[Mp4-tech] H264 Please help me about the CAVLC of H.264

[Song]

Thank you all for your help,
I can understand the decoding process now, but I cannot understand the encoding process yet.
Does any documents show the encoding theory?
Regards.
Bill
  ----- Original Message ----- 
  From: JK(Jeong Kwon) Kim 
  To: 'Song' ; mp4-tech lists.mpegif.org 
  Sent: Wednesday, September 28, 2023 2:17 PM
  Subject: RE: [Mp4-tech] H264 Please help me about the CAVLC of H.264
  It exactly follows the standard.
  level_prefix = 2
  suffixLength = 1
  level_suffix =0
  levelCode = (level_prefix << suffixLength) + level_suffix = 4
  Because levelCode is even, level[i] = (levelCode + 2) >> 1 = 3
  The table form of CAVLC can be easily understood, 
  so you had better read “JVT-F100d1.doc”
  By reading through both the standard and “JVT-F100d1.doc”,
  you can understand CAVLC concretely.
  I wish that this mail give you a slight help.
               JK Kim
------------------------------------------------------------------------------
  From: mp4-tech-bounces lists.mpegif.org [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Song
  Sent: Tuesday, September 27, 2023 8:34 PM
  To: mp4-tech lists.mpegif.org
  Subject: [Mp4-tech] H264 Please help me about the CAVLC of H.264
  Dear All,
  Please help me on CAVLC of H.264.
  I am reading the book, H.264 and MPEG-4 Video Compression Video Coding for Next-generation Multimedia,
  by Iain E. G. Richardson, about the CAVLC parts of H.264 at page 204, the book shows the following example:
  Reordered block:
  0,3,0,1,−1,−1,0,1,0. . .
  TotalCoeffs = 5 (indexed from highest frequency, 4, to lowest frequency, 0)
  total zeros = 3
  TrailingOnes = 3 (in fact there are four trailing ones but only three can be encoded as a ‘special
  case’)
  Encoding:
  Element                     Value                                             Code
  -----------------------------------------------------------------------------------------
  coeff token         TotalCoeffs = 5,                             0000100
                              TrailingOnes= 3 (use Table 1)
  TrailingOne sign (4)      +                                            0
  TrailingOne sign (3)      −                                             1
  TrailingOne sign (2)      −                                              1
  Level (1)             +1 (use suffixLength = 0)                 1 (prefix)
  Level (0)             +3 (use suffixLength = 1)                 001 (prefix) 0 (suffix)
  total zeros             3                                   111
  run before(4)         ZerosLeft = 3; run before =1          10
  run before(3)         ZerosLeft = 2; run before =0         1
  run before(2)         ZerosLeft = 2; run before =0         1
  run before(1)         ZerosLeft = 2; run before =1         01
  run before(0)         ZerosLeft = 1; run before = 1     No code required;
  last coefficient.
  The transmitted bitstream for this block is 000010001110010111101101.
  But I cannot understand the level(1) and level(0), how to get the prefix code value and suffix value? I look up the table of level_prefix, if value is 3, I can get the code of 0001, why does the example show me the 001 as code? 
  Why the suffix value is 0? why not 1? does that means 0 for +3, and 1 for -3?
  Thanks
  Regards.
  Bill.
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