already saturated.
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--pmode will increase utilization without reducing compression
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efficiency. In fact, since the modes are all measured in parallel it
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makes certain early-outs impractical and thus you usually get
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slightly better compression when it is enabled (at the expense of
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not skipping improbable modes). This bypassing of early-outs can
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cause pmode to slow down encodes, especially at faster presets.
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This feature is implicitly disabled when no thread pool is present.
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Default disabled
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.. option:: --pme, --no-pme
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Parallel motion estimation. When enabled the encoder will distribute
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motion estimation across multiple worker threads when more than two
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references require motion searches for a given CU. Only recommended
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if x265 is not already saturating CPU cores. :option:`--pmode` is
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much more effective than this option, since the amount of work it
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distributes is substantially higher. With --pme it is not unusual
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for the overhead of distributing the work to outweigh the
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parallelism benefits.
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This feature is implicitly disabled when no thread pool is present.
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--pme will increase utilization on many core systems with no effect
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on the output bitstream.
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Default disabled
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.. option:: --preset, -p <integer|string>
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Sets parameters to preselected values, trading off compression efficiency against
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encoding speed. These parameters are applied before all other input parameters are
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applied, and so you can override any parameters that these values control. See
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:ref:`presets <presets>` for more detail.
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0. ultrafast
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1. superfast
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2. veryfast
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3. faster
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4. fast
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5. medium **(default)**
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6. slow
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7. slower
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8. veryslow
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9. placebo
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.. option:: --tune, -t <string>
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Tune the settings for a particular type of source or situation. The changes will
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be applied after :option:`--preset` but before all other parameters. Default none.
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See :ref:`tunings <tunings>` for more detail.
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**Values:** psnr, ssim, grain, zero-latency, fast-decode.
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Input/Output File Options
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=========================
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These options all describe the input video sequence or, in the case of
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:option:`--dither`, operations that are performed on the sequence prior
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to encode. All options dealing with files (names, formats, offsets or
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frame counts) are only applicable to the CLI application.
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.. option:: --input <filename>
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Input filename, only raw YUV or Y4M supported. Use single dash for
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stdin. This option name will be implied for the first "extra"
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command line argument.
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**CLI ONLY**
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.. option:: --y4m
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Parse input stream as YUV4MPEG2 regardless of file extension,
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primarily intended for use with stdin (ie: :option:`--input` -
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:option:`--y4m`). This option is implied if the input filename has
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a ".y4m" extension
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**CLI ONLY**
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.. option:: --input-depth <integer>
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YUV only: Bit-depth of input file or stream
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**Values:** any value between 8 and 16. Default is internal depth.
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**CLI ONLY**
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.. option:: --total-frames <integer>
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The number of frames intended to be encoded. It may be left
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unspecified, but when it is specified rate control can make use of
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this information. It is also used to determine if an encode is
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actually a stillpicture profile encode (single frame)
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.. option:: --dither
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Enable high quality downscaling. Dithering is based on the diffusion
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of errors from one row of pixels to the next row of pixels in a
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picture. Only applicable when the input bit depth is larger than
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8bits and internal bit depth is 8bits. Default disabled
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**CLI ONLY**
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.. option:: --input-res <wxh>
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YUV only: Source picture size [w x h]
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**CLI ONLY**
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.. option:: --input-csp <integer|string>
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YUV only: Source color space. Only i420, i422, and i444 are
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supported at this time. The internal color space is always the
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same as the source color space (libx265 does not support any color
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space conversions).
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0. i400
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1. i420 **(default)**
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2. i422
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3. i444
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4. nv12
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5. nv16
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.. option:: --fps <integer|float|numerator/denominator>
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YUV only: Source frame rate
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**Range of values:** positive int or float, or num/denom
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.. option:: --interlace <false|tff|bff>, --no-interlace
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0. progressive pictures **(default)**
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1. top field first
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2. bottom field first
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HEVC encodes interlaced content as fields. Fields must be provided to
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the encoder in the correct temporal order. The source dimensions
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must be field dimensions and the FPS must be in units of fields per
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second. The decoder must re-combine the fields in their correct
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orientation for display.
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.. option:: --seek <integer>
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Number of frames to skip at start of input file. Default 0
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**CLI ONLY**
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.. option:: --frames, -f <integer>
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Number of frames of input sequence to be encoded. Default 0 (all)
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**CLI ONLY**
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.. option:: --output, -o <filename>
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Bitstream output file name. If there are two extra CLI options, the
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first is implicitly the input filename and the second is the output
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filename, making the :option:`--output` option optional.
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The output file will always contain a raw HEVC bitstream, the CLI
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does not support any container file formats.
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**CLI ONLY**
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.. option:: --output-depth, -D 8|10|12
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Bitdepth of output HEVC bitstream, which is also the internal bit
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depth of the encoder. If the requested bit depth is not the bit
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depth of the linked libx265, it will attempt to bind libx265_main
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for an 8bit encoder, libx265_main10 for a 10bit encoder, or
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libx265_main12 for a 12bit encoder, with the same API version as the
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linked libx265.
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If the output depth is not specified but :option:`--profile` is
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specified, the output depth will be derived from the profile name.
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**CLI ONLY**
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Profile, Level, Tier
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====================
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.. option:: --profile, -P <string>
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Enforce the requirements of the specified profile, ensuring the
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output stream will be decodable by a decoder which supports that
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profile. May abort the encode if the specified profile is
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impossible to be supported by the compile options chosen for the
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encoder (a high bit depth encoder will be unable to output
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bitstreams compliant with Main or MainStillPicture).
|
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The first version of the HEVC specification only described Main,
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Main10, and MainStillPicture. All other profiles were added by the
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Range Extensions additions in HEVC version two.
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8bit profiles::
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main, main-intra, mainstillpicture (or msp for short)
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main444-8 main444-intra main444-stillpicture
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10bit profiles::
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main10, main10-intra
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main422-10, main422-10-intra
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main444-10, main444-10-intra
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12bit profiles::
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main12, main12-intra
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main422-12, main422-12-intra
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main444-12, main444-12-intra
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16bit profiles::
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main444-16-intra main444-16-stillpicture
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**CLI ONLY**
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API users must call x265_param_apply_profile() after configuring
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their param structure. Any changes made to the param structure after
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this call might make the encode non-compliant.
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The CLI application will derive the output bit depth from the
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profile name if :option:`--output-depth` is not specified.
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.. option:: --level-idc <integer|float>
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Minimum decoder requirement level. Defaults to 0, which implies
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auto-detection by the encoder. If specified, the encoder will
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|
attempt to bring the encode specifications within that specified
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level. If the encoder is unable to reach the level it issues a
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warning and aborts the encode. If the requested requirement level is
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higher than the actual level, the actual requirement level is
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signaled.
|
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Beware, specifying a decoder level will force the encoder to enable
|
|
VBV for constant rate factor encodes, which may introduce
|
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non-determinism.
|
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The value is specified as a float or as an integer with the level
|
|
times 10, for example level **5.1** is specified as "5.1" or "51",
|
|
and level **5.0** is specified as "5.0" or "50".
|
|
|
|
Annex A levels: 1, 2, 2.1, 3, 3.1, 4, 4.1, 5, 5.1, 5.2, 6, 6.1, 6.2, 8.5
|
|
|
|
.. option:: --high-tier, --no-high-tier
|
|
|
|
If :option:`--level-idc` has been specified, the option adds the
|
|
intention to support the High tier of that level. If your specified
|
|
level does not support a High tier, a warning is issued and this
|
|
modifier flag is ignored. If :option:`--level-idc` has been specified,
|
|
but not --high-tier, then the encoder will attempt to encode at the
|
|
specified level, main tier first, turning on high tier only if
|
|
necessary and available at that level.
|
|
|
|
If :option:`--level-idc` has not been specified, this argument is
|
|
ignored.
