Quote:
Originally Posted by nevcairiel
The high peaks (or low valleys, if you want) look disturbing. I can only assume those are I frames, a smoother difference between the frame types would feel more appropriate.
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The peaks are not related to I-pictures. They represent the temporal layer 0 pictures. The default coding structure in xvc is a hierarchical B-picture tree with 15 B-pictures.
Giving higher quality to pictures of lower temporal layers actually improves the overall quality in general. If the coding settings are modified to give more equal distribution you will get worse quality in most pictures. The quality of the pictures in low temporal layers needs to be reduced and since the pictures in higher temporal layers use those pictures as reference pictures, there will be a negative impact on the prediction.
As long as the lowest quality pictures are of good quality and there are no visual problems I don't think there is anything inappropriate with a bit of peaks and valleys in objective quality scores. Colinhunt's graph indicates that for most of the sequence the lowest quality xvc pictures are actually better than the highest quality x265 pictures.
I would be very happy to hear comments and feedback regarding the visual quality.