[FFmpeg-devel] [PATCH] avcodec/vorbisdec: Dont treat overread as error

[FFmpeg-devel] [PATCH] avcodec/vorbisdec: Dont treat overread as error

[Michael Niedermayer]

This differs from libvorbis by
stddev:    2.44 PSNR: 88.58 MAXDIFF:   41 bytes:   834304/   834304
for the file from the ticket

Fixes: Ticket11427

Regression since: dc89cf804a811c0d25f4649a99f7fab4b5b416fa

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/vorbisdec.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/libavcodec/vorbisdec.c b/libavcodec/vorbisdec.c
index a778dc6b587..adbd7261832 100644
--- a/libavcodec/vorbisdec.c
+++ b/libavcodec/vorbisdec.c
@@ -1469,8 +1469,10 @@ static av_always_inline int vorbis_residue_decode_internal(vorbis_context *vc,
                             unsigned step = FASTDIV(vr->partition_size << 1, dim << 1);
                             vorbis_codebook codebook = vc->codebooks[vqbook];
 
-                            if (get_bits_left(gb) <= 0)
-                                return AVERROR_INVALIDDATA;
+                            if (get_bits_left(gb) < 0) {
+                                av_log(vc->avctx, AV_LOG_ERROR, "Overread %d bits\n", -get_bits_left(gb));
+                                return 0;
+                            }
 
                             if (vr_type == 0) {
 
-- 
2.49.0

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Re: [FFmpeg-devel] [PATCH] avcodec/vorbisdec: Dont treat overread as error

[Michael Niedermayer]

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On Sun, Apr 06, 2025 at 05:35:02PM +0200, Michael Niedermayer wrote:
> This differs from libvorbis by
> stddev:    2.44 PSNR: 88.58 MAXDIFF:   41 bytes:   834304/   834304
> for the file from the ticket
> 
> Fixes: Ticket11427
> 
> Regression since: dc89cf804a811c0d25f4649a99f7fab4b5b416fa
> 
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavcodec/vorbisdec.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)

will apply

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

He who knows, does not speak. He who speaks, does not know. -- Lao Tsu

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