Aliasing in preview, will this ever get fixed?

farss wrote on 2/20/2005, 5:36 AM
I know this has been mentioned in passing before but only in relation to other matters. I know it doesn't affect final output but it doesn't look too flash when you've got a client watching or trying to demo Vegas.
Just to re-iterate, this seems to be much more of a problem in PAL than it is in NTSC, yes I've checked it in a NTSC project. Also when previewing things HD on a decent sized monitor it looks pretty bad, again not the best way to showcase Vegas or HDV!
If you want to see what I'm talking about, just open a PAL DV 4:3 project. Put some white text on a black background, the default at 72 pt will do nicely. Set preview to Best/Full and enlarge the preview window so you see the full 720x576. R click and turn on Simulate Device Aspect. Notice the nasty tearing on the verticals. Now switch off Simulate Device Aspect, voila, it's gone. Just for a laugh, change the project to NSTC, the reverse happens. Either way it shouldn't be happening!
Now OK, for sure I normally preview on a real monitor except with HDV that isn't an option and with its wider PAR things start to look pretty sad at Best/Full and SDA on. I'm not trying ot preview at full fps either, I'm trying to check image quality BTW.
I do realise the last thing we need is more CPU load during preview doing fancy AA calcs or whatever but perhaps this task could be hived off to the GPU, I don't imagine there's too many users that aren't running with a GPU capable of the task.
At the very least can someone please acknowledge the problem?



nickle wrote on 2/20/2005, 6:34 PM
Yes it does what you say.

The only fixedsys font I have didn't show tearing but it did show a slight defect.

It may have something to do with truetype not scaling properly.

farss wrote on 2/20/2005, 10:32 PM
It's not a font scaling issue, it's how Vegas scales anything. Same thing happens with video, I simply chose text as anyone can create it and easily see the problem.
SimonW wrote on 2/21/2005, 3:55 AM
Yes, I have noticed this. I was doing some video the other day in 16:9 (the problem is even more noticeable with this ratio) and I found that the saved screenshots that I made were drastically higher in quality than the preview window.

I would imagine that there would be a cpu hit if the smoothing was applied however.
farss wrote on 2/21/2005, 4:11 AM
My thoughts too, however they do seem to be doing it anyways and just getting it wrong. In a NTSC 4:3 project there's no problem with SDA on, it only shows up when it's off and it's the other way around in PAL, figure that one out. And yes it all gets worse in 16:9 and in HD yikes.
Everyone I've shown a HDV demo to picks this immediately, I have to show it to them rendered to WMV 720p for them to get some idea of how good it really looks. And then you get the snide remarks "Yeah sure, Sony camera, Sony software....." and then I have to give them yet another spiel about Sony and SPD.
Maybe I should figure out how to get Varicam footage into Vegas and HDV footage into Liquid that way if either looks bad I can blame the camera / software and keep a straight face, Ah, hang on that's what Sony were recommending!
BillyBoy wrote on 2/21/2005, 7:27 AM
You said it yourself. It only shows in PREVIEW suggesting you've forgot what the purpose of preview is in this context. Yes, I tried what you suggested and yes I see the "problem".

Now you'll have to excuse me, I was going to the store, but as I always do I first run the shopping list through my spelling checker and I noticed a couple items being spelled incorrectly, so of course, I'm writing the list over. I know its only a shopping list, but imagine the embarrassment if I went to the store and someone looking over my shoulder saw that the list I was using had ketchup spelled incorrectly. I couldn't handle that being a "professional" grocery shopper.
Bob Greaves wrote on 2/21/2005, 7:48 AM
As a professional musician who also used to own a guitar repair shop I have long since passed the day when I could care less what someone else thinks of a pre-final appearance. In fact I am too busy getting great final results to worry about the impressions of an uninformed client at midstream.

People who worry about these sorts of problems usually cause more difficulty by worrying about it or by acting embarrased about it or cringing in front of a client. The implied meaning in your own reaction only confirms the worries of your client. You and your client would be better off saying something like, "I know, doesn't the preview look terrible? Thank God the final product gets a far better rendering."

Empathise with it like an understandible but misiunformed concern and move on as if it is absolutely nothing. Being productive is a lot easier when you learn how to focus on what matters in the end and learn how to set aside things that don't during the process.