|
|
|
|
.. option:: --ref <1..16>
|
|
|
|
Max number of L0 references to be allowed. This number has a linear
|
|
multiplier effect on the amount of work performed in motion search,
|
|
but will generally have a beneficial affect on compression and
|
|
distortion.
|
|
|
|
Note that x265 allows up to 16 L0 references but the HEVC
|
|
specification only allows a maximum of 8 total reference frames. So
|
|
if you have B frames enabled only 7 L0 refs are valid and if you
|
|
have :option:`--b-pyramid` enabled (which is enabled by default in
|
|
all presets), then only 6 L0 refs are the maximum allowed by the
|
|
HEVC specification. If x265 detects that the total reference count
|
|
is greater than 8, it will issue a warning that the resulting stream
|
|
is non-compliant and it signals the stream as profile NONE and level
|
|
NONE and will abort the encode unless
|
|
:option:`--allow-non-conformance` it specified. Compliant HEVC
|
|
decoders may refuse to decode such streams.
|
|
|
|
Default 3
|
|
|
|
.. option:: --allow-non-conformance, --no-allow-non-conformance
|
|
|
|
Allow libx265 to generate a bitstream with profile and level NONE.
|
|
By default it will abort any encode which does not meet strict level
|
|
compliance. The two most likely causes for non-conformance are
|
|
:option:`--ctu` being too small, :option:`--ref` being too high,
|
|
or the bitrate or resolution being out of specification.
|
|
|
|
Default: disabled
|
|
|
|
.. note::
|
|
|
|
:option:`--profile`, :option:`--level-idc`, and
|
|
:option:`--high-tier` are only intended for use when you are
|
|
targeting a particular decoder (or decoders) with fixed resource
|
|
limitations and must constrain the bitstream within those limits.
|
|
Specifying a profile or level may lower the encode quality
|
|
parameters to meet those requirements but it will never raise
|
|
them. It may enable VBV constraints on a CRF encode.
|
|
|
|
Also note that x265 determines the decoder requirement profile and
|
|
level in three steps. First, the user configures an x265_param
|
|
structure with their suggested encoder options and then optionally
|
|
calls x265_param_apply_profile() to enforce a specific profile
|
|
(main, main10, etc). Second, an encoder is created from this
|
|
x265_param instance and the :option:`--level-idc` and
|
|
:option:`--high-tier` parameters are used to reduce bitrate or other
|
|
features in order to enforce the target level. Finally, the encoder
|
|
re-examines the final set of parameters and detects the actual
|
|
minimum decoder requirement level and this is what is signaled in
|
|
the bitstream headers. The detected decoder level will only use High
|
|
tier if the user specified a High tier level.
|
|
|
|
The signaled profile will be determined by the encoder's internal
|
|
bitdepth and input color space. If :option:`--keyint` is 0 or 1,
|
|
then an intra variant of the profile will be signaled.
|
|
|
|
If :option:`--total-frames` is 1, then a stillpicture variant will
|
|
be signaled, but this parameter is not always set by applications,
|
|
particularly not when the CLI uses stdin streaming or when libx265
|
|
is used by third-party applications.
|
|
|
|
|
|
Mode decision / Analysis
|
|
========================
|
|
|
|
.. option:: --rd <0..6>
|
|
|
|
Level of RDO in mode decision. The higher the value, the more
|
|
exhaustive the analysis and the more rate distortion optimization is
|
|
used. The lower the value the faster the encode, the higher the
|
|
value the smaller the bitstream (in general). Default 3
|
|
|
|
Note that this table aims for accuracy, but is not necessarily our
|
|
final target behavior for each mode.
|
|
|
|
+-------+---------------------------------------------------------------+
|
|
| Level | Description |
|
|
+=======+===============================================================+
|
|
| 0 | sa8d mode and split decisions, intra w/ source pixels |
|
|
+-------+---------------------------------------------------------------+
|
|
| 1 | recon generated (better intra), RDO merge/skip selection |
|
|
+-------+---------------------------------------------------------------+
|
|
| 2 | RDO splits and merge/skip selection |
|
|
+-------+---------------------------------------------------------------+
|
|
| 3 | RDO mode and split decisions, chroma residual used for sa8d |
|
|
+-------+---------------------------------------------------------------+
|
|
| 4 | Currently same as 3 |
|
|
+-------+---------------------------------------------------------------+
|
|
| 5 | Adds RDO prediction decisions |
|
|
+-------+---------------------------------------------------------------+
|
|
| 6 | Currently same as 5 |
|
|
+-------+---------------------------------------------------------------+
|
|
|
|
**Range of values:** 0: least .. 6: full RDO analysis
|
|
|
|
Options which affect the coding unit quad-tree, sometimes referred to as
|
|
the prediction quad-tree.
|
|
|
|
.. option:: --ctu, -s <64|32|16>
|
|
|
|
Maximum CU size (width and height). The larger the maximum CU size,
|
|
the more efficiently x265 can encode flat areas of the picture,
|
|
giving large reductions in bitrate. However this comes at a loss of
|
|
parallelism with fewer rows of CUs that can be encoded in parallel,
|
|
and less frame parallelism as well. Because of this the faster
|
|
presets use a CU size of 32. Default: 64
|
|
|
|
.. option:: --min-cu-size <64|32|16|8>
|
|
|
|
Minimum CU size (width and height). By using 16 or 32 the encoder
|
|
will not analyze the cost of CUs below that minimum threshold,
|
|
saving considerable amounts of compute with a predictable increase
|
|
in bitrate. This setting has a large effect on performance on the
|
|
faster presets.
|
|
|
|
Default: 8 (minimum 8x8 CU for HEVC, best compression efficiency)
|
|
|
|
.. note::
|
|
|
|
All encoders within a single process must use the same settings for
|
|
the CU size range. :option:`--ctu` and :option:`--min-cu-size` must
|
|
be consistent for all of them since the encoder configures several
|
|
key global data structures based on this range.
|
|
|
|
.. option:: --limit-refs <0|1|2|3>
|
|
|
|
When set to X265_REF_LIMIT_DEPTH (1) x265 will limit the references
|
|
analyzed at the current depth based on the references used to code
|
|
the 4 sub-blocks at the next depth. For example, a 16x16 CU will
|
|
only use the references used to code its four 8x8 CUs.
|
|
|
|
When set to X265_REF_LIMIT_CU (2), the rectangular and asymmetrical
|
|
partitions will only use references selected by the 2Nx2N motion
|
|
search (including at the lowest depth which is otherwise unaffected
|
|
by the depth limit).
|
|
|
|
When set to 3 (X265_REF_LIMIT_DEPTH && X265_REF_LIMIT_CU), the 2Nx2N
|
|
motion search at each depth will only use references from the split
|
|
CUs and the rect/amp motion searches at that depth will only use the
|
|
reference(s) selected by 2Nx2N.
|
|
|
|
For all non-zero values of limit-refs, the current depth will evaluate
|
|
intra mode (in inter slices), only if intra mode was chosen as the best
|
|
mode for atleast one of the 4 sub-blocks.
|
|
|
|
You can often increase the number of references you are using
|
|
(within your decoder level limits) if you enable one or
|
|
both of these flags.
|
|
|
|
This feature is EXPERIMENTAL and functional at all RD levels.
|
|
|
|
.. option:: --rect, --no-rect
|
|
|
|
Enable analysis of rectangular motion partitions Nx2N and 2NxN
|
|
(50/50 splits, two directions). Default disabled
|
|
|
|
.. option:: --amp, --no-amp
|
|
|
|
Enable analysis of asymmetric motion partitions (75/25 splits, four
|
|
directions). At RD levels 0 through 4, AMP partitions are only
|
|
considered at CU sizes 32x32 and below. At RD levels 5 and 6, it
|
|
will only consider AMP partitions as merge candidates (no motion
|
|
search) at 64x64, and as merge or inter candidates below 64x64.
