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When flushing, MAX_FRAME_HEADER_SIZE bytes (always zero) are supposed to be written to the fifo buffer in order to be able to check the rest of the buffer for frame headers. It was intended to write these by writing a small buffer of size MAX_FRAME_HEADER_SIZE to the buffer. But the way it was actually done ensured that this did not happen: First, it would be checked whether the size of the input buffer was zero, in which case it buf_size would be set to MAX_FRAME_HEADER_SIZE and read_end would be set to indicate that MAX_FRAME_HEADER_SIZE bytes need to be written. Then it would be made sure that there is enough space in the fifo for the data to be written. Afterwards the data is written. The check used here is for whether buf_size is zero or not. But if it was zero initially, it is MAX_FRAME_HEADER_SIZE now, so that not the designated buffer for writing MAX_FRAME_HEADER_SIZE is written; instead the padded buffer (from the stack of av_parser_parse2()) is used. This works because AV_INPUT_BUFFER_PADDING_SIZE >= MAX_FRAME_HEADER_SIZE. Lateron, buf_size is set to zero again. Given that since 7edbd536, the actual amount of data read is no longer automatically equal to buf_size, it is completely unnecessary to modify buf_size at all. Moreover, modifying it is dangerous: Some allocations can fail and because buf_size is never reset to zero in this codepath, the parser might return a value > 0 on flushing. 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.