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Old 28th January 2021, 21:08   #2  |  Link
benwaggoner
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Join Date: Jan 2006
Location: Portland, OR
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Setting max bitrate (and vbv-bufsize; they both need to be set to have a useful impact) is mainly useful to reduce variability in bitrate for streaming or for decoder requirements. x265 should automatically constrain it and vbv-bufsize based on your profile, level, and tier, and generally selects the lowest profile and level compatible with your frame size and frame rate.

So setting it to something more constrained would be really based on the specifics of your use case.

Also, why are you annoyed by variability in file size? For encoding, your choices are basically to set quality and vary bitrate or set bitrate and vary quality. Setting an ABR will generally mean that your easiest content winds up being bigger files than needed and your hardest content will get fewer bits than needed to deliver the target quality.

It's possible to use crf and bitrate together, and file size will then be the lower of what needed for the CRF or the specified bitrate.
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