gamebox
16th April 2016, 10:20
Hello all. :) I've finally managed to upgrade my PC with a quad-core CPU (which I consider the bare minimum for HEVC encoding), and I already ran some tests to make myself familiar with HEVC options. I already have some questions:
- first, is it possible to switch off cutree but keep the AQ on? In x264 I was able to encode without mbtree but with Auto Variance AQ, and when I try the same in x265 it seems the AQ completely switches off.
- second, why the HEVC standard accepts only up to 6 reference frames? In x264 I encoded 720p using 9 references, as that was the maximum number that Level 4.1 decoder chips could handle - why the new format steps back here? To make it clear- my aim always is to encode using all the options mainstream video decoder chips (will) support, for maximum compression efficiency and video quality.
- third, is Slower x265 preset roughly comparable to Very Slow in x264? I want to encode using maximum "non-brute-force" (non-placebo) profile, and me Star and subme 7 to me seem the most complex "geometrical" motion search patterns available.
- fourth, how the deblock filter in x265 compares to x264? In x264 I typically set deblock to -1,-1 for general use and -2,-2 when transcoding very high quality sources using CRF16. In x265 deblock 0 results in too much blocking during fades etc, and deblock 1 already seems too strong and washes away some details.
- fifth, how quantizers and CRF in H.265 compare to H.264? Quant of 22 in H.264 was generally the last "fully acceptable" one for me, and 23 was usually the boundary where details start to blur too much. CRF 18 in x264 usually resulted in quants up to these values and I used it regularly, choosing CRF 16 only for very high quality sources. What are the approximate quants and CRF I should choose in x.265 to achieve similar results?
- sixth, is quad-core CPU (AMD Phenom II X4) with 2.7 GHz per core, 2MB L2 and 6MB L3 cache, really not sufficient for real-time decoding of 1080p HEVC? I still get "choppy" movement (as if the decoder skips B-frames) although all 4 cores get decent saturation of 60-70 %. My previous CPU (AMD Athlon II X2 at 2.7 GHz per core and 2MB L2) performed virtually identically using only 2 cores with approximately the same saturation. The decoding is done through relatively recent LAV filters.
And I want to say a big THANK YOU to Lord Mulder, whose wonderful Simple x264/x265 launcher saved me the trouble of upgrading the OS. :) Your software is one of the rare encoders that works on Windows XP, and it seems to work fairly well, as (for instance) MediaCoder kept crashing after I try to resume encoding after many hours (the problem seems system-time related). Besides, when transcoding using avs script as the source, Simple x264/x265 launcher occupies significantly less RAM on my system than AVS Proxy GUI + AVIDemux previously did.
Thanks for your time and patience, I'm eager to find out more about HEVC and resolve these issues I have at the moment. :)
- first, is it possible to switch off cutree but keep the AQ on? In x264 I was able to encode without mbtree but with Auto Variance AQ, and when I try the same in x265 it seems the AQ completely switches off.
- second, why the HEVC standard accepts only up to 6 reference frames? In x264 I encoded 720p using 9 references, as that was the maximum number that Level 4.1 decoder chips could handle - why the new format steps back here? To make it clear- my aim always is to encode using all the options mainstream video decoder chips (will) support, for maximum compression efficiency and video quality.
- third, is Slower x265 preset roughly comparable to Very Slow in x264? I want to encode using maximum "non-brute-force" (non-placebo) profile, and me Star and subme 7 to me seem the most complex "geometrical" motion search patterns available.
- fourth, how the deblock filter in x265 compares to x264? In x264 I typically set deblock to -1,-1 for general use and -2,-2 when transcoding very high quality sources using CRF16. In x265 deblock 0 results in too much blocking during fades etc, and deblock 1 already seems too strong and washes away some details.
- fifth, how quantizers and CRF in H.265 compare to H.264? Quant of 22 in H.264 was generally the last "fully acceptable" one for me, and 23 was usually the boundary where details start to blur too much. CRF 18 in x264 usually resulted in quants up to these values and I used it regularly, choosing CRF 16 only for very high quality sources. What are the approximate quants and CRF I should choose in x.265 to achieve similar results?
- sixth, is quad-core CPU (AMD Phenom II X4) with 2.7 GHz per core, 2MB L2 and 6MB L3 cache, really not sufficient for real-time decoding of 1080p HEVC? I still get "choppy" movement (as if the decoder skips B-frames) although all 4 cores get decent saturation of 60-70 %. My previous CPU (AMD Athlon II X2 at 2.7 GHz per core and 2MB L2) performed virtually identically using only 2 cores with approximately the same saturation. The decoding is done through relatively recent LAV filters.
And I want to say a big THANK YOU to Lord Mulder, whose wonderful Simple x264/x265 launcher saved me the trouble of upgrading the OS. :) Your software is one of the rare encoders that works on Windows XP, and it seems to work fairly well, as (for instance) MediaCoder kept crashing after I try to resume encoding after many hours (the problem seems system-time related). Besides, when transcoding using avs script as the source, Simple x264/x265 launcher occupies significantly less RAM on my system than AVS Proxy GUI + AVIDemux previously did.
Thanks for your time and patience, I'm eager to find out more about HEVC and resolve these issues I have at the moment. :)