Opened 10 years ago

Closed 10 years ago

#276 closed defect (fixed)

SaoMaxDepth unknown in APS

Reported by: tkunlin Owned by: bbross
Priority: minor Milestone:
Component: Text Version: WD5 (G1103) d2
Keywords: Cc: bbross, wjhan, jct-vc@…

Description

An APS does not contain a pps_id or sps_id pointing to an active sequence parameter set. As a consequence, the sequence size is not known when parsing an APS, and SaoMaxDepth can not be computed as :
SaoMaxDepth = Min( 4, Min( Floor( Log2( PicWidthInLCUs ) ), Floor( Log2( PicHeightInLCUs ) ) ) )

The coded SAO parameters can still be saved thanks to the sao_data_byte_count syntax element, and later parsed when SaoMaxDepth is known.

But is it the wanted behaviour ?
Shouldn't an APS contain a reference to a SPS ?

Change History (6)

comment:1 Changed 10 years ago by DefaultCC Plugin

  • Cc bbross wjhan jct-vc@… added

comment:2 Changed 10 years ago by ksuehring

I don't think that putting an SPS pointer into the APS is a good idea.

a) this would create two link chains to the SPS:

Slice->PPS->SPS
Slice->APS->SPS

which would require restrictions on SPS selection and could lead to potentially conflicting situations.

b) The general idea is to have parameter sets independently parsable. Theoretically the SPS could be replaced after the APS is transmitted. Thus the information could be misleading before the APS is actually used.

I think as long as the APS is parsable, it should be fine.

comment:3 Changed 10 years ago by tkunlin

I see your point.

In that case, a way for the SAO parameters to be parsed independently from a SPS
would be to have SaoMaxDepth coded as an explicit syntax element inside the APS.

comment:4 Changed 10 years ago by ksuehring

It seems the sao_data_byte_count syntax element has been removed in JCTVC-G1016. So we will indeed have a problem when we try to parse the APS. I think that was an editing mistake.

I guess a similar problem exists with ALF while AlfMaxDepth is not defined at all in the current WD.

comment:5 Changed 10 years ago by thomasd

Including sao_data_byte_count makes it "parsable" only in the sense of extracting binary chunks, is that right? To interpret the data a slice has to arrive which points at the APS and also at the SPS. That doesn't seem so nice, if so.

comment:6 Changed 10 years ago by bbross

  • Resolution set to fixed
  • Status changed from new to closed

The SAO/ALF APS SPS dependency is removed in D6 (H1003)

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