If it ever gets "fixed" all that means is less to have to set aside tactfully.
BillyBoy wrote on 2/21/2005, 8:15 AM
Good point. I always get amused when someone worries about trivial things ad nauseam, more so when its not part of the finished product or has nothing to do with how the application works, for example, worrying about the name of the application, the subject of many threads where a few obsess that its called Vegas, or similar, oh my God, what will my clients think type of posts.

Like I said, I need to go to the store, I'm not putting on a three piece suit, I won't wash the car first and as a real act of defiance I'm not shaving either or changing my shirt where I got a little bit of egg on it this morning. I guess I'm just a rebel. <wink>
jaegersing wrote on 2/21/2005, 11:36 AM
I'm not sure that going to the store is a good analogy. For anyone who is trying to earn money from video work, what the customer thinks is very important. If the customer has seen competitors with Edius (for example) showing full resolution, full frame-rate video, then he might not be convinced by the "trust me, it'll look great after 6 hours rendering" line. Of course, if you don't have to show works in progress, things are a lot easier, but sometimes you have to get customer concurrence at stages and make instant changes in reponse to feedback. It is much better if you can show high quality output rather than pixellated garbage.

By the way, I'd have thought that someone with egg on his shirt was more of a slob than a rebel! :)

Richard Hunter
johnmeyer wrote on 2/21/2005, 11:48 AM

I followed your steps and duplicated the problem. I also changed back to NTSC and the problem exists there as well, although not as much. Fortunately, the Simulate Device Aspect Ratio only impacts the computer display. I looked on the external monitor (attached via Firewire/Camera) and the display looked just fine.

I would guess that this problem results from the engineers using a pretty simple-minded stretching algorithm that they designed quickly just so you could do a quick check on things like round circles, etc. It definitely could have been done better.

However, I don't know about you, but when I am working interactively on a project in front of a client (which I hate to do, but it happens sometimes), I ALWAYS use the external monitor. First, it avoids all sorts of glitches -- of which this is just one -- that happend in the preview window. Second, the "look" on the TV screen is familiar to the client, whereas the computer monitor doesn't really look like video. Finally -- and this is the biggest reason -- it gets the client "out of my space." The monitor is several feet away, and I can sit the client down away from my keyboard and monitor which makes the whole thing more comfortable for both of us.
BillyBoy wrote on 2/21/2005, 12:07 PM
Lets see, so far this month I've been called scum and now a slob. I keep forgetting how "professional" some pretend this forum is. BTW, my little analogy was made up. Smarter people would have figured that out.
Spot|DSE wrote on 2/21/2005, 12:24 PM
Although I see this too, I generally keep the client on either the CRT or the Premiere monitor, where this isn't seen at all.
Keeping in mind that no matter what you lay the text over, it's uncompressed media being laid over something or other. It's also being interlaced unless you've got your project set up as progressive scan, so that doesn't help. As much as it sucks, I think a little client-education (which you are apparently already doing) is in order. Sony could do it like AVID where you only see half a frame/one field, but that carries it's own issues too. it's indeed tough when you have a client sitting next to you, but I try to keep their focus on the client monitor by constantly pointing to that. This is also where RAM renders are sweet, IMO.
farss wrote on 2/21/2005, 1:21 PM
This is scary BB and SPOT saying the same thing, perhaps in not the the same words but still the same thing. Both are missing the point here though.
I've been having clients looking over my shoulder for years now and yes I've been pointing at the external monitor and yes they've been quite happy, no problems there, it looks even better now I've got a 'real' monitor. I don't know if they actually notice the difference between the TV I used to use and a real monitor but the real one has more knobs and buttons so I guess they feel I must be a pro cause I got one.

But in case no one has noticed Sony recently put a cat amongst our pidgeons with HDV and so far as I know there's no way to run an external monitor at HiDef out of Vegas. So we're stuck with the internal preview monitor and that's when we start to have a problem. Most clients know what SD looks like, they see it every day and as some have pointed out they'd have to be pretty dim if all they were focusing on was how it looks on the preview monitor and even if they are that dim you just point your finger at the external monitor. But with HD we don't have that luxury and as many of them haven't seen HiDef much and even if they have then what they are focussed on is image quality. Seeing staircasing on diagonals doesn't exactly win them over big time. When you've got a high resolution image on a big monitor the eye naturally focusses on defects. You'd like them to focus on other things, like color grading or how the motion looks or the depth of field.
Now maybe I've missed something, perhaps I can solve this by finding a way to run an external monitor in HiDef out of Vegas, if anyones managed to do this then I'm all ears.

