Why the frame drift on the timeline?

michael_morlan wrote on 9/1/2004, 12:20 PM

I've noticed this since first using Vegas 4:

29.970fps clips placed on a 29.970fps tend to have their frames drift away from the frame tics marked on the Vegas timeline. For instance, a clip 16:16 long has its end at halfway between 00:00:16:16 and 00:00:16:17.

Even more interesting, with snapping on, markers and the cursor seem to snap at these off-frame points. So, the cursor is snapping at 00:00:16:16 + .5 of a frame.

A closer inspection reveals the timeline tics are running slightly shorter than the footage frames.

Even more interestingly, the problem seems to occur in a .veg within which I have been editing a project, but not in a newly-created .veg. If I completely clear all media from an existing .veg and drag some media onto the timeline, I observe this off-frame error as noted in the pic below:

http://michael-morlan.net/projects/vegas/vegas_timeline_error_02.gif

But, if I create a new .veg and drag the exact same media onto the timeline, it is perfectly aligned with the timeline tics as here:

http://michael-morlan.net/projects/vegas/vegas_timeline_error_01.gif

It is my considered opinion that the Vegas timeline display is actually SHRINKING!

Thoughts? Opinions? Solutions?

Michael

Comments

rmack350 wrote on 9/1/2004, 9:41 PM

If you set your timeline to "absolute frames" and then go look at the lengths of the clips in the media pool you may find that some of your clips are a little longer than some whole number of frames. This can especially happen a lot with audio streams.

When you select a bunch of clips from the pool and drop them onto the timeline they'll snap end to end, of course. And if some are longer than a whole number of frames then everything after will get bumped off the frame line as well. This shouldn't happen if you are actually cutting and trimming each clip on the time line. Just when you drop them whole.

Sound believable?

Rob Mack

John_Cline wrote on 9/2/2004, 5:12 AM

Is this footage that you have captured with the Vegas capture utility or is this footage from another source? Unlike every other video program, Vegas uses a frame rate of 29.970029970 (30000/1001), whereas everyone else uses 29.970 (2997/100).

Curiously, the Vegas frame rate it is absolutely correct and everyone else is doing it wrong. (Well, not wrong exactly, just less precise.)

I have noticed that when I bring in footage which was created or processed outside of Vegas, the frames on the timeline may not match up to the "ticks." One more annoying and very noticable effect is that if if you use footage that has been created outside Vegas and place it on the timeline, at 2 seconds 28 frames from the beginning of the clip, it will repeat a frame regardless of where you put it in the timeline. Usually, this isn't noticeable but its guaranteed to happen. Once I had a logo animation and at 2 seconds 28 frames into the animation, there was a really quick move and the animation would stutter at that point. It drove me NUTS until I figured out what was going on. I raised a stink about it here on the forums a year or more ago, but the reply I got from Sony ( then Sonic Foundry) was that they couldn't help it if they were doing the frame rate correctly and everyone else was doing it wrong.

The workaround turned out to be re-writing the header of the AVI file and change it from 2997/100 to 30000/1001 and that fixed it. I have a command line utility that will do this. I can post it on my web site if you need it.

John

michael_morlan wrote on 9/2/2004, 3:49 PM

Note, too, what I wrote about the cursor and markers/regions. They also end up snapping off-frame along with the video clip.

Why would they be affected by an off-frame length of a video clip?