Doom9's Forum - View Single Post - In HEVC, only QP=4 is truly lossless quantization... what about 0~3?

iAvoe · 2nd August 2018, 12:31

and with further study, I feel it is more like for instructing DCT transformation better, because in very low CRF mode, you want the output to be as sharp as possible, so they have increased the "--qp 0" gap where if the decision lands among 0~3, the DCT transformation is disabled because it's worth to output that detail untouched, but when it's 4, the divisor for DCT matrix became 1, so this is equivalent as "--qp 1" in x264, am I right?

2nd August 2018, 12:31	#3 \| Link
iAvoe Registered User Join Date: Sep 2017 Posts: 18	and with further study, I feel it is more like for instructing DCT transformation better, because in very low CRF mode, you want the output to be as sharp as possible, so they have increased the "--qp 0" gap where if the decision lands among 0~3, the DCT transformation is disabled because it's worth to output that detail untouched, but when it's 4, the divisor for DCT matrix became 1, so this is equivalent as "--qp 1" in x264, am I right? Last edited by iAvoe; 2nd August 2018 at 12:35.