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Audio Docs: Adsr Decay Rate (#1238)

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* Init adsr decay docs

* cleanup

* cleanup

* Revert some docs

* Cleaner docs

* count hex to dec

* scaled updates per frame

* Consistency

* Oops, fix meaning

* Avoid `decayRate` conflict with reverb `decayRate`

* PR suggestion
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engineer124 2022-05-30 04:31:43 +10:00 • committed by GitHub
parent d39ce02458
commit 8f1fd58f22
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GPG key ID: 4AEE18F83AFDEB23
5 changed files with 59 additions and 47 deletions
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43
src/code/audio_heap.c
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@ -10,32 +10,40 @@ void AudioHeap_DiscardSampleCaches(void);
void AudioHeap_DiscardSampleBank(s32 sampleBankId);
void AudioHeap_DiscardSampleBanks(void);
f32 func_800DDE20(f32 arg0) {
return 256.0f * gAudioContext.audioBufferParameters.unkUpdatesPerFrameScaled / arg0;
/**
* Effectively scales `updatesPerFrameInv` by the reciprocal of `scaleInv`
* `updatesPerFrameInvScaled` is just `updatesPerFrameInv` scaled down by a factor of 256.0f
* i.e. (256.0f * `updatesPerFrameInvScaled`) is just `updatesPerFrameInv`
*/
f32 AudioHeap_CalculateAdsrDecay(f32 scaleInv) {
return (256.0f * gAudioContext.audioBufferParameters.updatesPerFrameInvScaled) / scaleInv;
}
void func_800DDE3C(void) {
/**
* Initialize the decay rate table used for decaying notes as part of adsr
*/
void AudioHeap_InitAdsrDecayTable(void) {
s32 i;
gAudioContext.unk_3520[255] = func_800DDE20(0.25f);
gAudioContext.unk_3520[254] = func_800DDE20(0.33f);
gAudioContext.unk_3520[253] = func_800DDE20(0.5f);
gAudioContext.unk_3520[252] = func_800DDE20(0.66f);
gAudioContext.unk_3520[251] = func_800DDE20(0.75f);
gAudioContext.adsrDecayTable[255] = AudioHeap_CalculateAdsrDecay(0.25f);
gAudioContext.adsrDecayTable[254] = AudioHeap_CalculateAdsrDecay(0.33f);
gAudioContext.adsrDecayTable[253] = AudioHeap_CalculateAdsrDecay(0.5f);
gAudioContext.adsrDecayTable[252] = AudioHeap_CalculateAdsrDecay(0.66f);
gAudioContext.adsrDecayTable[251] = AudioHeap_CalculateAdsrDecay(0.75f);
for (i = 128; i < 251; i++) {
gAudioContext.unk_3520[i] = func_800DDE20(251 - i);
gAudioContext.adsrDecayTable[i] = AudioHeap_CalculateAdsrDecay(251 - i);
}
for (i = 16; i < 128; i++) {
gAudioContext.unk_3520[i] = func_800DDE20(4 * (143 - i));
gAudioContext.adsrDecayTable[i] = AudioHeap_CalculateAdsrDecay(4 * (143 - i));
}
for (i = 1; i < 16; i++) {
gAudioContext.unk_3520[i] = func_800DDE20(60 * (23 - i));
gAudioContext.adsrDecayTable[i] = AudioHeap_CalculateAdsrDecay(60 * (23 - i));
}
gAudioContext.unk_3520[0] = 0.0f;
gAudioContext.adsrDecayTable[0] = 0.0f;
}
void AudioHeap_ResetLoadStatus(void) {
@ -826,9 +834,10 @@ void AudioHeap_Init(void) {
gAudioContext.audioBufferParameters.samplesPerUpdateMax = gAudioContext.audioBufferParameters.samplesPerUpdate + 8;
gAudioContext.audioBufferParameters.samplesPerUpdateMin = gAudioContext.audioBufferParameters.samplesPerUpdate - 8;
gAudioContext.audioBufferParameters.resampleRate = 32000.0f / (s32)gAudioContext.audioBufferParameters.frequency;
gAudioContext.audioBufferParameters.unkUpdatesPerFrameScaled =
gAudioContext.audioBufferParameters.updatesPerFrameInvScaled =
(1.0f / 256.0f) / gAudioContext.audioBufferParameters.updatesPerFrame;
gAudioContext.audioBufferParameters.unk_24 = gAudioContext.audioBufferParameters.updatesPerFrame * 0.25f;
gAudioContext.audioBufferParameters.updatesPerFrameScaled =
gAudioContext.audioBufferParameters.updatesPerFrame / 4.0f;
gAudioContext.audioBufferParameters.updatesPerFrameInv = 1.0f / gAudioContext.audioBufferParameters.updatesPerFrame;
gAudioContext.sampleDmaBufSize1 = spec->sampleDmaBufSize1;
gAudioContext.sampleDmaBufSize2 = spec->sampleDmaBufSize2;
@ -898,8 +907,10 @@ void AudioHeap_Init(void) {
gAudioContext.maxAudioCmds * sizeof(u64));
}
gAudioContext.unk_3520 = AudioHeap_Alloc(&gAudioContext.notesAndBuffersPool, 0x100 * sizeof(f32));
func_800DDE3C();
// Initialize the decay rate table for adsr
gAudioContext.adsrDecayTable = AudioHeap_Alloc(&gAudioContext.notesAndBuffersPool, 256 * sizeof(f32));
AudioHeap_InitAdsrDecayTable();
for (i = 0; i < 4; i++) {
gAudioContext.synthesisReverbs[i].useReverb = 0;
}