[pulseaudio-discuss] useless timer ?

pl bossart bossart.nospam at gmail.com
Thu Jun 10 15:42:03 PDT 2010


In my never ending crusade against wakeups, I found out that when a
stream is opened with the PA_STREAM_AUTO_TIMING_UPDATE flag, a timer
is configured in steady state to fire every 1.5 seconds, then the
timing information is updated.
stream.c: #define AUTO_TIMING_INTERVAL_END_USEC (1500*PA_USEC_PER_MSEC)

However the documentation says that the timing information is updated
when a write is performed. With the current settings, PulseAudio
buffers up to 2 seconds, and half of this will be in the ALSA ring
buffer. Conclusion: the client will write new data more often than
this 1.5 s timer, and update the timing information. Plus when time
interpolation is used, there's really no reason to update the
information every 1.5s, every 10s would do.

So am I missing something or is this a useless wakeup? And even if it
served a purpose, why was 1.5s selected?
Thanks
- Pierre



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