mirror of
https://git.ffmpeg.org/ffmpeg.git
synced 2026-08-12 13:23:48 +00:00
Marth64
3525544e48
Signed-off-by: Marth64 <marth64@proxyid.net> Raw Captions With Time (RCWT) is a format native to ccextractor, a commonly used open source tool for processing 608/708 closed caption (CC) sources. It can be used to archive the original, raw CC bitstream and to produce a source file file for later CC processing or conversion. As a result, it also allows for interopability with ccextractor for processing CC data extracted via ffmpeg. The format is simple to parse and can be used to retain all lines and variants of CC. A free specification of RCWT can be found here: https://github.com/CCExtractor/ccextractor/blob/master/docs/BINARY_FILE_FORMAT.TXT This muxer implements the specification as of 01/05/2024, which has been stable and unchanged for 10 years as of this writing. This muxer will have some nuances from the way that ccextractor muxes RCWT. No compatibility issues when processing the output with ccextractor have been observed as a result of this so far, but mileage may vary and outputs will not be a bit-exact match. Specifically, the differences are: (1) This muxer will identify as "FF" as the writing program identifier, so as to be honest about the output's origin. (2) ffmpeg's MPEG-1/2, H264, HEVC, etc. decoders extract closed captioning data differently than ccextractor from embedded SEI/user data. For example, DVD captioning bytes will be translated to ATSC A53 format. This allows ffmpeg to handle 608/708 in a consistant way downstream. This is a lossless conversion and the meaningful data is retained. (3) This muxer will not alter the extracted data except to remove invalid packets in between valid CC blocks. On the other hand, ccextractor will by default remove mid-stream padding, and add padding at the end of the stream (in order to convey the end time of the source video).
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 means to alter decoded audio and video through a directed graph of connected 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.