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17th November 2015, 17:02 | #1 | Link |
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The state of h265 as of Nov 2015?
I haven't been following h265 at all. Can anyone summarize where it stands currently?
Current quality versus h264 (and also specifically in available PC encoders vs x264), what quality improvements are still expected (encoder tuning and yet-unimplemented features), current commonly used encoders and decoders, encoding and decoding speed and compatibility concerns and outlooks... How long do you think it will take for h265 to replace h264 as the de facto standard format for PC creation and consumption? Is Bluray UHD now the real beginning of widespread adoption? Last edited by shae; 17th November 2015 at 17:32. |
20th November 2015, 05:46 | #5 | Link |
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The way that testing was done makes me wonder how often Apples were being compared with Apples. In some instances CBR was used for one encoder and 2 pass VBR for another. The SSIM tuning was used for x264 but not for x265. Varying keyint settings. When a minimum encoding speed was required and 2 pass encoding was used I'm not sure if it applied to only the second pass, or both passes combined.
Ignoring those types of differences though, HEVC doesn't seem to be setting the world on fire. According to those tests x265, which generally rated the best in respect to bitrate for a specific quality, still didn't do all that much better than x264. 74% the bitrate of x264 when encoding speed wasn't a factor and around 90% for more realistic encoding speeds. Wasn't the original promise somewhere in the vicinity of 50%? Last edited by hello_hello; 20th November 2015 at 05:48. |
20th November 2015, 09:22 | #6 | Link | ||
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20th November 2015, 09:31 | #7 | Link |
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And it will take a couple more years to reach that. It just takes time until encoders mature. Note that it was never expected to reach 50% at the same encoding speed, so having a slower encode is expected.
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20th November 2015, 17:03 | #8 | Link | |
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Yeah, that was a problem. We didn't realize that quality would be measured only with Y-SSIM, otherwise we would have added --tune SSIM to our command line for these tests, and x265 would have done much better.
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20th November 2015, 18:09 | #9 | Link |
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Thanks for the info guys. I didn't mean to come across as being anti-x265 or anything like that. Just trying to look at it objectively.... and understand
If the speed requirements included both passes combined, it seems to me x265 would have faired better if CRF encoding was used. Probably harder to test given there's no bitrate control but assuming at the same bitrate CRF and 2 pass encode the same way, maybe in some cases a slower speed preset could have been used if a 1st pass wasn't required. There's some things I don't understand, such as why for the Ittiam HEVC Software Encoder, 2 pass encoding was used for the "ripping" tests while CBR encoding was used for the other two, or why (according to pdf) the ultrafast x265 preset was used for the "desktop 30fps" test while the superfast preset was used for the "server 60fps" test. Logically to me it should have been the other way around. |
20th November 2015, 21:17 | #10 | Link | |
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27th November 2015, 00:49 | #11 | Link |
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Thanks.
I don't find that comparison very informative. Besides the difficult to understand testing criteria and presentation it's not doing any subjective analysis. Is SSIM that helpful? Doesn't color matter? Doesn't it make sense to include UHD when testing H265? I remember fondly the nice codec comparisons of old (was it here?) of Divx3 vs Divx5 vs Xvid vs..., with screenshots showing problem areas, etc. Things I'd like to know are more along the lines of, for example, how's banding, how well is "line art" content handled, detail retention in dark areas, any problems in motion, is a given codec better than another in every one of the test samples... BTW, how crucial is manual tuning nowadays, both of global encode parameters and maybe even scene-specific? Audio encoding is practically "choose bitrate or quality". I still get the sense that video encoding is full of pitfalls, and an ideal encode needs manual work, plus extensive knowledge not only of the codec in general but also of the specific encoder. |
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h264, h265, hevc |
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