[Mp4-tech] Non zero Coefficients in deblocking filter

[Gary Sullivan]

Srikar,
I suggest to check what the reference software is doing.  If I remember correctly, the text is phrased so that certain things are prohibited (by disallowing the values of all transform coefficients being decoded as zero when some coded block pattern bits are set), so that the complexity of the decoding process is minimized.  The text and software do the same thing, but that is not obvious at first glance, because their equivalence depends on the exact phrasing of the text.  We had one or two correction efforts devoted to this topic in the past, so if you look in some old drafts you will find incorrect text.
Again, my basic advice is to check what you find in the JM reference software.
Best Regards,
Gary Sullivan
________________________________
From: mp4-tech-bounces lists.mpegif.org [mp4-tech-bounces lists.mpegif.org] On Behalf Of Srikar Dasari [srikar pelican-networks.com]
Sent: Monday, April 21, 2024 3:43 PM
To: mp4-tech lists.mpegif.org
Subject: [Mp4-tech] Non zero Coefficients in deblocking filter
Experts,
I have a question in the boundary calculation in deblocking filter. I kinda of asked this question earlier. I need some more clarification.
In the filtering process the boundary strength is set based on one of the conditions being, the luma block p0 or luma block q0 contains non-zero transform coefficient levels.
My question is,
Isn't this non-zero transform coefficient level condition, come from both CBP value and also from the TC (total coefficients) during the CAVLC decoding?
In other words, Do we have to consider the CBP pattern alone or Do we have to take into account TC being zero, in addition to CBP.
Please let me know, if I am not clear anywhere. Your answers are greatly appreciated.
Thanks,
Srikar
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