[pulseaudio-discuss] [RFC] Dynamic reconfiguration of sampling rate

Colin Guthrie gmane at colin.guthr.ie
Wed Jan 19 03:57:02 PST 2011

'Twas brillig, and pl bossart at 18/01/11 22:53 did gyre and gimble:
>>> In my normal usage, there is a potential (solvable) problem with this
>>> approach, though. I use Rhythmbox and most of my songs are at 44100 Hz,
>>> but there are some at 48000 Hz. If I start playing one of the 48000 Hz
>>> songs, all subsequent streams will be upsampled to 48000 Hz till I pause
>>> for >5 seconds.
>>> As you suggest, this will become less of a problem if we decrease the
>>> idle time required before suspend, and IMO this enough to make this a
>>> non-blocker.
>> I wonder what happens if we set the timeout to zero for ALSA devices?
> Arun, I just tried with load-module module-suspend-on-idle timeout=0,
> and it seems to work fine on the HDAudio output. I was able to switch
> back and forth between 44.1 and 48kHz tracks without audible issues. I
> am not sure what happens with Rhythmbox if you enabled the cross-fade
> between tracks, most likely you would remain at the rate defined by
> the first song.

I think the general idea was to stop the pops and clicks that would be
apparent on some devices (maybe some HDA?) when the device is opened and
closed (and also to be slightly more responsive but that's probably a
trivial advantage on any machine made this millennium!).

So I'm not sure we can idle at 0s as a general rule, but as I have very
limited test hardware (namely my laptop and couple other machine which
aren't really meant for testing!), I can't really say this with any
degree of confidence.



Colin Guthrie

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