Interlace flicker, a ghost story

TorS wrote on 1/23/2003, 7:03 AM
Background:
After a Format C: and re-install Vegas decided to be able to print to tape from timeline again. Then this happened:
1. I print to tape from timeline - to test things. Result: heavy flicker on everything that moves. Real strobo. Sound OK though.
2. After that, flicker was even present in preview. Never seen that before. The other events in the same project (parts that were not included in the print to tape selection) are fine.
3. Selected Reduce interlace flicker for the event in question. That immediately removed flicker from preview.
4. Print to tape from timeline again: Flicker gone.

So far it's a happy ending. But what is going on really? How could I have known that flicker would happen? And if I couldn't have, why isn't Reduce interlace flicker the default choice? Why must I even think about it?

(The take in question is very straight - tripod, no zoom, no pan, no FX, just my daughter eating a sandwich and explaining that ghosts don't exist and why we must be wary of them. It's shot in PAL DV, captured and rendered as same.)

Tor

Comments

Tyler.Durden wrote on 1/23/2003, 8:07 AM
Hi Tor,

Will changing the field order (without anti-flicker) resolve the issue? Will resample (without anti-flicker) resolve the issue?

Might be a field-order issue...



mph
Paul_Holmes wrote on 1/23/2003, 9:08 AM
"explaining that ghosts don't exist and why we must be wary of them"

I'd love to see that. Sounds funny! Of course it's probably in Norwegian and even though it's my ancestry I don't know a word. Oh, well!
TorS wrote on 1/23/2003, 9:14 AM
Hi Marty
Good to hear from you.
I've only done very short tests on your suggestions and only looked at them briefly (It's almost dinner-time here now).
Resample did not do away with the flicker. Changing the field order did, but I think movement blur was more pronounced with the field order change than with the reduce interlace flicker. Which only means that the flicker acted differently.
However, flicker did not re-appear at preview.

In the meantime I've had a couple of chrashes (Vegas) and I've changed the 1394 driver from Texas Instruments to Microsoft. (I have Vegas, Sound Forge, Paint Shop Pro, Finale and Digital Orchestrator Pro on this machine, alongside Media Player 9 - it's a Win98SE).
Gotta go to the kitchen now and make some noise with the pots and pans :-)

Tor


TorS wrote on 1/23/2003, 9:17 AM
Paul,
It is great. I'll show it to my wife again a couple of days before I have to shell out for the upgrade to Vegas 4. She loves it.

Tor
SonyDennis wrote on 1/23/2003, 9:23 AM
I agree with Marty that it is likely a field-order thing. If the source media field order was wrong, or if the rendered field order was wrong, the results would be that when an object moves, instead of being in positions 1-2-3-4-5-6 it would appear in positions 2-1-4-3-6-5, which would look rather stroboscopic. My NTSC MPEG-2 based PVR does that every now and then when I use the 'skip ahead' button. It's only detectable on motion. Using "Reduce Interlace Flicker" is not the solution, fixing the field order is.

Unrelated to that, depending on OS version, service packs, DirectX version, and probably your DV device, when you are paused (parked) on the Vegas timeline with External Monitor on, the display might be both fields (with flicker on moving objects) or just one field repeated two times (half the vertical resolution, but no flicker). Some people prefer one and some prefer the other, and I wish we could put a switch in there so you could choose, but it really seems to be determined by other factors, from what I've seen.

///d@
TorS wrote on 1/23/2003, 11:59 AM
Thanks a lot for the replies.
So far as I can see, it's lower field first all the way. The shot was made with a different camera than the one I printed to, both Sonys though. And I've changed the 1394 from Pinnacle to Pyro, trying to fix the print to tape thing.
So I can safely conclude that when it flickers, go for the field order button first? (Like ghosts don't exist, but you can't be too careful. My daughter knew it all along).