68c7186d94
Since commit 4aa0665f393847c35387a1c673e62346d0acfc95, the dynamic buffer destined for the contents of the current Cluster is no longer constantly allocated, reallocated and then freed after writing the content; instead it is reset and reused when closing a Cluster. Yet the code in mkv_write_trailer() still checked for whether a Cluster is open by checking whether the pointer to the dynamic buffer is NULL or not (instead of checking whether the position of the current Cluster is -1 or not). If a Cluster was not open, an empty Cluster would be output. One usually does not run into this issue, because unless there are errors, there are only three possibilities to not have an opened Cluster at the end of writing a packet: The first is if one sent an audio packet to the muxer. It might trigger closing and outputting the old Cluster, but because the muxer caches audio packets internally, it would not be output immediately and therefore no new Cluster would be opened. The second is an audio packet that does not contain data (such packets are sometimes sent for side-data only, e.g. by the FLAC encoder). The only difference to the first scenario is that such packets are not cached. The third is if one explicitly flushes the muxer by sending a NULL packet via av_write_frame(). If one also allows for errors, then there is also another possibility: Caching the audio packet may fail in the first scenario. If one calls av_write_trailer() after the first scenario, the cached audio packet will be output when writing the trailer, for which a Cluster is opened and everything is fine; because flushing the muxer does currently not output the cached audio packet (if one is cached), the issue also does not exist if an audio packet has been cached before flushing. The issue only exists in one of the other scenarios. 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.