> On Wed, 21 Jan 2004, George Kola wrote:
> > Command? create quicktime playable MP4). I find that MPEG-4 has A/V...
> > Command? towards the end (one stream is behind the other), but MPEG...
> > Command? fine. Any suggestions ?.
>
> Something doesn't scan right in that paragraph - seems as if one or
> two words per sentence were replaced with "... Command?".
>
> It seems to indicate an A/V sync issue but the mention of which
> is behind the other is missing. Is the audio ahead of the video or
> the other way around? And by how much? Does the gap between
> audio and video increase as the movie plays or is it a fixed amount
> thruout the movie?
I am sorry for the messup. I am posting it correctly this time :). I
find that the generated MPEG-1 and MPEG-2 have perfect A/V sync (Thanks to
people here for helping me with it). I find that the MPEG-4 (two pass) has
A/V sync issue. The audio slowly drifts behind the video. In the beginning,
both are in sync. I am using two pass because I want to get the best quality
possible at a given bitrate of 250 kbps. We want to stream it over broadband.
Noticable lag starts occuring in the last 15 minutes of the clip. The lag is
0 at the beginning, becomes 4 seconds at 45 minutes and becomes close to 10
seconds at 60 minutes. I wanted to know how to correct it.
>
> What program(s) were you using to play the .mp4 file? Some
> players (windows ones as I recall) do not deal well with variable bitrate
> MPEG-1 Layer 2 or 3 audio - is that what you were using or did you create
> AAC audio or constant bitrate MPEG-1 audio?
I am using MPEG-4 Video and AAC Audio in MP4 container and
using quicktime to play it. I also tried with Windows media player.
> I've created numerous MP4 files that play well (no A/V sync issues)
> with both MPlayer and Apple's Quicktime Player.
>
It would be great, if I am also able to create such MP4 files :).
> Is the data you are working with from a analog->DV capture or from
> a digital (miniDV or Digital8) camcorder?
>
It is a miniDV camcorder.
> > One more question -- for video capture under windows or MAC OSX,
> > does anyone know of any software that can capture to Raw DV ?. Would it
> > help with A/V sync problem.
>
> I do not believe it will help. A/V sync issues are not, as a
> general rule, introduced by the system that does the DV capture.
Thanks, then I do not have to bother about the DV capture.
Thanks,
George
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