|
|
|
|
The AMP partitions which are searched are derived from the current
|
|
best inter partition. If Nx2N (vertical rectangular) is the best
|
|
current prediction, then left and right asymmetrical splits will be
|
|
evaluated. If 2NxN (horizontal rectangular) is the best current
|
|
prediction, then top and bottom asymmetrical splits will be
|
|
evaluated, If 2Nx2N is the best prediction, and the block is not a
|
|
merge/skip, then all four AMP partitions are evaluated.
|
|
|
|
This setting has no effect if rectangular partitions are disabled.
|
|
Default disabled
|
|
|
|
.. option:: --early-skip, --no-early-skip
|
|
|
|
Measure full CU size (2Nx2N) merge candidates first; if no residual
|
|
is found the analysis is short circuited. Default disabled
|
|
|
|
.. option:: --fast-intra, --no-fast-intra
|
|
|
|
Perform an initial scan of every fifth intra angular mode, then
|
|
check modes +/- 2 distance from the best mode, then +/- 1 distance
|
|
from the best mode, effectively performing a gradient descent. When
|
|
enabled 10 modes in total are checked. When disabled all 33 angular
|
|
modes are checked. Only applicable for :option:`--rd` levels 4 and
|
|
below (medium preset and faster).
|
|
|
|
.. option:: --b-intra, --no-b-intra
|
|
|
|
Enables the evaluation of intra modes in B slices. Default disabled.
|
|
|
|
.. option:: --cu-lossless, --no-cu-lossless
|
|
|
|
For each CU, evaluate lossless (transform and quant bypass) encode
|
|
of the best non-lossless mode option as a potential rate distortion
|
|
optimization. If the global option :option:`--lossless` has been
|
|
specified, all CUs will be encoded as lossless unconditionally
|
|
regardless of whether this option was enabled. Default disabled.
|
|
|
|
Only effective at RD levels 3 and above, which perform RDO mode
|
|
decisions.
|
|
|
|
.. option:: --tskip-fast, --no-tskip-fast
|
|
|
|
Only evaluate transform skip for NxN intra predictions (4x4 blocks).
|
|
Only applicable if transform skip is enabled. For chroma, only
|
|
evaluate if luma used tskip. Inter block tskip analysis is
|
|
unmodified. Default disabled
|
|
|
|
Analysis re-use options, to improve performance when encoding the same
|
|
sequence multiple times (presumably at varying bitrates). The encoder
|
|
will not reuse analysis if the resolution and slice type parameters do
|
|
not match.
|
|
|
|
.. option:: --analysis-mode <string|int>
|
|
|
|
Specify whether analysis information of each frame is output by encoder
|
|
or input for reuse. By reading the analysis data writen by an
|
|
earlier encode of the same sequence, substantial redundant work may
|
|
be avoided.
|
|
|
|
The following data may be stored and reused:
|
|
I frames - split decisions and luma intra directions of all CUs.
|
|
P/B frames - motion vectors are dumped at each depth for all CUs.
|
|
|
|
**Values:** off(0), save(1): dump analysis data, load(2): read analysis data
|
|
|
|
.. option:: --analysis-file <filename>
|
|
|
|
Specify a filename for analysis data (see :option:`--analysis-mode`)
|
|
If no filename is specified, x265_analysis.dat is used.
|
|
|
|
Options which affect the transform unit quad-tree, sometimes referred to
|
|
as the residual quad-tree (RQT).
|
|
|
|
.. option:: --rdoq-level <0|1|2>, --no-rdoq-level
|
|
|
|
Specify the amount of rate-distortion analysis to use within
|
|
quantization::
|
|
|
|
At level 0 rate-distortion cost is not considered in quant
|
|
|
|
At level 1 rate-distortion cost is used to find optimal rounding
|
|
values for each level (and allows psy-rdoq to be effective). It
|
|
trades-off the signaling cost of the coefficient vs its post-inverse
|
|
quant distortion from the pre-quant coefficient. When
|
|
:option:`--psy-rdoq` is enabled, this formula is biased in favor of
|
|
more energy in the residual (larger coefficient absolute levels)
|
|
|
|
At level 2 rate-distortion cost is used to make decimate decisions
|
|
on each 4x4 coding group, including the cost of signaling the group
|
|
within the group bitmap. If the total distortion of not signaling
|
|
the entire coding group is less than the rate cost, the block is
|
|
decimated. Next, it applies rate-distortion cost analysis to the
|
|
last non-zero coefficient, which can result in many (or all) of the
|
|
coding groups being decimated. Psy-rdoq is less effective at
|
|
preserving energy when RDOQ is at level 2, since it only has
|
|
influence over the level distortion costs.
|
|
|
|
.. option:: --tu-intra-depth <1..4>
|
|
|
|
The transform unit (residual) quad-tree begins with the same depth
|
|
as the coding unit quad-tree, but the encoder may decide to further
|
|
split the transform unit tree if it improves compression efficiency.
|
|
This setting limits the number of extra recursion depth which can be
|
|
attempted for intra coded units. Default: 1, which means the
|
|
residual quad-tree is always at the same depth as the coded unit
|
|
quad-tree
|
|
|
|
Note that when the CU intra prediction is NxN (only possible with
|
|
8x8 CUs), a TU split is implied, and thus the residual quad-tree
|
|
begins at 4x4 and cannot split any futhrer.
|
|
|
|
.. option:: --tu-inter-depth <1..4>
|
|
|
|
The transform unit (residual) quad-tree begins with the same depth
|
|
as the coding unit quad-tree, but the encoder may decide to further
|
|
split the transform unit tree if it improves compression efficiency.
|
|
This setting limits the number of extra recursion depth which can be
|
|
attempted for inter coded units. Default: 1. which means the
|
|
residual quad-tree is always at the same depth as the coded unit
|
|
quad-tree unless the CU was coded with rectangular or AMP
|
|
partitions, in which case a TU split is implied and thus the
|
|
residual quad-tree begins one layer below the CU quad-tree.
|
|
|
|
.. option:: --nr-intra <integer>, --nr-inter <integer>
|
|
|
|
Noise reduction - an adaptive deadzone applied after DCT
|
|
(subtracting from DCT coefficients), before quantization. It does
|
|
no pixel-level filtering, doesn't cross DCT block boundaries, has no
|
|
overlap, The higher the strength value parameter, the more
|
|
aggressively it will reduce noise.
|
|
|
|
Enabling noise reduction will make outputs diverge between different
|
|
numbers of frame threads. Outputs will be deterministic but the
|
|
outputs of -F2 will no longer match the outputs of -F3, etc.
|
|
|
|
**Values:** any value in range of 0 to 2000. Default 0 (disabled).
|
|
|
|
.. option:: --tskip, --no-tskip
|
|
|
|
Enable evaluation of transform skip (bypass DCT but still use
|
|
quantization) coding for 4x4 TU coded blocks.
|
|
|
|
Only effective at RD levels 3 and above, which perform RDO mode
|
|
decisions. Default disabled
|
|
|
|
.. option:: --rdpenalty <0..2>
|
|
|
|
When set to 1, transform units of size 32x32 are given a 4x bit cost
|
|
penalty compared to smaller transform units, in intra coded CUs in P
|
|
or B slices.
|
|
|
|
When set to 2, transform units of size 32x32 are not even attempted,
|
|
unless otherwise required by the maximum recursion depth. For this
|
|
option to be effective with 32x32 intra CUs,
|
|
:option:`--tu-intra-depth` must be at least 2. For it to be
|
|
effective with 64x64 intra CUs, :option:`--tu-intra-depth` must be
|
|
at least 3.
