[Mp4-tech] [H.264 Video]

[Gary Sullivan]

Pankaj Bajpai et al,
A "hierarchical GOP" (assuming I'm interpreting the term properly) is a
coding structure in which the use of reordering between picture decoding
order and picture output order takes the form of building up a
coarse-to-fine structuring of temporal dependencies.
For example, there might be a first conceptual layer consisting of an I
frame followed by P frames at a very low frame rate.
Then the second conceptual layer would consist of more P frames that are
inserted between the frames of the first layer in output order, using
the frames of the first layer (and possibly some preceding frames of the
second layer also) as references for the decoding process.
Then the third conceptual layer would consist of more P frames that are
inserted between the frames of the second layer in output order, using
the frames of the first and second layer (and possibly some preceding
frames of the third layer also) as references for the decoding process.
etc.
The frames of the various layers are interleaved in the bitstream in a
manner ensuring that all references needed by each picture are found at
earlier positions in decoding order and ensuring that the total amount
of decoded picture buffer memory does not exceed the capacity specified
for the profile and level.
This is easier to sketch on a piece of paper than to describe in words.
It's a very good structure in terms of coding efficiency.  It is not
such a good structure in terms of end-to-end delay.
Best Regards,
Gary Sullivan
+> -----Original Message-----
+> From: mp4-tech-bounces lists.mpegif.org 
+> [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of pankaj bajpai
+> Sent: Thursday, August 04, 2023 10:19 PM
+> To: mp4-tech lists.mpegif.org
+> Subject: [Mp4-tech] [H.264 Video]
+> 
+> Recently two of the sequences "HCBP1_HHI_A" and 
+> "HCBP2_HHI_A" are uploaded  on the JVT site at following link
+> 
+>  http://ftp3.itu.ch/av-arch/jvt-site/bitstream_exchange/
+> 
+> Their description say these are Baseline profile sequences 
+> and has "Hierarchical GOP".
+>  
+> Can anyone tell what exactly is "Hierarchical GOP". My 
+> decoder is not able to decode these sequences.
+> 
+> With regards
+> pankaj
+> 
+> 
+> 
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