Liam_Vegas wrote on 2/21/2005, 1:35 PM
I've been following this thread for a while... as sometime in the not too distant future I'll be stepping into this world as well. The previewing problem is soemething that concerns me. It does sound as if all we can do is work off the internal preview monitor - and that does seem like a step backwards.

So... I got to thinking is there some half-way solution to this. When I use the external monitor currently it is often to check out some small aspect of the timeline to see exacly how it looks on a real TV. I sort of look at this a bit like waiting for a RAM render of a short segment. Can we do something similar to view a small HDV clip on an external "HD TV" monitor.

Just a wild idea.... how about a creative use of of the AveL LinkPlayer2? This "HD DVD" player sits on your LAN... and can be setup to scan a folder on a shared drive... and then play whatever it finds there.

I can imagine a script gets written (by some clever soul) that renders the selected region on the timeline to HD format and places that file in this "Monitored" folder. The AVeL Linkplayer then plays out that video automatically at full HD quality.

Of course this is ALL theory... as I don't have ANY HD gear - yet.
nickle wrote on 2/21/2005, 1:51 PM
The patient says "It hurts when I do this."

The doctor says "well don't do that."

My 2 cents isn't going to be worth 2 cents but I noticed pal stretches the display from 720x576 to 787x576 so it tears.

While NTSC shrinks from 720x480 to 655x480 and has no tearing or any other problems other than squashing the width.

Other than that I don't what it is doing or why I would want to know.

But it brings up the question that if the device is different 655x480 (squashed) why I am editing at 720x480?
farss wrote on 2/21/2005, 1:58 PM
Simple answer there, Pixel Aspect Ratio!
Video uses non square pixels. So each pixel of digital video needs to be stretched so you see the images at the correct aspect. This is where the problem comes into play.
BillyBoy wrote on 2/21/2005, 2:28 PM
Just because you got me curious can you do a screen shot to aproxmate what you're seeing on your preview monitor?

I'm using a newer LCD 22 inch at my "external monitor" now, while not HD if you want to count pixels, its close and I feed it out of the Canopus 300 with component output out the D1 jack. While I can see some distortion I got to get within a couple inches of the screen to see it. It isn't that it jumps out at you. In fact doing the white text on black background at 72 pixels as you suggested all I see isn't pixelation, rather the outer edge of any vertical letter like a "L" or "I" appears a tad brighter, otherwise its still very sharp, no way staircase. I think anyone doing this thing for hours on end is more critical of what's wrong, where some "client" or lay person likely isn't going to see it unless you point it out.

You seeing worse breakup then than what I'm describing Bob? Anyone?
johnmeyer wrote on 2/21/2005, 2:29 PM
... and the problem DOES happen in NTSC, but it isn't as noticeable.

farss, I am guilty of missing the main point, namely that with HD you HAVE to rely entirely on the preview. That really does make it much more important to have a true "hi-fi" preview, without glitches or artifacts.
FrigidNDEditing wrote on 2/21/2005, 2:51 PM
I think that liam has a decent solution here for the problem in general of not having an easy way to output HD videos that someone has done to an HDTV, and for only 249.99 or so.

Good solution for now, and later in some cases in my book.

Spot|DSE wrote on 2/21/2005, 3:53 PM
I didn't catch the HD in there either...sorry.
I acknowledge the problem, you're seeing vid at either 1/4 or 1/8 resolution, and that's a problem on it's own.
For the HD side of things, I'm running to my second monitor (premiere) which is an HD capable monitor. Sizing at Preview/Auto but dragged to full size. Not having an issue with aliasing. I guess maybe I'm missing what it is you're trying to achieve if this doesn't answer the question.
epirb wrote on 2/21/2005, 4:08 PM
heres a screen cap of the problem in question, its more noticable with motion .
but if you look close at the fender flairs and "a" pillar by the windshield you'll see the effect.
jaegersing wrote on 2/21/2005, 8:49 PM
BiilyBoy, if your analogy was made up, then my reply (which was a poor attempt at humour) does not apply to you, right? I never intended to call you anything, so please don't look for trouble where none exists. That's definitely not smart.