Once again I will go back to Dark Shikari this time from
another thread:
Quote:
Originally Posted by Chengbin
If I want the highest quality encodes without time limit, is CRF better or 2 pass? Suppose I encode a video using CRF x, and it output a video that is 800MB, now I use 2 pass, and specify the size to 800, which way of encoding would provide higher quality?
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Quote:
Originally Posted by Dark Shikari
Neither.
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Quote:
Originally Posted by Chengbin
Oops, let me change that to which way of encoding between the 2 would create a better encode?
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Quote:
Originally Posted by Dark Shikari
Neither.
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Quote:
Originally Posted by Chengbin
So they're the same? 2 pass is only to hit a specific file size? I thought the first pass is to analyze the video file to see where to distribute the bits or something like that.
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Quote:
Originally Posted by Dark Shikari
CRF, 1pass, and 2pass all use the same bit distribution algorithm. 2-pass tries to approximate CRF by using the information from the first pass to decide on a constant quality factor. 1-pass tries to approximate CRF by guessing a quality factor over time and varying it to reach the target bitrate.
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So if you don't want to believe Dark Shikari and waste your time doing 2-pass encodes with needless slow first passes for pretty much no gain in quality go ahead, but don't continue to spread misleading statements that then constantly have to be corrected. 2-pass is purely for wanting to hit specific sizes for your encodes as 1-pass CRF is for when you do not care about final size. 2-pass does not give you magical better quality. As detmek says the streams will not be bit-identical, which I didn't say they would be, but you will not see any perceptible quality difference between them assuming you have the exact same settings and they are equivalent size. If you are seeing noticeable differences even under those constraints then you need to report it as it is most likely a bug.