Program length discrepancy - DVDA2 vs Vegas

cbrillow wrote on 11/23/2004, 5:51 AM

While trying to track down the source of some incorrectly-placed markers in a DVDA2 project, I found that DVDA2 is reporting the a different 'runtime' than Vegas.

Specifically:

The end of the project on the Vegas timeline is at 1:41:38;0
In DVDA2, the length of the project shows 1:41:31;28 -- a 6-second difference!

I looked at the rendered MPEG properties in the Vegas Media Pool, which shows the "correct" time of 1:41:38 -- same as the timeline length. Playing the MPEG in Media Player also shows the correct length.

As a test, I rendered the Vegas project to avi, and this file also shows the correct time of 1:41:38. A second render to MPEG reproduced the original results -- a reported program length difference of 6 seconds.

One of the implications of all this is that DVD chapter points, which originate as markers in the Vegas project, show slightly different times in DVDA2. A test burn of the DVD shows that they appear to be in the correct positions, however.

It appears that there's a time calculation problem in DVDA2 that results in an incorrect display, but correctly-burned DVD. Has anybody else run into a similar problem?

Comments

johnmeyer wrote on 11/23/2004, 7:59 AM

DVDA does not put the markers at the exact same locations that they are in Vegas. Very annoying. Sony is aware of this but does not promise a fix. Apparently it has to do with the fact that MPEG-2 files are encoded into GOPs (Groups Of Pictures) and the markers can only be placed at the beginning of each group. If the video is encoded outside of Vegas, those groups already exist. Of course, Sony could fix the problem by either forcing a new GOP at any marker location in Vegas, or by breaking any GOP that spans an existing marker location in DVDA, but they don't seem eager to do this.

cbrillow wrote on 11/23/2004, 10:43 AM

Thanks for your comment. While the issue with marker positioning within a GOP is annoying, it doesn't seem like this would affect the timing more than a half-second or so, given that GOPs are limited in size. And that wouldn't account for the difference in reported length between Vegas and DVDA2. That's what really troubles me.

My original intent was to look at the edit list in Vegas and move a couple of misplaced markers to the same point in the timeline in DVDA2. Given the fact that the timeline showed a 6 second difference between the two modules made me wonder if there's something missing from my MPEG2.

jeremyk wrote on 11/24/2004, 11:18 AM

I think the problem here is that DVDA uses non-drop timecode regardless of the timecode setting in Vegas when you render your mpeg file.

Try setting the Vegas timecode to non-drop and see if the timings agree.

Jeremy

cbrillow wrote on 11/24/2004, 5:38 PM

Hmmmmm... thanks for the suggestion -- this is an area I know nothing about, only having recently run across the term. But it's certainly worth reading up on and giving a try.