JVET-B0036 Simplification of the common test condition for fast simulation [X. Ma, H. Chen, H. Yang (Huawei)]

Chaired by J. Boyce

A simplified test condition is proposed for RA and AI configurations to reduce simulation run-time. For RA configuration, each RAS (Random Access Segment, approximately 1s duration) of the full-length sequence can be used for simulation independent of other RAS. And therefore the simulation of the full-length sequence can be split to a set of parallel jobs. For AI configuration, RAP pictures of the full-length sequence are chosen as a snapshot of the original for simulation. It is claimed that the compression performance when using the original test condition can be reflected faithfully by using the proposed new test condition, while the encoding run-time is significantly reduced.

Encoding of Nebuta for QP22 RA takes about 10 days. The contribution proposes parallel encoding for RA Segments.

A small mismatch is seen when parallel encoding done, because of some cross-RAP encoder dependencies. Sources of mismatches identified in contribution. It was suggested that the ALF related difference is due to a bug in decoder dependency across random access points, which has been reported in a software bug report.

It was proposed to encode only some of the intra frames, or to use the parallel method.

If RA is changed in this way, LD will become the new bottleneck.

Software was not yet available in the contribution. Significant interest was expressed in having this software made available.

We want to restrict our encoder to not use cross-RAP dependencies, so that parallel encoding would have no impact on the results.

It was agreed to create a BoG (coordinated by K. Suehring and H. Yang) to remove cross-RAP dependencies in the encoder software/configurations. It was agreed that if this could be done during the meeting, the common test conditions defined at this meeting would include this removal of the dependencies. (see notes under B0074).

Decision (SW): Adopt to JEM SW, once the SW is available and confirmed to have identical encoding results, with cross-RAP dependencies removed. Also add to common test conditions.

Decoding time reporting is typically done in ratios. Decoding time calculation can be based either on adding parallel decoding times, or the non-parallel decoding, but the same method should be used for both the Anchor and the Test.

It is proposed for AI to just use the I frames from the RA config, in order to reduce the AI encode time.

This was further discussed Tuesday as part of the common test conditions consideration.