void COSSAudioSource::ProcessAudio(void)
{
#ifdef SNDCTL_DSP_GETERROR
audio_errinfo errinfo;
if (m_audioSrcFrameNumber == 0) {
ioctl(m_audioDevice, SNDCTL_DSP_GETERROR, &errinfo);
} else {
ioctl(m_audioDevice, SNDCTL_DSP_GETERROR, &errinfo);
if (errinfo.rec_overruns > 0) {
debug_message("overrun error found in audio - adding "U64" samples",
SrcBytesToSamples(errinfo.rec_ptradjust));
close(m_audioDevice);
InitDevice();
m_audioSrcSampleNumber = 0;
}
}
#endif
if (m_audioSrcFrameNumber == 0) {
// Pull the trigger and start the audio input
int enablebits;
ioctl(m_audioDevice, SNDCTL_DSP_GETTRIGGER, &enablebits);
enablebits |= PCM_ENABLE_INPUT;
ioctl(m_audioDevice, SNDCTL_DSP_SETTRIGGER, &enablebits);
}
// for efficiency, process 1 second before returning to check for commands
for (int pass = 0; pass < m_maxPasses; pass++) {
audio_buf_info info;
int rc = ioctl(m_audioDevice, SNDCTL_DSP_GETISPACE, &info);
Timestamp currentTime = GetTimestamp();
if (rc<0) {
error_message("Failed to query OSS GETISPACE");
info.bytes = 0;
}
uint32_t bytesRead = read(m_audioDevice, m_pcmFrameBuffer, m_pcmFrameSize);
if (bytesRead < m_pcmFrameSize) {
debug_message("bad audio read");
continue;
}
Timestamp timestamp;
if (info.bytes == m_audioOssMaxBufferSize) {
// means the audio buffer is full, and not capturing
// we want to make the timestamp based on the previous one
// When we hit this case, we start using the m_timestampOverflowArray
// This will give us a timestamp for when the array is full.
//
// In other words, if we have a full audio buffer (ie: it's not loading
// any more), we start storing the current timestamp into the array.
// This will let us "catch up", and have a somewhat accurate timestamp
// when we loop around
//
// wmay - I'm not convinced that this actually works - if the buffer
// cleans up, we'll ignore m_timestampOverflowArray
if (m_timestampOverflowArray != NULL &&
m_timestampOverflowArray[m_timestampOverflowArrayIndex] != 0) {
timestamp = m_timestampOverflowArray[m_timestampOverflowArrayIndex];
} else {
timestamp = m_prevTimestamp + SrcSamplesToTicks(m_audioSrcSamplesPerFrame);
}
if (m_timestampOverflowArray != NULL)
m_timestampOverflowArray[m_timestampOverflowArrayIndex] = currentTime;
debug_message("audio buffer full !");
} else {
// buffer is not full - so, we make the timestamp based on the number
// of bytes in the buffer that we read.
timestamp = currentTime - SrcSamplesToTicks(SrcBytesToSamples(info.bytes));
if (m_timestampOverflowArray != NULL)
m_timestampOverflowArray[m_timestampOverflowArrayIndex] = 0;
}
#ifdef DEBUG_TIMESTAMPS
debug_message("info.bytes=%d t="U64" timestamp="U64" delta="U64,
info.bytes, currentTime, timestamp, timestamp - m_prevTimestamp);
#endif
m_prevTimestamp = timestamp;
if (m_timestampOverflowArray != NULL) {
m_timestampOverflowArrayIndex = (m_timestampOverflowArrayIndex + 1) %
m_audioOssMaxBufferFrames;
}
ProcessAudioFrame(m_pcmFrameBuffer, m_pcmFrameSize, timestamp);
}
}
void CALSAAudioSource::ProcessAudio(void)
{
int err;
if (m_audioSrcFrameNumber == 0) {
// Start the device
if ((err = snd_pcm_start(m_pcmHandle)) < 0) {
error_message("Couldn't start the PCM device: %s", snd_strerror(err));
}
}
snd_pcm_status_t *status;
snd_pcm_status_alloca(&status);
// for efficiency, process 1 second before returning to check for commands
for (int pass = 0; pass < m_maxPasses && m_stop_thread == false; pass++) {
u_int8_t* pcmFrameBuffer;
pcmFrameBuffer = (u_int8_t*)malloc(m_pcmFrameSize);
// The alsa frames is not the same as the pcm frames used to feed the encoder
// Calculate how many alsa frames is neccesary to read to fill one pcm frame
snd_pcm_uframes_t num_frames = m_pcmFrameSize / (m_audioSrcChannels * sizeof(u_int16_t));
// Check how many bytes there is to read in the buffer, it will be used to calculate timestamp
snd_pcm_status(m_pcmHandle, status);
unsigned long avail_bytes = snd_pcm_status_get_avail(status) * (m_audioSrcChannels * sizeof(u_int16_t));
Timestamp currentTime = GetTimestamp();
Timestamp timestamp;
// Read num_frames frames from the PCM device
// pointed to by pcm_handle to buffer capdata.
