[alsa-devel] View alsa-lib plugins setup for any app?
tiwai at suse.de
Wed Oct 22 07:58:45 CEST 2008
At Wed, 22 Oct 2008 09:55:01 +1300,
Eliot Blennerhassett wrote:
> On Tuesday 21 October 2008 19:34:49 Takashi Iwai wrote:
> > Sorry, I don't understand well your question. Do you want to see the
> > alsa-plugin chain of a running application from the outside,
> Yes. Basically see something that looks like the result of "aplay -v", but for
> a running app from the outside.
> E.g. to see if the app is using dmix, plughw etc, what parameters the app sees
> vs how the card is accessed.
> Best if this info was available like the proc files for the driver, but if it
> required running the app in a special context (debugger-like or LD_PRELOAD)
> that would probably still be useful.
> The app should not have to be recompiled.
Well, right now it's almost impossible because the alsa-lib stuff is
purely a user-space thing and not exposed to anywhere else.
An easy hack is to add snd_pcm_dump() to snd_pcm_hw_params() in
alsa-lib (better with a conditional check, such as a certain
environment variable). But this function may be called recursively,
it should have a certain re-entrace check.
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