Audio sync - problem of muxing?

[dcrht]

Hi, I have a converted a bunch of x264 videos with mencoder, aac with nero aac encoder, then mux them with yamb.

All videos have audio delay of about 0.3 seconds. If I watch them on VLC player, or using MOV container, they are fine.

Can anybody help me please? :confused:

[bond]

moved

reencode the aac taking the constant delay into account, as described in various posts and guides on this site

[rberger]

moved

reencode the aac taking the constant delay into account, as described in various posts and guides on this site

I'm not sure cutting is a solution, given that an AAC encoder might nondeterministically throw in extra samples and get your stream seriously off sync anyway. I just AAC encoded a 5.1 wav with Nero which received extra samples during the encoding process amounting to a whopping 97 millisecond delay.

Now Nero tries to compensate for this via "external signaling" through container means, in this case the chapter list:


MP4Box -info 4.m4a
* Movie Info *
Timescale 90000 - Duration 00:45:01.953
Fragmented File no - 1 track(s)
File Brand mp42 - version 0
Created: GMT Tue Feb 24 23:12:18 2009

File has no MPEG4 IOD/OD

Chapters:
Chapter #1 - 00:00:00.097 - ""

iTunes Info:
Encoder Software: Nero AAC codec / 1.3.3.0
....


but as soon as you mux that with a video stream obviously this chapter list fix doesn't make much sense anymore. And since the only other means to time shift a track - edit lists - doesn't seem to be honored by most playback software you're seriously screwed.

So currently I don't see the combination AAC/MP4 being a viable solution for compatible quality video encoding. It would be if edit lists were better supported on the demuxing end, but as said they don't seem to be. Maybe it works better with Matroska, don't know.