FFmpeg - The two pass in VP9 generates a empty output file for the first pass

Question

When I try to encode a video file with a two pass in ffmpeg, the output file of the first pass is empty using vp9. Hence I can not proceed with the second part.

Code for the two-pass:

1.pass:

ffmpeg -y -s:v 3840x1920 -framerate 30 -i video_framerate_resolution.yuv -c:v libvpx-vp9 -crf 20
-pass 1 -an -f avi NULL && \

2.pass

ffmpeg -s:v 3840x1920 -framerate 30 -i video_framerate_resolution.yuv -c:v libvpx-vp9
-pass 2 -b:v 1000K -f avi out.avi

Any help would be greatly appreciated. Thanks.

Answer 1

You don't need to generate a file for the first pass. The purpose is simply to send the frames to the encoder so that it can log stats. However, you should skip the muxer.

So, Pass 1

ffmpeg -s:v 3840x1920 -framerate 30 -i video_framerate_resolution.yuv -c:v libvpx-vp9 -b:v 1000k -pass 1 -an -f null -

Pass 2

ffmpeg -s:v 3840x1920 -framerate 30 -i video_framerate_resolution.yuv -c:v libvpx-vp9 -pass 2 -b:v 1000K out.avi