Is there a known fix for ffmpeg 2-pass errors on Windows? The command
ffmpeg -i input.mp4 -c:v libvpx-vp9 -b:v 2M -pass 1 -an -f null NUL && ^
ffmpeg -i input.mp4 -c:v libvpx-vp9 -b:v 2M -pass 2 -c:a libopus output.webm
as suggested by https://trac.ffmpeg.org/wiki/Encode/VP9 doesn't give consistent errors. Initially, it complained about not being able to open ffmpeg2pass-0.log if I remember correctly. Online suggestions involving -passlogfile just didn't do anything. Eventually, the error disappeared and got replaced by claims of not being able to initialize the encoder.