JCTVC-G206 CE8.c.4: SAO and ALF virtual boundary processing with cross9x9 [C.-Y

Chen, C.-M. Fu, C.-Y. Tsai, Y.-W. Huang, S. Lei (MediaTek), S. Esenlik, M.

Narroschke, T. Wedi (Panasonic)]

This contribution reports results of CE8.c.4-1 and CE8.c.4-2, which are a combination of CE8.c.2 using single-source SAO and ALF virtual boundary (VB) processing and CE8.d.1 using cross9x9 and

snowflake5x5 and a combination of CE8.c.3 using multi-source SAO and ALF VB processing and CE8.d.1, respectively. When compared with the JCTVC-F900 anchor, CE8.c.4-1 reportedly achieves 0.0%, -0.2%, -0.3%, and 0.1% BD-rates for HE-AI, HE-RA, HE-LDB, and HE-LDP, respectively, and CE8.c.4-2 reportedly achieves 0.0%, -0.2%, -0.4%, -0.1% BD-rates for the four conditions respectively, where negative numbers mean gains and positive numbers mean losses. The gain of using cross9x9 is roughly unchanged when CE8.c.2 and CE8.c.3 are considered. It is also reported that both CE8.c.4-1 and CE8.c.4-2 have subjective qualities close to HM-4.0, and CE8.c.4-2 is better than CE8.c.4-1.

JCTVC-G433 CE8.c.4: Cross-check of MediaTek/Panasonic's SAO and ALF virtual boundary processing with cross9x9 JCTVC-G206 [T. Yamakage, T.

Watanabe (Toshiba)]

JCTVC-G207 CE8.c.5: Non-cross-slices SAO [C.-M. Fu, C.-Y. Tsai, C.-Y. Chen, Y.-W.

Huang, S. Lei (MediaTek), M. Budagavi (TI)]

This contribution reports results of CE8.c.5. In HM-4.0, non-cross-slices SAO skips each to-be-processed pixel requiring any pixel from any other slice. However, the skipping technique may cause some potential problem in visual quality. In JCTVC-F093 and JCTVC-F232, any pixel from any other slice is avoided by

using a padding technique and by modifying pixel classification patterns, respectively. In this proposal, it is found that the padding technique and modification of pixel classification patterns are conceptually the same and can be combined into one single solution. Simulation results reportedly show that the proposed method achieves no coding efficiency loss and better subjective quality in comparison with the anchor when non-cross-slices SAO and multiple slices per picture are used.

JCTVC-G414 CE8.c.5: Cross-check of MediaTek/TI's non-cross-slices SAO JCTVC-G207 [T. Yamakage, T. Watanabe (Toshiba)]

Subtest D

JCTVC-G208 CE8.d.1: Snowflake5x5 and cross9x9 for luma and chroma ALF shapes [C.-Y. Tsai, C.-[C.-Y. Chen, C.-M. Fu, [C.-Y.-W. Huang, S. Lei (MediaTek), I. S. Chong, M. Karczewicz (Qualcomm), T. Yamakage, T. Watanabe, T. Chujoh

(Toshiba)]

This contribution reports results of CE8.d.1. In HM-4.0, snowflake5x5 and cross11x5 filter shapes have nine and eight multiplications, respectively, and are used for both luma and chroma in ALF. In this proposal, snowflake5x5 and cross9x9 are used, and they both have nine multiplications to better utilize multipliers without increasing the number of multipliers in hardware. Simulation results reportedly show 0.1%, 0.4%, 0.6% and 0.3% coding efficiency gains for HE-AI, HE-RA, HE-LDB, and HE-LDP, respectively, with roughly the same encoding time and 1%-2% decoding time increase. Apparently cross9x9 needs more line buffers than cross11x5, so it is suggested to combine this proposal with ALF line buffer removal techniques.

JCTVC-G133 CE8: Crosscheck of JCTVC-G208 - Snowflake5x5 and cross9x9 for luma and chroma ALF shapes [M. Budagavi (TI)] [late]

JCTVC-G648 CE8 Subtest d, Tool 2: ALF filters with 9 coefficients and up to vertical-size 7 [P. Lai, F. C. A. Fernandes (Samsung), H. Guermazi, F. Kossentini,

M.Horowitz (eBrisk)]

This contribution presents ALF method using two filter shapes both having 9 coefficients: star-5x5 and cross-11x7. Compared to the previously adopted proposal JCTVC-F303, one coefficient has been added to construct cross-11x7, and extended its vertical-size to 7. The proposed method reports gains of

0.1/0.2/0.3/0.2 BD-rate for AI/RA/LDB/LDP structures as compared to HM4.0, with average of 2% / 1%

enc / dec time increases on Linux cluster server.

JCTVC-G613 CE8 Subset d.2: Cross-Verification of Samsung’s Filter Shapes and Coefficients constraints [I. S. Chong, M. Karczewicz (Qualcomm)]

JCTVC-G130 CE8 Subtest d - Chroma ALF with reduced vertical filter size [M. Budagavi, V. Sze, M. Zhou (TI)]

This contribution presents results for Nx3 chroma ALF filters when integrated into HM 4.0. Nx3 chroma ALF filters have a vertical size of 3 when compared to filters in HM 4.0 which have vertical size of 5.

The filter set of 7x3 diamond + 11x3 cross with 3x3 center is reported to have following BD-Rate results (Y, U, V): AI-HE: 0.0%, 0.4%, 0.5%; RA-HE: 0.0%, 0.8%, 0.5%; LB-HE: 0.0%, 0.7%, 0.5%;LP-HE:

0.0%, 0.7%, 0.4%. The worst case number of multiplications for this filter set is reported to be the same

as for HM-4.0 filter set. Results for other Nx3 filter sets that have vertical size of 3 are also presented.

Filters with reduced vertical size are asserted to be useful from the point of view of reducing number of line buffers required and/or external memory bandwidth. Nx3 filters are claimed to result in a 50%

reduction in line buffer/external memory bandwidth requirements compared to HM-4.0 chroma ALF filters.

JCTVC-G652 CE8 Subtest d: Cross-check of Tool 3 (JCTVC-G130): Chroma ALF with reduced vertical filter size, proposed by TI [P. Lai, F. C. A. Fernandes (Samsung)]

Subtest E

JCTVC-G665 CE8.e.3: ALF coefficient prediction [K. Andersson (Ericsson)]

This contribution is a core experiment report on JCTVC-F076 which exploits that adaptive loop filter coefficients typically are largest towards the middle of the filter. The BDR can be improved by 0.1%

compared to HM-4.1 for random access and low delay for the common conditions at similar encoding and decoding time.

JCTVC-G928 CE8.e.3: Cross-check of Ericsson's ALF coefficient prediction JCTVC-G665 [T. Yamakage, T. Watanabe (Toshiba)] [late]

Subtest F

(original proposal withdrawn)

JCTVC-G060 CE8 Subtest F: Verification results of Panasonic's Proposal [F. Kossentini, H. Guermazi (eBrisk Video Inc.)]

Subtest G

JCTVC-G056 CE8 Subtest G: Adaptive Loop Filtering of Chrominance Samples Using Luma Map [F. Kossentini, H. Guermazi, N. Mahdi, M. Horowitz (eBrisk Video Inc.)]

This contribution presents a technique for the Adaptive Loop Filtering (ALF) of chrominance samples that employs the map used in ALF of the luminance samples. The proposed technique reduces the average decoding time (~1%) while also achieving better U/V BD-Rate (0.21%-0.19%) performance than those of HM4.0.