Rendering / Deinterlacing / Horizontal Lines

Aaron K wrote on 5/27/2009, 10:26 AM
After spending several hours trying to figure out why I kept getting horizontal lines in my rendered video, I have finally figured out the problem. While there are several threads on this forum that talk about deinterlacing and rendering, I couldn't quite find the answer I was looking for.

The problem was that any horizontal motion in my source videos would causing jagged horizontal lines in the rendered video. I could get it to look fine in the preview window, but during and after rendering is when the lines showed up. Here are the settings that I used to fix the problem:

Using NTSC DV, 29.97 fps, 720 x 480 for my project and MPEG-2, 29.97 fps, 720 x 480 source videos...

1) Project properties set to "None (progressive)" for the field order.
2) Deinterlace method set to "Blend" (but I've read that Interpolate should work, too)
Here is where I kept getting hung up...
3) When choosing "Render As..." I had to go to "Custom" and then the "Video" tab. I changed the Field Order to "None (progressive)" and this solved my problem. By default, it was set to "Lower field first" for the AVI template I was using.

Hopefully if anyone else is having this problem, the above solution will help.

Comments

Former user wrote on 5/27/2009, 10:35 AM
What is your final destination (computer screen, TV, etc)?

If it is for a TV/DVD, then do not de-interlace.

Dave T2
Aaron K wrote on 5/27/2009, 11:31 AM
Hi Dave,

It will be used for the Web and viewing on a computer. If I burn this to a DVD and show it on a TV, will it cause problems using these settings? Also, if I change my rendering setting to "Upper field first," for example, to show on a TV/DVD, will it look okay on the TV, even though it looks bad on the computer screen?

Thanks for your insight.
Former user wrote on 5/27/2009, 11:39 AM
For a DVD on a TV viewing, you want to keep it LOWER FIELD FIRST if you are using DV source material. If you change it to UPPER FIELD, it will look bad.

If you are making the video for WEB or Computer viewing, you normally would use PROGRESSIVE rendering. Some codecs do this automatically, some you have to tell to render to progressive. The project settings do not affect the rendering. They only affect how the video is treated while it is on the timeline.

Dave T2
Aaron K wrote on 5/27/2009, 2:03 PM
Hi Dave,

Thanks for the further information. Forgive me if this was answered in another thread, but why you would not always use progressive rendering? Wouldn't this help to "future-proof" the video as well as optimize it for viewing on progressive scan LCD TVs?

Also, why is it that the source videos on the DVDs look fine on TV, look fine on the computer, and even look fine when I capture the video in Vegas? The only time I had an issue is during the rendering process. Ideally, I would want my finished video to look good on both a computer and a TV, just like my source DVDs do.

Also, what is interesting is that Sony Vegas captured the video from the DVDs, and when I look at the properties of each clip, they are all set to "Upper Field First." (I did not change the properties; this is just what they were set to upon importing.) Perhaps this is another reason I'm having a display problem?

I really appreciate your help, and I really want to understand the reason behind using different settings.

Thank you!
farss wrote on 5/27/2009, 2:13 PM
"The project settings do not affect the rendering. They only affect how the video is treated while it is on the timeline."

This is not true.
The de-interlace method specified in the project properties will have an impact on how Vegas handles scaling of interlaced material.

Bob.
farss wrote on 5/27/2009, 2:19 PM
Where you're getting confused is that the DVD playing software used in a PC will de-interlace interlaced video. depending on how you set the internal preview in Vegas you can have it display both fields at once hence you see the interlacing. This can be very useful however seeing them does not mean anything is wrong with your video.
The Secondary display device in Vegas can be set to de-interlace much the same as the DVD playing software does.

Streaming content e.g. WMV, Flash etc is a different matter. You may need to de-interlace the video before you send it to the encoder.

Bob.
Aaron K wrote on 5/27/2009, 2:49 PM
Hi Bob,

I'm still a little unclear, then, as to why rendering my video using anything besides "None (progressive)" would cause horizontal lines to show up when I'm playing the file on Windows Media Player, for example.

The MPEG-2 source videos captured from the DVDs are interlaced ("upper field first" according to the media properties), and they play just fine on Windows Media Player---no horizontal motion problems. Why can't I also render in Sony Vegas using "Upper Field First" or "Lower Field First" without having issues? Shouldn't they display correctly in Windows Media Player, too?

Obviously there is something else I am doing wrong. When I am playing the video in the timeline using "Good" or "Best" as my preview setting, I don't see any horizontal motion problems. When I use "Preview" quality, I see horizontal motion issues.

Under both my project properties and rendering settings, I have selected "Best" for rendering. When the video actually starts to render, I see terrible horizontal motion problems in the preview window as it's rendering, but only if I am using "Lower Field First" or "Upper Field First." After the video is rendered and I am playing it back in Windows Media Player, I still see horizontal motion problems.

What am I doing wrong? I would think that even if my video was rendered using "Lower Field First," Windows Media Player would be able to de-interlace it properly, like it does with the source videos.

Aaron
farss wrote on 5/27/2009, 4:10 PM
"Shouldn't they display correctly in Windows Media Player, too?"

Perhaps not, I'm not that familiar with all its settings. VLC lets you adjust the de-interlacing algorithm.
Basically if the authored DVD looks correct played back on a CRT TV it IS correct.

Reading what you're saying though I'm also concerned that you might not be rendering at the same frame size. Can you post a frame grab somewhere or else feel free to email one to me, address is in my profile. Grab a frame with fast motion that shows your problem as bad as it gets.

I've used Vegas to re-edit several DVDs without these kinds of problems at all and I did nothing I'd consider unusual.

Bob.
Aaron K wrote on 5/28/2009, 6:45 AM
Thanks, Bob. I'll send you a sample right now. I really appreciate it!
Aaron K wrote on 5/28/2009, 6:54 AM
Basically if the authored DVD looks correct played back on a CRT TV it IS correct.

I haven't burned a DVD yet, but it would stand to reason that VLC Media Player would be able to play an interlaced video without any problems. Since it doesn't look right, I must be doing something wrong during the rendering process.

Reading what you're saying though I'm also concerned that you might not be rendering at the same frame size.

All of the videos have been scaled to a smaller size, but I made sure that the deinterlace was set to "blend." It looks fine in "Good" or "Best" preview modes, but maybe you cannot render scaled video in anything but progressive?