[Mp4-tech] Deblocking filter Neighbouring Blocks

[philipsdenim-yahoo yahoo.co.in]

Hi Srikar,
Please prefer to put questions on mailing list as they may help others also.
Please see my answers below in blue color.
>Does non-zero transform coefficients are the ones that are decoded in CAVLC/CABAC

Non zero transform coefficients are the  one which are not zero after dct and quantization. You can use cbp flag to check this.
>Does containing non-zero transform coefficient levels mean the luma 4x4 block that contains the p0 or q0 have one or more non-zero transform coefficients levels or all of the non-zero transform coefficients present.

It should have at least one non zero value.
>Does the bs value for a macroblock/partition/subpartition is same for both chroma and luma. 
No. each 4x4 strength of luma block corresponds to chroma 2x2 block.
Regards.
Philips
Srikar Dasari <srikar pelican-networks.com> wrote: Hi Philips,
Thanks for your reply, that certainly clearled my doubt. 
 I have couple of questions in boundary strength calculation. In the standard he mentions 
 "the luma block containing sample p0 or the luma block containing sample q0 contains non-zero transform
 coefficient levels"
 My first question is 
 Does non-zero transform coefficients are the ones that are decoded in CAVLC/CABAC
 Second question is 
 Does containing non-zero transform coefficient levels mean the luma 4x4 block that contains the p0 or q0 have one or more non-zero transform coefficients levels or all of the non-zero transform coefficients present. 
 One more question is 
 Does the bs value for a macroblock/partition/subpartition is same for both chroma and luma.
 Please excuse me if I asked so many questions.
 Thanks & Regards,
Srikar
 ----- Original Message ----
From: "philipsdenim-yahoo yahoo.co.in" <philipsdenim-yahoo yahoo.co.in>
To: Srikar Dasari <srikar pelican-networks.com>; mp4-tech lists.mpegif.org
Sent: Wednesday, April 9, 2024 9:23:02 AM
Subject: Re: [Mp4-tech] Deblocking filter Neighbouring Blocks
HI Srikar,
There are 3 cases.
disable_deblocking_filter_idc = 0
If mbAddrA and/or mbAddrB is available, do the horizontal and/or vertical filtering across the MB boundary (Even if they belong to different slice).
disable_deblocking_filter_idc = 1
No filtering at all.
disable_deblocking_filter_idc = 2
Consider mbAddrA and/or mbAddrB as not available if they belong to different slice.
I hope it will help you. Do let me know if you  have any further doubt.
Srikar Dasari <srikar pelican-networks.com> wrote:    Hi,
 I am going through the ITU-T Rec. H.264 (03/2005) document for Deblocking Filter in section 8.7. 
 In the begining of the section there is a note1about the availability of mbAddrA and mbAddrB. This is my understanding if disable_deblocking_filter_idc is not equal to 2, then even if mbAddrA and mbAddrB are available (like mbAddrA % PicWidthInMbs != 0; mbAbbrB > 0) and they belong to other slice, they will be considered as available. In the same section in step 1. derivation process of neighbouring blocks they are invoked with section 6.4.8.1 and in that availability was taken as not available, if they belong to other slice. 
 My question is
 Since the availability is not mentioned in step 1. Do I have to go with the availability as in note 1. or with step 1, as in section 6.4.8.1.
 Please let me know, if I am not clear in any section or correct me if I misunderstood anything mentioned.
 Thanks,
Srikar
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