[pulseaudio-discuss] [RFC] Alsa UCM integration.

Margarita Olaya magi at slimlogic.co.uk
Thu Feb 24 21:34:50 PST 2011


On Thu, Feb 24, 2011 at 2:20 PM, pl bossart <bossart.nospam at gmail.com> wrote:
>> The initial version of the UCM module is available at the following link:
>> http://git.slimlogic.co.uk/cgi-bin/cgit.cgi/pulseaudio.git/log/?h=9.20-ucm_module
>> I'm still working in the module, It is work in progress to verify the
>> current verb when the stream is closed, also it is needed to add more
>> code to work with the profiles and the use cases. Sink, source and
>> device data could be taken from the proplist of the verb, and this is
>> pending too.
> Hi Margarita,
> I looked at your patches and have the following comments:

Thanks for the review and feedback on the meeting.

> - any reason why your version of PulseAudio is 1.3 years old. The
> previous patches on your branch are from 2009-11-18, quite a while
> ago. It'll make upstreaming difficult.

Well, I had some troubles at the begging so I started  by taking an
stable rls but for sure I'll move soon the code to latest commit
before upstream it.

> - you now have a separate module-alsa-ucm module, but it's called with
> a device name as a parameter. So if I have one USB headphone and one
> USB mic, this module will be called twice. It's not clear to me then
> how the virtual device would be handled, and how this is different
> from inserting all the code in module-alsa-card as you did it in your
> previous version?

the idea was to have at least one card working, so yes this is pretty
much the same approach than the code in module-alsa-card. Do you have
any idea on how to manage virtual cards? I'm not clear on they way
that ALSA manages virtual cards.

> - can you explain why you set the verb using the hook
> PA_CORE_HOOK_SINK_INPUT_NEW, with priority PA_HOOK_EARLY+15. There are
> other audio-policy related modules that may use different hooks, such
> as PA_CORE_HOOK_SINK_INPUT_PUT. I would think you want to set the verb
> at the UCM level after all this logic has made decisions, at the last
> possible moment before data start flowing.

The initial approach was a bit different but after the IRC discussion
I agree to use a different  hook so verb will be set after all the
analysis with profiles has been done but it is needed first to map a
profile with a verb instead of the current approach with roles.

> - how do we make use of modifiers?
I have not really thought about this.

> - is there a better way to detect that UCM is supported, instead of
> having a #define in module-alsa-card.c?

there will be, that is on my to-do list atm


> I realize I have more questions than suggestions, this is a good start anyway...
> Thanks,
> -Pierre
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