Audio delay in files

Former user wrote on 9/9/2014, 7:41 AM
On another post, I saw someone mention the audio delay that is reported by Mediainfo in some video files, specifically AVCHD.

I am curious about this. Why is there a delay? Does software recognize this and compensate? Is this a limitation of cameras?

I know in some cases this is only 67ms, but was curious why it is there at all.

Comments

musicvid10 wrote on 9/9/2014, 8:23 AM
Because modern codecs are not interleaved the way AVI used to be, determining sync is a lot of guesswork.
The delay is there to compensate for average latency, in itself a moving target.
That's why playback sync in VLC and Quicktime Player and Youtube will often be different with the same material, and why some hardware seem to always play out of sync. Vizio recalled tens of thousands of LCD sets a few years back for that very reason (and the factory refurbs were quite reasonably priced).

Yamb/MP4Box will mux with a user-defined delay, but what a pita!

Former user wrote on 9/9/2014, 8:30 AM
I guess the days of crystal sync are gone. I was just curious. I notice TMPGEnc mpeg editor has a audio delay user setting in it.
musicvid10 wrote on 9/9/2014, 8:35 AM
With all the mp4 compression tricks these days, lots of stuff happens.
Variable frame rate (video) is especially troublesome. They got most of the problems with vbr audio fixed.