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Old 22nd January 2019, 22:24   #34  |  Link
Asmodian
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Join Date: Feb 2002
Location: San Jose, California
Posts: 4,406
Quote:
Originally Posted by asarian View Post
Why not?! Leaving a feature disabled can sometimes improve quality; and sometimes having the feature enabled will not impact quality.
For one, the second sentence does not say sometimes.

It also does not make sense technically. If you do not wait for all previous frames to be encoded sometimes you cannot chose what would have been the best reference block because it isn't available yet.

Quote:
When frame threading is disabled, the entirety of all reference frames are always fully available (by definition) and thus the available pixel area is not restricted at all, and this can sometimes improve compression efficiency. Because of this, the output of encodes with frame parallelism disabled will not match the output of encodes with frame parallelism enabled; but when enabled the number of frame threads should have no effect on the output bitstream except when using ABR or VBV rate control or noise reduction.
Also, what would the bold mean if "no effect on the output bitstream" means "no effect on quality"?

Edit: Maybe it is saying that once --frame-threads = 2 more frame threads should have no effect? I find this hard to believe, because more incomplete frames seems like it has to mean fewer reference blocks available, but it might be what is meant and I don't know how the details of reference block selection interacts with frame parallelism.
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Last edited by Asmodian; 22nd January 2019 at 22:40.
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