bnnm c61b28e042 avcodec/atrac3: Add multichannel joint stereo ATRAC3
Multichannel joint stereo simply interleaves stereo pairs (6ch: 2ch + 2ch + 2ch), so each pair is decoded separatedly.

***

To test my changes, I converted examples to wav with ffmpeg.exe (old and new), and compared them to see they are byte-exact.

Regular 2ch files (JS and normal) were straightforward to test.

For multichannel, to check each JS pair is correctly decoded separatedly I did:
- manually demux 6ch.msf into 3 pairs and convert them (2ch_1.wav + 2ch_2.wav + 2ch_3.wav)
- convert the 6ch.msf file to wav (with my changes)
- manually demux the 6ch.wav into 3 pairs (6ch_d1.wav + 6ch_d2.wav + 6ch_d3.wav)
- compare each pair (ex. 2ch_3.wav vs 6ch_d3.wav): all pairs are byte-exact.

The new code just processes each JS pair separatedly, there are no algorithm changes.
It could be improved a bit but I'm not sure about typical styles.
I've only seen 6ch .MSF (probably the AT3 spec only supports 2ch audio).

Signed-off-by: bnnm <bananaman255@gmail.com>
2017-02-01 19:14:12 +01:00
2017-01-27 17:06:42 +01:00
2017-01-30 18:44:08 +01:00
2016-11-27 20:46:20 +01:00
2016-10-26 20:52:43 +02:00

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.
  • ffserver is a multimedia streaming server for live broadcasts.
  • 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.

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