|
|
|
|
Note that in HEVC an intra transform unit (a block of the residual
|
|
quad-tree) is also a prediction unit, meaning that the intra
|
|
prediction signal is generated for each TU block, the residual
|
|
subtracted and then coded. The coding unit simply provides the
|
|
prediction modes that will be used when predicting all of the
|
|
transform units within the CU. This means that when you prevent
|
|
32x32 intra transform units, you are preventing 32x32 intra
|
|
predictions.
|
|
|
|
Default 0, disabled.
|
|
|
|
**Values:** 0:disabled 1:4x cost penalty 2:force splits
|
|
|
|
.. option:: --max-tu-size <32|16|8|4>
|
|
|
|
Maximum TU size (width and height). The residual can be more
|
|
efficiently compressed by the DCT transform when the max TU size
|
|
is larger, but at the expense of more computation. Transform unit
|
|
quad-tree begins at the same depth of the coded tree unit, but if the
|
|
maximum TU size is smaller than the CU size then transform QT begins
|
|
at the depth of the max-tu-size. Default: 32.
|
|
|
|
Temporal / motion search options
|
|
================================
|
|
|
|
.. option:: --max-merge <1..5>
|
|
|
|
Maximum number of neighbor (spatial and temporal) candidate blocks
|
|
that the encoder may consider for merging motion predictions. If a
|
|
merge candidate results in no residual, it is immediately selected
|
|
as a "skip". Otherwise the merge candidates are tested as part of
|
|
motion estimation when searching for the least cost inter option.
|
|
The max candidate number is encoded in the SPS and determines the
|
|
bit cost of signaling merge CUs. Default 2
|
|
|
|
.. option:: --me <integer|string>
|
|
|
|
Motion search method. Generally, the higher the number the harder
|
|
the ME method will try to find an optimal match. Diamond search is
|
|
the simplest. Hexagon search is a little better. Uneven
|
|
Multi-Hexegon is an adaption of the search method used by x264 for
|
|
slower presets. Star is a three step search adapted from the HM
|
|
encoder: a star-pattern search followed by an optional radix scan
|
|
followed by an optional star-search refinement. Full is an
|
|
exhaustive search; an order of magnitude slower than all other
|
|
searches but not much better than umh or star.
|
|
|
|
0. dia
|
|
1. hex **(default)**
|
|
2. umh
|
|
3. star
|
|
4. full
|
|
|
|
.. option:: --subme, -m <0..7>
|
|
|
|
Amount of subpel refinement to perform. The higher the number the
|
|
more subpel iterations and steps are performed. Default 2
|
|
|
|
+----+------------+-----------+------------+-----------+-----------+
|
|
| -m | HPEL iters | HPEL dirs | QPEL iters | QPEL dirs | HPEL SATD |
|
|
+====+============+===========+============+===========+===========+
|
|
| 0 | 1 | 4 | 0 | 4 | false |
|
|
+----+------------+-----------+------------+-----------+-----------+
|
|
| 1 | 1 | 4 | 1 | 4 | false |
|
|
+----+------------+-----------+------------+-----------+-----------+
|
|
| 2 | 1 | 4 | 1 | 4 | true |
|
|
+----+------------+-----------+------------+-----------+-----------+
|
|
| 3 | 2 | 4 | 1 | 4 | true |
|
|
+----+------------+-----------+------------+-----------+-----------+
|
|
| 4 | 2 | 4 | 2 | 4 | true |
|
|
+----+------------+-----------+------------+-----------+-----------+
|
|
| 5 | 1 | 8 | 1 | 8 | true |
|
|
+----+------------+-----------+------------+-----------+-----------+
|
|
| 6 | 2 | 8 | 1 | 8 | true |
|
|
+----+------------+-----------+------------+-----------+-----------+
|
|
| 7 | 2 | 8 | 2 | 8 | true |
|
|
+----+------------+-----------+------------+-----------+-----------+
|
|
|
|
At --subme values larger than 2, chroma residual cost is included
|
|
in all subpel refinement steps and chroma residual is included in
|
|
all motion estimation decisions (selecting the best reference
|
|
picture in each list, and chosing between merge, uni-directional
|
|
motion and bi-directional motion). The 'slow' preset is the first
|
|
preset to enable the use of chroma residual.
|
|
|
|
.. option:: --merange <integer>
|
|
|
|
Motion search range. Default 57
|
|
|
|
The default is derived from the default CTU size (64) minus the luma
|
|
interpolation half-length (4) minus maximum subpel distance (2)
|
|
minus one extra pixel just in case the hex search method is used. If
|
|
the search range were any larger than this, another CTU row of
|
|
latency would be required for reference frames.
|
|
|
|
**Range of values:** an integer from 0 to 32768
|
|
|
|
.. option:: --temporal-mvp, --no-temporal-mvp
|
|
|
|
Enable temporal motion vector predictors in P and B slices.
|
|
This enables the use of the motion vector from the collocated block
|
|
in the previous frame to be used as a predictor. Default is enabled
|
|
|
|
.. option:: --weightp, -w, --no-weightp
|
|
|
|
Enable weighted prediction in P slices. This enables weighting
|
|
analysis in the lookahead, which influences slice decisions, and
|
|
enables weighting analysis in the main encoder which allows P
|
|
reference samples to have a weight function applied to them prior to
|
|
using them for motion compensation. In video which has lighting
|
|
changes, it can give a large improvement in compression efficiency.
|
|
Default is enabled
|
|
|
|
.. option:: --weightb, --no-weightb
|
|
|
|
Enable weighted prediction in B slices. Default disabled
|
|
|
|
Spatial/intra options
|
|
=====================
|
|
|
|
.. option:: --strong-intra-smoothing, --no-strong-intra-smoothing
|
|
|
|
Enable strong intra smoothing for 32x32 intra blocks. This flag
|
|
performs bi-linear interpolation of the corner reference samples
|
|
for a strong smoothing effect. The purpose is to prevent blocking
|
|
or banding artifacts in regions with few/zero AC coefficients.
|
|
Default enabled
|
|
|
|
.. option:: --constrained-intra, --no-constrained-intra
|
|
|
|
Constrained intra prediction. When generating intra predictions for
|
|
blocks in inter slices, only intra-coded reference pixels are used.
|
|
Inter-coded reference pixels are replaced with intra-coded neighbor
|
|
pixels or default values. The general idea is to block the
|
|
propagation of reference errors that may have resulted from lossy
|
|
signals. Default disabled
|
|
|
|
Psycho-visual options
|
|
=====================
|
|
|
|
Left to its own devices, the encoder will make mode decisions based on a
|
|
simple rate distortion formula, trading distortion for bitrate. This is
|
|
generally effective except for the manner in which this distortion is
|
|
measured. It tends to favor blurred reconstructed blocks over blocks
|
|
which have wrong motion. The human eye generally prefers the wrong
|
|
motion over the blur and thus x265 offers psycho-visual adjustments to
|
|
the rate distortion algorithm.
|
|
|
|
:option:`--psy-rd` will add an extra cost to reconstructed blocks which
|
|
do not match the visual energy of the source block. The higher the
|
|
strength of :option:`--psy-rd` the more strongly it will favor similar
|
|
energy over blur and the more aggressively it will ignore rate
|
|
distortion. If it is too high, it will introduce visal artifacts and
|
|
increase bitrate enough for rate control to increase quantization
|
|
globally, reducing overall quality. psy-rd will tend to reduce the use
|
|
of blurred prediction modes, like DC and planar intra and bi-directional
|
|
inter prediction.
