inline void VCR::onAudioCB(AudioIOData& io) {
// cached, because it may be being used in a different thread
sampletime r = mAudioReadIndex;
sampletime w = mAudioWriteIndex;
unsigned channels = io.channelsOut();
if (channels > mAudioChans) channels = mAudioChans;
unsigned numAudioFrames = io.framesPerBuffer();
unsigned numSamples = numAudioFrames * channels;
unsigned length = mAudioRing.size();
sampletime ahead = w - r; // how much writer is ahead of reader
if (ahead > (length - numSamples)) {
// not enough space left in ringbuffer!
fprintf(stderr, "audio underflow\n");
mAudioUnderflows++;
return;
}
sampletime wnext = w + numSamples;
unsigned wu = (unsigned)(w % length);
//printf("writing %u samples to %llu\n", numSamples, wnext);
for (unsigned c=0; c < channels; c++) {
float * src = io.outBuffer(c);
float * dst = &mAudioRing[0];
unsigned wc = wu + c;
unsigned srcIdx = 0;
while (srcIdx < numAudioFrames) {
dst[wc] = src[srcIdx];
srcIdx++;
wc += mAudioChans;
if (wc >= length) wc -= length;
}
}
// update write head position
mAudioWriteIndex = wnext;
}
