Removing Moire before render?

[Eric Kruis]

I just authored to dvd from original footage shot at 1920*1080i, 16Mps avchd. (Used DVDA) I finally got the render to an acceptable level of quality but I noticed what is probably defined as "moire" effect.

The footage is of a diesel locomotive and passenger car powering to it's destination. The moire is especially prevalent around the locomotives radiator fans and even the railroad tracks.

Is there a way to eliminate this in the render settings? I read something about gaussian blur but will this cause blurriness as a side effect?

Thanks,

Eric

[Ian Stark]

Try this:

On your Vegas timeline, right click on the clip, click properties, then uncheck Maintain aspect ratio and check Reduce interlace flicker. Click OK. Re-render, burn etc.

Any better?

[Tom Roper]

The added moire is created in the rescaling step from 1920x1080 to 720(704)x480 by Vegas, which uses a simple bicubic or bilinear algorithm.

Would be advisable to get it rescaled first to 720x480 using the Lanczos algorithm before working with it in Vegas or DVDA. Handbrake (a free download) can do this.

[Adam Stanislav]

Looks like aliasing to me, not moire. DVDA is not known for good resampling. Try resampling the video to the right size (720x480 NTSC or 720x576 PAL) with the proper PAR for widescreen before you even load DVDA.

[Eric Kruis]

If I rescale the video before editing, only problem will be if I want the choice to offer both DVD and BluRay versions of a video. I would have to edit each version (bluray and dvd) from scratch, no?

[Jerry Amende]

Yeah, I don't believe that's moiré; looks more like an interlacing problem to me.

You are aware that you should set a de-interlace method (either Blend or Interpolate) in your Project Properties when resizing Interlaced video, aren't you?

...Jerry

[Eric Kruis]

Jerry,

I had set the project settings to interpolate fields. Upper field first.

To be honest, I haven't quite understood the difference between blend and interpolate. Or whether upper or lower fields for field order.

I am just getting the feet wet with hd, and I am finding it can get pretty technical.

Also, I just downloaded Handbrake. Trying to make sense of it right now.

[Ian Stark]

Perhaps there's a reason why this won't work in your scenario but every time I have 'jaggies' caused by temporal displacement of interlaced fields I do what I mentioned in my earlier post and it works perfectly.

Can anyone tell me if I'm doing something I shouldn't? I'm working primarily with HDV, some SD, and I am in PAL land.

[Eric Kruis]

Ian,

I tried your tip but in the preview window it didn't change anything. Still the "jaggies". I haven't rendered out to mpg2 yet though. I'll try rending next.

Thanks.

[Jerry Amende]

@Eric,

Suggest you set your Project Properties using the "Match Media Settings" wizard. Normally 1080i footage will show up as upper field first. When you render SD Vegas will automagically change that to lower field first - but you don't have to concern yourself with that.

My understanding is that Vegas resizes by deinterlacing, resizing & re-interlacing. Blend vs Interpolate are merely two different methods of deinterlacing. Some suggest using "Blend" for slow moving footage; "Interpolate" for fast moving footage. I, frankly, haven't seen much difference.

HandBrake really doesn't come into play when rendering for DVD - it's used to produce progressive footage.

Finally, one thing I forgot to mention in my earlier post - make sure you set your "Video Rendering Quality" to "Best" as that signals Vegas to use the superior bicubic resizing algorithm.

Hope this helps!
...Jerry

Edit: One more thing, here's a tutorial I made a while back to resize 1080i to SD DVD. It's not perfect, but normally works pretty good. There are many-many long threads about how to get good quality SD DVD by going outside of Vegas, but this method works with Vegas alone: http://www.youtube.com/watch?v=kjXZMUnSPxE

[Tom Roper]

I'm sorry, I didn't look at the pictures before posting. It does look more like an aliasing problem than moire, but there is something else to consider, field order.

1080/59.94i (HD) is upper field first.
480/59.94i (DVD) is lower field first.

I don't know if the pictures were of a moving train or a parked train.

When it comes to de-interlacing, Vegas blend or interpolate are both inferior to yadif. That's why I still think there could be an advantage to resizing and decombing with Handbrake to 480/29.97p before using Vegas or DVDA. My $0.02

Otherwise agree with all Jerry says.

[Jerry Amende]

Originally Posted by Tom Roper

When it comes to de-interlacing, Vegas blend or interpolate are both inferior to yadif. That's why I still think there could be an advantage to resizing and decombing with Handbrake to 480/29.97p before using Vegas or DVDA.

That can be done and, indeed, HandBrake is superior to Vegas as it uses yadif for deinterlacing & Lanczos for resizing. However, you might get some stutter as you will be going from 59.94 fields (not frames) per second to 29.97 fields per second. If stutter is not an issue, this should work fine (although certainly a more complicated workflow). So, it becomes a tradeoff.

...Jerry

[Eric Kruis]

I still have tons to learn!

I am going to continue working on the interlacing issues. However, if you look at the first photo, notice the locomotive grill vents. When viewing the actual footage (train is moving) the horizontal vents wave like a flag on a blustery day. Would that not be moire?

[Jerry Amende]

I guess it could be moiré, but this is what I'd call moiré

...Jerry

[Phil Lee]

Hi

It is a de-interlacing problem.

Some things to check, you need to make sure rendering is set to Best, otherwise de-interlacing will not take place when you render. What Vegas needs to do is de-interlaced the 1080i to progressive, then resize, then re-interlace, if the rendering method isn't set to best some steps are skipped.

Check that on Project Properties full-resolution rendering quality is set to Best, and de-interlace method is set to Blend. When you render to the DVD template, click Customise, width ideally should be 704x576 or 480 so I suggest changing it as that puts it closer to the aspect ratio of 1920x1080. Field order change to upper field first, tick prioritize quality over speed, slide the quality level to maximum and up the maximum bit rate to 8000. Click the Project tab and set video rendering quality to best and have another go.

Even if everything is perfect with the settings, if you are viewing on a computer you can get this effect if your media player doesn't de-interlace the footage. So in effect there is nothing wrong with the render, it's just your computer. VLC media player for example usually doesn't de-interlace unless you tell it to. If you bring it back onto the Vegas timeline, depending on settings, you may also see this effect.

Windows Media player should automatically de-interlace so worth trying to play it in that if you haven't already.

As others have eluded to, Vegas doesn't do a very good job in resizing, so you may never get a pleasing downsize to SD. You can always try adding a tiny amount of Gaussian blur, just enough to barely see a difference in the HD footage, this will help remove some of the detail that will be causing some issues when resizing down. Also note it will never look that good on a computer, for one you can't help compare it to the original HD version, and second interlaced standard definition really needs to be watched on a TV with a good de-interlacer across a large room!

Regards

Phil