[pulseaudio-discuss] pulseaudio seems to resample without need

Tanu Kaskinen tanuk at iki.fi
Sat Apr 28 07:59:44 PDT 2012

On Sat, 2012-04-28 at 16:40 +0200, moebius wrote:
> Well, I'm french and when reading my last message again it seems 
> strangely not really friendly ; well it's absolutely not my purpose and 
> I want to thank you again for paying attention to my problem...

You're welcome :) The message doesn't feel unfriendly to me, it's sort
of neutral tone, so no worries about me getting offended :)

> Le 28/04/2012 16:14, moebius a écrit :
> > Bonjour,
> >
> > Well, I can obtain, with pulseaudio, what I need : I just have to set
> > emu card at 48000 but it's not a good thing because when using alsa
> > directly or jack, I need to reset at 44100 in alsamixer ; it would be
> > nice to just set once sample rate at 44100.
> >
> > I don't understand exactly what to ask at alsa developer because I don't
> > really want alsa doing what pulseaudio want ; it seems better that
> > pulseaudio detect the correct sample rate of the card and then open the
> > session at right sample rate, isn't it ?

When PulseAudio opens the device, PulseAudio tells Alsa that it's
opening the device with a specific sample rate. If the opening succeeds,
for example using 48000 Hz, but the hardware actually runs at 44100 Hz,
then that is sounds a lot like a bug in Alsa. PulseAudio shouldn't need
to care if the sound card happens to have some obscure mixer control for
switching the sound card internal sample rate. Telling the sample rate
when opening the device should be enough.

So, opening the device at 48000 Hz should result in 48000 Hz playback.
That's not happening, so that's one issue. There seems to be also
another issue: PulseAudio fails to open the device at 44100 Hz, while
other programs succeed in doing that. That might be a PulseAudio bug or
an Alsa bug - it's impossible to know without further investigation. You
can file a bug about it at [1] if you want. Maybe someone will fix it
someday, but at least I don't see it as a very high priority, because
it's just one hardware model and it's only an inconvenience for you, not
a showstopper.

[1] https://bugs.freedesktop.org/enter_bug.cgi?product=PulseAudio


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