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Andreas Rheinhardt d9182f04ca cbs_mpeg2: Fix parsing of picture and slice headers 
1. The extra information in slice headers was parsed incorrectly:
In the first reading pass to derive the length of the extra information,
one should look at bits n, n + 9, n + 18, ... and check whether they
equal one (further extra information) or zero (end of extra information),
but instead bits n, n + 8, n + 16, ... were inspected. The second pass
of reading (where the length is already known and the bytes between the
length-determining bits are copied into a buffer) did not record what
was in bits n, n + 9, n + 18, ..., presuming they equal one. And during
writing, the bytes in the buffer are interleaved with set bits and
written. This means that if the detected length of the extra information
was greater than the real length, the output was corrupted. Fortunately
no sample is known that made use of this mechanism: The extra information
in slices is still marked as reserved in the specifications. cbs_mpeg2
is now ready in case this changes.

2. Furthermore, the buffer is now padded and slightly different, but
very similar code for reading resp. writing has been replaced by code
used for both. This was made possible by a new macro, the equivalent
to cbs_h2645's fixed().

3. These changes also made it possible to remove the extra_bit_slice
element from the MPEG2RawSliceHeader structure. Said element was always
zero except when the detected length of the extra information was less
than the real length.

4. The extra information in picture headers (which uses essentially the
same syntax as the extra information in slice headers) has simply been
forgotten. This meant that if this extra information was present, it was
discarded during reading; and unfortunately writing created invalid
bitstreams in this case (an extra_bit_picture - the last set bit of the
whole unit - indicated that there would be a further byte of data,
although the output didn't contain said data).

This has been fixed; both types of extra information are now parsed via
the same code and essentially passed through.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2019-07-27 22:00:43 +01:00
compat compat/cuda/ptx2c: don't drop final newline 2019-05-24 19:23:39 +02:00
doc avfilter/af_dynaudnorm: add more descriptive aliases for options 2019-07-24 15:20:47 +01:00
ffbuild Merge commit '7e5bde93a1' 2019-03-10 19:31:13 -03:00
fftools ffmpeg_opt: Respect default disposition when select audio/video 2019-07-03 10:33:44 +08:00
libavcodec cbs_mpeg2: Fix parsing of picture and slice headers 2019-07-27 22:00:43 +01:00
libavdevice Bump minor versions again on master to keep 4.2 versions separate from master 2019-07-21 18:36:31 +02:00
libavfilter libavfilter/dnn: move dnn files from libavfilter to libavfilter/dnn 2019-07-26 13:07:43 -03:00
libavformat avcodec/adpcm: add support for 5.1 ADPCM MS 2019-07-26 11:57:06 +01:00
libavresample avresample: remove deprecated attribute from the AVAudioResampleContext struct 2018-01-09 10:56:53 -03:00
libavutil Bump minor versions again on master to keep 4.2 versions separate from master 2019-07-21 18:36:31 +02:00
libpostproc Bump minor versions again on master to keep 4.2 versions separate from master 2019-07-21 18:36:31 +02:00
libswresample Bump minor versions again on master to keep 4.2 versions separate from master 2019-07-21 18:36:31 +02:00
libswscale Bump minor versions again on master to keep 4.2 versions separate from master 2019-07-21 18:36:31 +02:00
presets presets: remove moldering iPod presets 2014-06-17 16:15:04 -08:00
tests avcodec/adxenc: add EOF header 2019-07-25 15:13:09 +01:00
tools tools/target_dec_fuzzer: Free parser in case of avcodec_open2() failure 2019-07-21 12:33:35 +02:00
.gitattributes fate: add SCC test 2017-01-27 17:06:42 +01:00
.gitignore tools/python: add script to convert TensorFlow model (.pb) to native model (.model) 2019-07-01 10:23:47 -03:00
.travis.yml Merge commit '899ee03088' 2019-03-14 15:53:16 -03:00
Changelog Changelog: Add 4.2 cut marker 2019-07-21 18:25:21 +02:00
configure avutil/mips: optimize UNPCK&SAD macros with MSA2.0 instruction. 2019-07-10 12:54:57 +02:00
CONTRIBUTING.md Add CONTRIBUTING.md 2016-09-18 10:02:13 +01:00
COPYING.GPLv2
COPYING.GPLv3
COPYING.LGPLv2.1
COPYING.LGPLv3
CREDITS CREDITS: redirect to Git log, remove current outdated content 2013-01-31 18:02:52 +01:00
INSTALL.md INSTALL.md: Fix Markdown formatting 2019-01-31 10:29:16 -09:00
LICENSE.md LICENSE: Clarify --enable-nonfree. 2019-05-10 01:18:58 +02:00
MAINTAINERS MAINTAINERS: remove myself as mailing list maintainer 2019-03-21 11:34:13 -08:00
Makefile tools: Add fuzzer for demuxers 2019-05-31 22:44:30 +02:00
README.md Remove the ffserver program 2018-01-06 18:31:37 +00:00
RELEASE RELEASE: Update value for post 4.2 branch 2019-07-21 18:37:32 +02:00

README.md

FFmpeg README

FFmpeg is a collection of libraries and tools to process multimedia content such as audio, video, subtitles and related metadata.

Libraries

  • libavcodec provides implementation of a wider range of codecs.
  • libavformat implements streaming protocols, container formats and basic I/O access.
  • libavutil includes hashers, decompressors and miscellaneous utility functions.
  • libavfilter provides a mean to alter decoded Audio and Video through chain of filters.
  • libavdevice provides an abstraction to access capture and playback devices.
  • libswresample implements audio mixing and resampling routines.
  • libswscale implements 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, ismindex and qt-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.