Possible bug when saving project w/ trimmed media?

prairiedogpics wrote on 7/1/2004, 7:47 AM
I recently completed an 1.5 hour project and just for neatness' sake, I re-saved it to another drive, using the "save with trimmed media option".
When I open up this new saved version some clips in the project are not correct: specifically, I had some mpeg clips on the timeline (the only source I have for these is mpeg, no alternative DV AVI files). There are clips from the same mpeg file in the correct locations on the timeling, but they are not from the correct location in the original mpeg file (offset by several seconds).

Is there a problem with mpeg clips on the timeline when saving with trimmed media? Sony?

Dan

Comments

prairiedogpics wrote on 7/1/2004, 12:21 PM
bump
stormstereo wrote on 7/1/2004, 1:29 PM
I'm guessing here.

An AVI file usually has a sort of "keyframe" on every frame. This makes it possible to edit accurately on any chosen frame. An mpeg, which is a delivery format, has not. When you render to mpeg it's possible to select how often a "keyframe" should occur in the mpeg stream.

Let's say there's a "keyframe" every two seconds in your mpegs. After saving a trimmed copy Vegas would then not know exactly how you edited since it looks for these keyframes. Vegas uses the nearest keyframe available to calculate your edit. I THINK.

Now, how do you avoid this? I would render the original mpeg to an AVI BEFORE I start using it on the timeline. Yes, there's a recompression step in doing so but if you use the normal DV-template there should not be much difference, if any, noticable. Do some test renders to AVI first, on short segments, just to compare the quality to the original mpeg.

Anyone who could give a 100 % correct answer are welcome to spill their beans.
Best/Tommy
prairiedogpics wrote on 7/2/2004, 6:09 AM
stormstereo,
You were correct. I rendered the individual mpeg clips separately, and then added the newly rendered DV AVI files as takes to their corresponding locations. Then I deleted the first "raw mpeg" takes in each instance, leaving the DV AVI substitute takes. I then re-saved the whole project with saved/trimmed media, and re-opened it. Bingo. Everything was as it should be. Now that project can be put to bed.

Thanks for the help.

Dan
stormstereo wrote on 7/4/2004, 1:47 PM
Great, feels good to be helpful (when it works), hehe!
Best/Tommy