[Mp4-tech] [video][H.264] Regarding disable_deblocking_filter_idc

[Gary Sullivan]

The value of 2 for disable_deblocking_filter_idc has the effect of
turning off the filtering of the boundaries between different slices,
while filtering normally within each slice.
The primary example uses for that are error resilience and so-called
"gradual random access".  It avoids having error/drift "mismatches"
propagate across the boundary of slices.  For example, an encoder can
send an I slice and turn off the deblocking filter for the boundaries of
the slice so that any mis-match in neighboring areas will not affect the
I slice decoded region.
Best Regards,
Gary Sullivan
+> -----Original Message-----
+> From: mp4-tech-bounces lists.mpegif.org 
+> [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Smitha Joseph
+> Sent: Thursday, April 07, 2024 1:01 AM
+> To: mp4-tech lists.mpegif.org
+> Subject: Re: [Mp4-tech] [video][H.264] Regarding 
+> disable_deblocking_filter_idc
+> 
+> Hi,
+> 
+> Thanks for the replies. I had an additional doubt. 
+> In the JVT code, the encoder configuration file has aparameter which
+> sets the value disable_deblocking_filter_idc  to 1 or 0. But the
+> standard specifies that disable_deblocking_filter_idc can 
+> have a value
+> 2 also, when does encoder set this parameter value to 2.
+> 
+> Thanks,
+> Smitha Joseph
+> 
+> On Apr 7, 2024 12:31 PM, Adarsh Golikeri <golikeri gmail.com> wrote:
+> > Hi,
+> > 
+> > In the encoder congiguration file, there are parameters for "Loop
+> > filter" which allow for enabling/disabling the deblocking 
+> filter. If
+> > the filter is enabled, then the boundary strength is 
+> chosen according
+> > to :
+> > 
+> > boundary is an intra-intra / inter-intra MB boundary : 
+> strength = 4 (strongest)
+> > boundary is an intra-inter / inter-inter non-MB boundary 
+> (i.e within
+> > an MB) : strength = 3
+> > boundary is an inter-inter boundary, with coded 
+> coefficients : strength = 2
+> > boundary between MBs using different reference pictures / different
+> > number of reference pictures / have MV values differing by 
+> more than
+> > one luma sample : strength = 1
+> > otherwise : strength = 0.
+> > 
+> > Hope that helped,
+> > 
+> > Bye !
+> > 
+> > Adarsh
+> > 
+> > On Apr 6, 2024 3:02 AM, Smitha Joseph <smithajo gmail.com> wrote:
+> > > Hi,
+> > >
+> > > The H.264 standard specifies the parameter
+> > > disable_deblocking_filter_idc in the slice header which specifies
+> > > whether the deblocking filter is disabled for the
+> > > macroblock/macroblock edges in that slice. The details of how the
+> > > parameter disables filtering at the decoder side for the 
+> different
+> > > values is clear from the standard. My doubt is how does 
+> the encoder
+> > > decide whether to enable or disable filtering for each
+> > > macroblock/macroblock edges in a slice?
+> > >
+> > > Thanks,
+> > > Smitha Joseph
+> > > _______________________________________________
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