[alsa-devel] Compressed Audio Playback/Capture through ALSA framework

Patrick Lai plai at codeaurora.org
Thu Mar 17 06:00:01 CET 2011

On 3/16/2011 7:21 PM, Koul, Vinod wrote:
> On Wed, 2011-03-16 at 23:38 +0530, Mark Brown wrote:
>> On Wed, Mar 16, 2011 at 01:00:09PM -0500, pl bossart wrote:
>>> On Wed, Mar 16, 2011 at 12:53 PM, Mark Brown
>>>> It'd make the tie up with algorithms part much easier as we could have
>>>> an interface for transferring the compressed data alone and then
>>>> externally describe how that's plumbed into any other DSP that's going
>>>> on and the physical outputs - it'd help with treating the data transfer
>>>> as a standalone problem.
>>> Still not convinced. Why would you need to 'externally describe' how
>>> compressed data is linked to post-processing. It's all part of DSP
>>> firmware, why should anyone care how the decoder provides data to
>>> post-processes? You can control post-processes with ALSA controls as
>>> for regular PCM.
>> The problem is figuring out which controls are where and what can be
>> joined up with what.  This is a problem with regular PCM too but it gets
>> much worse when everything is virtual.  Media controller should provide
>> a route to allowing applications to figure out what's going on in the
>> hardware.
> Wouldn't a virtual sound card solve this? I was thinking of representing
> all DSP elements in a virtual card.

I think it would work to certain extend but what if DSP can instantiate 
elements at run-time, how can we deal with this use case under current 
ALSA framework?

Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

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