[Mp4-tech] RE: Mp4-tech Digest, Vol 44, Issue 15

[Pradeep Kumar P]

Siva,
Dear Siva,
Your query is slightly confusing. But I would like to answer, with the
understanding I have. You mean to ask why LPS have a range 2 
and MPS have range DRange-2?
As far the knowledge I have, this (biari_encode_symbol_final() or
decode_termination ()) is used for "end_of_slice" and "mb_type=I_PCM." If
any one of this happens, the CABAC decoding needs to be terminated, followed
by the reading the next syntax elements in the sequence, which are not
encoded using CABAC. At time of decoding the binVal, the 
codlOffset will have 9 bits in it, which corresponds to the CABAC encoded
syntax element. Next non-CABAC syntax elements should be read after this.
If you look at the CABAC encoding side, keeping a range 2 for the LPS will
lead to a renormalization process giving 7 bit output, 
(to reach from 2 to 256). Two more unambiguous bit are added to it. (Refer
to ITU Document JVT-G050, on CABAC encoding )
At the decoding also the same range is used (same context model )and if
binVal is 1(LPS), CABAC decoding is terminated and value in the codlOffset
is discarded. 
The next non-CABAC coded syntax element can be read from the bit stream.
So it appears that keeping Range =2 for LPS,  leading to 7 bit by
renormalization, plus extra 2 bits (one to indicate rbsp_stop_one_bit for
the slice) will automatically adjust the CABAC to non-CABAC stream boundary
enabling easy alignment at decoder. 
At the decoder if the binval is 1, decode terminate will
 not execute renormalisation, and decoder will not read more bits than
produced by the encoder for the slice. (Refer to ITU Document JVT-G050, on
CABAC decoding )
This is the explanation I have on your query with my limited knowledge.
More query, you may better ask the creators of CABAC!!!!
regards
Pradeep Kumar P
Patni Computers System Ltd
SEEPZ, Mumbai.
-----Original Message-----
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Subject: Mp4-tech Digest, Vol 44, Issue 15
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Today's Topics:
   1. Doubt in biari_encode_symbol_final (sivajanakiraman zapak.com)
   2. Building JM10.2 decoder code (Mayank Agarwal)
----------------------------------------------------------------------
Message: 1
Date: Wed, 14 Mar 2024 18:47:28 +0530
From: "sivajanakiraman zapak.com" <sivajanakiraman zapak.com>
Subject: [Mp4-tech] Doubt in biari_encode_symbol_final
To: mp4-tech lists.mpegif.org
Message-ID: <200703141317.l2EDHY6W005988 smtp1.zapak.com>
Content-Type: text/plain
Dear Experts,
I am a beginner in H.264/AVC. I am working with CABAC. I have a doubt in
binary encoding. In the reference software among the 3functions used for
binary encoding, biari_encode_symbol uses rlps table to find the
range,biari_encode_symbol_eq_prob uses probability of 0.5 & not using the
rlps table, in biari_encode_symbol_final i want to know why the range for
symbol'1' is taken as 2 and the range for symbol'0' is taken as Erange -2 .
Thanks in advance.
regards
siva.J 
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------------------------------
Message: 2
Date: Thu, 15 Mar 2024 10:51:44 +0530
From: "Mayank Agarwal" <mayank_2001 hotmail.com>
Subject: [Mp4-tech] Building JM10.2 decoder code
To: mp4-tech lists.mpegif.org
Message-ID: <BAY125-F15894CFC791B61325262DF82720 phx.gbl>
Content-Type: text/plain; format=flowed
Hi all,
I am tryong to run JM10.2 reference decoder code on Visual Studio.It has 
been mentioned in the Readme.txt to give decoder.cfg as argument.In decoder 
configuration file decoder.cfg test.264 is mentioned as the configuration 
file but this file is missing from the JM folder.Can anyone tell me how can 
i be able to build the reference code and also from where i can download 
H.264 encoded streams.If i want to give any other H.264 encoded stream as 
input to the decoder then how will i be able to do that.
Regards,
Mayank
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