// Returns the number of frames actually read.
// TODO On certain alsa configurations, e.g. when using dsnoop with low sample rate, the period gets too small. What to do about that?
snd_pcm_sframes_t framesRead;
if((framesRead = snd_pcm_readi(m_pcmHandle, pcmFrameBuffer, num_frames)) == -EPIPE) {
snd_pcm_prepare(m_pcmHandle);
// Buffer Overrun. This means the audio buffer is full, and not capturing
// we want to make the timestamp based on the previous one
// When we hit this case, we start using the m_timestampOverflowArray
// This will give us a timestamp for when the array is full.
//
// In other words, if we have a full audio buffer (ie: it's not loading
// any more), we start storing the current timestamp into the array.
// This will let us "catch up", and have a somewhat accurate timestamp
// when we loop around
//
// wmay - I'm not convinced that this actually works - if the buffer
// cleans up, we'll ignore m_timestampOverflowArray
if (m_timestampOverflowArray != NULL && m_timestampOverflowArray[m_timestampOverflowArrayIndex] != 0) {
timestamp = m_timestampOverflowArray[m_timestampOverflowArrayIndex];
} else {
timestamp = m_prevTimestamp + SrcSamplesToTicks(avail_bytes);
}
if (m_timestampOverflowArray != NULL)
m_timestampOverflowArray[m_timestampOverflowArrayIndex] = currentTime;
debug_message("audio buffer full !");
} else {
if (framesRead < (snd_pcm_sframes_t) num_frames) {
error_message("Bad audio read. Expected %li frames, got %li", num_frames, framesRead);
free(pcmFrameBuffer);
continue;
}
// buffer is not full - so, we make the timestamp based on the number
// of bytes in the buffer that we read.
timestamp = currentTime - SrcSamplesToTicks(SrcBytesToSamples(avail_bytes));
if (m_timestampOverflowArray != NULL)
m_timestampOverflowArray[m_timestampOverflowArrayIndex] = 0;
}
//debug_message("alsa read");
#ifdef DEBUG_TIMESTAMPS
debug_message("avail_bytes=%lu t="U64" timestamp="U64" delta="U64,
avail_bytes, currentTime, timestamp, timestamp - m_prevTimestamp);
#endif
m_prevTimestamp = timestamp;
if (m_timestampOverflowArray != NULL) {
m_timestampOverflowArrayIndex = (m_timestampOverflowArrayIndex + 1) % m_audioMaxBufferFrames;
}
#ifdef DEBUG_TIMESTAMPS
debug_message("pcm forward "U64" %u", timestamp, m_pcmFrameSize);
#endif
if (m_audioSrcFrameNumber == 0 && m_videoSource != NULL) {
m_videoSource->RequestKeyFrame(timestamp);
}
m_audioSrcFrameNumber++;
CMediaFrame *frame = new CMediaFrame(PCMAUDIOFRAME,
pcmFrameBuffer,
m_pcmFrameSize,
timestamp);
ForwardFrame(frame);
}
}
