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Account for floating point error in resampling

This commit is contained in:
Jeffrey Pfau 2014-01-16 02:12:35 -08:00
parent 4e88cc86d9
commit 94cc48faf1
1 changed files with 13 additions and 9 deletions
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22
src/platform/sdl/sdl-audio.c
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@ -46,9 +46,10 @@ static void _pulldownResample(struct GBASDLAudio* context, struct StereoSample*
int32_t right[BUFFER_SIZE]; int32_t right[BUFFER_SIZE];
// toRead is in GBA samples // toRead is in GBA samples
// TODO: Do this with fixed-point math
int toRead = samples / context->ratio; int toRead = samples / context->ratio;
while (samples > 0) { while (samples > 0) {
int currentRead = BUFFER_SIZE >> 2; int currentRead = BUFFER_SIZE >> 1;
if (currentRead > toRead) { if (currentRead > toRead) {
currentRead = toRead; currentRead = toRead;
} }
@ -57,22 +58,25 @@ static void _pulldownResample(struct GBASDLAudio* context, struct StereoSample*
unsigned i; unsigned i;
for (i = 0; i < read; ++i) { for (i = 0; i < read; ++i) {
context->drift += context->ratio; context->drift += context->ratio;
while (context->drift >= 0) { while (context->drift >= 1.f) {
output->left = left[i]; output->left = left[i];
output->right = right[i]; output->right = right[i];
++output; ++output;
--samples; --samples;
#ifndef NDEBUG
if (samples < 0) {
abort();
}
#endif
context->drift -= 1.f; context->drift -= 1.f;
if (samples < 0) {
return;
}
} }
} }
if (read < BUFFER_SIZE >> 2) { if (read < BUFFER_SIZE >> 2) {
memset(output, 0, toRead); if (samples > 1) {
return; memset(output, 0, samples * sizeof(struct StereoSample));
return;
} else {
// Account for lost sample due to floating point conversion
toRead = 1;
}
} }
} }
} }