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FFmpeg git repo
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This check is intended to be avoid buffer overflows, yet there are four problems with it: 1. It has an in-built off-by-one error: len == out_end - out is perfectly fine and nothing to worry about. This off-by-one error led to the pixel in the lower-right corner not being set properly for the back frame of the sample from the rl2 FATE-test. This pixel is copied to every frame which is the reason for the update to the reference file of said test. With this patch, the output of the decoder matches the output as captured from the reference decoder* (apart from the fact that said reference somehow lacks the top part of the frame (copied over from the background frame)). 2. Given that the stride of the buffer may be different from the width of the video (despite one pixel taking one byte), there is a second check lateron making the first check redundant (if one returns immediately; a simple break at the second check is not sufficient, because it only exits the inner loop). 3. The check is based around the assumption of the stride being positive (it has this in common with the other check which will be fixed in a future commit). 4. Even after fixing the off-by-one error, the check in question is still triggered by all the non-background frames in the FATE sample as well as by A1100100.RL2. In all these cases, they use len == 255 and val == 128. For videos with background frame this just means "copy from the background frame", which would be done anyway lateron.* Yet for videos without it copying it is necessary to avoid leaving uninitialized parts in the video. *: Available in https://samples.mplayerhq.hu/game-formats/voyeur-rl2/ **: Due to this, the code that copies the rest from the back frame is no longer executed for any of the samples available on the sample server. Given that these are only the files from the demo version of this game, I don't know whether this code is executed for any file in existence or not. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com> |
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compat | ||
doc | ||
ffbuild | ||
fftools | ||
libavcodec | ||
libavdevice | ||
libavfilter | ||
libavformat | ||
libavutil | ||
libpostproc | ||
libswresample | ||
libswscale | ||
presets | ||
tests | ||
tools | ||
.gitattributes | ||
.gitignore | ||
.mailmap | ||
.travis.yml | ||
Changelog | ||
configure | ||
CONTRIBUTING.md | ||
COPYING.GPLv2 | ||
COPYING.GPLv3 | ||
COPYING.LGPLv2.1 | ||
COPYING.LGPLv3 | ||
CREDITS | ||
INSTALL.md | ||
LICENSE.md | ||
MAINTAINERS | ||
Makefile | ||
README.md | ||
RELEASE |
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 means to alter decoded audio and video through a directed graph of connected 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
andqt-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.