[FFmpeg-user] Poor quality output when converting avi to mp4

[Gyan]

You have to run

mp4box -aviraw video hd.avi       which will create hd_video.h264

The h264 file cannot be played by many (most?) players but it can be used
by ffmpeg, as shown in the subsequent command. The h264 file only contains
video, no audio so it has to be combined with the audio from the original
source. The 2nd command does that.