Derek Buitenhuis
dae3679a9b
Advanced edit list support is entirely broken for fragmented MP4s,
currently. mov_fix_index is never run in mov_build_index, since
in fragmented MP4s the stco, stsz, stts, and stsc boxes have zero
entries, with the index being filled in as each fragment's trun
box is seen.
The result of this is that the skip samples is never set properly,
since half the code thinks it doesn't need to, as advanced_editlist
is enabled, but as mov_fix_index is never called, it doesnt get set.
This means that any edits for e.g. priming are not properly applied
as skip samples side data.
This also means remuxing to fragmented MP4 from progressive MP4 with
lavf will quietly drop the edit list, currently.
Example:
$ ffmpeg -loglevel quiet -advanced_editlist 1 -i non_fragmented.mp4 -f md5 -
MD5=d02d929f8eb4edef624758a298d5f7c6
$ ffmpeg -loglevel quiet -advanced_editlist 0 -i non_fragmented.mp4 -f md5 -
MD5=d02d929f8eb4edef624758a298d5f7c6
$ ffmpeg -loglevel quiet -advanced_editlist 1 -i fragmented.mp4 -f md5 -
MD5=e38b110f586fa886ff94e0ca98a95d59 <-- wrong, extra samples are output instead of being skipped
$ ffmpeg -loglevel quiet -advanced_editlist 0 -i fragmented.mp4 -f md5 -
MD5=d02d929f8eb4edef624758a298d5f7c6
We cannot call mov_fix_index after reading a trun box
since mov_fix_index seems to assume it is only called once, on a
fully complete index, an multiple calls to it don't seem like
they'd work, so the "best" option seems to be disabling advanced
edit list support entirely for the time being, as it is broken
for these types of files.
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
FFmpeg README
FFmpeg is a collection of libraries and tools to process multimedia content such as audio, video, subtitles and related metadata.
Libraries
libavcodecprovides implementation of a wider range of codecs.libavformatimplements streaming protocols, container formats and basic I/O access.libavutilincludes hashers, decompressors and miscellaneous utility functions.libavfilterprovides means to alter decoded audio and video through a directed graph of connected filters.libavdeviceprovides an abstraction to access capture and playback devices.libswresampleimplements audio mixing and resampling routines.libswscaleimplements color conversion and scaling routines.
Tools
- ffmpeg is a command line toolbox to manipulate, convert and stream multimedia content.
- ffplay is a minimalistic multimedia player.
- ffprobe is a simple analysis tool to inspect multimedia content.
- Additional small tools such as
aviocat,ismindexandqt-faststart.
Documentation
The offline documentation is available in the doc/ directory.
The online documentation is available in the main website and in the wiki.
Examples
Coding examples are available in the doc/examples directory.
License
FFmpeg codebase is mainly LGPL-licensed with optional components licensed under GPL. Please refer to the LICENSE file for detailed information.
Contributing
Patches should be submitted to the ffmpeg-devel mailing list using
git format-patch or git send-email. Github pull requests should be
avoided because they are not part of our review process and will be ignored.