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Before this patch, the DFPWM1a encoder was marked as supporting variable frame sizes. The DFPWM1a format converts eight bytes of input into one output byte and so it simply padded the number of data output by frame->nb_samples * frame->ch_layout.nb_channels / 8 + (frame->nb_samples % 8 > 0 ? 1 : 0) This has several bugs: a) The additional byte leads to eight additional input byte being read; this can read into the frame's padding, i.e. the data can be uninitialized. b) The criterion for whether one should pad is wrong: nb_samples * nb_channels should be tested for divisibility by eight. c) The created frames can be undecodable (at least with our decoder): Our decoder requires the number of bits per frame to divisible by the number of channels, yet the above approach does not guarantee this. d) The padding will be added in the middle of the stream (potentially for every packet). This commit fixes all of this by removing the variable frame size cap and using AVCodecInternal.pad_samples to pad the last frame so that nb_samples * nb_channels is always a multiple of eight. The lavf-dfpwm FATE-test was affected by a). The frames originated from lavfi and were part of an audio frame pool, so that the padding contained data from an earlier (bigger) frame. Now the last frame is properly filled with silence. Reported-by: Paul B Mahol <onemda@gmail.com> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
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.