dc2f6b54ac
Up until e7ddafd5, the Matroska muxer wrote two SeekHeads: One at the beginning referencing the main level 1 elements (i.e. not the Clusters) and one at the end, referencing the Clusters. This second SeekHead was useless and has therefore been removed. Yet the SeekHead-related functions and structures are still geared towards this usecase: They are built around an allocated array of variable size that gets reallocated every time an element is added to it although the maximum number of Seek entries is a small compile-time constant, so that one should rather include the array in the SeekHead structure itself; and said structure should be contained in the MatroskaMuxContext instead of being allocated separately. The earlier code reserved space for a SeekHead with 10 entries, although we currently write at most 6. Reducing said number implied that every Matroska/Webm file will be 84 bytes smaller and required to adapt several FATE tests; furthermore, the reserved amount overestimated the amount needed for for the SeekHead's length field and how many bytes need to be reserved to write a EBML Void element, bringing the total reduction to 89 bytes. This also fixes a potential segfault: If !mkv->is_live and if the AVIOContext is initially unseekable when writing the header, the SeekHead is already written when writing the header and this used to free the SeekHead-related structures that have been allocated. But if the AVIOContext happens to be seekable when writing the trailer, it will be attempted to write the SeekHead again which will lead to segfaults because the corresponding structures have already been freed. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@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 a mean to alter decoded Audio and Video through chain of 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.