Re: [PATCH 00/11] Add AXD Audio Processing IP driver

[Qais Yousef]

On 10/28/2014 02:54 PM, Lars-Peter Clausen wrote:
> On 10/28/2014 02:18 PM, Qais Yousef wrote:
> > On 10/28/2014 11:55 AM, Clemens Ladisch wrote:
> > > Qais Yousef wrote:
> > > > AXD Audio Processing IP performs audio decoding, encoding, mixing,
> > > > equalisation,
> > > > synchronisation and playback.
> > > What exactly do you mean with "synchronisation" and "playback"?
> >
> > Synchronisation refers to accurate audio playout relative to a master
> > clock source including compensation of drift between the master clock
> > source and the playout clock of the audio hardware. Hence allowing
> > synchronised audio playout across multiple independent devices.
> >
> > Playback simple refers to the fact that AXD is capable of managing audio
> > playout hardware like I2S and SPDIF interfaces.
> >
> >
> > > > It doesn't fit in alsa subsystem but I Cced them to confirm.
> > > ... because those two words sound like something that a sound card 
> > > could do.
> >
> > The problem mainly stems from the fact that we take a variety of
> > compressed audio as input and we could perform audio encoding. The
> > problem with the compressed audio is that the range of decoders and
> > configuration supported in alsa is limited and there's no support for
> > taking raw pcm and producing compressed output. I'm not an expert on
> > alsa but when I looked it looked like there's more infra structure
> > required.
> >
> > [...]
>
> This doesn't sound to different from any of the other supported audio 
> DSPs. ALSA seems to have 95% of what you need. And the missing 5% is 
> probably stuff that is not specific to your hardware but rather 
> something that other hardware will need as well. The framework is not 
> set in stone you can make modifications and add the features that are 
> missing to make your hardware work.
>
> E.g. look at sound/soc/intel/ for an example of a audio DSP.
>
> No integrating this into ALSA will quite likely result in a quite 
> messy situation for you on the long run.
>
> - Lars
OK thanks for the reference. To be honest it felt like 15-20% of the 
features are missing but I'll need to look at the specifics and 
judge/estimate better.

Thanks,
Qais
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