[alsa-devel] question on hardware
tiwai at suse.de
Fri Apr 17 15:36:10 CEST 2009
At Thu, 9 Apr 2009 13:26:50 +0530,
Harsha, Priya wrote:
> The issue that I am facing with creating a snd_kcontrol is that I am
> not able to bind that value to a stream.
> Say I start the application
> and set the type of that control to voice and open another instance
> of that application and set the type to audio.
Another instance must have a different stream, right? Then it must
have a different substream number. In the scenario a la emu10k1,
you'll have a control per each substream. So this won't conflict.
> There might be a
> clash and I might get the wrong stream type to the driver. Also, the
> stream ids passed cannot also be guaranteed to reach the right
The "stream id" you are referring to might be different from what I'm
thinking of. Please elaborate your terminology before further
questions. It's a bit hard to illustrate your use-case from your
descriptions, so far...
> >-----Original Message-----
> >From: alsa-devel-bounces at alsa-project.org [mailto:alsa-devel-bounces at alsa-project.org] On Behalf Of Harsha,
> >Sent: Thursday, April 09, 2009 1:07 PM
> >To: alsa-devel at alsa-project.org
> >Cc: Takashi Iwai; David Dillow; Lee Revell; Clemens Ladisch
> >Subject: Re: [alsa-devel] question on hardware
> >Hi ,
> >I need more help here. I tried looking at the .conf file but I have another requirement here.
> >Let me put my requirements here. Please suggest me ways to get this done
> >1. When I get a .prepare call in my driver, I need to know the stream type
> >2. When I return from that call, I need to send to the user the locally allocated stream id
> >This is specific to the sound card/ DSP I am developing the driver for. The application is also proprietary. Is this
> >possible at all? Please suggest me ways to do the same.
> >>-----Original Message-----
> >>From: David Dillow [mailto:dave at thedillows.org]
> >>Sent: Tuesday, December 09, 2008 6:14 PM
> >>To: Harsha, Priya
> >>Cc: Clemens Ladisch; alsa-devel at alsa-project.org; Lee Revell
> >>Subject: Re: [alsa-devel] question on hardware mixing
> >>On Tue, 2008-12-09 at 14:25 +0530, Harsha, Priya wrote:
> >>> If I define mixer controls to switch between each substream, I would
> >>> not be able to handle multiple streams at time....
> >>Check into the ALSA configuration file syntax -- there are number of
> >>things you can do there, like define a 'voice' device that uses hooks to
> >>set a control setting (snd_kcontrol) when you open a PCM. You can use
> >>that control setting to let your driver know if the PCM channel is being
> >>used for voice or audio traffic.
> >>Look at how the EMU10K1 handles surround sound audio
> >>in /etc/alsa/cards/EMU10K1.conf
> >>I started to do some similar things for sis7019 surround sound, but
> >>they've never made it out of my office due to lack of time/testing HW.
> >>> I had asked this in my earlier follow up email as well - can I use
> >>> snd_pcm_t->private_data to communicate if it's a voice or audio
> >>> I understand this private_data gets copied to substream->private data
> >>> which will reach the driver...
> >>> Am I right here?
> >>I can't answer this specifically, but I believe the answer is in the
> >>name -- 'private'. This is for the ALSA system to use, you can hang your
> >>own data off a substream using snd_pcm_substream_chip(). Besides, how do
> >>you plan on setting it in the snd_pcm_t type?
> >>I think that if you set up some controls, use the config file language,
> >>and have your audio apps open a 'voice' device, you can get where you
> >Alsa-devel mailing list
> >Alsa-devel at alsa-project.org
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