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

[Richard Fitzgerald]

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.

> > > Is the objection here not that crec is wrapping the data with
> > > a WAV file? Should we perhaps just expand this so that if you
> > > request a different format it uses the raw data mode that it uses
> > > when you let the output go to stdout.
> > > 
> > 
> > Funny I thought we'd already added a flag for saving to the file raw.
> > It's raw when you pipe it to stdout.
>