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

[Vinod Koul]

On Thu, Feb 14, 2013 at 10:13:57AM +0100, Takashi Iwai wrote:
> At Thu, 14 Feb 2013 14:12:51 +0530,
> Vinod Koul wrote:
> > 
> > this add new API for sound compress to support gapless playback.
> > As noted in Documentation change, we add API to send metadata of encoder and
> > padding delay to DSP. Also add API for indicating EOF and switching to
> > subsequent track
> > 
> > Also bump the compress API version
> > 
> > Signed-off-by: Jeeja KP <jeeja.kp at intel.com>
> > Signed-off-by: Vinod Koul <vinod.koul at intel.com>
> > ---
> >  v5:
> > - update metadata value with 8 words
> 
> What's the reason behind this change?  I can think of metadata like EQ
> parameters, but the magic number 8 is in question :)
Yes the concern was that there might be an issue with parameters which are not
single dwords, so 8 dwords was what came to my mind. 8 why, i picked the number
:). Seems decent enough and not too big. For even bigger pparameters I was
thinking to split..

If you think we should have 16/32 dwrods, am okay with it.

> I'm no enthusiastic over minimalism like Apple, so I don't mind this
> change, but just out of curiosity...
> 
> Also, another spot:
> 
> > @@ -145,6 +160,10 @@ struct snd_compr_codec_caps {
> >  						struct snd_compr_codec_caps)
> >  #define SNDRV_COMPRESS_SET_PARAMS	_IOW('C', 0x12, struct snd_compr_params)
> >  #define SNDRV_COMPRESS_GET_PARAMS	_IOR('C', 0x13, struct snd_codec)
> > +#define SNDRV_COMPRESS_SET_METADATA	_IOW('C', 0x14,\
> > +						 struct snd_compr_metadata)
> > +#define SNDRV_COMPRESS_GET_METADATA	_IOW('C', 0x15,\
> > +						 struct snd_compr_metadata)
Yes!
> 
> Isn't it _IOWR()?
If this is only thing, let me send the update or you want a beverage :)

--
~Vinod