[x264-devel] RD P-skip patch

[Robert Swain]

Hello,

I have found a situation in which this patch is very useful. I've been testing with various raw HD clips available from an FTP. I can provide the link if required but I haven't got it to hand.

The raw source is the bluesky.yuv clip. It is 1920x1080 25fps progressive YV12/I420. (I don't remember which.) I have resized it to 720x400 and have encoded at a lowish bitrate of 1Mbps. The background is a sort of gradient between orange and lighter orange. When the camera pans the blocks in the sky move abnormally and then jump every so often which looks very bad. I tried a number of different things to avoid the problem but the only thing that had any significant effect was the RD P-skip patch that Loren wrote but never committed.

Here is a clip of the current revision without the P-skip patch:
http://www.swains.plus.com/x264/x264.274.vanilla.mp4
And here is one with the patch:
http://www.swains.plus.com/x264/x264.274.rdopskip.mp4

As you see it's quite an improvement. Not perfect but pretty good.

Would it be worthwhile committing the patch for this purpose? I'm thinking probably not, but is there some way we could alter the patch such that the RD P-skip code is used only when there's very little texture in the block as this would appear to be when it's most effective?

Regards,
Robert Swain (a.k.a. superdump on IRC)
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