Re: [RFC PATCH v2 0/7] Add audio support in v4l2 framework

Shengjiu Wang
2023-08-02T12:02:48Z

On Wed, Aug 2, 2023 at 7:22 PM Takashi Iwai <tiwai@suse.de> wrote:
>
> On Wed, 02 Aug 2023 09:32:37 +0200,
> Hans Verkuil wrote:
> >
> > Hi all,
> >
> > On 25/07/2023 08:12, Shengjiu Wang wrote:
> > > Audio signal processing has the requirement for memory to
> > > memory similar as Video.
> > >
> > > This patch is to add this support in v4l2 framework, defined
> > > new buffer type V4L2_BUF_TYPE_AUDIO_CAPTURE and
> > > V4L2_BUF_TYPE_AUDIO_OUTPUT, defined new format v4l2_audio_format
> > > for audio case usage.
> > >
> > > The created audio device is named "/dev/audioX".
> > >
> > > And add memory to memory support for two kinds of i.MX ASRC
> > > module
> >
> > Before I spend time on this: are the audio maintainers OK with doing
> > this in V4L2?
> >
> > I do want to have a clear statement on this as it is not something I
> > can decide.
>
> Well, I personally don't mind to have some audio capability in v4l2
> layer. But, the only uncertain thing for now is whether this is a
> must-have or not.
>

Thanks, I am also not sure about this. I am also confused that why
there is no m2m implementation for audio in the kernel. Audio also
has similar decoder encoder post-processing as video.

>
> IIRC, the implementation in the sound driver side was never done just
> because there was no similar implementation? If so, and if the
> extension to the v4l2 core layer is needed, shouldn't it be more
> considered for the possible other route?
>

Actually I'd like someone could point me to the other route. I'd like to
try.

The reason why I select to extend v4l2 for such audio usage is that v4l2
looks best for this audio m2m implementation. v4l2 is designed for m2m
usage. if we need implement another 'route', I don't think it can do better
that v4l2.

I appreciate that someone can share his ideas or doable solutions.
And please don't ignore my request, ignore my patch.

Best regards
Wang shengjiu