Fast VP9-to-AV1 Transcoding based on Block Partitioning Inheritance

This paper proposes a fast VP9-to-AV1 video transcoding algorithm based on block partitioning inheritance. The proposed algorithm relies on the reuse of VP9 block partitioning during the AV1 re-encoding process. This way, the exhaustive search for the best block size option is avoided to save encoding time. The reuse of VP9 block partitioning is proposed based on a statiscal analysis that shows the relation of block parititioning sizes between VP9 and AV1. The analysis demontrates that there is a high probability of the AV1 encoding process to choose block sizes of the same size as in the VP9 encoding. Experimental results show that the proposed algorithm is able to accelerate the VP9-to-AV1 transcoding process by 28% on average at the cost of only 4% increase in the BD-Rate when compared with the complete decoding and reencoding process.