[alsa-devel] [PATCH] cmipci - allow capture of raw spdif subframes

[Takashi Iwai]

At Tue, 13 Nov 2007 16:47:38 +0300,
Timofei V. Bondarenko wrote:
> 
> Takashi Iwai wrote:
> > At Wed, 07 Nov 2007 15:12:46 +0300,
> > Timofei V. Bondarenko wrote:
> >> Hi.
> >>
> >> Enable capturing of raw 32bit IEC958_SUBFRAME.
> >>
> >> The 24-bits PCM data can be obtained using iec958 plugin.
> >>
> >> Known problem: captured stream may begin with either left or right 
> >> subframe. Since the iec958 plugin doesn't decode preamble it may swap 
> >> the channels sometime.
> >>
> >> Regards,
> >> 	Tim.
> > 
> > Applied this one, too.
> > (Do you happen to have a fix for iec958 plugin, too? :)
> 
> Not yet.
> I'm in doubt about a clean way to drop one subframe from the raw stream.
> Could you give me a hint?

It'll be tricky, yes.  We can prepend a zero in the first shot and
keep one pending channel data to shift.  For example,

  raw: R0 L0 R1 L1 R2 L2 ... R(n-1) L(n-1) | R(n) L(n) ... 
  dec: 0  R0 L0 R1 L1 R2 ... L(n-2) R(n-1) | L(n-1) R(n) ...


Takashi