[alsa-devel] [PATCH] crec: Add option to specify codec ID

[Vinod Koul]

On Fri, Nov 18, 2016 at 10:11:08AM +0000, Richard Fitzgerald wrote:
> On Fri, 2016-11-18 at 09:23 +0530, Vinod Koul wrote:
> > On Wed, Nov 16, 2016 at 02:53:21PM +0000, Richard Fitzgerald wrote:
> > > On Wed, 2016-11-16 at 13:48 +0000, Charles Keepax wrote:
> > > > On Wed, Nov 16, 2016 at 01:07:55PM +0000, Richard Fitzgerald wrote:
> > > > > On Wed, 2016-11-16 at 18:35 +0530, Vinod Koul wrote:
> > > > > > On Wed, Nov 16, 2016 at 11:44:09AM +0000, Richard Fitzgerald wrote:
> > > > > > > This patch adds a -I command line option to set the codec ID,
> > > > > > > either from a defined set of string values or as a number.
> > > > > > 
> > > > > > Can you explain why you want to add this? The utility cant really record a
> > > > > > mp3 file!
> > > > > 
> > > > > You need to be able to pass a codec ID that the driver supports, and to
> > > > > indicate which codec you're trying to use. It's not useful to only be
> > > > > able to open the "PCM" codec. It doesn't really matter whether crec
> > > > > understands the content of the data, we're just pulling raw data, most
> > > > > likely for test/debug.
> > > > > 
> > > > > The wm_adsp driver on Wolfson/Cirrus codecs uses the new BESPOKE stream
> > > > > ID so we need a way to pass that. And we'd also need it for any drivers
> > > > > that had streams using other codec IDs.
> > 
> > Ah that was my guess too.
> > 
> > I am okay to be able to add bespoke format and use that to dump raw data.
> > But I am not okay to add codec formats which we dont support..
> > 
> 
> Well a raw dump would support MP3 because that is doesn't require any
> header and the framing is part of the data stream. So no special
> handling needed there. This may also apply to some of the other formats
> (I'm not an expert on them) so I'd rather have the option to be able to
> raw-dump any format and leave it to the user to decide whether that's
> sensible.
> 
> If you're debugging you may not care about the file format, you're
> actually interested in the raw data you get from the codec so dumping
> the output to a raw file would be useful even if you can't load that
> file into a music player.

While I agree with you on this, am worried that adding codecs may make
people think that we can record mp3 file for exmaple, which is not the case.

I think we can add pcm and bespoke as formats supported and allow any format to
be dumped to stdio. That way it is pretty clear to people ...

Thanks
-- 
~Vinod