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22nd May 2018, 20:20 | #61 | Link | |
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It may be that all the UHD HDR stuff actually is using the chromaloc 0 positioning, which works because both encoders and decoders ignore it. Any error at 2160p isn't likely to be visible; worse case it would be 25% the impact CUE was at 1080p. But I get nervous about what might happen if some encoders and/or players do it correctly and some don't, for content at lower resolutions. And no one seems to have a good test pattern for this. |
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19th February 2019, 03:04 | #63 | Link | ||
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chromaloc
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VapourSynth ClipInfo() show Chroma Location: Left VapourSynth Docs: Quote:
I'm confused. What the right way? PS: Im encode through vspipe.exe --y4m video.vpy - Last edited by redbtn; 19th February 2019 at 03:06. |
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19th February 2019, 11:25 | #65 | Link | |||
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My VS script Quote:
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12th March 2019, 17:26 | #66 | Link |
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Hi
Do I need special switches for HDR besides the ones I already use? I currently use: --profile main10 --output-depth 10 --colorprim bt2020 My encoded movies work as HDR on my TV look realy good. So my primary question is do I need "--hdr-opt" as it is often referred to in this forum but mostly on older threads. |
12th March 2019, 18:51 | #67 | Link |
Derek Prestegard IRL
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You should use this, yes. It applies offsets to chroma QPs to improve quality for HDR encoding.
You should really signal --transfer smpte2084 (to signal the PQ curve) and --colormatrix bt2020nc. You should also signal HDR10 static metadata e.g. --master-display and --max-cll if available. This will give your display as much info as possible to present the best possible HDR image. https://x265.readthedocs.io/en/default/cli.html |
13th March 2019, 10:01 | #68 | Link | |
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I can easily set: --transfer smpte2084 --colormatrix bt2020nc --hdr-opt But how do I set " --master-display" and "--max-cll" that looks really complicated. |
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13th March 2019, 10:27 | #69 | Link |
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Most people look up the source parameters using MediaInfo and then use those values. For master-display these have to be re-calculated but most sources seem to use the very same parameters for the color coordinates anyway where MediaInfo will say "Mastering display color primaries : Display P3" and it's the exact values you find as an example in the x265 docs.
https://x265.readthedocs.io/en/defau...master-display Also if MediaInfo says "Chroma subsampling : 4:2:0 (Type 2)" set --chromaloc 2. |
13th March 2019, 12:09 | #70 | Link | |
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I checked some encoded HDR files and the max-cll values are set correctly. Also the master-display information is included but I can't see those values in the ripped original files with media info - kinda strange. Last edited by blublub; 13th March 2019 at 12:24. |
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2nd April 2020, 21:46 | #71 | Link |
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What does --max-cll and --master-display actually do?
I am trying to get into HDR encoding, but it seems a bit complicated. Basically this is my command line for SDR videos: --crf 18.0 --fps 24000/1001 This gives me actual perfect quality with 12-bit x265 (dark scenes and fades are perfect too). I do not see the point of using additional settings, I do not care about optimizing the bitrate, it is very low anyway. I play videos on my PC (MPC-HC + madVR), so I do not care about compatibility either. This is what I currently have for HDR: --crf 18.0 --fps 24000/1001 --hdr10 --colorprim bt2020 --transfer smpte2084 --colormatrix bt2020nc HDR playback works and looks ok (LG OLED C8), but you cannot compare the HDR source and encode like you can with SDR. Can I be missing something by not using max-cll and master-display? What if I use them, but set them wrong? |
3rd April 2020, 16:44 | #72 | Link | |
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--maxcll It specifies the nit value of the brightest single pixel (MaxCLL - Max Content Light Level), and the nit average nit value of the brightest single frame (MaxFall, or Max Frame Average Light Level).
Master Display encodes the color volume that the display used in mastering was. The idea is that pixels with values outside of what the mastering display could be clipped because the colorist couldn't have seen those differences. Higher end consumer TVs can deliver a lot more brightness than typical grading monitors. Quote:
That'll put in null values for the SEI metadata, which tells the TV that the values are undefined, which TVs know what to do with. It is much better to use null values than specify incorrect ones! |
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3rd April 2020, 18:44 | #73 | Link |
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From what we've seen, the max-cll and master-display params end up doing little to nothing most of the time
You never know what future behavior will be, so I agree with the recommendation to make them exact or null. |
3rd April 2020, 19:43 | #74 | Link |
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Thanks for the info.
And can I use the 12-bit x265 encoder with a 10-bit source? With SDR content, 12-bit encoding provides significantly better results (dark scenes and fades), but I wonder if it can somehow break the accuracy with HDR. 10-bit encoding definitely creates slight artifacts at low and medium bitrates during dark scenes and fades, 12-bit would probably eliminate that, just like with SDR content. |
3rd April 2020, 20:10 | #75 | Link | |
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I'm not familiar with MaxFALL being used much; could be used for average power level adjustments. Dynamic metadata is much, much, much more useful! |
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3rd April 2020, 20:44 | #76 | Link | |
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3rd April 2020, 21:06 | #77 | Link |
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As I said, I only encode videos for personal use and I play them on PC, so compatibility is of no concern. I only care whether it provides accurate results (as it does with SDR content).
On a side note, are hardware decoders not able to decode 12-bit video? It does not seem to require any more power (GPU or CPU) when played on PC. |
4th April 2020, 05:56 | #79 | Link | |
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