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Andreas Rheinhardt df3269f5f7 avcodec/rv10: Reduce number of exceptions when reading VLC value 
RealVideo 1.0 uses an insane way to encode DC coefficients: There are
several symbols that (for no good reason whatsoever) have multiple
encodings, leading to longer codes than necessary.

More specifically, the tree for the 256 luma symbols contains 255 codes
belonging to 255 different symbols on the left; going further right,
the tree consists of two blocks of 128 codes each of length 14 encoding
consecutive numbers (including two encodings for the symbol missing among
the 255 codes on the left); this is followed by two blocks of codes of
length 16 each containing 256 elements with consecutive symbols (i.e.
each of the blocks allows to encode all symbols). The rest of the tree
consists of 2^11 codes that all encode the same symbol.

The tree for the 256 chroma symbols is similar, but is missing the
blocks of length 256 and there are only 2^9 consecutive codes that
encode the same symbol; furthermore, the chroma tree is incomplete:
The right-most node has no right child.

All of this caused problems when parsing these codes; the reason is that
the code for this predates commit b613bacca9
which added support for explicit symbol tables and thereby removed the
requirement that different codes have different symbols. In order to
address this, the trees used for parsing were incomplete: They contained
the 255 codes on the left and one code for the remaining symbol. Whenever
a code not in these trees was encountered, it was dealt with in
special cases (one for each of the blocks mentioned above).

This commit reduces the number of special cases: Using a symbols table
allows to treat the blocks of consecutive symbols like ordinary codes;
only the blocks encoding a single symbol are still treated specially
(in order not to waste memory on tables for them).

In order to not increment the size of the tables used to initialize the
VLCs both the symbols as well as the lengths are now run-length encoded.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2020-12-08 17:51:45 +01:00
compat avfilter/scale_cuda: add lanczos algorithm 2020-11-04 01:43:21 +01:00
doc hlsenc: expand hls_fmp4_init_filename with strftime() 2020-12-08 21:02:23 +08:00
ffbuild ffbuild: Refine MIPS handling 2020-07-23 16:30:02 +02:00
fftools fftools/ffprobe: add support for HDR10+ metadata 2020-12-05 19:20:11 -03:00
libavcodec avcodec/rv10: Reduce number of exceptions when reading VLC value 2020-12-08 17:51:45 +01:00
libavdevice avdevice/decklink: remove the duplicated warning message 2020-12-05 09:00:53 +08:00
libavfilter avfilter/aeval: add timeline support for aeval 2020-12-08 15:34:14 +01:00
libavformat hlsenc: expand hls_fmp4_init_filename with strftime() 2020-12-08 21:02:23 +08:00
libavresample
libavutil hwcontext_vulkan: wait and signal semaphores when transferring to CUDA 2020-12-05 23:53:23 +01:00
libpostproc Bump minor versions after branching 4.3 2020-06-08 22:49:04 +02:00
libswresample swresample/audioconvert: Fix left shift of negative value 2020-09-30 10:50:45 +02:00
libswscale lsws/x86/yuv2rgb: Fix compilation with mmxext or ssse3 disabled. 2020-11-14 15:37:57 +01:00
presets
tests avfilter/af_earwax: fix filter behavior 2020-12-07 21:09:08 +01:00
tools tools/target_bsf_fuzzer: set bitstream filter options 2020-11-20 19:20:33 -03:00
.gitattributes
.gitignore
.mailmap mailmap: add entry for myself 2020-07-13 11:24:04 +08:00
.travis.yml
Changelog avformat/mspdec: Microsoft Paint (MSP) demuxer 2020-12-06 20:03:47 +11:00
configure avcodec/dxva2: add AV1 decode support 2020-11-12 15:55:16 +01:00
CONTRIBUTING.md
COPYING.GPLv2
COPYING.GPLv3
COPYING.LGPLv2.1
COPYING.LGPLv3
CREDITS
INSTALL.md
LICENSE.md
MAINTAINERS avformat: add amv muxer 2020-11-09 14:58:38 +10:00
Makefile tools/enum_options: fix build and add to Makefile 2020-11-20 15:20:24 +01:00
README.md
RELEASE RELEASE: We are after the 4.3 branch point, update for that 2020-06-10 00:20:24 +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.