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ls_encode_line() encodes one line of input from left to right and to do so it uses the values of the left, upper left, upper and upper right pixels for prediction (i.e. the values that a decoder gets when it decodes the already encoded part of the picture). So a simple algorithm would use a buffer that can hold two lines, namely the current line as well as the last line and swap the pointers to the two lines after decoding each line. Yet if one is currently encoding the pixel with index k of a line, one doesn't need any pixel with index < k - 1 of the last line at all and similarly, no pixels with index >= k have been written yet. So the overlap in the effective lifetime is pretty limited and since the last patch (which stopped reading the upper left pixel and instead reused the value of the upper pixel from the last iteration of the loop) it is inexistent. Ergo one only needs one line and doesn't need to swap the lines out. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
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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
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.
Languages
C
90.1%
Assembly
7.9%
Makefile
1.3%
C++
0.2%
Objective-C
0.2%
Other
0.1%