Re: [FFmpeg-devel] [PATCH v7 3/4] ogg/vorbis: implement header packet skip in chained ogg bitstreams.

From: Romain Beauxis <romain.beauxis@gmail.com>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH v7 3/4] ogg/vorbis: implement header packet skip in chained ogg bitstreams.
Date: Sat, 24 May 2025 13:08:06 -0500
Message-ID: <CABWZ6OSdBm6x_Opw3qf3mt8MD8kQ0dkFr+Y9n5Q9DJ3Gh_rTRw@mail.gmail.com> (raw)
In-Reply-To: <20250524004031.GI29660@pb2>

Le ven. 23 mai 2025 à 19:40, Michael Niedermayer <michael@niedermayer.cc> a
écrit :
>
> Hi Romain
>
> On Wed, May 21, 2025 at 05:05:37PM -0500, Romain Beauxis wrote:
> > ---
> >  libavcodec/vorbis_parser.h                 | 11 ++++
> >  libavcodec/vorbisdec.c                     | 75 +++++++++++++---------
> >  libavformat/oggparsevorbis.c               | 63 +++++++++++++++++-
> >  tests/ref/fate/ogg-vorbis-chained-meta.txt |  3 -
> >  4 files changed, 115 insertions(+), 37 deletions(-)
>
> make -j32 libavformat/tests/seek && libavformat/tests/seek
~/tickets/2739/lavf_ogm_seeking_borked.ogm
> CC      libavcodec/libvorbisenc.o
> CC      libavcodec/version.o
> CC      libavcodec/vorbis_parser.o
> CC      libavcodec/vorbisdec.o
> CC      libswresample/version.o
> CC      libavutil/version.o
> CC      libavformat/oggparsevorbis.o
> CC      libavformat/version.o
> AR      libswresample/libswresample.a
> AR      libavutil/libavutil.a
> AR      libavcodec/libavcodec.a
> AR      libavformat/libavformat.a
> LD      libavformat/tests/seek
> [ogg @ 0x558349c4f3c0] Headers mismatch for stream 1: expected 3 received
2.
> [ogg @ 0x558349c4f3c0] Headers mismatch for stream 2: expected 3 received
2.
> ret: 0         st: 0 flags:1 dts:-0.083417 pts: 0.000000 pos:    887
size:  3347
> ret: 0         st:-1 flags:0  ts:-1.000000
> ret: 0         st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos:    887
size:  3347
> ret: 0         st:-1 flags:1  ts: 1.894167
> ret: 0         st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos:    887
size:  3347
> ret: 0         st: 0 flags:0  ts: 0.792458
> ret: 0         st: 1 flags:1 dts: 12.481333 pts: 12.481333 pos:2855209
size:   269
> ret: 0         st: 0 flags:1  ts:-0.333666
> ret: 0         st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos:    887
size:  3347
> ret: 0         st: 1 flags:0  ts: 2.576667
> ret: 0         st: 1 flags:1 dts: 2.785333 pts: 2.785333 pos: 559697
size:   255
> ret: 0         st: 1 flags:1  ts: 1.470833
> ret: 0         st: 1 flags:1 dts: 1.164000 pts: 1.164000 pos: 192278
size:   275
> ret: 0         st: 2 flags:0  ts: 0.365000
> ret: 0         st: 2 flags:1 dts: 0.332000 pts: 0.332000 pos:  18959
size:   271
> Segmentation fault (core dumped)
>
> on samples server: ffmpeg-bugs/trac/ticket2739/lavf_ogm_seeking_borked.ogm

Thanks for pointing this one out. I got tricked by the permissive memory
model on macos where it wouldn't segfault but was able to reproduce and fix
on a debian machine.

I'm gonna send an updated patchset. I've also added a FATE test for this
sample, given it's importance during this review, it seems natural to
include it.

-- Romain

> thx
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> The worst form of inequality is to try to make unequal things equal.
> -- Aristotle
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