x265 HEVC Encoder

[Z2697]

Originally Posted by benwaggoner

Yeah, if only it worked! I've never been able to get a single frame to duplicate as documented, even with some pretty extreme settings. I've not tried in a 4.x build, but don't recall any patches for that part.

Maybe it only works in 2-pass or something?

I'm not sure "which" duplication you are referring to, the first case is the encoding side:

What it does is actually removing frames and using SEI to tell decoder to duplicate existing frames, which actually should be called de-duplication I think.

Maybe you are not looking at the right place (i.e. you think it's duplicating frames while it actually deletes frames), but assuming you are not able to get frames to trigger the de-duplication during encoding:

There's PSNR thresholding, can be configured via --dup-threshold parameter.
If you use low enough threshold, eventually some frames will be de-duped, but of course this should only be used in experiments, low threshold will just destroy the video.

The second case: the decoding side...

You need a decoder that's able to recognize and utilize the picture timing SEI (which only tells decoder to double or triple the frame, no actual timestamp is stored) and I guess things will... "just work"... yeah, who knows, the most common decoder (avcodec) doesn't support it so I can't test.

Originally Posted by benwaggoner

The tool is reasonably useful with the proper tools; there just aren't any good open source ones currently. The hardest part is the degrain-and-parameterize before encoding.

The rendering has some challenges with repeated patterns, due to the "drunken walk" nature of selecting a random 32x32 block out of a 64x64 block: pixels near the middle are much more heavily sampled than those near the edge. I so wish computer science degrees required some basic statistics! I work with a lot of engineers who are whizzes at linear algebra, but go blank when I ask "is that statistically significant?"

Maybe I just hate noises in general
But I agree, it (FGS) has potential... just it still has a long way to go.