[Live-devel] Audio skipping - Seems to be timing related

[Braden Ackerman]

Greetings,

Thank you Ross for your response mid-week.
I believe I've correctly implemented your suggestion, but I'm still
experiencing the same issue.

Recap: I'm trying to send mu-law audio over RTP. The audio comes from the
microphone on an ios device, via AudioQueue.

I'm following testWaveAudioStreamer.
I've subclassed FramedSource and pass the audio through
uLawFromPCMAudioSource after it's stored in a circular FIFO buffer (after
being returned from the ios AudioQueue callback after mic capture).

Issue: I get "skipping" ~ 0.5 sec audio, then ~ 0.5 sec silence.
The buffer is still under running (causing a sleep in deliverFrame() which
I believe should never be happening once I have this correctly implemented).

As per Ross' excellent suggestion I've set fDurationInMicroseconds like
this:

    int fNumChannels =1;

    int fBitsPerSample = 16;

    int fSamplingFrequency = 8000;

     unsigned fPlayTimePerSample = 1e6/(double)fSamplingFrequency;

      unsigned bytesPerSample = (fNumChannels*fBitsPerSample)/8;

    fDurationInMicroseconds =(unsigned)((fPlayTimePerSample*fFrameSize)/
bytesPerSample);

-----

The fDurationInMicroseconds works out to 500000 microseconds, which would
make sense as each buffer returned from the ios AudioQueue is about 0.5
seconds.

I'll paste some output from VLC. If anyone can point me in the right
direction to correct my error here I'd appreciate it immensely.

FYI, I'll be posting this code publicly once it's working for all to use.

Thanks so much for your time, and the hard work on an excellent library.

Best regards,

Braden Ackerman

VLC complains like this:

main warning: timing screwed, stopping resampling

main warning: buffer too late (179500), up-sampling

main warning: buffer way too late (358875), dropping buffer

main warning: buffer way too late (230875), dropping buffer

main warning: buffer way too late (356000), dropping buffer

main warning: buffer way too late (228000), dropping buffer

main warning: buffer way too late (356000), dropping buffer

main warning: buffer way too late (228000), dropping buffer

main warning: buffer way too late (356000), dropping buffer

main warning: buffer way too late (347500), dropping buffer

main warning: buffer way too late (219500), dropping buffer

main warning: buffer way too late (347500), dropping buffer

main warning: buffer way too late (219500), dropping buffer

main warning: buffer way too late (347500), dropping buffer

main warning: buffer way too late (219500), dropping buffer

main debug: audio output is starving (-720558), playing silence

main warning: buffer way too late (322098), dropping buffer

main warning: buffer way too late (194098), dropping buffer

main warning: buffer way too late (322098), dropping buffer

main warning: buffer way too late (194098), dropping buffer

main warning: buffer way too early (-177606), clearing queue

main warning: timing screwed, stopping resampling

main warning: buffer too early (-51609), down-sampling

main warning: timing screwed, stopping resampling

main warning: buffer too late (128016), up-sampling

main warning: buffer way too early (-231484), clearing queue

main warning: timing screwed, stopping resampling

main warning: buffer way too late (245727), dropping buffer

main warning: buffer too late (117727), up-sampling

main warning: buffer way too late (297227), dropping buffer

main warning: buffer way too early (-126440), clearing queue

main warning: timing screwed, stopping resampling

main warning: buffer way too late (195604), dropping buffer

main warning: buffer too late (67604), up-sampling

main warning: audio output out of sync, adjusting dates (-44447 us)

main warning: computed PTS is out of range (36360), clearing out

main warning: timing screwed, stopping resampling

main warning: not synchronized (-44445 us), resampling

main warning: buffer too early (-44445), down-sampling

main debug: audio output is starving (-971888), playing silence

rtp warning: 1 packet(s) lost

main debug: End of audio preroll

rtp warning: 1 packet(s) lost

main debug: End of audio preroll

main warning: resampling stopped after 1060698 usec (drift: 0)

main warning: buffer too late (179500), up-sampling

rtp warning: 1 packet(s) lost

rtp warning: 1 packet(s) lost

main debug: End of audio preroll

main warning: resampling stopped after 894671 usec (drift: -179375)

rtp warning: 1 packet(s) lost

main debug: End of audio preroll

main warning: buffer too late (179500), up-sampling

main warning: buffer way too early (-370330), clearing queue

main warning: timing screwed, stopping resampling
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