With all the talk about VP9 and AV1 and VVC and different encoder implementations for all of them, I thought it might be fun to set up an open challenge for folks to deliver the best possible quality for each.
To that end, in a semi-inebriated late-night conversation at IBC, we defined a scenario relevant to some important real-world scenarios that reasonably stress current encoders.
- Tears of Steel
- 1.0, 1.5, and 2.0 Mbps ABR
- 4 Mbps peak bitrate
- 12 Mbps VBV
- Max 5 sec (120 frame) GOP
- No preprocessing
Here's the source I used (.y4m.7z):
https://1drv.ms/u/s!AlvIQZWsyeO-kKpoG5f3PHAFhWcGig
And my current best HEVC x265 encodes:
1.0:
https://1drv.ms/v/s!AlvIQZWsyeO-kKpmDQlxoY-00rk3AQ
1.5:
https://1drv.ms/v/s!AlvIQZWsyeO-kKplp2EQ8-Q4bCNVZw
2.0:
https://1drv.ms/v/s!AlvIQZWsyeO-kKpZkpw-WQKF1dSF_g
I didn't do any content specific encoding in these. I just did the slowest, highest quality encode 2-pass I had the patience for. Basically
- --preset placebo
- --cu-lossless
- --tskip
- -F 1
- --ref 6
- --bframes 16
- --aq-mode 3
- --rd-refine
If I had infinite patience I'd add --me sea and --subme 7 for PlusUltraPlacebo.
Update 6/3/2021
To evaluate anime/line art encoding I'm adding Netflix's Sol Levante as a second source for testing. It's an interesting compression challenge with a lot of titles/credits that can be shrunk down enormously, and some very complex hybrid line art/CGI sequences that x265 can't make look great at even 12 Mbps. It should be very interesting for rate control!
Sol Levante's
4K HDR source is available under Creative Commons, from which I derived an
8-bit SDR 1080p .y4m, as 8-bit SDR playback and testing is still a lot more available.
I've kicked off a 1000 Kbps test encode with x265 for reference that I should post tomorrow. The challenge follows the same constraints for bitrate, VBV, etcetera.