[FFmpeg-devel] [Patch] AAC encoder improvements

[Michael Niedermayer]

On Sat, May 04, 2013 at 10:54:25PM -0300, Claudio Freire wrote:
> On Sat, May 4, 2013 at 10:31 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> >> >>              adjust_frame_information(cpe, chans);
> >> >> +            if (cpe->ms_mode) {
> >> >> +                /* Re-evaluate psy model and quantization selection based on
> >> >> +                   MS-transformed channels */
> >> >> +                s->psy.model->analyze(&s->psy, start_ch, coeffs, wi);
> >> >> +                for (ch = 0; ch < chans; ch++) {
> >> >> +                    s->cur_channel = start_ch * 2 + ch;
> >> >> +                    s->coder->search_for_quantizers(avctx, s, &cpe->ch[ch], s->lambda);
> >> >> +                }
> >> >> +            }
> >> >
> >> > shouldnt this and the previous hunks be in seperate patches or is
> >> > there some dependance ?
> >>
> >> Well, they're related, as they both pertain to joint stereo, but
> >> there's no hard dependency between them, that's true. I did begin with
> >> the first hunk, feeling that those artifacts were due to bad choices,
> >> and it's not enough on its own. The really important hunk is the
> >> second, re-doing quantization.
> >
> > how can it be tested ?
> > there doesnt seem to be a difference in the output with the second
> > hunk applied
> 
> I imagine you enabled joint stereo? (-stereo_mode auto in ffmpeg)
> Without it, the code doesn't do anything. And, of course, stereo input
> that can benefit from it (any real track with vocals should).

I thought it was enabled by default ...
setting it to auto shows a difference but i see no improvment from
the patch, PSNR worsens for most files i tried rather
Is that expected ?

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No snowflake in an avalanche ever feels responsible. -- Voltaire
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