[FFmpeg-devel] Flac encoder and MPEG4 ALS

Jai Menon realityman
Sun Mar 30 22:53:12 CEST 2008


On Sunday 30 March 2008 13:55:49 Kostya wrote:
> On Sun, Mar 30, 2008 at 09:44:51AM -0400, Justin Ruggles wrote:
> > Kostya wrote:
>
> [...]
>
> > > I've looked at it once. Seems the most features are for floating-point
> > > mode, baseline decoder should be comparatively easy. Especially if you
> > > are the person who writes encoder to it ;)
> >
> > It has 2 entropy coders, plus another for floating-point.  It has 2 ways
> > of doing multi-channel.  There are also several prediction methods.  The
> > spec does not specifically say what is "baseline" vs. extended, but it
> > would be simple enough to break down the task.
>
> IIRC, both entropy coders are VLC - classical Shannon-Fano scheme and
> classical Golomb codes. Prediction is also standard LPC and RLS, the latter
> is quite rare in codecs though (MLP, APE, TTA ?).
 and iirc golomb rice codes are used only for the tail end residuals, those in 
center are encoded using block gilbert-moore codes........but i may be wrong

Regards
Jai Menon
<realityman at gmx.net>





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