OT: Question re AVC video and audio sync

PeterDuke schrieb am 08.09.2014 um 04:49 Uhr

AVCHD video recorded with my Sony camera shows according to Mediainfo that the audio delay is -80ms, i.e. 80ms in advance of the video. A recording of a makeshift slapstick or clapperboard shows the audio and video to be in sync in Vegas.

If I pass the video through tsMuxer to make another .m2ts file, Mediainfo does not report any audio delay, and such video when viewed in Vegas has the audio 80ms delayed.

How is this audio delay indicated to Mediainfo and Vegas, but apparently misinterpreted by tsMuxer? Is it a flag or a calculation?

Kommentare

musicvid10 schrieb am 08.09.2014 um 17:21 Uhr

It's a flag for the decoder. I too have done muxing operations when it disappeared.
I was able to re-insert the needed delay using Yamb/MP4Box, with lots of trial and error and cursing under my breath.

PeterDuke schrieb am 09.09.2014 um 02:15 Uhr

Thanks musicvid10.

My Sony camera is rather old and I have now replaced it with a new Panasonic. The audio delay with the Panasonic is -40ms (40 ms advance), but the good thing is that the audio delay flag is retained by tsMuxer, and the audio stays in sync.

I was looking to use tsMuxer to join the segments of long scenes that had been split (2GB max for Sony, 4GB max for Panasonic). Fortunately, Sony provides software that will do this, so I don't need tsMuxer. Panasonic does not provide such software, but it looks like I can use tsMuxer.

I was just trying to understand the process better to avoid problems.