[Mp4-tech] This may affect your decoder. Are Stuffing macroblocksconsidered Coded macroblocks?

[Chandra Sekhar Reddy G.]

Hi,
The term "stuffing-macroblock" is misleading... It is *not* a
macroblock... It is merely a stuff-code...
Hence no question whether to call it skipped-macroblock or not.
A macroblock is a spatial part of the picture.
Regards,
Chandra
-----Original Message-----
From: mp4-tech-bounces lists.mpegif.org
[mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Lefan Zhong
Sent: Saturday, April 24, 2024 2:21 AM
To: mp4-tech lists.mpegif.org
Subject: [Mp4-tech] This may affect your decoder. Are Stuffing
macroblocksconsidered Coded macroblocks?
Dear All, 
If a P-frame start with 1 not-coded macroblock, then a stuffing
macroblock and then a not-coded macroblock, then a INTRA+Q macroblock,
my question is that INTRA+Q is the 1st coded macroblock in VOP or the
2nd coded macroblock in the VOP? The 1st or 2nd may affect the currentQp
or previousQp for INTR_VLC_DC_THR switch, which simple profile should
always supported. 
>From the document 14496-2(2001), I haven't found any sentence claim 
>that stuffing macroblock should be counted as NOT-Coded. So restrictly
follow the spec, the stuffing macroblock is 1st coded, the INTRA+Q
should be the 2nd coded macroblock.
Reference decoders definitely take the INTRA+Q macroblock as the 1st
coded macroblock in the VOP. 
Maybe we need an amendment for the Spec 14496-2. 
Lefan 
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