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Old 10th April 2017, 15:49   #1175  |  Link
r0lZ
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Quote:
Originally Posted by Araldwenn View Post
I see there is many other options to choose (CRF, CQ, 2 pass, ABR). Which one should I use to have the best quality with a decent file size, I mean something about 15/20 Gb ?
Personally, I prefer CRF, that gives ALWAYS a better result than 2-pass for the same global bitrate. But with CRF, it is not easy to predict (even approximately) the resulting file size, because it compresses much more the "easy" movies such as the Pixar films in computer graphics than the "difficult" ones like the live action films of the 80's, or the old 3D movies of the 50's with much noise. That's normal, because CRF adapts automatically its compression to the image, something that doesn't do 2-pass or, of course, ABR (= 1-pass). CRF is also better than CQ because it compresses more the blurred part of the images with fast action (motion blur), because it is impossible for the human eye to distinguish the loss of quality in moving images (unless you press the pause button, of course). It has therefore more bitrate to spend for the slow or static images, where small defects are more visible. CRF is therefore the more intelligent way to encode a video, and I don't understand why peoples continue to use 2-pass. (2-pass should be used ONLY when the final file size must be precisely controlled, like when you encode to put the movie on a DVD.)

The CRF value to use is another question. IMO, the default value of 23 is a good compromise between quality and disc space, but I prefer to use 20 for movies where the image quality matters much (like Sin City 2). However, even with CRF 20, you will never obtain a 20GB file. That's way too high IMO. Don't forget that the huge file sizes of the commercial BDs are so high simply for commercial reasons. A movie (with 1 AC3 audio stream) can be perfectly encoded with 4 to 8 GB, depending of the "difficulty" to encode it and its length. More than 10 GB is IMO total nonsense. You cannot see the difference with the same movie encoded at 8 or even 6 GB. Try it. Encode two movies with, say, CRF 20 and CRF 12, and ask a friend to show you both of them in random order. I'm sure you will not see what is what.

Anyway, you are free to use any CRF value. It is often explained that subtracting 3 to the CRF value has roughly the effect of doubling the size of the video stream. It's not really accurate, but take that in mind when you will try different values. (So, for example, CRF 10 may produce a video stream about 10 times larger than CRF 20, for an almost imperceptible visual improvement. But similarly, using CRF 26 may produce a really bad quality.)

Trust your eyes ONLY, and don't try to encode at a specific bitrate.

And, to reply to your initial question, if you re-encode in Full-SBS, then BD3D2MK3D is the tool to use! ;-)
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Last edited by r0lZ; 10th April 2017 at 15:59. Reason: typo
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