[pulseaudio-discuss] pulseaudio (V5) incorrect rate detection on usb sound card with raspberry

[Alexander E. Patrakov]

29.10.2014 15:37, Alexander E. Patrakov wrote:
> 29.10.2014 15:14, mailing lists пишет:
>>
>> Alexander, thank you very much for the detailed explanation.
>>
>>> The theory is very simple. It probes at startup whether the configured
>>> sample rate and the alternate sample rate (both can be seen in
>>> /etc/pulse/daemon.conf) are supported. If none is supported, PulseAudio
>>> picks a somewhat-random rate that is supported by the card. The result
>>> of this step is either one or two rates that are known to be supported.
>>
>> but (I suppose) that the default|alternative rates declared in
>> etc/pulse/daemon.conf are contrasted with the rates detected from alsa
>> devices and the common ones considered for use. When I played with
>> this two variables on the laptop, the frecuencies were rounded to the
>> nearest frecuency supported by the usb sound card, this did not happen
>> when I changed the values on the raspberry, and we talk of the same
>> sound card. It doesn't matter what I put is was always "Device front:1
>> doesn't support 44100 Hz, changed to 48000 Hz". it sounds like PA did
>> a fallback to a "safe" sample rate.
>>
>> Here is the verbose (-vvv) output:
>>
>> http://pastebin.com/wfgxATEq
>
> I have looked. Your log contains this line:
>
> I: [pulseaudio] alsa-util.c: Device front:0 doesn't support 44100 Hz,
> changed to 48000 Hz.
>
> So this is not a PulseAudio problem. Maybe some ALSA misconfiguration. I
> have to guess here, unfortunately.
>
> Could you please post the output of the following debugging commands
> (they play one second of silence and describe how they do it) while
> PulseAudio is not running?
>
> aplay -vv -d 1 -f cd -D hw:0 /dev/zero
>
> aplay -vv -d 1 -f cd -D front:0 /dev/zero
>

Upon reading your log further, I have a better guess. It looks like your 
sound card supports only 48 kHz for capture, and, while capture is 
active, also requires playback to be open at 48 kHz.

You can work around this limitation by setting the card profile to
"output:analog-stereo" using pacucontrol.

-- 
Alexander E. Patrakov