[pulseaudio-discuss] pulseaudio seems to resample without need

moebius moebius1 at free.fr
Sat Apr 28 07:14:18 PDT 2012


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 ?

I can't study what makes the difference because I'm not a programer.


Le 28/04/2012 14:28, Tanu Kaskinen a écrit :
> 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.

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