MP4, sound, sampling rate
Posted: 14 Apr 2004 15:21
I'm posting this information in the hope that it might be of interest to VLC developers. I have VLC 0.7.1 running on Windows ME with Direct X 8.1.
I have downloaded various MP4 videos from the net and use VLC to play them. Everything works fine. More recently I have been experimenting with encoding my own MP4 videos (not using VLC as encoder).
I found that when I played back my own encodes I got the famous VLC "sound wobble" - occassional resampling causing the sound to speed up and slow down.
I set about trying to find out what the difference was between the MP4's I had downloaded and the ones I had encoded myself. The only real difference I could find was that the downloads had audio tracks encoded at 32kHz audio sampling while I was using 44.1kHz.
I re-encoded my own videos using 32kHz audio sampling and the "sound wobble" dissapeared.
I have downloaded various MP4 videos from the net and use VLC to play them. Everything works fine. More recently I have been experimenting with encoding my own MP4 videos (not using VLC as encoder).
I found that when I played back my own encodes I got the famous VLC "sound wobble" - occassional resampling causing the sound to speed up and slow down.
I set about trying to find out what the difference was between the MP4's I had downloaded and the ones I had encoded myself. The only real difference I could find was that the downloads had audio tracks encoded at 32kHz audio sampling while I was using 44.1kHz.
I re-encoded my own videos using 32kHz audio sampling and the "sound wobble" dissapeared.