What does "Reduce Interlace Flicker"

Post » Tue Nov 02, 2010 7:32 am


our community discusses the flag "Reduce Interlace Flicker".
Does it make sense to use it on video takes? Or only for still pics?

If I use it on video takes, is it the same like "progressive render" or "deinterlacing"?
We all don't know the difference.

I would be pleased to get some technical advice on it.

Thanks in advance.

User avatar
Posts: 548
Joined: Mon Jul 16, 2007 12:35 am

Post » Tue Nov 02, 2010 11:38 am

Message Deleted by User.
User avatar
Sami Blackburn
Posts: 522
Joined: Tue Jun 20, 2006 1:56 am

Post » Tue Nov 02, 2010 12:27 am

It introduces motion blur to reduce the flicker. Sometimes it is more annoying to look at then the flicker.

User avatar
Tom Flanagan
Posts: 529
Joined: Fri Jul 20, 2007 7:51 pm

Post » Tue Nov 02, 2010 4:45 am

Thanks for your comments. Going to look for Dennis' Post.

Best regards from Bavaria
User avatar
laila hassan
Posts: 511
Joined: Mon Oct 09, 2006 8:53 am

Post » Mon Nov 01, 2010 8:53 pm

>> using "Blend" deinterlacing, which is different from "Reduce Interlace Flicker".

Mmh, at least the results are absolutely identically. It doesn't matter if you do interlacing by using the blend method or if you use "reduce interlace flicker".

User avatar
Star Dunkels Macmillan
Posts: 517
Joined: Thu Aug 31, 2006 10:00 am

Post » Tue Nov 02, 2010 7:37 am

John, I doubt that. Motion Bluring affects motion between different frames. If there is no motion nothing happens if Motion Bluring is applied. Nor does it if there is only one frame.
But if I apply "Reduce Interlace Flicker" to a single frame event it looks exactly as if I'd done a Deinterlacing with blending fields. "Exactly" means: I proofed it having both a deinterlaced event in track one and same clip with "reduced interlaced flicker" in the track below. Preview quality is set to "Best (Full)". Now if I toggle between those two tracks preview is absolutely equal.

So to me it looks like "Reduce Interlace Flicker" uses same methods like Deinterlacing with blended fields does.

User avatar
Nathan Barker
Posts: 519
Joined: Sat Jun 09, 2007 11:55 pm

Post » Tue Nov 02, 2010 9:20 am

Try using "Reduce Interlace Flicker" on a pan especially with indoor or stage lighting. The motion blur will be quite noticeable.

User avatar
Elisabete Gaspar
Posts: 505
Joined: Thu Aug 31, 2006 7:15 am

Post » Mon Nov 01, 2010 11:26 pm

Mmh, I made a test sequence now. I created a circle in a graphic software imported it into Vegas. Moved it then fast using Pan/Crop and rendered the result to interlaced PAL-DV.

Then I ...

- rendered it to PAL-DV using "Reduce Interlace Flicker"

- same render now deinterlacing it choosing "progressive scan" in the render dialog

- same render but applying motion-blur - lowest level which gave me a noticalbe result

So I ended up having 4 DV-AVIs and I grabbed a screenshot out of the middle of each of these sequences.

--> Please take a look here

You will see that "Reduce Interlace Flicker" and Deinterlacing gave me absolutely same results whereas Motion-Bluring looks quite different to "Reduce Interlace Flicker.

User avatar
Heather beauchamp
Posts: 501
Joined: Mon Aug 13, 2007 12:05 pm

Post » Tue Nov 02, 2010 12:18 am

... and based on my last test I made another render test to took the render times of a deinterlacing, "Reduce Interlace Flicker" and Motion-Blur. I had a sequence of 20 seconds, a graphic (rendered to AVI before) with motion rendered it using deinterlacing, "Reduce interlace Flicker" and Motion-Bluring with the lowest value possible (length 1 field, which is rarely noticable in the result, but still quite different from "Reduce Interlace Flicker").
The render times are:

- Deinterlacing (using Blend Fields): 53 seconds
- "Reduce Interlace Flicker": 74 seconds
- Motion-Blur: 224 seconds

O.k. - so this states:

- Even if Deinterlacing (with blending fields) and "Reduce Interlace Flicker" might look same in some cases there must be a difference between those two methods.

