[FFmpeg-user] The option of -hwaccel device doesn't works well(FFmpeg n3.4)

[Baek Seung Hoon]

(Its mail continuous previous my one.. sorry)
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I wonder know what is different ffmpeg internal sequence following 2
commands..

1.
 > ffmpeg -y -i ./input.mp4 -filter_complex
"[0:v]hwupload_cuda=device=0,scale_npp=w=960:h=540[map0]" -map "[map0]"
-c:v h264_nvenc -c:a copy ./output.mp4

2.
 > ffmpeg -y -hwaccel cuvid -i ./input.mp4 -filter_complex
"[0:v]hwupload_cuda=device=0,scale_npp=w=960:h=540[map0]" -map "[map0]"
-c:v h264_nvenc -c:a copy ./output.mp4

In fact, the performance is similar as 861 fps for encoding.
Could I ask you what role "hwaccel cuvid" is in the above command?

Thanks again :)
BRs,