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audio: change output rate to 47340Hz, add resampler with small margin to elimiate pops/clicks due to output rate fluctuation

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output rate is picked such that 1024 samples at that rate equal exactly 710 samples at the SPU's output rate
This commit is contained in:
StapleButter
2017-12-11 18:41:05 +01:00
parent c639152541
commit 73bf4471ee
3 changed files with 51 additions and 11 deletions
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49
src/libui_sdl/main.cpp
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@ -96,7 +96,46 @@ void UpdateWindowTitle(void* data)
void AudioCallback(void* data, Uint8* stream, int len)
{
SPU::ReadOutput((s16*)stream, len>>2);
// resampling:
// buffer length is 1024 samples
// which is 710 samples at the original sample rate
//SPU::ReadOutput((s16*)stream, len>>2);
s16 buf_in[710*2];
s16* buf_out = (s16*)stream;
int num_in = SPU::ReadOutput(buf_in, 710);
int num_out = 1024;
int margin = 6;
if (num_in < 710-margin)
{
int last = num_in-1;
if (last < 0) last = 0;
for (int i = num_in; i < 710-margin; i++)
((u32*)buf_in)[i] = ((u32*)buf_in)[last];
num_in = 710-margin;
}
float res_incr = num_in / (float)num_out;
float res_timer = 0;
int res_pos = 0;
for (int i = 0; i < 1024; i++)
{
// TODO: interp!!
buf_out[i*2 ] = buf_in[res_pos*2 ];
buf_out[i*2+1] = buf_in[res_pos*2+1];
res_timer += res_incr;
while (res_timer >= 1.0)
{
res_timer -= 1.0;
res_pos++;
}
}
}
int EmuThreadFunc(void* burp)
@ -111,15 +150,9 @@ int EmuThreadFunc(void* burp)
ScreenDrawInited = false;
Touching = false;
// DS:
// 547.060546875 samples per frame
// 32823.6328125 samples per second
//
// 48000 samples per second:
// 800 samples per frame
SDL_AudioSpec whatIwant, whatIget;
memset(&whatIwant, 0, sizeof(SDL_AudioSpec));
whatIwant.freq = 32824; // 32823.6328125
whatIwant.freq = 47340;
whatIwant.format = AUDIO_S16LSB;
whatIwant.channels = 2;
whatIwant.samples = 1024;