[pulseaudio-discuss] pulseaudio seems to resample without need

[Tanu Kaskinen]

On Sat, 2012-04-28 at 13:10 +0200, moebius wrote:
> Bonjour,
> I've tried to post in the list but my message doesn't appear ; perhaps 
> there's a problem with the attached fille....so I post directly to you, 
> sorry for  the inconvenient

Yes, the largish attachment may have caused your message to go to the
moderation queue.

> Bonjour,
> 
> Thank for your answer.
> 
> In fact, after changing samplerate in alsamixer and test immediat 
> result, I've reseted pulseaudio and test for changes again  with no success.
> Now, after your mail and before testing, I've copied daemon.conf in 
> ~./pulse/ and decomment and modify the sample rate line :
> 
> ; default-sample-format = s16le
> default-sample-rate = 44100
> ; default-sample-channels = 2
> 
> here are my soundcards ;the ensonic one is just here for driving midi 
> devices ; for audio, I use the EMU one :
> 
> cat /proc/asound/cards
>     0 [AudioPCI       ]: ENS1371 - Ensoniq AudioPCI
>                          Ensoniq AudioPCI ENS1371 at 0xd880, irq 16
>     1 [EMU0404        ]: Audigy2 - E-mu 0404b PCI [MAEM8852]
>                          E-mu 0404b PCI [MAEM8852] (rev.0, 
> serial:0x40021102) at 0xdc00, irq 19
> 
> NB : the motherboard soundcard is disabled.
> 
> I join the pulse log
> It contains this strange line :
> 
> (   0.064|   0.000) I: [pulseaudio] alsa-util.c: Device surround41:1 
> doesn't support 44100 Hz, changed to 48000 Hz.

This explains why you have to set the internal rate to 48000 when using
PulseAudio. If Jack and aplay can open the device in the 44100 mode, I
don't know why PulseAudio fails to do that. Presumably the device
opening sequence is done a bit differently in PulseAudio than e.g. in
aplay (I think the setup function calls can be called with different
order, and some Alsa drivers behave differently depending on the order).
So if you have the motivation, you could study what makes the
difference.

You could also ask on the alsa-devel mailing list if the driver
maintainer could improve the driver so that it would set the internal
rate automatically correctly when the device is opened. So if PulseAudio
opens the device in the 48000 mode, then the driver should set the
internal rate automatically to 48000 Hz.

-- 
Tanu