[pulseaudio-discuss] Crash when testing PulseAudio 3.0 on a Pandaboard ES.

[David Henningsson]

On 01/31/2013 07:11 PM, Tanu Kaskinen wrote:
> On Thu, 2013-01-31 at 17:04 +0100, David Henningsson wrote:
>> [Adding Arun, Liam and Feng to CC]
>>
>> On 01/30/2013 12:15 PM, Luke Yelavich wrote:
>>> Got it thanks, applied along with using alsa 1.0.26.
>>>
>>> However, it seems we have another one, and this has produced another, bigger stacktrace, which is attached. Still the PandaBoardES with the same UCM config I sent to the list.
>>>
>>
>> This looks like: https://bugs.freedesktop.org/show_bug.cgi?id=53036
>
> Yep.
>
>> But can we reconfirm that "PlaybackChannels" or "CaptureChannels" are
>> really required?
>
> Required in what sense? UCM itself doesn't require those, but the
> current pulseaudio code requires those values (the assertion is there
> for a reason). It's of course possible to change pulseaudio code if you
> feel like it, but I think it would make useful to improve those
> configuration files.

I think a better solution than an assert failure would be either
1) Default to stereo for playback and capture, or
2) Fall back to not using UCM at all.

>> None of the files Ubuntu ships today have it, and AFAIU
>> it has not been required in the past (i e PA 2.1). Is there any
>> documentation of this, so if it really is required, we know how to add it?
>
> PA 2.1 didn't have UCM support.

Ah. Missed that.

> I don't know why Ubuntu ships any UCM
> configuration files at all, if they have never been tested (at least not
> with PulseAudio).

They are shipped together with udev rules that set a verb at bootup in 
order to have a less messed up mixer OOTB.

> I'm not aware of any documentation (apart from the little[1] that I
> started to write and never finished).

This is a major problem with UCM. There is little or no official 
documentation, nor official examples of how to write UCM files the right 
way. Liam, is there any progress on this issue?

> This is how you define
> PlaybackChannels for a device in the UCM configuration:
>
> SectionDevice."speakers-output" {
> 	...
>
> 	Value {
> 		PlaybackPCM "hw:RX51,0"
> 		PlaybackChannels "2"
> 	}
> }
>
> Here is an example of configuration that has been confirmed to work with
> PulseAudio: [2].
>
> [1] http://www.alsa-project.org/main/index.php/Use_Case_Manager
> [2] https://gitorious.org/~tanuk2/alsa/tanuk2s-alsa-lib/commit/53d1042d80ac73d8809fa3f9ee1308682a51c7bc

Thanks. I especially like the
exec "echo 
WOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO"

command and I assume that PA will also fail with an assertion failure if 
you leave out this command? ;-)


-- 
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic