[FFmpeg-devel] [PATCH 3/6] avformat/matroskaenc: Split updating CodecPrivate from writing it

Michael Niedermayer michael at niedermayer.cc
Tue Jun 21 18:22:48 EEST 2022


On Tue, Jun 21, 2022 at 04:34:15AM +0200, Andreas Rheinhardt wrote:
> Up until now, updating extradata was very ad-hoc: The amount of
> space reserved for extradata was not recorded when writing the
> header; instead the AAC code simply presumed that it was enough.
> This commit changes this by recording how much space is available.
> 
> This brings with it that the code for writing of and reserving space
> for the CodecPrivate and for updating it diverges. They are therefore
> split; this allows to put other common tasks like seeking to
> right offset as well as writing padding (in case the new extradata did
> not fill the whole reserved space) to this common function.
> 
> The code for filling up the reserved space is smarter than the code
> it replaces; therefore it is no longer necessary to reserve more
> than necessary just to be sure that one can add an EBML Void element
> (whose minimum size is two) lateron. This is the reason for the change
> to the aac-autobsf-adtstoasc test.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
>  libavformat/matroskaenc.c            | 120 ++++++++++++++++++---------
>  tests/ref/fate/aac-autobsf-adtstoasc |   4 +-
>  2 files changed, 84 insertions(+), 40 deletions(-)

triggers assert in fate

ffmpeg/ffmpeg -nostdin         -i fate-suite//audiomatch/tones_afconvert_16000_mono_aac_lc.m4a         -f segment -segment_time 1 -map 0 -flags +bitexact -codec copy -segment_format_options live=1         -segment_list ffmpeg/tests/data/adts-to-mkv.m3u8 -y ffmpeg/tests/data/adts-to-mkv-%03d.mkv

  Metadata:
    major_brand     : M4A 
    minor_version   : 0
    compatible_brands: M4A mp42isom
    creation_time   : 2024-12-23T09:22:20.000000Z
    iTunSMPB        :  00000000 00000840 000002C0 0000000000007D00 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
  Duration: 00:00:02.18, start: 0.132000, bitrate: 35 kb/s
  Stream #0:0[0x1](eng): Audio: aac (LC) (mp4a / 0x6134706D), 16000 Hz, mono, fltp, 20 kb/s (default)
    Metadata:
      creation_time   : 2024-12-23T09:22:20.000000Z
      vendor_id       : [0][0][0][0]
[segment @ 0x562c56aa3f40] Opening 'ffmpeg/tests/data/adts-to-mkv-000.mkv' for writing
Assertion codecpriv_size < max_payload_size failed at libavformat/matroskaenc.c:1239
Aborted (core dumped)

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

Take away the freedom of one citizen and you will be jailed, take away
the freedom of all citizens and you will be congratulated by your peers
in Parliament.
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