[vorbis-dev] patents and separate entropy coding

[Frank Klemm]

Ist there any patent in transforming 2 channel data in the following way:

 * input are vectors x1 and x2 (usually the left and right channel)
 * Make a simple linear correlation 
       x2 = a1*x1 + b1   and 
       x1 = a2*x2 + b2
 * Calculate r = a1*a2
 * Calculate a = (atan (a1) + atan (1/a2)) / pi + 1
   ( a has a range from 0...2:
     x1 = 0 : a = 0.0  or  2.0
     x1 =-x2: a = 0.5
     x2 = 0 : a = 1.0
     x1 = x2: a = 1.5
   )
 * optional: if (a >= 1.) a -= 1.
   (Note: Then it is possible that the S signal is stronger than the M
   signal)
 * Quantize a to a' and store a' in the bit stream
 * make a transformation for L and R to CH1 and CH2 with
   S = sin (pi/2 a') and C = cos (pi/2 a')     

    / CH1 \     / C -S \   / L \
   (       ) = (        ) (     )
    \ CH2 /     \+S  C /   \ R /

 * Compress CH1 and CH2 instead of L and R

 * If there are multiple channels, you can use the multiple r to estimate
   the useful precision of the a'(n) and store this (no_of_bits) with
   additional 2 or 3 bits.

 * Remark: no_of_bits = 1 is like MS <=> LR switching used in MP2, MP3, AAC,
   MP+ and much much more.

 * Remark: I'm using this technique to (lossless) compress technical signals
   for years. This method you can found in many ancient books under the
   terms "MDS", "Merkmalsextraktion", "Merkmalsraum".

 * This can be extended to multi channel coding.


-- 
Mit freundlichen Grüßen
Frank Klemm
 
eMail | pfk at uni-jena.de       home: pfk at schnecke.offl.uni-jena.de
phone | +49 (3641) 64-2721    home: +49 (3641) 390545
sMail | R.-Breitscheid-Str. 43, 07747 Jena, Germany

--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.