> On phones I think less so right now, if you're talking about using AV1 to get noticeably better rates than VP9.
Yes, otherwise what would be the point of using AV1 in the first place. Many (most?) Android phones already have hardware VP9 and HEVC encoders. iPhones only support HEVC, so you know what the choice has to be to maximize the compatibility. HEVC and VP9 offer pretty much identical subjective visual quality for a given bitrate for the purpose of video calling - I tested a lot.
But anyway, even if you were able to run a realtime software-only AV1 encoder on a phone, there's still the concern of heat and battery life. Mobile devices usually aren't designed to run at 100% CPU load for any kind of extended period of time. Hardware codecs are much more power-efficient.
There is just one pass in video telephony because you can't wait for the call to be over to start a second pass before you send the video.
Re:Google Duo rolls out realtime AV1
by microcolonel on Tuesday April 21, 2020 @07:16PM
(#22940349)
I did not mean passes in the sense of two-pass rate control.
On large PCs it's been possible for a while, through SVT-AV1. On phones I think less so right now, if you're talking about using AV1 to get noticeably better rates than VP9.
That said, it's possible that they have a reduced set of tools/passess that can run in realtime on a phone, and it looks like the rate is extremely low, which also improves encoding complexity. Even software VP9 encoding has been rare on phones though up to this point, so I'm not sure exactly what is meant by this change.