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59 lines
2.5 KiB
Text
59 lines
2.5 KiB
Text
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SPS allows you to program signal processing using simple expressions.
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Many aspects of SPS code are similar to C (including comments).
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You can create new variables just by using them, and you can read
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and write predefined variables (of which each effect has its own)
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to interact with the effect. Note that variables are all floating
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point numbers (no strings), and the maximum length of a variable's
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name is 8 characters (anything longer will be ignored).
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So, to create a variable, you can simply use it, for example:
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x = 5;
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You can also use a variety of operators and math functions to
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modify variables, see the Operators and Functions tabs above.
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Code can include C and C++ style comments:
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// using the doubleslash comments until the end of the line
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/* using the classic C comments
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comment a block of text */
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You can combine operators and functions into expressions, such
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as:
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x = 5 * cos(y) / 32.0; // this does some leetness right here
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You can use multiple expressions by seperating them with one or
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more semicolons, for example:
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x = x * 17.0; x = x / 5; y = pow(x,3.0);
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It is worth noting that extra whitespace (spaces, newlines) is
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ignored, so if you need to space things out for clarity, you can.
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Variables that are predefined for your effect to use:
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nch: number of channels of PCM stream (1 or 2)
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srate: samplerate of stream (i.e. 44100)
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slider1, slider2, slider3, slider4: the four sliders. Each has a range of 0.0..1.0
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trig1, trig2, trig3, trig4: the four trigger buttons. These should be reset to 0.0
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by your code when you've caught the trigger
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Variables that your per-sample code can modify to apply its effect:
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spl0 = left/mono channel sample, -1.0..1.0
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spl1 = right channel sample, if nch == 2, -1.0..1.0
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skip = set this to > 0 to drop the current sample and not output it
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(this effectively can be used to speed up the output
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repeat = set this to > 0 to process this sample again after
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outputting (this effectively can be used to slow down
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the output. Note that the most you can slow down the
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output due to Winamp architecture limitations is by 50%)
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Now to the important part, how to actually make meaningful effects:
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A simple volume control might be:
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spl0 = spl0*slider1; spl1=spl1*slider1;
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To slow down the output to half speed:
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tmp=bnot(tmp); repeat=tmp;
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To speed up the output to double speed:
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tmp=bnot(tmp); skip=tmp;
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To swap left and right channels:
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tmp=spl0; spl0=spl1; spl1=tmp;
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etc
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