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https://github.com/JorjBauer/aiie.git
synced 2024-08-14 19:29:00 +00:00
account for missing cycles auto-filled when speaker is quiescent
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@ -15,8 +15,6 @@ extern "C"
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#include "globals.h"
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#include "timeutil.h"
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#define SDLSIZE (4096)
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// But we want to keep more than just that, so we can fill it full every time
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#define CACHEMULTIPLIER 2
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@ -25,14 +23,10 @@ extern "C"
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static volatile uint32_t bufIdx = 0;
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static volatile uint8_t soundBuf[CACHEMULTIPLIER*SDLSIZE];
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static pthread_mutex_t togmutex = PTHREAD_MUTEX_INITIALIZER;
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static struct timespec sdlEmptyTime, sdlStartTime;
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extern struct timespec startTime; // defined in aiie (main)
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static volatile uint32_t skippedSamples = 0;
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volatile uint8_t audioRunning = 0;
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// How many cpu cycles do we lag "real time"? (Enough to give us a
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// solid audio buffer fill...)
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#define PLAYBACK_LAG ((SDLSIZE/44100)*1023000)
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// Debugging by writing a wav file with the sound output...
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//#define DEBUG_OUT_WAV
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@ -59,16 +53,10 @@ static void audioCallback(void *unused, Uint8 *stream, int len)
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audioRunning = 2;
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} else if (audioRunning==1) {
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// waiting for first fill; return an empty buffer.
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printf("pre\n");
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memset(stream, 0x80, len);
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return;
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}
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// calculate when the buffer will be empty again
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do_gettime(&sdlEmptyTime);
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timespec_add_us(&sdlEmptyTime, ((float)len * (float)1000000)/(float)44100, &sdlEmptyTime);
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sdlEmptyTime = tsSubtract(sdlEmptyTime, sdlStartTime);
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static uint8_t lastKnownSample = 0; // saved for when the apple is quiescent
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if (bufIdx >= len) {
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@ -84,12 +72,15 @@ static void audioCallback(void *unused, Uint8 *stream, int len)
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if (bufIdx) {
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// partial buffer exists
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memcpy(stream, (void *)soundBuf, bufIdx);
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// and it's a partial underrun
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// and it's a partial underrun. Track the number of samples we skipped
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// so we can keep the audio buffer in sync.
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skippedSamples += len-bufIdx;
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memset(&stream[bufIdx], lastKnownSample, len-bufIdx);
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bufIdx = 0;
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} else {
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// No big deal - buffer underrun might just mean nothing
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// is trying to play audio right now.
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skippedSamples += len;
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memset(stream, 0x80, len);
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// memset(stream, lastKnownSample, len);
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@ -131,8 +122,6 @@ SDLSpeaker::SDLSpeaker()
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pthread_mutex_init(&togmutex, NULL);
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_init_darwin_shim();
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lastCycleCount = 0;
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lastSampleCount = 0;
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}
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@ -143,10 +132,6 @@ SDLSpeaker::~SDLSpeaker()
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void SDLSpeaker::begin()
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{
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do_gettime(&sdlStartTime);
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do_gettime(&sdlEmptyTime);
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sdlEmptyTime = tsSubtract(sdlEmptyTime, sdlStartTime);
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SDL_AudioSpec audioDevice;
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SDL_AudioSpec audioActual;
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SDL_memset(&audioDevice, 0, sizeof(audioDevice));
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@ -176,9 +161,21 @@ void SDLSpeaker::toggle(uint32_t c)
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if (lastFilledTime == 0) {
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lastFilledTime = expectedCycleNumber;
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}
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uint32_t audioBufferSamples = expectedCycleNumber - lastFilledTime;
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uint32_t newIdx = bufIdx + audioBufferSamples;
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// This subtracts skippedSamples because those were filled automatically
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// by the audioCallback when we had no data.
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int32_t audioBufferSamples = expectedCycleNumber - lastFilledTime - skippedSamples;
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// If audioBufferSamples < 0, then we need to keep some
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// skippedSamples for later; otherwise we can keep moving forward.
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if (audioBufferSamples < 0) {
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skippedSamples = -audioBufferSamples;
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audioBufferSamples = 0;
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} else {
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// Otherwise we consumed them and can forget about it.
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skippedSamples = 0;
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}
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int32_t newIdx = bufIdx + audioBufferSamples;
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if (audioBufferSamples == 0) {
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// If the toggle wouldn't result in at least 1 buffer sample change,
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// then we'll blatantly skip it here. If this turns out to be
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@ -195,10 +192,8 @@ void SDLSpeaker::toggle(uint32_t c)
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return;
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}
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if (newIdx >= sizeof(soundBuf)) {
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printf("Buffer overrun: size %d idx %d\n", sizeof(soundBuf), newIdx);
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// printf("ERROR: buffer overrun, dropping data; need to increase buffer\n");
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printf("ERROR: buffer overrun: size %lu idx %d\n", sizeof(soundBuf), newIdx);
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newIdx = sizeof(soundBuf)-1;
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}
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lastFilledTime = expectedCycleNumber;
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