|
|
|
|
:option:`--psy-rdoq` will adjust the distortion cost used in
|
|
rate-distortion optimized quantization (RDO quant), enabled by
|
|
:option:`--rdoq-level` 1 or 2, favoring the preservation of energy in the
|
|
reconstructed image. :option:`--psy-rdoq` prevents RDOQ from blurring
|
|
all of the encoding options which psy-rd has to chose from. At low
|
|
strength levels, psy-rdoq will influence the quantization level
|
|
decisions, favoring higher AC energy in the reconstructed image. As
|
|
psy-rdoq strength is increased, more non-zero coefficient levels are
|
|
added and fewer coefficients are zeroed by RDOQ's rate distortion
|
|
analysis. High levels of psy-rdoq can double the bitrate which can have
|
|
a drastic effect on rate control, forcing higher overall QP, and can
|
|
cause ringing artifacts. psy-rdoq is less accurate than psy-rd, it is
|
|
biasing towards energy in general while psy-rd biases towards the energy
|
|
of the source image. But very large psy-rdoq values can sometimes be
|
|
beneficial, preserving film grain for instance.
|
|
|
|
As a general rule, when both psycho-visual features are disabled, the
|
|
encoder will tend to blur blocks in areas of difficult motion. Turning
|
|
on small amounts of psy-rd and psy-rdoq will improve the perceived
|
|
visual quality. Increasing psycho-visual strength further will improve
|
|
quality and begin introducing artifacts and increase bitrate, which may
|
|
force rate control to increase global QP. Finding the optimal
|
|
psycho-visual parameters for a given video requires experimentation. Our
|
|
recommended defaults (1.0 for both) are generally on the low end of the
|
|
spectrum.
|
|
|
|
The lower the bitrate, the lower the optimal psycho-visual settings. If
|
|
the bitrate is too low for the psycho-visual settings, you will begin to
|
|
see temporal artifacts (motion judder). This is caused when the encoder
|
|
is forced to code skip blocks (no residual) in areas of difficult motion
|
|
because it is the best option psycho-visually (they have great amounts
|
|
of energy and no residual cost). One can lower psy-rd settings when
|
|
judder is happening, and allow the encoder to use some blur in these
|
|
areas of high motion.
|
|
|
|
.. option:: --psy-rd <float>
|
|
|
|
Influence rate distortion optimizated mode decision to preserve the
|
|
energy of the source image in the encoded image at the expense of
|
|
compression efficiency. It only has effect on presets which use
|
|
RDO-based mode decisions (:option:`--rd` 3 and above). 1.0 is a
|
|
typical value. Default 0.3
|
|
|
|
**Range of values:** 0 .. 2.0
|
|
|
|
.. option:: --psy-rdoq <float>
|
|
|
|
Influence rate distortion optimized quantization by favoring higher
|
|
energy in the reconstructed image. This generally improves perceived
|
|
visual quality at the cost of lower quality metric scores. It only
|
|
has effect when :option:`--rdoq-level` is 1 or 2. High values can
|
|
be beneficial in preserving high-frequency detail like film grain.
|
|
Default: 1.0
|
|
|
|
**Range of values:** 0 .. 50.0
|
|
|
|
|
|
Slice decision options
|
|
======================
|
|
|
|
.. option:: --open-gop, --no-open-gop
|
|
|
|
Enable open GOP, allow I-slices to be non-IDR. Default enabled
|
|
|
|
.. option:: --keyint, -I <integer>
|
|
|
|
Max intra period in frames. A special case of infinite-gop (single
|
|
keyframe at the beginning of the stream) can be triggered with
|
|
argument -1. Use 1 to force all-intra. Default 250
|
|
|
|
.. option:: --min-keyint, -i <integer>
|
|
|
|
Minimum GOP size. Scenecuts closer together than this are coded as I
|
|
or P, not IDR. Minimum keyint is clamped to be at least half of
|
|
:option:`--keyint`. If you wish to force regular keyframe intervals
|
|
and disable adaptive I frame placement, you must use
|
|
:option:`--no-scenecut`.
|
|
|
|
**Range of values:** >=0 (0: auto)
|
|
|
|
.. option:: --scenecut <integer>, --no-scenecut
|
|
|
|
How aggressively I-frames need to be inserted. The higher the
|
|
threshold value, the more aggressive the I-frame placement.
|
|
:option:`--scenecut` 0 or :option:`--no-scenecut` disables adaptive
|
|
I frame placement. Default 40
|
|
|
|
.. option:: --rc-lookahead <integer>
|
|
|
|
Number of frames for slice-type decision lookahead (a key
|
|
determining factor for encoder latency). The longer the lookahead
|
|
buffer the more accurate scenecut decisions will be, and the more
|
|
effective cuTree will be at improving adaptive quant. Having a
|
|
lookahead larger than the max keyframe interval is not helpful.
|
|
Default 20
|
|
|
|
**Range of values:** Between the maximum consecutive bframe count (:option:`--bframes`) and 250
|
|
|
|
.. option:: --lookahead-slices <0..16>
|
|
|
|
Use multiple worker threads to measure the estimated cost of each
|
|
frame within the lookahead. When :option:`--b-adapt` is 2, most
|
|
frame cost estimates will be performed in batch mode, many cost
|
|
estimates at the same time, and lookahead-slices is ignored for
|
|
batched estimates. The effect on performance can be quite small.
|
|
The higher this parameter, the less accurate the frame costs will be
|
|
(since context is lost across slice boundaries) which will result in
|
|
less accurate B-frame and scene-cut decisions.
|
|
|
|
The encoder may internally lower the number of slices to ensure
|
|
each slice codes at least 10 16x16 rows of lowres blocks. If slices
|
|
are used in lookahead, they are logged in the list of tools as
|
|
*lslices*.
|
|
|
|
**Values:** 0 - disabled (default). 1 is the same as 0. Max 16
|
|
|
|
.. option:: --b-adapt <integer>
|
|
|
|
Set the level of effort in determining B frame placement.
|
|
|
|
With b-adapt 0, the GOP structure is fixed based on the values of
|
|
:option:`--keyint` and :option:`--bframes`.
|
|
|
|
With b-adapt 1 a light lookahead is used to choose B frame placement.
|
|
|
|
With b-adapt 2 (trellis) a viterbi B path selection is performed
|
|
|
|
**Values:** 0:none; 1:fast; 2:full(trellis) **default**
|
|
|
|
.. option:: --bframes, -b <0..16>
|
|
|
|
Maximum number of consecutive b-frames. Use :option:`--bframes` 0 to
|
|
force all P/I low-latency encodes. Default 4. This parameter has a
|
|
quadratic effect on the amount of memory allocated and the amount of
|
|
work performed by the full trellis version of :option:`--b-adapt`
|
|
lookahead.
|
|
|
|
.. option:: --bframe-bias <integer>
|
|
|
|
Bias towards B frames in slicetype decision. The higher the bias the
|
|
more likely x265 is to use B frames. Can be any value between -90
|
|
and 100 and is clipped to that range. Default 0
|
|
|
|
.. option:: --b-pyramid, --no-b-pyramid
|
|
|
|
Use B-frames as references, when possible. Default enabled
|
|
|
|
Quality, rate control and rate distortion options
|
|
=================================================
|
|
|
|
.. option:: --bitrate <integer>
|
|
|
|
Enables single-pass ABR rate control. Specify the target bitrate in
|
|
kbps. Default is 0 (CRF)
|
|
|
|
**Range of values:** An integer greater than 0
|
|
|
|
.. option:: --crf <0..51.0>
|
|
|
|
Quality-controlled variable bitrate. CRF is the default rate control
|
|
method; it does not try to reach any particular bitrate target,
|
|
instead it tries to achieve a given uniform quality and the size of
|
|
the bitstream is determined by the complexity of the source video.
|
|
The higher the rate factor the higher the quantization and the lower
|
|
the quality. Default rate factor is 28.0.
|
|
|
|
.. option:: --crf-max <0..51.0>
|
|
|
|
Specify an upper limit to the rate factor which may be assigned to
|
|
any given frame (ensuring a max QP). This is dangerous when CRF is
|
|
used in combination with VBV as it may result in buffer underruns.
|
|
Default disabled
|
|
|
|
.. option:: --crf-min <0..51.0>
|
|
|
|
Specify an lower limit to the rate factor which may be assigned to
|
|
any given frame (ensuring a min compression factor).
