JVET-T0093 AHG12: On signalling for high-bit depth [Y. Kidani, K. Kawamura, K. Unno (KDDI)]

This contribution was discussed in JVET session 11 at 2205 on Monday 12 October (chaired by GJS & JRO).

This contribution proposes a signalling for high-bit depth video coding in VVC. In the previous meeting, JVET-S0243 presentation slides reported that coding gains of some tools are reduced or lost as QP decreases in high-bit depth video sequences. JCCR is one of the reported tools, and the verification effort can be reduced if JCCR is disabled in the low QP range for high-bit depth coding. In this contribution, the additional applicable condition of JCCR with the pre-defined QP threshold is proposed against VVC ver.1. With this condition, JCCR can be disabled when block based QP is equal to or smaller than the pre-defined QP threshold. Simulation results under JVET-T0047 reportedly show the coding loss is negligible without one PQ test sequence (Market33Clip4000r2).

It was noted that such a change would need to be conditioned on high bit depth (or something else that differs from version 1 usage).

It was also noted that losses were observed in some test results (Market3Clip4000r2).

The claimed benefit is reduced conformance testing for high bit depths. For high-bit-depth decoders that decode lower bit depth bitstreams, it would still need to implement the feature.

Another participant said that since this introduces new conditions, and since JCCR needs to be supported for lower bit depths, it might actually complicate conformance testing.

No action was taken on this.