[alsa-devel] [RFC] compress: add support for gapless playback

Vinod Koul vinod.koul at intel.com
Wed Feb 6 15:00:12 CET 2013

On Wed, Feb 06, 2013 at 07:59:56AM -0600, Pierre-Louis Bossart wrote:
> >>>>+	if (!stream->ops->set_metadata)
> >>>>+		return -ENXIO;
> >
> >>>Is this really a fatal error? Or do we want to mandate that gapless
> >>>be supported by all implementations?
> >
> >>Fatal err? if DSP doesnt support metadata callback then we are reporting error
> >>ENXIO to userpsace. No we shouldnt mandate, its upto DSP folks to see what they
> >>should and can support.
> >
> >Well, up to userspace to see how it handles the error anyway.  For
> >example an application may want to fall back to PCM playback with
> >gapless done on the CPU if the driver doesn't do it.  But then given
> >that there's more than one piece of metadata in the struct perhaps we
> >need some way for the application to figure out what's supported?
> Maybe we should expose what's supported as part of the decoder query
> process, i.e. expose support for metadata as part of the decoder
> capabilities rather than as part of the set_metadata part? Error
> checks after inits are painful. we could have a "metadata_support"
> bit-field that the application could check.
Well I agree that would be a smarter way to handle. Make one of the reserved
fields in decoder caps for metadata support.


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