[FFmpeg-devel] atrac1 decoder and aea demuxer rev 6

[Michael Niedermayer]

On Wed, Sep 09, 2009 at 11:03:59PM +0200, Maxim wrote:
> Michael Niedermayer schrieb:
> > On Sun, Sep 06, 2009 at 08:12:04PM +0200, Benjamin Larsson wrote:
> >   
> >> Changes:
> >>     
> > [...]
> >   
> >> Changed some code.
> >>     
> >
> > :)
> >
> >
> >   
> >> Did not do anything to the qmf routines that will be shared with atrac3
> >> as it will be a svn copy and I'll take comments on that when the code is
> >>  split out in it's own file.
> >>
> >> Thanks for all the comments so far.
> >>     
> > [...]
> >
> >   
> >> +
> >> +static const uint8_t bfu_bands_t[4]  = {0, 20, 36, 52}; // number of BFUs in each QMF band
> >> +
> >> +/* number of spectral lines in each BFU */
> >> +static const uint8_t specs_per_bfu[52] = {
> >> +     8,  8,  8,  8,  4,  4,  4,  4,  8,  8,  8,  8,  6,  6,  6,  6, 6, 6, 6, 6, // low band
> >> +     6,  6,  6,  6,  7,  7,  7,  7,  9,  9,  9,  9, 10, 10, 10, 10,             // midle band
> >> +    12, 12, 12, 12, 12, 12, 12, 12, 20, 20, 20, 20, 20, 20, 20, 20              // high band
> >> +};
> >>     
> >
> > i guess i knew it once but what is a bfu? ill probably figure it out in a
> > few seconds when looking at the use of these but i think it could help if
> > its written out here somewhere
> >   
> 
> bfu = block floating unit = group of spectral frequencies having the
> same quantization parameters like word length and scale factor...

sounds like a nice adition to the doxy in there

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Asymptotically faster algorithms should always be preferred if you have
asymptotical amounts of data
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