JVET-AM0216 AHG12: Fixes for 12-bit internal bit depth in ECM [R. Yu, V. Seregin, M. Karczewicz (Qualcomm)]

The contribution reports that enabling 12-bit internal bit depth in ECM-17.0 result in a relatively large coding performance drop for chroma components compared to using 10-bit internal bit depth. The contribution claims that issues are identified to be related to some CCCM-based tools and proposes corresponding fixes to address those issues.

The fixes are reported to be implemented on top of ECM-17.0. When enabling 12-bit internal bit depth together with the proposed fixes, the BD-rate impact over ECM-17.0 with 12-bit internal bit depth is reported as follows:

AI: -0.02%, -0.42%, -0.34% for Y, U, V respectively

RA: 0.01%, -1.66%, -1.64% for Y, U, V respectively

LDB: -0.02%, -3.88%, -3.10% for Y, U, V respectively

The BD-rate impact over ECM-17.0 with 10-bit internal bit depth is reported as follows:

AI: -0.28%, 0.09%, 0.05% for Y, U, V respectively

RA: -0.57%, 0.06%, -0.07% for Y, U, V respectively

LDB: -0.70%, 0.13%, -0.33% for Y, U, V respectively

It is suggested to include the proposed fixes in the next version of ECM.

Decision(SW/BF): Adopt JVET-AM0216