[Mp4-tech] Why I or B frame can have one fixed QP?

[Tourapis, Alexis]

Dear James,
There is no quantization limitation in H.264/AVC. I am guessing your observation relates to the current Rate Control algorithm supported by the JM software. This should only be seen as an example design.
Best regards,
Alexis 
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From: mp4-tech-bounces lists.mpegif.org [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Gary Sullivan
Sent: Saturday, May 06, 2024 8:31 PM
To: James (Jianpeng) Dong; mp4-tech-bounces lists.mpegif.org; mp4-tech lists.mpegif.org
Subject: RE: [Mp4-tech] Why I or B frame can have one fixed QP?
I don't think it's true that an I or B frame can only have one fixed QP value in the JM reference software.  No, there is no requirement of fixed QP in the standard.  QP can change (from any value to any other value) on a macroblock (16x16) basis in the standard.
Best Regards,
Gary Sullivan
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	From: mp4-tech-bounces lists.mpegif.org [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of James (Jianpeng) Dong
	Sent: Friday, May 05, 2024 4:43 PM
	To: mp4-tech-bounces lists.mpegif.org; mp4-tech lists.mpegif.org
	Cc: jianpengdong yahoo.com
	Subject: [Mp4-tech] Why I or B frame can have one fixed QP?
	Dear experts, 
	Just wondering why I or B frame can only have one fixed QP in H.264 JM reference software? Is a fixed QP required by H.264/AVC standard? 
	Thanks,
	James
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