JVET-K0485 CE9-related: A simplified bi-directional optical flow (BIO) design based on the combination of CE9.5.2 test 1 and CE9.5.3 [X. Xiu, Y. He, Y. Ye (InterDigital), C.-Y. Chen, C.-Y. Lai, Y.-W. Huang, S.-M. Lei (MediaTek)] [late]

This contribution proposes one combined bi-directional optical flow (BIO) method based on CE9.5.2 test 1 with a simpler gradient filter {−1, 0, 1} and CE9.5.3 with two-stage BIO early termination. Simulation results show that compared to VTM-1.0, the proposed scheme provides on average {Y, U, V} BD-rate savings of {2.80%, 0.94%, 0.68%} for RA with average encoding and decoding time of 108% and 123%.

This combination has slightly better performance than CE9.5.3 and slightly worse than CE9.5.2. However, the encoder/decoder run times (as reported so far relative to VTM) seem to be even faster than for CE9.5.3. Further, the worst case complexity is largely reduced (e.g. from >100 mul/sample to 13 mul/sample, and the compression benefit is large.

It was later reported that the method provides 1.2% BR reduction in BMS.

Decision (BMS): Adopt JVET-K0485.