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pulseaudio

libpulseaudio playback / ui synchronization

I have successfully setup pulse audio asynchronous playback stream using pa_stream_connect_playback() call.

Now I am facing a problem of synchronizing my UI with the playback. In my render loop I need to estimate current playing sample from the beginning of playback:

loop {
  let current_sample = ???

  // handle inputs and render UI synchronized to current_sample
}

I tried to use pa_stream_get_timing_info().read_index but it jumps in big increments.

What is the best strategy to have good synchronization?

Should I query pa_stream_get_timing_info on every frame and use current latency as a compensation for current clock read instead? This gets especially complicated in the presence of pa_stream_cork calls and occasional underflows.

Is there a more precise way?

Solution

  • I have discovered the pa_stream_get_time function. Its implementation has all the details I need.