[Mp4-tech] h.264 direct_8x8_inference_flag

[nitthilankj]

At the encoder when does the direct_8x8_inference_flag get set....
One condition is that when frame_mbs_only flag =0 ..means that when the
encoding type is field and in case of adaptive frame field configuration
when the MB type is decided as field...is that all or are there other
condition to look out for.
-----Original Message-----
From: mp4-tech-bounces lists.mpegif.org
[mailto:mp4-tech-bounces lists.mpegif.org]On Behalf Of Alexis Michael
Tourapis
Sent: Tuesday, February 22, 2024 12:42 AM
To: 'nitthilankj'; mp4-tech lists.mpegif.org
Subject: RE: [Mp4-tech] h.264 direct_8x8_inference_flag
This flag impacts the derivation of the motion vectors of the collocated
partitions. Enabling it would result in motion vectors being computed at the
8x8 block level instead of 4x4. To make it clearer see figure:
x o | o x
o o | o o
- - - - -
o o | o o
x o | o x
In this motion vectors for blocks in the collocated marked as "o" will take
the motion vector of block "x" and use that instead.
And yes it does affect spatial direct since spatial direct tests a
"stationarity" condition of the collocated to derive motion vectors.
Best regards
Alexis
-----Original Message-----
From: mp4-tech-bounces lists.mpegif.org
[mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of nitthilankj
Sent: Monday, February 21, 2024 1:00 AM
To: mp4-tech lists.mpegif.org
Subject: [Mp4-tech] h.264 direct_8x8_inference_flag
What is its significance..Does this affect direct spatial mv derivation?
k.j.nitthilan
d&d engg.
tata elxsi
bangalore.
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