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27th April 2021, 15:48 | #2 | Link | |
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In theory all decoders should output the same thing, but some might have additional error correction For PAL DV it shouldn't matter, because it's 4:2:0 For NTSC DV it definitely matters, because of how codec and host application interpolate and resample 4:1:1. Cedocida uses something similar to bilinear chroma upscaling. ffmpeg/libavcodec based decoders return the original 4:1:1 color samples for NTSC DV, so you have control over how chroma is upsampled and transformed. There are some situations where you might want "blocky" color edges (such as nearest neighbor/point, e.g. for multiple generations) , but others where you might want smoother color edges |
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28th April 2021, 21:17 | #3 | Link | |
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But it has different chroma alignment than standard YUV4:2:0:
If I remember correctly it created reinterpolate420 for exactly this case: https://forum.doom9.org/showthread.php?t=82787 (you might want to replace tomsmocomp by nnedi3.) Quote:
This mostly avoids any stairstepping.
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28th April 2021, 22:15 | #4 | Link | |
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If you recall , cedocida configuration allows you to select and "force" YV12 output and DV YV12 chroma sampling for decoder settings (you uncheckmark YUY2 and the other boxes) . So this works for PAL DV. You have the original 4:2:0, and you can choose whatever method to resample. The problem is NTSC DV, where cedocida does not have 4:1:1 output option (ie. it's always resampled by cedocida, and not very nicely) . A better option would be ffmpeg/libavcodec based decoders, which do output the original 4:1:1 Note you can also control the chroma location interpretation and algorithm used with internal avs resizer or avsresize, but if codec already resampled the chroma, then it's possibly done incorrectly. If you start with original DV chroma sampling, then you have more control and ensure it's done correctly Chroma in/out placement http://avisynth.nl/index.php/Convert#Chroma_placement Avsresize chromaloc http://avisynth.nl/index.php/Avsresize |
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29th April 2021, 08:34 | #6 | Link |
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Thank you for explanation, i read the linked.
Can you please advice how to use nnedi3 to get best results? If i understand it properly, nnedi3 is able to compute every second missing line But for C we have one line and three missing. Also i want to ask: if we have two frames after each other, if the lines are: Y Cr Cr Y Y Cb Cb Y Y Cr Cr Y Y Cb Cb Y or Y Cb Cr Y Y Cr Cb Y Y Cb Cr Y Y Cr Cb Y |
29th April 2021, 19:08 | #7 | Link | ||
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If it's something like DVD-video, you need to stay with interlaced 4:2:0 - you cannot "interpolate" missing lines Quote:
If you look at the "dither" package for avisynth, there are diagrams in the documentation. There is a weblink below, you need to scroll down a bit to see the diagrams http://avisynth.nl/index.php/Dither_...her_resize16nr Also see this diagram https://www.adamwilt.com/pix-sampling.html |
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29th April 2021, 22:06 | #8 | Link |
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The goal is to have 50p using TGMC, best what i can get from the PAL DV source. About format i did not think until now. So it seems the 4:2:0 is kind of standard.
If i understand, i may interpolate somehow, but i need to have different output than 4:2:0, correct? Last edited by Terka; 29th April 2021 at 22:10. |
29th April 2021, 23:51 | #9 | Link | |
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Correct, there is no chroma interpolation in that case The other discussion referred to 4:2:0 to 4:2:2 upsampling - this is "upscaling" the chroma - if it's done with nearest neighbor (point resize in avisynth), pixels are just duplicated. This leads to "blocky" color borders. If instead you used another algorithm (such as nnedi3 or others), you could get smoother, perhaps "better" results, or at least less blocky There are times when you might want "blocky" results - to preserve the samples with nearest neighbor - when you have multiple generations of up/down scaling. This can be lossless if done properly. But if you used the other algorithms (nnedi3 or others), they are not reversible losslessly |
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30th April 2021, 10:01 | #10 | Link |
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Its rather complicated also because the interlace. My goal is to achieve the best i can pull of of the source.
Luma is compressed by 50% because of interlace 4:2:0 Cr by 50% and again by 25% => 12,5% Cb by 50% and again by 25% => 12,5% I might go for upsampling. Question is which should i use - if going to 4:2:2 or even 4:4:4 is not overkill. Not sure how the filesize will change. I can imagine that some kind of coloring based on the Luma, which has 4times higher resolution. |
30th April 2021, 15:51 | #11 | Link | ||
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Upsampling depends a lot on the source quality. Sometimes there are other problems with the chroma In general, I'd say upsampling the chroma has marginal benefits Quote:
http://forum.doom9.net/showthread.php?t=173005 |
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30th April 2021, 21:36 | #12 | Link | |
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Thank you.
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I see spots in one of the chroma channels. They appear on one frame and disappear. |
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30th April 2021, 21:49 | #13 | Link | |
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How often is DV from consumer source "pristine" ? "Spots" are probably chroma noise. It probably is not a good idea to upscale spots and noise - you'd probably need to filter it first |
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4th May 2021, 09:34 | #16 | Link |
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Thank you, here is an example from the camera
https://www.uschovna.cz/zasilka/LBUXBY89KYFZ72KR-74Z/ |
4th May 2021, 18:56 | #17 | Link |
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That clip is typical "quality" of consumer PAL DV
The amount and type of denoising to apply is really subjective and up to personal taste If you're using QTGMC, that already denoises by default Personally, I prefer details over loss of details, so I'm more cautious with denoising |
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