|
|
|
|
.. option:: --vbv-bufsize <integer>
|
|
|
|
Specify the size of the VBV buffer (kbits). Enables VBV in ABR
|
|
mode. In CRF mode, :option:`--vbv-maxrate` must also be specified.
|
|
Default 0 (vbv disabled)
|
|
|
|
.. option:: --vbv-maxrate <integer>
|
|
|
|
Maximum local bitrate (kbits/sec). Will be used only if vbv-bufsize
|
|
is also non-zero. Both vbv-bufsize and vbv-maxrate are required to
|
|
enable VBV in CRF mode. Default 0 (disabled)
|
|
|
|
Note that when VBV is enabled (with a valid :option:`--vbv-bufsize`),
|
|
VBV emergency denoising is turned on. This will turn on aggressive
|
|
denoising at the frame level when frame QP > QP_MAX_SPEC (51), drastically
|
|
reducing bitrate and allowing ratecontrol to assign lower QPs for
|
|
the following frames. The visual effect is blurring, but removes
|
|
significant blocking/displacement artifacts.
|
|
|
|
.. option:: --vbv-init <float>
|
|
|
|
Initial buffer occupancy. The portion of the decode buffer which
|
|
must be full before the decoder will begin decoding. Determines
|
|
absolute maximum frame size. May be specified as a fractional value
|
|
between 0 and 1, or in kbits. In other words these two option pairs
|
|
are equivalent::
|
|
|
|
--vbv-bufsize 1000 --vbv-init 900
|
|
--vbv-bufsize 1000 --vbv-init 0.9
|
|
|
|
Default 0.9
|
|
|
|
**Range of values:** fractional: 0 - 1.0, or kbits: 2 .. bufsize
|
|
|
|
.. option:: --qp, -q <integer>
|
|
|
|
Specify base quantization parameter for Constant QP rate control.
|
|
Using this option enables Constant QP rate control. The specified QP
|
|
is assigned to P slices. I and B slices are given QPs relative to P
|
|
slices using param->rc.ipFactor and param->rc.pbFactor unless QP 0
|
|
is specified, in which case QP 0 is used for all slice types. Note
|
|
that QP 0 does not cause lossless encoding, it only disables
|
|
quantization. Default disabled (CRF)
|
|
|
|
**Range of values:** an integer from 0 to 51
|
|
|
|
.. option:: --lossless, --no-lossless
|
|
|
|
Enables true lossless coding by bypassing scaling, transform,
|
|
quantization and in-loop filter processes. This is used for
|
|
ultra-high bitrates with zero loss of quality. Reconstructed output
|
|
pictures are bit-exact to the input pictures. Lossless encodes
|
|
implicitly have no rate control, all rate control options are
|
|
ignored. Slower presets will generally achieve better compression
|
|
efficiency (and generate smaller bitstreams). Default disabled.
|
|
|
|
.. option:: --aq-mode <0|1|2|3>
|
|
|
|
Adaptive Quantization operating mode. Raise or lower per-block
|
|
quantization based on complexity analysis of the source image. The
|
|
more complex the block, the more quantization is used. This offsets
|
|
the tendency of the encoder to spend too many bits on complex areas
|
|
and not enough in flat areas.
|
|
|
|
0. disabled
|
|
1. AQ enabled **(default)**
|
|
2. AQ enabled with auto-variance
|
|
3. AQ enabled with auto-variance and bias to dark scenes
|
|
|
|
.. option:: --aq-strength <float>
|
|
|
|
Adjust the strength of the adaptive quantization offsets. Setting
|
|
:option:`--aq-strength` to 0 disables AQ. Default 1.0.
|
|
|
|
**Range of values:** 0.0 to 3.0
|
|
|
|
.. option:: --qg-size <64|32|16>
|
|
|
|
Enable adaptive quantization for sub-CTUs. This parameter specifies
|
|
the minimum CU size at which QP can be adjusted, ie. Quantization Group
|
|
size. Allowed range of values are 64, 32, 16 provided this falls within
|
|
the inclusive range [maxCUSize, minCUSize]. Experimental.
|
|
Default: same as maxCUSize
|
|
|
|
.. option:: --cutree, --no-cutree
|
|
|
|
Enable the use of lookahead's lowres motion vector fields to
|
|
determine the amount of reuse of each block to tune adaptive
|
|
quantization factors. CU blocks which are heavily reused as motion
|
|
reference for later frames are given a lower QP (more bits) while CU
|
|
blocks which are quickly changed and are not referenced are given
|
|
less bits. This tends to improve detail in the backgrounds of video
|
|
with less detail in areas of high motion. Default enabled
|
|
|
|
.. option:: --pass <integer>
|
|
|
|
Enable multi-pass rate control mode. Input is encoded multiple times,
|
|
storing the encoded information of each pass in a stats file from which
|
|
the consecutive pass tunes the qp of each frame to improve the quality
|
|
of the output. Default disabled
|
|
|
|
1. First pass, creates stats file
|
|
2. Last pass, does not overwrite stats file
|
|
3. Nth pass, overwrites stats file
|
|
|
|
**Range of values:** 1 to 3
|
|
|
|
.. option:: --stats <filename>
|
|
|
|
Specify file name of of the multi-pass stats file. If unspecified
|
|
the encoder will use x265_2pass.log
|
|
|
|
.. option:: --slow-firstpass, --no-slow-firstpass
|
|
|
|
Enable a slow and more detailed first pass encode in multi-pass rate
|
|
control mode. Speed of the first pass encode is slightly lesser and
|
|
quality midly improved when compared to the default settings in a
|
|
multi-pass encode. Default disabled (turbo mode enabled)
|
|
|
|
When **turbo** first pass is not disabled, these options are
|
|
set on the first pass to improve performance:
|
|
|
|
* :option:`--fast-intra`
|
|
* :option:`--no-rect`
|
|
* :option:`--no-amp`
|
|
* :option:`--early-skip`
|
|
* :option:`--ref` = 1
|
|
* :option:`--max-merge` = 1
|
|
* :option:`--me` = DIA
|
|
* :option:`--subme` = MIN(2, :option:`--subme`)
|
|
* :option:`--rd` = MIN(2, :option:`--rd`)
|
|
|
|
.. option:: --strict-cbr, --no-strict-cbr
|
|
|
|
Enables stricter conditions to control bitrate deviance from the
|
|
target bitrate in ABR mode. Bit rate adherence is prioritised
|
|
over quality. Rate tolerance is reduced to 50%. Default disabled.
|
|
|
|
This option is for use-cases which require the final average bitrate
|
|
to be within very strict limits of the target; preventing overshoots,
|
|
while keeping the bit rate within 5% of the target setting,
|
|
especially in short segment encodes. Typically, the encoder stays
|
|
conservative, waiting until there is enough feedback in terms of
|
|
encoded frames to control QP. strict-cbr allows the encoder to be
|
|
more aggressive in hitting the target bitrate even for short segment
|
|
videos. Experimental.
|
|
|
|
.. option:: --cbqpoffs <integer>
|
|
|
|
Offset of Cb chroma QP from the luma QP selected by rate control.
|
|
This is a general way to spend more or less bits on the chroma
|
|
channel. Default 0
|
|
|
|
**Range of values:** -12 to 12
|
|
|
|
.. option:: --crqpoffs <integer>
|
|
|
|
Offset of Cr chroma QP from the luma QP selected by rate control.