- "Reduce Interlace Flicker" and Vegas Motion-Blur must be completely different methods because it gives different results and quite different render times.

So now: What exactly is the difference between Deinterlacing using Blend Fields and "Reduce interlace Flicker"???

User avatar
Posts: 549
Joined: Fri Feb 16, 2007 12:01 am

Post » Tue Nov 02, 2010 9:20 am

I learned to use Reduce Interlace Flicker sparingly. Overuse degrades the crisp lines of video. I use it mainly to stabilize letters or geometric patterns on screen.

It works good for softening images...like when I do parties and most of the women are...mature. It softens the facial lines and creases.
User avatar
Javier Borjas
Posts: 493
Joined: Tue Nov 13, 2007 12:34 pm

Post » Mon Nov 01, 2010 10:57 pm

I think that reduce interlace works on the fields, not between frames.
I find it is most usefull on still images, text and such.

User avatar
Andres Lechuga
Posts: 479
Joined: Sun Aug 12, 2007 2:47 pm

Post » Mon Nov 01, 2010 11:51 pm

>> I think that reduce interlace works on the fields, not between frames.

Yes, I think that's it!

User avatar
Luna Lovegood
Posts: 528
Joined: Thu Sep 14, 2006 12:45 pm

Post » Tue Nov 02, 2010 1:06 am

Message Deleted by User.
User avatar
luis ortiz
Posts: 520
Joined: Sun Oct 07, 2007 2:21 pm

Post » Tue Nov 02, 2010 12:07 am

>> If you want to be fair to yourself, you should take, for example,
>> 3-5 (not just one) random still shots from each of the three files
>> before you make a conclusion about anything.

I took that one (still) which gives the best impression of what is done to the video. I made lots of tests and at last I chose that test sequence which makes rather clear what happens if I use "Reduce Interlace Flicker".

>> Better yet, specifically look for (and hopefully find) still shots where
>> the results of technique 1 differ from the results of technique 2.

That's it. I can't find one where the results differ. Anything I tested - "Reduce Interlace Flicker" always gave me same results as Deinterlacing using the blend method. Proofed after rendering on internal preview, quality set to "Best (Full)".

>> One test of 3-5 still shots would attempt to find the difference between
>> deinterlacing and reduce interlace flicker. The other test would examine
>> 3-5 still shots comparing the results of reduce interlace flicker to motion blur.

Exactly what I did ...

>> Comparing all three in one test confuses the issue. After all, nowhere have
>> you stated that you were unsure as to the difference between deinterlacing
>> and motion blur.

I don't find the results shown by the screenshots confusing. It's very clear what happens to the video. The confusing part is the fact, that all the render times differ so much.
So at least both these screenshots and the render times states the very difference between "Reduce Interlace Flicker" and Motion-Blur.

The only thing I don't understand is why Deinterlacing and "Reduce Interlace Flicker" gives me same results but different render times.

>> Also, did you consider including a sample deinterlaced by the interpolate method

Sure - I tested that one too, but took no screenshots of it. Using the interpolate method for deinterlacing differs both from "Reduce Interlace Flicker" and from MotionBlur. Using my circle example the interpolated Deinterlacing eleminates one of the two fields and interpolate all the lines of one of the fields. No result what would help me understanding.

But I surely do some further tests ...

User avatar
Ross Zombie
Posts: 502
Joined: Wed Jul 11, 2007 11:40 am

Post » Tue Nov 02, 2010 2:37 am

Meanwhile I found out

- "Reduce Interlace Flicker" is an intra-frame process (against inter-frame process of Motion-Blur).
- "Reduce Interlace Flicker works by vertical blending fields in a fixed amount ("The interlace filter applies a small amount of vertical-only filtering" - quote from SonicDennis).
- The very difference to the deinterlacing process is "Reduce Interlace Flicker" works even if there is no motion what makes it perfect for the use of stills (and of course another difference is deinterlacing ends in having progressive video then).

O.k. - thanks for the input :-) Marco
User avatar
Batricia Alele
Posts: 559
Joined: Mon Jan 22, 2007 2:12 am

Return to Vegas Pro Forum