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Function for calculating audio rate for target FPS

This commit is contained in:
Jeffrey Pfau 2014-07-20 23:24:02 -07:00
parent c9f74b43af
commit b14f22191c
3 changed files with 8 additions and 2 deletions
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5
src/gba/gba-audio.c
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@ -4,6 +4,7 @@
#include "gba-io.h" #include "gba-io.h"
#include "gba-serialize.h" #include "gba-serialize.h"
#include "gba-thread.h" #include "gba-thread.h"
#include "gba-video.h"
const unsigned GBA_AUDIO_SAMPLES = 512; const unsigned GBA_AUDIO_SAMPLES = 512;
const unsigned GBA_AUDIO_FIFO_SIZE = 8 * sizeof(int32_t); const unsigned GBA_AUDIO_FIFO_SIZE = 8 * sizeof(int32_t);
@ -751,3 +752,7 @@ void GBAAudioDeserialize(struct GBAAudio* audio, const struct GBASerializedState
audio->eventDiff = state->audio.eventDiff; audio->eventDiff = state->audio.eventDiff;
audio->nextSample = state->audio.nextSample; audio->nextSample = state->audio.nextSample;
} }
float GBAAudioCalculateRatio(struct GBAAudio* audio, float desiredFPS, float desiredSampleRate) {
return desiredSampleRate * GBA_ARM7TDMI_FREQUENCY / (VIDEO_TOTAL_LENGTH * desiredFPS * audio->sampleRate);
}

2
src/gba/gba-audio.h
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@ -251,4 +251,6 @@ struct GBASerializedState;
void GBAAudioSerialize(const struct GBAAudio* audio, struct GBASerializedState* state); void GBAAudioSerialize(const struct GBAAudio* audio, struct GBASerializedState* state);
void GBAAudioDeserialize(struct GBAAudio* audio, const struct GBASerializedState* state); void GBAAudioDeserialize(struct GBAAudio* audio, const struct GBASerializedState* state);
float GBAAudioCalculateRatio(struct GBAAudio* audio, float desiredFPS, float desiredSampleRatio);
#endif #endif

3
src/platform/sdl/sdl-audio.c
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@ -43,8 +43,7 @@ static void _GBASDLAudioCallback(void* context, Uint8* data, int len) {
memset(data, 0, len); memset(data, 0, len);
return; return;
} }
float ratio = 280896.0f * FPS_TARGET / GBA_ARM7TDMI_FREQUENCY; audioContext->ratio = GBAAudioCalculateRatio(audioContext->audio, FPS_TARGET, audioContext->obtainedSpec.freq);
audioContext->ratio = audioContext->obtainedSpec.freq / ratio / (float) audioContext->audio->sampleRate;
struct GBAStereoSample* ssamples = (struct GBAStereoSample*) data; struct GBAStereoSample* ssamples = (struct GBAStereoSample*) data;
len /= 2 * audioContext->obtainedSpec.channels; len /= 2 * audioContext->obtainedSpec.channels;
if (audioContext->obtainedSpec.channels == 2) { if (audioContext->obtainedSpec.channels == 2) {