|
|
This is a general way to spend more or less bits on the chroma
|
|
channel. Default 0
|
|
|
|
**Range of values:** -12 to 12
|
|
|
|
.. option:: --ipratio <float>
|
|
|
|
QP ratio factor between I and P slices. This ratio is used in all of
|
|
the rate control modes. Some :option:`--tune` options may change the
|
|
default value. It is not typically manually specified. Default 1.4
|
|
|
|
.. option:: --pbratio <float>
|
|
|
|
QP ratio factor between P and B slices. This ratio is used in all of
|
|
the rate control modes. Some :option:`--tune` options may change the
|
|
default value. It is not typically manually specified. Default 1.3
|
|
|
|
.. option:: --qcomp <float>
|
|
|
|
qComp sets the quantizer curve compression factor. It weights the
|
|
frame quantizer based on the complexity of residual (measured by
|
|
lookahead). Default value is 0.6. Increasing it to 1 will
|
|
effectively generate CQP
|
|
|
|
.. option:: --qpstep <integer>
|
|
|
|
The maximum single adjustment in QP allowed to rate control. Default
|
|
4
|
|
|
|
.. option:: --qblur <float>
|
|
|
|
Temporally blur quants. Default 0.5
|
|
|
|
.. option:: --cplxblur <float>
|
|
|
|
temporally blur complexity. default 20
|
|
|
|
.. option:: --zones <zone0>/<zone1>/...
|
|
|
|
Tweak the bitrate of regions of the video. Each zone takes the form:
|
|
|
|
<start frame>,<end frame>,<option> where <option> is either q=<integer>
|
|
(force QP) or b=<float> (bitrate multiplier).
|
|
|
|
If zones overlap, whichever comes later in the list takes precedence.
|
|
Default none
|
|
|
|
Quantization Options
|
|
====================
|
|
|
|
Note that rate-distortion optimized quantization (RDOQ) is enabled
|
|
implicitly at :option:`--rd` 4, 5, and 6 and disabled implicitly at all
|
|
other levels.
|
|
|
|
.. option:: --signhide, --no-signhide
|
|
|
|
Hide sign bit of one coeff per TU (rdo). The last sign is implied.
|
|
This requires analyzing all the coefficients to determine if a sign
|
|
must be toggled, and then to determine which one can be toggled with
|
|
the least amount of distortion. Default enabled
|
|
|
|
.. option:: --qpfile <filename>
|
|
|
|
Specify a text file which contains frametypes and QPs for some or
|
|
all frames. The format of each line is:
|
|
|
|
framenumber frametype QP
|
|
|
|
Frametype can be one of [I,i,P,B,b]. **B** is a referenced B frame,
|
|
**b** is an unreferenced B frame. **I** is a keyframe (random
|
|
access point) while **i** is a I frame that is not a keyframe
|
|
(references are not broken).
|
|
|
|
Specifying QP (integer) is optional, and if specified they are
|
|
clamped within the encoder to qpmin/qpmax.
|
|
|
|
.. option:: --scaling-list <filename>
|
|
|
|
Quantization scaling lists. HEVC supports 6 quantization scaling
|
|
lists to be defined; one each for Y, Cb, Cr for intra prediction and
|
|
one each for inter prediction.
|
|
|
|
x265 does not use scaling lists by default, but this can also be
|
|
made explicit by :option:`--scaling-list` *off*.
|
|
|
|
HEVC specifies a default set of scaling lists which may be enabled
|
|
without requiring them to be signaled in the SPS. Those scaling
|
|
lists can be enabled via :option:`--scaling-list` *default*.
|
|
|
|
All other strings indicate a filename containing custom scaling
|
|
lists in the HM format. The encode will abort if the file is not
|
|
parsed correctly. Custom lists must be signaled in the SPS
|
|
|
|
.. option:: --lambda-file <filename>
|
|
|
|
Specify a text file containing values for x265_lambda_tab and
|
|
x265_lambda2_tab. Each table requires MAX_MAX_QP+1 (70) float
|
|
values.
|
|
|
|
The text file syntax is simple. Comma is considered to be
|
|
white-space. All white-space is ignored. Lines must be less than 2k
|
|
bytes in length. Content following hash (#) characters are ignored.
|
|
The values read from the file are logged at :option:`--log-level`
|
|
debug.
|
|
|
|
Note that the lambda tables are process-global and so the new values
|
|
affect all encoders running in the same process.
|
|
|
|
Lambda values affect encoder mode decisions, the lower the lambda
|
|
the more bits it will try to spend on signaling information (motion
|
|
vectors and splits) and less on residual. This feature is intended
|
|
for experimentation.
|
|
|
|
Loop filters
|
|
============
|
|
|
|
.. option:: --deblock=<int>:<int>, --no-deblock
|
|
|
|
Toggle deblocking loop filter, optionally specify deblocking
|
|
strength offsets.
|
|
|
|
<int>:<int> - parsed as tC offset and Beta offset
|
|
<int>,<int> - parsed as tC offset and Beta offset
|
|
<int> - both tC and Beta offsets assigned the same value
|
|
|
|
If unspecified, the offsets default to 0. The offsets must be in a
|
|
range of -6 (lowest strength) to 6 (highest strength).
|
|
|
|
To disable the deblocking filter entirely, use --no-deblock or
|
|
--deblock=false. Default enabled, with both offsets defaulting to 0
|
|
|
|
If deblocking is disabled, or the offsets are non-zero, these
|
|
changes from the default configuration are signaled in the PPS.
|
|
|
|
.. option:: --sao, --no-sao
|
|
|
|
Toggle Sample Adaptive Offset loop filter, default enabled
|
|
|
|
.. option:: --sao-non-deblock, --no-sao-non-deblock
|
|
|
|
Specify how to handle depencency between SAO and deblocking filter.
|
|
When enabled, non-deblocked pixels are used for SAO analysis. When
|
|
disabled, SAO analysis skips the right/bottom boundary areas.
|
|
Default disabled
|
|
|
|
VUI (Video Usability Information) options
|
|
=========================================
|
|
|
|
x265 emits a VUI with only the timing info by default. If the SAR is
|
|
specified (or read from a Y4M header) it is also included. All other
|
|
VUI fields must be manually specified.
|
|
|
|
.. option:: --sar <integer|w:h>
|
|
|
|
Sample Aspect Ratio, the ratio of width to height of an individual
|
|
sample (pixel). The user may supply the width and height explicitly
|
|
or specify an integer from the predefined list of aspect ratios
|
|
defined in the HEVC specification. Default undefined (not signaled)
|
|
|
|
1. 1:1 (square)
|
|
2. 12:11
|
|
3. 10:11
|
|
4. 16:11
|
|
5. 40:33
|
|
6. 24:11
|
|
7. 20:11
|
|
8. 32:11
|
|
9. 80:33
|
|
10. 18:11
|
|
11. 15:11
|
|
12. 64:33
|
|
13. 160:99
|
|
14. 4:3
|
|
15. 3:2
|
|
16. 2:1
|
|
|
|
.. option:: --display-window <left,top,right,bottom>
|
|
|
|
Define the (overscan) region of the image that does not contain
|
|
information because it was added to achieve certain resolution or
|
|
aspect ratio (the areas are typically black bars). The decoder may
|
|
be directed to crop away this region before displaying the images
|
|
via the :option:`--overscan` option. Default undefined (not
|
|
signaled).
|
|
|
|
Note that this has nothing to do with padding added internally by
|
|
the encoder to ensure the pictures size is a multiple of the minimum
|
|
coding unit (4x4). That padding is signaled in a separate
|
|
"conformance window" and is not user-configurable.
