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Wiki > Main > WavpackHybridSupport (compare)

Difference: WavpackHybridSupport (r3 vs. r2)

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.

Milestones

  • Correctly decode hybrid files on a PC with Rockbox code (complete and verified for stereo files but unverified )
  • Implement support for buffering two (or more) files in a codec-independent manner
  • Ensure real-time decoding on a Rockbox 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 http://q3q.us/hybrid.patch http://q3q.us/hybrid2.patch . This does NOT run on a device; use http://q3q.us/codec-executor.tar.bz2 to run the codec! Currently modifying Rockbox buffering code to handle more than one file at a time.

r5 - 17 Aug 2009 - 19:39:36 - BryanJacobs

Revision r3 - 20 Jun 2009 - 23:56 - BryanJacobs
Revision r2 - 16 Jun 2009 - 15:48 - BryanJacobs
Copyright by the contributing authors.