Single Frame Flash - now you see it...now you don't

Liam_Vegas wrote on 3/30/2004, 11:10 PM
Many of you may remember some older posts refering to an odd single frame flash that sometimes pops up when previewing or rendering.

In prior occasions when this ocurred I believed that it was due to a slip-up on my part where I had been a little less than 100% careful with a long-form multi-camera edit and that I somehow managed to let a frame get out of place (this DEFINITELY was the reason in several examples I found).

I just experienced another example of this... and it was definitely some kind of bug.

I was previewing the timeline and suddenly up pops a flash-frame from a completely different part of the timeline in a totally different clip. By single frame stepping through the timeline I located the exact frame where this was happening. Only thing was that it could not possibly be coming from that clip as it was a totally continuous video clip there was no other video above/below that point that could be "interfering" with the video. Skip one frame before this point and you got the correct video and one frame after this frame and again the correct video.

Odd.

I saved this VEG into a new file (just did a Save-As and renamed the file) in the hopes that I would then have a really great example to show Sony.

I shut down Vegas and then opened up the saved Veg expecting to find the problem still there and to my surprise - NO PROBLEM. Now... in case anyone asks the obvious question... I made absolutely NO changes between the point that I verified the problem frame on the preview - saved the veg - shutdown vegas - reloaded the <apparently> bad veg - and verified that the bogus frame was no longer there.

So... I am left with the belief that you can have some VERY weird things that may ocurr while previewing from the timeline. I am not sure if the problem I experienced would have made it into a real RENDER from the timeline (rather than just the preview)... but it does make me a little paranoid that something like this could slip into ANY project I render.

Anyone else seen something like this?

Comments

craftech wrote on 3/31/2004, 5:56 AM
The Flash Frame phenomenon has been going on since version 3 and will unlikely be fixed in version 5 because SF/Sony techs can't reproduce it. The last time it was posted (around a month ago) SonyEPM suggested setting the ram preview allocation to zero. I did that and just got a flash frame in a project I did two weeks ago. After a second render it disappeared. I am sure they would like to fix it,but if they can't reproduce it, they can't fix it.
The only time I seem to get it is when I use a very long credit roll, but I am not sure it is related.
OTOH they haven't done anything to improve the limited credit roll generator since version 2. Now that's something they could make more versaitile, user friendly, and professional.

John
filmy wrote on 3/31/2004, 6:12 AM
>>>Anyone else seen something like this?<<<

Oh yes we have. :)

Just happened a few days ago matter of fact. Lots of posts around here about this but as near as I can figure out there is some sort of cache going on. So, for example, you have a frame at time 1:02:34:01 and then you, with ripple on, cut out some stuff so the timeline ripples and now that frame is at 1:00:12:25. *HOWEVER* when you play the time line you still see that frame at 1:02:34:01 *or* you see a black frame there. I have seen both. The black frame issue really bugs me more - I can trim the media, I can shorten the media or I can extend the media prior and that black frame is still there. (and this has nothing to do with the black frame/gap issue) It is random, it is not easy to reproduce - so it just is.

Sometimes saving the project fixes it. Sometimes closing and reopening the project helps.
Chienworks wrote on 3/31/2004, 6:42 AM
I had one just this morning. I split a clip where i wanted it to end and deleted the portion to the right of the split. At this point the cursor should have been sitting on an empty frame but i saw the last frame of the source clip in the preview window. Nothing was visible on the timeline. I zoomed all the way in to the sample level (the width of the timeline on the screen was then 50 samples, or about 1/1000th of a second) and i saw it: a tiny piece of a video clip about 10 pixels wide or about 1 sample long. The audio event that was after the part i had deleted was lined up with the end of this tiny fragment instead of being lined up with the frame boundry.

I deleted the tiny fragment and all was well. The following audio event auto-rippled up next to the cursor and i had black in the preview window. Now that i think of it, i don't recall ever seeing this happen before auto-ripple. I see it once in a while now. The only times it has happened is when i split and delete the right portion after the split. It doesn't do it every time of course, but that's the only situation in which i've seen it happen. I'll have to do some more experimenting and see if it happens only when auto-ripple is on.
roxy11 wrote on 3/31/2004, 8:42 AM
I've just finishied rendering my first project in Vegas, and, prior to the render,.... I had a couple flash frames occur at the end between two text boxes (from the media generator). I was using the text boxes rather than the credit roll, because I couldn't seem to get a slow enough credit roll with the amount of text I was using. Being new to Vegas, I find myself just going in and experimenting. Anyway, the two flash frames were from an entirely different part of the nearly 2 hr project, and it really baffled me as to how they got there. The project is a videotaping of Howard Zinn speaking at a nearby college, and since the flash frames showed him standing there smiling, and they appeared between two text boxes of a brief bio of him,.... I thought I'd just leave them there as a synhcronistic apparition of sorts. But they no longer appeared after the render, ...although now there appears to be a slight, brief text glitch at that point. I would rather have kept the flash frames , than see that glitch. Maybe I'll re-render.
filmy wrote on 3/31/2004, 10:22 AM
In my case is normally has nothing to do with text or spliting an event - it is just somewhere down the line the actual media is pulled up but a single frame remains in a buffer somewhere it seems. But this is a perfect example of why it can't really be reproduced - everyone has something a bit different going on when it happens.
rmack350 wrote on 3/31/2004, 10:58 AM
I'm inclined to think there are two different problems causing similar effects.

Filmy, your explanation seems pretty plausible since we know Vegas does cache away frames. In fact, for RAM previews it just caches enough frames to get the selected area to play. So maybe Vegas isn't flushing frames as well as it needs to.

I'm still convinced that video not actually quantizing to frames is another culprit. This seems to happen when the audio stream of a clip is a little longer than the video. Ripple may snap to the longer audio section and then your subsequent media can start off the frame marks. You can also force all your generated media and stills to be fractionally longer than a whole number of frames. It's pretty easy in an NTSC project.

I'd love for someone to disuade me of my fractional frames obsession. I keep hoping I'm full of it.

Rob Mack
RedEyeRob wrote on 3/31/2004, 7:25 PM
THere are two different glotches like this I have seen. For one I found a consistant source. I was getting an out of place fram pop upwhere two clips join. It was always when capturing a clip on one of my Fat 32 drives that was over the 4G limit and a new file was created. When those two files were on the timeline a frame for somewhere else on the timline would apear between the clips.

The other problem is a flash frame usually appearing at transition. I can usually get rid of that by ajusting the length or position of the transition by a few frames.

johnmeyer wrote on 3/31/2004, 7:45 PM
I wrote a short script that will look for really short gaps or overlaps on the first selected track. If you have multiple tracks, you have to run it separately for each track. It simply places a marker at the location where a problem is suspected, and then lets you figure out what to do. I don't claim miracles, but it can help.

Here it is:

Audit for short blank gaps
craftech wrote on 4/1/2004, 5:52 AM
1. I never use autoripple (gave up on it because it never worked right)

2. I DO use quantize to frames.

3. My flash frames are NOT a the place where the 4GB sections join (thought of that one a long time ago)

4. I have never actually found a flash frame no matter how far I stretched out the timeline.

5. They don't consistently appear around transitions or gaps.

6. They DO seem to occur in videos which include a credit roll which is really unintuitive and overly involved to slow down.

7. It is just another reason for me not to jump on the "Please charge me more money for Vegas 5, but don't make me wait too long for it lest I soil myself" bandwagon along with the many other things which don't seem to get fixed when a new version comes out.

John