[vorbis] channel coupling in rc2

Aleksandar Dovnikovic aldov at eunet.yu
Mon Sep 3 12:10:01 PDT 2001

Hello Jernej,

Monday, 03 September, 2001, 18:59:35, you wrote:

MLF>> Which of the bitrates in RC2 utilize channel coupling and which don't?
JS> All stereo (2-channel). Lossy coupling is used for 128kbit and lower,
JS> lossless coupling is used at 160kbit and higher.

Not exactly... here's the info straight from Monty:

- up to 96kbps lossless stereo to 4/6kHz (depending on block),
  point/6phase/lossless stereo above that

- 128 lossless stereo to 4/6kHz, 6phase/lossless to 11kHz,
  point/6phase/lossless stereo above

- 160 lossless stereo to 4/6kHz, 8phase/lossless to 11kHz,
  point/8phase/6phase/lossless above

- 192 lossless stereo to 4/6kHz, 8 phase/lossless above 

- 256+ lossless coupling 

The trigger between different stereo models is currently amplitude
based (how far the spectral energy is from the noise floor).
The trigger threshholds are also increasingly conservative as bitrate

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