2-pass h.265 transcoding with hardware acceleration (nVidia CUDA/NVENC)

[alonsomosley]

I am very happy to see that DVDFab got HW-acceleration feature for 2-pass transcoding! As I tested it I was not sure what I get.

DVDfab does not show "first pass of two passes / second pass of two passes", I see only a nearly constant CPU and GPU usage (at about halftime there should be some change) and if I abort the transcoding procedure at an early stage I get a playable segment of the video (which should be not possible)... All these suggest that there is no real 2-pass encoding going on.

I must assume that 2-pass HW-accelerated transcoding is applied as a single-pass with some "lookahead". Could you clarify this for us?

PS: some h.264 files fail to transcode too, I have to set all decoders to DXVA from CUDA to get it work, and DVDFab shows only a single-pass transcoding. But I guess the files were not correcty in some ways...

[Mona]

CUDA should be supported in 2-pass, please post dvdfab_internal.log file and fabcheck_internal.log file, which could be helpful to check the problem. Thanks.

[Wilson.Wang]

hi alonsomosley,

cuda two pass use NVENC HardWare two pass, will not like soft x264 two pass have two encode flow(pass 1 get some data, pass 2 use pass 1 data),
It will be run on Nvidia driver and Nvenc chips.
About error problem, please post log.

Yours,
Wilson