What They Say
The 8K Association discussed ‘per-title’ encoding (“per-title encoding” is a Netflix term that refers to creating encoding parameters on a scene-by-scene basis) of 8K content with Jan Ozer. There were two sets of content:
- a stationary talking head scene along with a dance sequence, which showed a lot of motion blur due to the capture frame rate.
- Another was 8K at 60 fps in an HDR and BT.2020 format. A dynamic action sequence was chosen for encoding.
The low motion images can be encoded at data rates as low as 2.46Mbps with an SSIM score of 0.993. The scenes with motion blur could be encoded at 7.8 Mbps with a 0.996 SSIM score. However, a soccer sequence used 43.4 Mbps, reaching a 0.998 SSIM score (although it was expected that multipass encoding and or AI/ML would have allowed further reductions).
Further questions include the difference between HDR and SDR and whether PSNR is a useful metric any more. It’s also not clear that metrics such as SSIM and VMAF have been validated for 8K HDR content. although Ozer’s blog said that SSIMWave’s SSIMPLus has been tested to ensure that HDR ratings match actual subjective ratings to a high degree.
What We Think
Ozer has more information on his blog. (BR)
Footage from a River Plate soccer match was used
