Really stupid preview question.

farss wrote on 7/8/2004, 7:21 AM
Here's what I just don't get. On my system and lets ignore whether its right wrong or plagued with every virus known to man, when I have Vegas play out vanila DV, no FXs, nothing requiring rendering, why does the preview quality make a difference to the frame rate?
Assuming I'm monitor at native res with Simulate Device Aspect then OK somewhere some pixel remapping has to go on to adjust for the non square DV pixels, yet it makes not a tad of difference if that's set on or off.
But here's where I see it getting really wierd. If I reduce the size of the preview window the frame rate goes UP! But doing that should mean Vegas has to do more work, there's no longer a one to one correspondance between the source pixels and those being displayed.
Not really a big issue for me, but I'm now getting the sort of client who like to watch and this even happens with an external monitor. I'm not asking for anything to be fixed, just trying to see why it is so.

Comments

Spot|DSE wrote on 7/8/2004, 7:37 AM
If it's just plain vanilla DV, nothing added, your framerate should be 29.97 or 25.00 no matter what you have the preview window set to. If it does, then you have something going on with your system that isn't good.
The size of the preview window, when small, affects the way Vegas scales the information. For instance, set the preview to Preview/Auto and size it very small. Notice that locally and externally, you see pixelated media. Vegas is scaling down. Now leave the Preview at same size, and set to full, Vegas is doing no scaling now, and your pixelation will go away. In fact, I run my system with Preview set to full, and view externally, leaving the Preview hidden behind other windows when I'm on a laptop. I usually do the same on a single monitor desktop.
Anyway, reducing the window, if set to auto, scales your image. But you should be seeing full framerate, full rez on DV, all the time, until you add a filter, title, or other modification to the stream.
farss wrote on 7/8/2004, 7:45 AM
SPOT thanks,
looks like I need to do some deeper digging, like I say not a show stopper but me thinks I should invest some time to find out why its not performing as it should.
I can assure you on my system with vanilla DV the only way I can get 25fps (I'm PAL) with a preview window at 720x 576 is in Draft, as I up the quality the frame rate drops, down to about 12 fps at Best.
Render times seem about average for the system.
PAW wrote on 7/8/2004, 8:19 AM
Farss,

i am woking in PAL & native DV works as SPOT says, full frame rate until you start changing the media with FX etc

If your source media matches the project setting Vegas will send it straight out at full frame rate

What is your source media & project setting? Do they match?

Paul
farss wrote on 7/8/2004, 5:51 PM
Yes,
they ALL match. What I didn't mention though is I'm running dual monitors with the preview window set at 720x576. It's fine if the preview is half full frame, that's the bit I don't figure. I have seen a number of posts along the same line.
farss wrote on 7/9/2004, 3:18 PM
OK, did some more tests and things get wierder.
With internal preview:
Project: 720x576x32 25i
Preview: 360x288x32 25p
Preview (Auto)

Preview runs at 25 fps.

Good so far

Enlarge window to get preview at

720x576x32 25i

and frame rate drops to 18fps

Thats what I don't get, why have we gone from 25p to 25i and dropped frame rate.

OK, now trying external preview, via ADVC-300, OHCI compliant device etc.

Go back to a small preview window at 360x288, frame rate is 25 fps although for some odd reason Vegas tells me I'm now previewing at 25p but when I click External Preview frame rate drops to 15fps!
Also I get the big red (Frame Recompressed) Why is the frame being recompressed, this is just vanilla DV straight up, nothing done to it!
Now here's the even wierder part, play the clip out from the Media Explorer NOT a problem, NO red (Frame Recompressed) and runs at 25 fps although Vegas is still telling me its 25p NOT 25i!

Just to see what would happen I disabled Enable Recompression fo Edited Frames in Options, will NOT play out to external monitor from TL! So perhaps the real issue here is why Vegas thinks it needs to recompress the frames as it feeds them out to the external monitor, I'm not certain but that just makes no sense to me.

Like I say this isn't stopping me from working and everything else would seem fine. Why it's bugging me though is this, I'm thinking to buy a decent studio monitor, what earthly use is a $10K monitor if I cannot preview at 25fps!!

Just one other thing that MAY have a bearing (and I hope not), my audio is going out using ASIO drivers to Firewire-410. This shouldn't be an issue, it's a silent movie but you never know. If anyone thinks this is an issue I'll swap the audio drivers back and see what happens.