I'm trying to transcode an uncompressed AVI ~27GB in size to an MP4. I'm using the following command:
ffmpeg -i input.avi -c:v libx264 -preset slow -crf 20 -c:a copy output.mp4
The resultant MP4 file is about the size I would expect (~650MB) and when I open it in WMP it has the right length (5:29) but clicking play does nothing. I have transcoded it using Handbrake and it works fine but I'd like to know why this command does not work. Thanks!