The Joint Collaborative Team on Video Coding (jct-vc) of itu-t wp3/16 and iso/iec jtc 1/ sc 29/ wg 11 held its tenth meeting during 11-20 July 2012 at the City Conference Centre (ccc), a k. a

JCTVC-J0372 Cross-check of JCTVC-J0091 on Chroma QP offset and deblocking filter [J. Xu (Sony)] [late]
JCTVC-J0343 Use of Chroma QP offsets in Deblocking [S. Kanumuri, G. J. Sullivan (Microsoft)]

This appears to propose the same change as J0091. No separate presentation therefore seemed necessary.

JCTVC-J0186 On Deblocking Filter and DC Component of Quantization Matrices [K Sato (Sony)]

When quantization matrices are applied, the QPs in a bitstream and the ones actually used for encoding / decoding differ. However, not the latters but the formers are used for deblocking filtering with the current HEVC specification. To correct this gap, it was proposed by JCTVC-I0280 that the value of all QM components be taken into account for deblocking at the 9^th JCTVC meeting in Geneva.

The author partly supports this idea. However, taking all QM components into account requires increase in complexity. In addition, higher frequency components do not affect blocking artefacts so much.

This contribution proposes for only the DC component of quantization matrices to be used to adjust QP for deblocking filtering.

A rationale for this could be a scenario where through the quant matrices different QP values are used for different transform sizes. Otherwise, this could simply be implemented via tc offset.

The decoder operation becomes more complex as it is necessary to determine the transforms sizes on both sides of the boundary and adjust the QP value accordingly.

The original proponents of I0280 also verbally express that they support this proposal.

The general opinion is that the benefit is not obvious enough to justify the additional decoder complexity.