[FFmpeg-devel] [PATCH v2 3/8] aaccoder: fix M/S coding

[Michael Niedermayer]

On Fri, Jul 03, 2015 at 12:01:44AM -0300, Claudio Freire wrote:
> On Thu, Jul 2, 2015 at 3:13 PM, Rostislav Pehlivanov
> <atomnuker at gmail.com> wrote:
> > There were some mistakes in the code for M/S stereo, this commit fixes them. The start variable was not being reset for every window and every access to the coefficients was incorrect as well. This fixes that by properly addressing the coefficients using both windows and setting the start on every window to zero.
> > ---
> >  libavcodec/aaccoder.c | 15 ++++++++-------
> >  1 file changed, 8 insertions(+), 7 deletions(-)
> >
> > diff --git a/libavcodec/aaccoder.c b/libavcodec/aaccoder.c
> > index 3fcc8b4..33cbe7b 100644
> > --- a/libavcodec/aaccoder.c
> > +++ b/libavcodec/aaccoder.c
> > @@ -1143,6 +1143,7 @@ static void search_for_ms(AACEncContext *s, ChannelElement *cpe,
> >      if (!cpe->common_window)
> >          return;
> >      for (w = 0; w < sce0->ics.num_windows; w += sce0->ics.group_len[w]) {
> > +        start = 0;
> >          for (g = 0;  g < sce0->ics.num_swb; g++) {
> >              if (!cpe->ch[0].zeroes[w*16+g] && !cpe->ch[1].zeroes[w*16+g]) {
> >                  float dist1 = 0.0f, dist2 = 0.0f;
> > @@ -1152,22 +1153,22 @@ static void search_for_ms(AACEncContext *s, ChannelElement *cpe,
> >                      float minthr = FFMIN(band0->threshold, band1->threshold);
> >                      float maxthr = FFMAX(band0->threshold, band1->threshold);
> >                      for (i = 0; i < sce0->ics.swb_sizes[g]; i++) {
> > -                        M[i] = (sce0->pcoeffs[start+w2*128+i]
> > -                              + sce1->pcoeffs[start+w2*128+i]) * 0.5;
> > +                        M[i] = (sce0->pcoeffs[start+(w+w2)*128+i]
> > +                              + sce1->pcoeffs[start+(w+w2)*128+i]) * 0.5;
> >                          S[i] =  M[i]
> > -                              - sce1->pcoeffs[start+w2*128+i];
> > +                              - sce1->pcoeffs[start+(w+w2)*128+i];
> >                      }
> > -                    abs_pow34_v(L34, sce0->coeffs+start+w2*128, sce0->ics.swb_sizes[g]);
> > -                    abs_pow34_v(R34, sce1->coeffs+start+w2*128, sce0->ics.swb_sizes[g]);
> > +                    abs_pow34_v(L34, sce0->coeffs+start+(w+w2)*128, sce0->ics.swb_sizes[g]);
> > +                    abs_pow34_v(R34, sce1->coeffs+start+(w+w2)*128, sce0->ics.swb_sizes[g]);
> >                      abs_pow34_v(M34, M,                         sce0->ics.swb_sizes[g]);
> >                      abs_pow34_v(S34, S,                         sce0->ics.swb_sizes[g]);
> > -                    dist1 += quantize_band_cost(s, sce0->coeffs + start + w2*128,
> > +                    dist1 += quantize_band_cost(s, sce0->coeffs + start + (w+w2)*128,
> >                                                  L34,
> >                                                  sce0->ics.swb_sizes[g],
> >                                                  sce0->sf_idx[(w+w2)*16+g],
> >                                                  sce0->band_type[(w+w2)*16+g],
> >                                                  lambda / band0->threshold, INFINITY, NULL);
> > -                    dist1 += quantize_band_cost(s, sce1->coeffs + start + w2*128,
> > +                    dist1 += quantize_band_cost(s, sce1->coeffs + start + (w+w2)*128,
> >                                                  R34,
> >                                                  sce1->ics.swb_sizes[g],
> >                                                  sce1->sf_idx[(w+w2)*16+g],
> 
> 
> LGTM.

applied

thanks

[...]

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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

You can kill me, but you cannot change the truth.
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