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This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
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. Few developers
follow pull requests so they will likely be ignored.