|
|
|
|
.. option:: --overscan <show|crop>
|
|
|
|
Specify whether it is appropriate for the decoder to display or crop
|
|
the overscan area. Default unspecified (not signaled)
|
|
|
|
.. option:: --videoformat <integer|string>
|
|
|
|
Specify the source format of the original analog video prior to
|
|
digitizing and encoding. Default undefined (not signaled)
|
|
|
|
0. component
|
|
1. pal
|
|
2. ntsc
|
|
3. secam
|
|
4. mac
|
|
5. undefined
|
|
|
|
.. option:: --range <full|limited>
|
|
|
|
Specify output range of black level and range of luma and chroma
|
|
signals. Default undefined (not signaled)
|
|
|
|
.. option:: --colorprim <integer|string>
|
|
|
|
Specify color primitive to use when converting to RGB. Default
|
|
undefined (not signaled)
|
|
|
|
1. bt709
|
|
2. undef
|
|
3. **reserved**
|
|
4. bt470m
|
|
5. bt470bg
|
|
6. smpte170m
|
|
7. smpte240m
|
|
8. film
|
|
9. bt2020
|
|
|
|
.. option:: --transfer <integer|string>
|
|
|
|
Specify transfer characteristics. Default undefined (not signaled)
|
|
|
|
1. bt709
|
|
2. undef
|
|
3. **reserved**
|
|
4. bt470m
|
|
5. bt470bg
|
|
6. smpte170m
|
|
7. smpte240m
|
|
8. linear
|
|
9. log100
|
|
10. log316
|
|
11. iec61966-2-4
|
|
12. bt1361e
|
|
13. iec61966-2-1
|
|
14. bt2020-10
|
|
15. bt2020-12
|
|
16. smpte-st-2084
|
|
17. smpte-st-428
|
|
18. arib-std-b67
|
|
|
|
.. option:: --colormatrix <integer|string>
|
|
|
|
Specify color matrix setting i.e set the matrix coefficients used in
|
|
deriving the luma and chroma. Default undefined (not signaled)
|
|
|
|
0. GBR
|
|
1. bt709
|
|
2. undef
|
|
3. **reserved**
|
|
4. fcc
|
|
5. bt470bg
|
|
6. smpte170m
|
|
7. smpte240m
|
|
8. YCgCo
|
|
9. bt2020nc
|
|
10. bt2020c
|
|
|
|
.. option:: --chromaloc <0..5>
|
|
|
|
Specify chroma sample location for 4:2:0 inputs. Consult the HEVC
|
|
specification for a description of these values. Default undefined
|
|
(not signaled)
|
|
|
|
.. option:: --master-display <string>
|
|
|
|
SMPTE ST 2086 mastering display color volume SEI info, specified as
|
|
a string which is parsed when the stream header SEI are emitted. The
|
|
string format is "G(%hu,%hu)B(%hu,%hu)R(%hu,%hu)WP(%hu,%hu)L(%u,%u)"
|
|
where %hu are unsigned 16bit integers and %u are unsigned 32bit
|
|
integers. The SEI includes X,Y display primaries for RGB channels,
|
|
white point X,Y and max,min luminance values. (HDR)
|
|
|
|
Example for D65P3 1000-nits:
|
|
|
|
G(13200,34500)B(7500,3000)R(34000,16000)WP(15635,16450)L(10000000,1)
|
|
|
|
Note that this string value will need to be escaped or quoted to
|
|
protect against shell expansion on many platforms. No default.
|
|
|
|
.. option:: --max-cll <string>
|
|
|
|
Maximum content light level and maximum frame average light level as
|
|
required by the Consumer Electronics Association 861.3 specification.
|
|
|
|
Specified as a string which is parsed when the stream header SEI are
|
|
emitted. The string format is "%hu,%hu" where %hu are unsigned 16bit
|
|
integers. The first value is the max content light level (or 0 if no
|
|
maximum is indicated), the second value is the maximum picture
|
|
average light level (or 0). (HDR)
|
|
|
|
Note that this string value will need to be escaped or quoted to
|
|
protect against shell expansion on many platforms. No default.
|
|
|
|
.. option:: --min-luma <integer>
|
|
|
|
Minimum luma value allowed for input pictures. Any values below min-luma
|
|
are clipped. Experimental. No default.
|
|
|
|
.. option:: --max-luma <integer>
|
|
|
|
Maximum luma value allowed for input pictures. Any values above max-luma
|
|
are clipped. Experimental. No default.
|
|
|
|
Bitstream options
|
|
=================
|
|
|
|
.. option:: --annexb, --no-annexb
|
|
|
|
If enabled, x265 will produce Annex B bitstream format, which places
|
|
start codes before NAL. If disabled, x265 will produce file format,
|
|
which places length before NAL. x265 CLI will choose the right option
|
|
based on output format. Default enabled
|
|
|
|
**API ONLY**
|
|
|
|
.. option:: --repeat-headers, --no-repeat-headers
|
|
|
|
If enabled, x265 will emit VPS, SPS, and PPS headers with every
|
|
keyframe. This is intended for use when you do not have a container
|
|
to keep the stream headers for you and you want keyframes to be
|
|
random access points. Default disabled
|
|
|
|
.. option:: --aud, --no-aud
|
|
|
|
Emit an access unit delimiter NAL at the start of each slice access
|
|
unit. If :option:`--repeat-headers` is not enabled (indicating the
|
|
user will be writing headers manually at the start of the stream)
|
|
the very first AUD will be skipped since it cannot be placed at the
|
|
start of the access unit, where it belongs. Default disabled
|
|
|
|
.. option:: --hrd, --no-hrd
|
|
|
|
Enable the signalling of HRD parameters to the decoder. The HRD
|
|
parameters are carried by the Buffering Period SEI messages and
|
|
Picture Timing SEI messages providing timing information to the
|
|
decoder. Default disabled
|
|
|
|
.. option:: --info, --no-info
|
|
|
|
Emit an informational SEI with the stream headers which describes
|
|
the encoder version, build info, and encode parameters. This is very
|
|
helpful for debugging purposes but encoding version numbers and
|
|
build info could make your bitstreams diverge and interfere with
|
|
regression testing. Default enabled
|
|
|
|
.. option:: --hash <integer>
|
|
|
|
Emit decoded picture hash SEI, so the decoder may validate the
|
|
reconstructed pictures and detect data loss. Also useful as a
|
|
debug feature to validate the encoder state. Default None
|
|
|
|
1. MD5
|
|
2. CRC
|
|
3. Checksum
|
|
|
|
.. option:: --temporal-layers,--no-temporal-layers
|
|
|
|
Enable a temporal sub layer. All referenced I/P/B frames are in the
|
|
base layer and all unreferenced B frames are placed in a temporal
|
|
enhancement layer. A decoder may chose to drop the enhancement layer
|
|
and only decode and display the base layer slices.
|
|
|
|
If used with a fixed GOP (:option:`b-adapt` 0) and :option:`bframes`
|
|
3 then the two layers evenly split the frame rate, with a cadence of
|
|
PbBbP. You probably also want :option:`--no-scenecut` and a keyframe
|
|
interval that is a multiple of 4.
|
|
|
|
Debugging options
|
|
=================
|
|
|
|
.. option:: --recon, -r <filename>
|
|
|
|
Output file containing reconstructed images in display order. If the
|
|
file extension is ".y4m" the file will contain a YUV4MPEG2 stream
|
|
header and frame headers. Otherwise it will be a raw YUV file in the
|
|
encoder's internal bit depth.
|
|
|
|
**CLI ONLY**
|
|
|
|
.. option:: --recon-depth <integer>
|
|
|
|
Bit-depth of output file. This value defaults to the internal bit
|
|
depth and currently cannot to be modified.
|
|
|
|
**CLI ONLY**
|
|
|
|
.. option:: --recon-y4m-exec <string>
|
|
|
|
If you have an application which can play a Y4MPEG stream received
|
|
on stdin, the x265 CLI can feed it reconstructed pictures in display
|
|
order. The pictures will have no timing info, obviously, so the
|
|
picture timing will be determined primarily by encoding elapsed time
|
|
and latencies, but it can be useful to preview the pictures being
|
|
output by the encoder to validate input settings and rate control
|
|
parameters.
|
|
|
|
Example command for ffplay (assuming it is in your PATH):
|
|
|
|
--recon-y4m-exec "ffplay -i pipe:0 -autoexit"
|
|
|
|
**CLI ONLY**
|
|
|
|
.. vim: noet
|