On Wed, May 01, 2024 at 09:10:51PM +0000, Tom Vaughan wrote: > When I attempt to pass vbv-end and vbv-end-fr-adj parameters to x265, FFMPEG > fails. > > x265 [error]: vbv-end-fr-adj cannot be enabled when total number of frames is > unknown > > x265 needs to know how many frames it is encoding so that it knows when the > vbv-end logic needs to kick in. In this case it would be after 96% of the > source video is encoded. Despite specifying a duration of 30 seconds ( -t 30 > ) on both input and output (using a 60 second source video), x265 does not > know the total number of frames (but FFMPEG surely does). > > ffmpeg -i test_uhdsdr_1min.mov -t 30 -an -sn -dn -c:v libx265 -b:v 12000k > -maxrate 8M -bufsize 18M -x265-params > vbv-init=0.9:vbv-end=0.9:vbv-end-fr-adj=.96:rc-lookahead=48:qg-size=32:scenecut=0:no-open-gop=1:frame-threads=0:repeat-headers=1:nr-inter=400:nr-intra=100:psy-rd=0:cbqpoffs=0:crqpoffs=3 > -t 30 test_uhdsdr_96.mp4
you can specify total_frames along with vbv-end-fr there is in general not a 1:1 correspondance between duration and the number of frames the frame rate may vary, there may be skiped frames or damaged frames that where lost and so on. in case of some 2 pass mode it should be possible to get the exact number of frames in the 2nd pass. Otherwise my gut feelng is that a time based instead of a frame number based threshold would have been easier to work with if you are thinking that the total frame number should be set automatically and not by hand. I agree, its just not easy to do that in all cases. It could maybe be done in specific cases but in the general case it would need 2 passes to be reliable. thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Dictatorship: All citizens are under surveillance, all their steps and actions recorded, for the politicians to enforce control. Democracy: All politicians are under surveillance, all their steps and actions recorded, for the citizens to enforce control.
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