[FFmpeg-devel] [PATCH] Fix for issue #829 ("ffvorbis outputs?crackling sound, libvorbis plays fine")

[Reimar Döffinger]

On Mon, May 11, 2009 at 07:17:49PM +0200, Michael Niedermayer wrote:
> On Mon, May 11, 2009 at 11:08:56AM +0300, Siarhei Siamashka wrote:
> > On Monday 11 May 2009, Michael Niedermayer wrote:
> > > On Sun, May 10, 2009 at 12:06:54PM +0300, Siarhei Siamashka wrote:
> > [...]
> > > >  libavcodec/vorbis_dec.c |   10 +++++-----
> > > >  1 files changed, 5 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/libavcodec/vorbis_dec.c b/libavcodec/vorbis_dec.c
> > > > index 49d6e8e..f626bce 100644
> > > > --- a/libavcodec/vorbis_dec.c
> > > > +++ b/libavcodec/vorbis_dec.c
> > > > @@ -1039,16 +1039,16 @@ static uint_fast8_t
> > > > vorbis_floor0_decode(vorbis_context *vc, float
> > > > two_cos_w=2.0f*cos(wstep*iter_cond); // needed all times
> > > >
> > > >                  /* similar part for the q and p products */
> > > > -                for(j=0;j<order;j+=2) {
> > > > -                    q *= lsp[j]  -two_cos_w;
> > > > -                    p *= lsp[j+1]-two_cos_w;
> > > > +                for(j=1;j<order;j+=2) {
> > > > +                    q *= lsp[j-1]-two_cos_w;
> > > > +                    p *= lsp[j]  -two_cos_w;
> > >
> > > am i missing something or is all what you change equivalent to
> > > for order-1 vs. for order ?
> > 
> > You are not missing anything. This has exactly the same effect. I can
> > change the patch to use 'order-1' if you like it better this way.
> 
> if changing a single line does the trick id prefer that

And also check if
> for(j=0;j+1<order;j+=2) {
is maybe also correct and more intuitive (to me it looks like
lsp would be treated like an array of size order, and the loop
would go as far as possible without overreading).