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27th March 2012, 08:36 | #1 | Link |
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Join Date: Jul 2009
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X264 CRF source related?
Hi all
I am trying to better understand CRF encodings and I have a dumb question which I didn't find it an answer (yet): almost everyone suggests to have a CRF value higher for HD content (e.g. 22) with respect of DVD (e.g. 20), but why? I would have expected the opposite: since CRF targets quality rate it seems like I am wasting more quality (with a higher CRF value) for higher quality source (BD) compared to DVD. Any hint is more than welcome Regards A |
27th March 2012, 08:49 | #2 | Link |
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Join Date: Mar 2005
Location: Finland
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I think the actual reason for that suggestion is that you'll be watching both the HD and the SD encodes on the same display. SD gets upscaled, which makes encoding artifacts more annoying and therefore compensating with a lower CRF may be a good idea.
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27th March 2012, 11:44 | #3 | Link |
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Join Date: Dec 2002
Location: EUR
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Also, for the same reason, I think it makes some sense to encode 16:9 SD material at a slightly lower CRF value than 4:3 SD material. Unless, of course, you happen to use a 4:3 display in which case the opposite would be true.
-- Nikolaj Last edited by nixo; 27th March 2012 at 11:50. |
27th March 2012, 17:39 | #4 | Link |
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Join Date: Jul 2009
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Let's put it simpler...
If I rip from the same source (Blu-ray) but make different resolution (480p, 720p, 1080p) does it still make sense to have a higher CRF for the 480p compared to the 720p and 1080p? I used to Rip DVD at RF 20 but I'm switching to BD and I wonder if it makes any sense to differentiate between the 480p rip and the hd rip. Thnx A |
28th March 2012, 15:03 | #6 | Link |
Telewhining
Join Date: Mar 2010
Posts: 272
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Run some test encodes at incrementing crf values and watch them on your display at a normal distance, and when you start seeing noticeable artifacts, just bump it down 1 crf and go with that. It really depends on your display - on some displays you can't tell the difference between 18 and 22. On others its obvious.
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