Mp3 out of sync

Randy Vild wrote on 6/22/2005, 10:35 PM

This is very weird one. I rendered an mp3 and posted it on the web. I needed to make an adjustment to it so I downloaded the file to my desktop and put it in Vegas track. Now the first time listening to it was good then after that as you go about 60%-100% through the audio is out of sync. In fact when the digital timline shows no audio it will still read audio (I guess because it is out of sync) this it very mind blowing...any ideas?

-Randini

Comments

farss wrote on 6/22/2005, 11:22 PM

mp3 files always contain 18mS of silence at the head and tail, it's part of the spec. But I checked a file I've just rendered out by syncing the wavforms near the start and over 38 seconds there is less than 1 mS drift. I wouldn't say it's sample accurate but given the difference in how .wav and .mp3 works that's not surprising.

bgc wrote on 6/22/2005, 11:35 PM

the difference in .wav and .mp3 has to do with the transform window length used in the encoding.
i'm pretty sure it's a constant offset. i'd worry more about the quality degradation than the time offset ;)

Chienworks wrote on 6/23/2005, 4:14 AM

If there is a reason to use the .mp3 file for further editing instead of going back to the original .wav source, then that reason needs to be ferreted out, severely scolded, and eliminated! In a case like this the original uncompressed versions should certainly be kept around and used for future editing rather than trying to use the compressed version.