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All the same, with estate of instructions on the Internet, on forums, I have this problem.
ffmpeg -y -i input.mp4 -vcodec libvpx-vp9 -crf 31 -minrate 1500k -maxrate 4350k -pix_fmt yuv420p10le -colorspace 9 -slices 4 -color_range 2 -tile-columns 2 -quality good -g 240 -c:a libopus -b:a 128k -pass 1 NUL && ^ ffmpeg -i input.mp4 -vcodec libvpx-vp9 -crf 31 -minrate 1500k -maxrate 4350k -pix_fmt yuv420p10le -colorspace 9 -color_range 2 -tile-columns 3 -slices 4 -quality good -g 240 -map_metadata:g -1 -map_metadata:s:v -1 -map_metadata:s:a -1 -map_chapters -1 -c:a libopus -b:a 128k -pass 2 output.mp4
I am a windows user. Most people use ffmpeg on Linux, so the two-pass encoding uses /dev / null. I'm not interested, because on windows it does not work. Read as the instruction on trac-page ffmpeg (trac.ffmpeg.org). It says:

Note. Windows users should use NUL instead of / dev / null and ^ instead of \ .

But it didn't help. I used:

NUL

NULL

/dev/NUL

/dev/NULL

but to no avail. It seems I am disappointed, never fully immersed in the study of ffmpeg. (recently only began his explore).

There is the same theme, there also say you need to use NUL.(Click)

Screens(I not have 10 rep):
1 Screen
2 Screen

I ask for the help of professionals in this case.Or still, will have to torment the emulator...

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1 Answer 1

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FFmpeg tries to detect the output container format based on the output filename but since NUL is not an actual filename, the format has to be specified. You may use the null muxer.

ffmpeg -y -i input.mp4 -vcodec libvpx-vp9 -crf 31 -minrate 1500k -maxrate 4350k -pix_fmt yuv420p10le -colorspace 9 -slices 4 -color_range 2 -tile-columns 2 -quality good -g 240 -c:a libopus -b:a 128k -pass 1 -f null NUL && ffmpeg -i input.mp4 -vcodec libvpx-vp9 -crf 31 -minrate 1500k -maxrate 4350k -pix_fmt yuv420p10le -colorspace 9 -color_range 2 -tile-columns 3 -slices 4 -quality good -g 240 -map_metadata:g -1 -map_metadata:s:v -1 -map_metadata:s:a -1 -map_chapters -1 -c:a libopus -b:a 128k -pass 2 output.mp4

(I haven't checked the rest of your parameters)

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  • Thank you so much for your help. I hate when the instruction is outdated or completely wrong. And Yes, there was no -b:v 0 parameter in my command
    – SEN5AI
    Oct 13, 2019 at 12:20
  • @SEN5AI Which instruction do you believe is outdated or wrong? The wiki (trac.ffmpeg.org/wiki/Encode/H.264) clearly uses the -f option to specify an output format in the first pass, and it says “In pass 1, you need to specify an output format (with -f) …”
    – slhck
    Oct 14, 2019 at 8:14
  • THERE was no indication which option to use for windows
    – SEN5AI
    Oct 19, 2019 at 10:55

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