[Mp4-tech] Help Required On H.264

[Tourapis, Alexis]

Dear Hari,
I would first suggest that you download JVT-S079. That would provide you
some information on how to configure the reference software.
As for decisions between intra and inter coded pictures (I can see you
are not asking about Macroblocks ;)), if you do not set the parameter
"RDPictureDecision", then such is done in a periodic fashion based on
the IntraPeriod flag. Note that this period is also affected by the
second parameter you mentioned, i.e., NumberBframes. That is, if you set
NumberBFrames to 2, and IntraPeriod to 5, then you will have an intra
frame every (NumberBFrames + 1) * IntraPeriod = (2 + 1)*5 = 15 frames.
Similarly for NumberBFrames = 1 and IntraPeriod = 3 you will have Intra
frames repeated every 6 frames, i.e.,
I0-B1-P2-B3-P4-B5-I6
One thing you have to observe however is that the above represents
timing order but not coding order. Instead coding order is as
I0-P2-B1-P4-B3-I6-B5 to better take advantage of the bipredictive
properties of B slices and improve coding efficiency (note that you do
not have to do so but it is a good idea). I would suggest trying to find
on the internet more information on how prediction on B slices within
AVC (or even B frames in older standards such as MPEG-2) work to
understand why there is an advantage in doing this in general. I would
also suggest though also checking how AVC can also take advantage of
Hierarchical coding structures to further improve performance.
Best regards,
Alexis
  _____  
From: mp4-tech-bounces lists.mpegif.org
[mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of hari prasath
Sent: Tuesday, September 19, 2023 12:26 AM
To: mp4-tech lists.mpegif.org
Subject: [Mp4-tech] Help Required On H.264
Dear Experts,
I had posted a doubt few days back and i got reply from the experts.I
would like to thank the experts who helped me.
I have a new doubt now,I am using the JM 10.2 Reference Encoder and I am
debudgging the code to understand the motion estimation module of it.I
want to know where exactly in the reference code(JM 10.2) the encoding
decision for the frame is taken...i.e how the encoder decides wheather
to code the current frame as Intra or Inter....on what criteria it takes
the decision.My test input is foreman sequence(3 frames) with frame
dimensions of 176x144.
Moreover in the encoder.cfg configuration file it is given that
NumberBFrames =1....what does it mean,Is it that out of three frames in
the input sequence one frame is to be coded as B frame...if so,which
frame among the three is B frame,How the encoder decides upon it? 
Thanks to the experts in advance
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