[FFmpeg-devel] [PATCH] ALAC Encoder

[Michael Niedermayer]

On Sun, Aug 17, 2008 at 11:17:27AM -0300, Ramiro Polla wrote:
> On Sun, Aug 17, 2008 at 10:15 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> > On Sun, Aug 17, 2008 at 09:09:00AM +0530, Jai Menon wrote:
> >> Hi,
> >>
> >> On Sunday 17 Aug 2008 8:05:14 am Michael Niedermayer wrote:
> >> > On Sun, Aug 17, 2008 at 04:14:43AM +0530, Jai Menon wrote:
> > [...]
> >> > > +static void alac_stereo_decorrelation(AlacEncodeContext *s)
> >> > > +{
> >> > > +    int32_t *left = s->sample_buf[0], *right = s->sample_buf[1];
> >> > > +    int32_t tmp;
> >> > > +    int i;
> >> > > +
> >> > > +    for(i=0; i<s->avctx->frame_size; i++) {
> >> > > +        tmp = left[i];
> >> > > +        left[i] = (tmp + right[i]) >> 1;
> >> > > +        right[i] = tmp - right[i];
> >> > > +    }
> >> > >
> >> > > +    s->interlacing_leftweight = 1;
> >> > > +    s->interlacing_shift = 1;
> >> >
> >> > i do not belive this is optimal
> >> >
> >>
> >> It may not be optimal in the sense that I do not adaptively select the
> >> decorrelation scheme, but this is just the first iteration which aims at
> >> getting a basic encoder into svn. And it is better than doing no
> >> deorrelation. I did initially try out an adaptive approach but the difference
> >> in compression wasn't that great. I'm looking into how this can be done in a
> >> better manner. Till then, I was hoping if we could go with this.
> >
> > see the pca.c/h i posted in a reply to ramiro a few days ago
> > it might be worth a try ...
> 
> Speaking of that... I haven't finished integrating it in MLP (I'm
> working on some other stuff atm), but it seems to be what I need.

> Could you get it cleaned up and committed like you suggested?

done

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I know you won't believe me, but the highest form of Human Excellence is
to question oneself and others. -- Socrates
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