Interlace aliasing problem (AGAIN)

farss wrote on 5/30/2006, 12:10 AM
I know we've mentioned this before but now it's really starting to get in the way BIG time.
Simple enough task. letterbox 16:9 into a 4:3 frame, what could be simpler, right. Well forget it, anything with motion is a disaster, massive artifacts on the edges, I'm not talking little things that you'd need a broadcast monitor to see, I'm talking big, ugly square blocks. At first I thought I had a bad attack of macroblocking, that is until I realised at the same bitrate the 4:3 source footage was fine!

I have tried every configuration to no avail, Best makes no difference, Project De-Interlace method makes no difference, the only switch that'll fix it is Reduce Interlace Flicker but as noted that does soften things up and the items in motion do get really soft, somehow I think this switch is masking the problem rather than dealing with it. I can also make the problem disappear by turning off Maintain Aspect Ratio in the events properties, no more aliasing but rather tall dudes in the frame!

All I've done is drop the 16:9 footage onto a 4:3 PAL DV timeline, only reason is I need 4:3 as the other programs to go onto the DVD are 4:3 so I'm making everything 4:3, simple eh, well NOT with Vegas.

Sorry if I sound a tad irate but to fix this I'll loose a day re-encoding many hours of footage. I've already had to recapture half of it as the DSR-11 wouldn't track the clients tape properly, grrr. And what's worse the result will be less than optimal.

Bob.

Comments

apit34356 wrote on 5/30/2006, 12:32 AM
A silly question, the 16:9 is not PAL? Sounds like 16:9ntsc going to 4:3PAL.
farss wrote on 5/30/2006, 12:44 AM
Sorry, everything is PAL.

Bob.
apit34356 wrote on 5/30/2006, 1:10 AM
Farss, I know you are fairly knowledgeable in the world of PAL, conversions and vegas. SO, that said, its probably sometime simple. The bit rate for letter box 16:9 and 4:3 can be the same, but gops will not match, and the 4:3 file should be larger if there is a lot of motion. If there is a lot motion in the 16:9, it will not enlarge well if the encoding was op.s for 16:9 and mininum detail, tho its looks good view as 16:9. If this was encoded with xivd, enlargement is a lost cause.

But, I don't think I fully understand your problem and what you have tried. Sorry.
Grazie wrote on 5/30/2006, 1:50 AM
All I've done is drop the 16:9 footage onto a 4:3 PAL DV timeline, only reason is I need 4:3 as the other programs to go onto the DVD are 4:3 so I'm making everything 4:3, simple eh, well NOT with Vegas.

Bob - I've just repeated this. In Preview yes it is not good at all. SHOFT+B gives the same .. . BUT, rendered to a new track or rendered out it is fine here. Soooo... it would appear that the Preview, less than "Good - Auto" here, aint doing it. Anything that we need to "see" for the purposes of editing decisions, easily, I can repeat that the best preview I get is "Good-Auto".

Soooo... Previewing with this type of "mix" need top be piped to "Good-Auto". As I say rendered and the jaggies go.

It looks like a maths brickwall being hit for Previewing quality. I've now just experimented WITH 4:3 under the 16:9 clip .. looks great!!!

I did try ..

Grazie
farss wrote on 5/30/2006, 3:36 AM
Ignore anything about bitrates, I first saw this when looked at the final DVD but really that means nothing.

Same thing happens rendering to avi.

Very simple to repro.

Take 50i 16:9 PAL SD DV footage. Drop that into 50i PAL SD 4:3 SD DV project and render out as 4:3, view on external monitor. The output will naturally be letterboxed, that's what I want, 16:9 in the middle of 4:3, all well in that respect. However when anything moves, in this case pages being turned or someone moving their arm, along the vertical edges there's HUGE artifacts. Best way to describe them is dogs teeth, probably around 10 lines high, in width they're as wide as the oject moves between fields.

Bob.
farss wrote on 5/30/2006, 3:39 AM
Grazie,
some preview modes only show one (1) field, you really need to send this to an external CRT monitor.

Bob.
Grazie wrote on 5/30/2006, 4:17 AM
Bob?!?! -

. . . some preview modes only show one (1) field, you really need to send this to an external CRT monitor.

Well, how do YOU know I DIDN'T? . .Well I DID. It is good on ExtMon onto my JVC!

Now I don't know the point you are wanting to make with me. I've tested out and it works. It renders out fine and I can Preview to ExtMon.

G
Marco. wrote on 5/30/2006, 4:29 AM
The Vegas preview setting also affects the external preview output. So I think Grazie maybe isn't wrong. For proofing external preview the preview setting should be set to "Best (Full)". You can't value an external output with having set the preview settings other than "Best (Full)" or "Best (Auto)" set to full display size.

I' ve done some of those 16:9 to a 4:3-project integrations and it always worked perfect. Having set the video render quality to Best, Deinterlace Method to Blend Fields and preview set to Best (Full) when proofing the scenes from Vegas on an external video monitor.

Marco

farss wrote on 5/30/2006, 5:14 AM
I need to be a bit smarter about how I evaluate things.

When I was trying every which way to make this problem go away I was previewing by doing a RAM render. Only problem is if you change the De-Interlace Method that doesn't force Vegas to re-render what's in RAM, it goes through the motion (very quickly) but doesn't redo the render.

So Yes, setting Full Resolution Render Quality to Best, De-Interlace Method to Blend and flushing the RAM buffer and all looks fine.
Once rendered to RAM I don't think the Preview quality makes any difference for internal or external preview.

One oddity, changing De-Interlace Method in Project Properties doesn't activate the Save or Apply buttons in the dialogue box, strange.

So thanks Grazie and Marco. Now all I've got to do is recapture and encode these problem files, which means having to bludge a DSR-45 again. Why do I have to recapture, well I was running out of disk space so I deleted the AVI files once they were encoded, bummer.
Why do I need a DSR-45, well my DSR-11 has gone to the hospital for a clean and the other one I bludged just didn't set well with these tapes.

The good news is my Dell 2407 turned up today, hope it's the version with the upgrade to fix the banding and it has no dead pixels.

Bob.
ztalk112 wrote on 5/31/2006, 12:36 PM
Now that the main issue has been resolved, a question . . . short of closing Vegas down, how do you flush the RAM buffer?

Thanks in anticipation.
farss wrote on 5/31/2006, 2:26 PM
Render another section of the video to it.

Bob.