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Wiki > Main > SummerOfCode > SummerOfCode2009 > WavpackHybridSupport (r4)

Rockbox Support for Wavpack Hybrid Compression

Wavpack Hybrid Compression

The Wavpack audio codec supports an unusual "hybrid" compression mode. In this mode, a traditional lossy file is complemented by a "correction" file. When the two are decoded together, the original input bitstream can be recreated exactly. The lossy file may also be decoded on its own.

Rockbox currently handles lossy files but ignores the correction files.


  • Correctly decode hybrid files on a PC with Rockbox code (complete and verified for stereo files)
  • Implement support for buffering two (or more) files in a codec-independent manner (vaguely working)
  • Ensure real-time decoding on a Rockbox target (decoding but not tested real-time on target)
  • Implement seeking in hybrid files with correction info present (should already work imprecisely, but untested)
  • Add support for and check more obscure formats, like hybrid mono lossless and old-style hybrid shaping code

Useful Info

Wavpack spec description: here. Wavpack file format: here.

Current Status

Decoding of stereo hybrid lossless files functions off-target. The patch is at . This does NOT run on a device; use to run the codec!

Decoding on-target works via a modification to the buffering system at . This will NOT play nice with other files and is not ready for general consumption.

Currently fixing buffering code interactions to avoid data corruption
r4 - 28 Jun 2009 - 00:24:40 - BryanJacobs

Copyright by the contributing authors.