20e8be0c20
The following three commits created a regression by writing initially invalid mkv headers: 650e17d88b63b5aca6e0a43483e89e64b0f7d2dd avformat/matroskaenc: write a CRC32 element on Tags 3bcadf822711720ff0f8d14db71ae47cdf97e652 avformat/matroskaenc: write a CRC32 element on Info ee888cfbe777cd2916a3548c750e433ab8f8e6a5 avformat/matroskaenc: postpone writing the Tracks master Symptoms: - You can no longer playback a file that is still processed by ffmpeg, e.g. VLC fails playback - You can no longer stream a file to a client while if is still being processed - Various diagnosing tools show header errors or incomplete headers (e.g. ffprobe, mediainfo, mkvalidator) Note: The symptoms do not apply to completed files or ffmpeg runs that were interrupted with 'q' Cause: The mentioned commits made changes in a way that some header elements are only partially written in mkv_write_header, leaving the header in an invalid state. Only in mkv_write_trailer, these elements are finished correctly, but that does only occur at the end of the process. Regression: Before these commits were applied, mkv headers have always been valid, even before completion of ffmpeg. This has worked reliably over many versions of ffmpeg, to it was an obvious regression. Bugtracker: This issue has been recorded as #5977 which is resolved by this patch Patch: The patch adds a new function 'end_ebml_master_crc32_preliminary' that preliminarily finishes the ebml element without destroying the buffer. The buffer can be used to update the ebml element later during mkv_write_trailer. But most important: mkv_write_header finishes with a valid mkv header again. Signed-off-by: James Almer <jamrial@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.
- ffserver is a multimedia streaming server for live broadcasts.
- 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.