[Mp4-tech] the CAVLC code design in MPEG4 (part10)

[i.g.richardson rgu.ac.uk]

Hello
I think you should refer to the original proposal for these codes and perhaps contact the authors if you require further information about the motivation for the design:
JVT Document JVT-C028, G.Bjontegaard and K. Lillevold, “Context-Adaptive VLC Coding of Coefficients”, Fairfax, VA, May 2002
You can get this document from ftp.imtc-files.org/jvt-experts
Regards
Iain Richardson
-----Original Message-----
From: yux porchlight.ca [mailto:yux porchlight.ca] 
Sent: 26 November 2023 15:46
To: Iain Richardson (ensigr)
Cc: yux porchlight.ca; mp4-tech lists.mpegif.org
Subject: RE: [Mp4-tech] the CAVLC code design in MPEG4 (part10)
Thanks a lot, Richardson,
I have read your tutorial. It is very helpful. The image of what to do to implement the code is clear. I am wondering if you could help me with some further questions, as how the code is designed as like below. Thanks in advance.
1. How is the context represented while designing the lookup tables?
  I may guess that some empirical distributions are built up
  for non-zero coefficient in all positions? E.g., p(x1) for
  the first non-zero quantized coefficient, p(x2) for the second.
  (The first here is the last one in the zigzag as the coding
  process is carried on in the inverse order).
  Is this right for the CAVLC design in MPEG4(part10)?
  If yes, is it possible for me to find a report on this?
  If no, how is the context represented and formed?
2. What is the design criterion for these tables? For example,
  what is the point behind the '0...01x...xs' structure of Level
  VLC1-6? Or, what is done from the context to code tables?
3. What is the criterion to determine the table switch threshold
  for VLC0-6? Or how does it depend on the number of non-zero
  coefficients in neighbouring blocks?
Thanks again and best regards,
shaun
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