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a5180007 · 27th August 2014, 08:47

x264 PSNR usually looks like this:

(EDIT : downscale with Repair(Lanczos, Gaussian), upscale with Lanczos)

I find x264 CRF 23 to be a fair rule of thumb for the maximum compression before downscaling -indeed it also depends of the downscaling ratio, in the above example with large steps of 1.5:1, the limit is CRF 25.

So there is little point comparing x265 to x264 for compressions above x264 CRF 23.
I haven't done the same tests for x265 (due to my CPU poor performance

), but shouldn't the same apply with default x265 CRF ? If not, on what criteria is that default CRF of 28 based ?

27th August 2014, 08:47	#44 \| Link
a5180007 Registered User Join Date: Jun 2014 Location: Marrakech, Morocco Posts: 253	x264 PSNR usually looks like this: (EDIT : downscale with Repair(Lanczos, Gaussian), upscale with Lanczos) I find x264 CRF 23 to be a fair rule of thumb for the maximum compression before downscaling -indeed it also depends of the downscaling ratio, in the above example with large steps of 1.5:1, the limit is CRF 25. So there is little point comparing x265 to x264 for compressions above x264 CRF 23. I haven't done the same tests for x265 (due to my CPU poor performance ), but shouldn't the same apply with default x265 CRF ? If not, on what criteria is that default CRF of 28 based ? Last edited by a5180007; 27th August 2014 at 13:23.