[vorbis] fake stereo

[SyP]

Hello all,

I created today a fake stereo piece of music (the left and right
channels were completely equal), and encoded it with the all the modes
the RC2 encoder supports, and found that:

          *        *  dual   *   waste   * waste *                    *
mode      * joint  * stereo  *    in     * in %  *                    *
          * stereo *   /2    *   kbits   * of JS *                    *
***********************************************************************
mode 350K * 232.4  * 138.5   **  93.9      40.4                       *
**************************************************    LOSSLESS        *
mode 256K * 177.8  * 138.5   **  39.3      22.1       COUPLING        *
***********************************************************************
mode 192K * 147.0  * 102.5   **  44.5      30.3                       *
**************************************************                    *
mode 160K * 120.7  *  68.5   **  52.2      43.2                       *
**************************************************                    *
mode 128K * 101.2  *  51.0   **  50.2      49.6        LOSSY          *
**************************************************    COUPLING        *
mode  96K *  66.1  *  38.0   **  28.1      42.5                       *
**************************************************                    *
mode  80K *  53.9  *  38.0   **  15.9      29.5                       *
**************************************************                    *
mode  64K *  44.0  *  29.5   **  14.5      33.0                       *
***********************************************************************

notes:
- In 128K mode joint stereo was almost as bad as dual stereo
- some dual stereo modes gave the same bitrates, i.e. 96K=80K,
  350K=256K
- the percentiles represents the approximate size gain which could be
  achievable if Vorbis would handle fake stereo files smarter
- I know this experiment may seem silly, since I could preferably
  convert the song to mono before encoding, but there could be a
  number of CDs of older recordings, which were originally recorded as
  mono and burned as fake stereo, right?

Comments?
  

-- 
Cheers,             _____________________________
  SyP              (_Szabolcs Péter  PGP Key ID:
_____________________)ICQ# 69968772  0x098AEC13

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