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

[Michael Niedermayer]

On Sun, May 10, 2009 at 12:06:54PM +0300, Siarhei Siamashka wrote:
> Hello,
> 
> -- 
> Best regards,
> Siarhei Siamashka

>  vorbis_dec.c |   10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> e20c143c53ac71f5135d4139be815d0aab188ecd  0006-Fix-for-issue-829-ffvorbis-outputs-crackling-soun.patch
> From 289c9acd419f1f314dcf4be02cdc2b80e157d16c Mon Sep 17 00:00:00 2001
> From: Siarhei Siamashka <siarhei.siamashka at gmail.com>
> Date: Sun, 10 May 2009 10:50:20 +0300
> Subject: [PATCH] Fix for issue #829 ("ffvorbis outputs crackling sound, libvorbis plays fine")
> 
> This problem affects floor0 encoded files. Tracked down by valgrind (was
> reported as the use of uninitialized memory).
> 
> With this patch applied, tiny_psnr now reports the following when ffvorbis
> is compared to libvorbis-1.0beta4 output for 'lsp-test.ogg' sample:
> 
> stddev:    0.76 PSNR: 98.69 bytes:  3498380/  3498452
> ---
>  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 ?

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

Why not whip the teacher when the pupil misbehaves? -- Diogenes of Sinope
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