[benwaggoner]

There was a presentation on optimization of x265 at SMPTE yesterday, as part of the Compression track I chaired.

A couple of specific optimizations available in 3.2 were called out.

First, --selective-sao 3 only applies SAO for I and P frames, but delivers almost all the potential quality benefit of SAO with a ~4% speedup. This follows general literature that SAO isn't helpful with bi-prediction.

I wouldn't be surprised to see that added to --preset slower down the road.

Second, using --rd 4 and --dynamic-rd 3 instead of --rd 6 for CRF with VBV gives full rd 6 quality at peaks, at the cost of slightly higher bitrates (but similar quality) when CRF instead of VBV is the limiting factor. Speedup is estimated at ~9%, but obviously will vary based on how often the VBV cap is the constraint.