[alsa-devel] unable to do simultaneous playback and recording

[Takashi Iwai]

At Thu, 20 Aug 2009 11:45:40 +0530 (IST),
prashant chopade wrote:
> 
> Hello,
> 
> As per discussion, I know that ALSA driver does not have support for
> simultaneous playback and recording.

Huh?  The full-duplex is of course supported.
Your example shown in the thread doesn't indicate the multi playbacks
or so.

> We are using AD1981B codec, so our hardware has a support for
> simultaneous playback and recording of an audio.

I think you are confused.


> So what exactly I have to do to get a support for simultaneous
> playback and recording? 
> Shall I have to use sound server demons?
> 
> Is it really possible to do simultaneous playback and recording in
> linux?

Define your meaning of "simultaneous playback and recording" more
exactly.

If it's about full-duplex, the answer is definitely yes.
If it's multi-streams, the answer is yes, but there are choices, e.g.
dmix/dsnoop plugin or a sound server.


Takashi


> 
> Thanks & Regards,
> Prashant C.
> 
> 
> --- On Wed, 19/8/09, Takashi Iwai <tiwai at suse.de> wrote:
> 
> From: Takashi Iwai <tiwai at suse.de>
> Subject: Re: [alsa-devel] unable to do simultaneous playback and recording
> To: "prashant chopade" <prashantchopade at yahoo.com>
> Cc: alsa-devel at alsa-project.org
> Date: Wednesday, 19 August, 2009, 5:50 PM
> 
> At Tue, 18 Aug 2009 05:05:10 -0700 (PDT),
> prashant chopade wrote:
> > 
> > 
> > 
> > 
> > 
> > Hello,
> > 
> > We using linux-2.6.27 on target board-AT91SAM9263EK.
> >  We are using ALSA library utilities (aplay &
> > arecord). But by using these utilities we can’t do simultaneous playback and
> > recording.
> > 
> >  
> > 
> > We performed following activity to come to this conclusion:
> > 
> >  
> > 
> > //At the background we were recording
> > 
> > #arecord –f cd record_test_file &
> > 
> >  
> > 
> > //At the forefront we were playing pre-recorded audio file
> > 
> > #aplay –f cd pre_recorded_file
> > 
> >  
> > 
> > Our observation is that, recording stops when start playing
> > file.
> 
> In the API side, the above should work fine.  It must be the driver 
> that doesn't work with full-duplex.
> 
> 
> Takashi
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> 
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