Deinterlacing question

Post » Sun Jan 09, 2011 3:20 am

I'm sorry if this is a bonehead question - if it is, I'll go quietly...

I shoot in 60i with a Canon HV30, and have spent a fair amount of time rendering from Vegas into a variety of progressive formats. I understand why the deinterlaced video always looks worse than the original, either in terms of detail or motion smoothness. But when I play the original clip in, say, Windows Media Player, it looks great: smooth and sharp. Well of course it does - it's interlaced ... but doesn't it still have to be deinterlaced as it's being played on my LCD monitor? If so, why does it look so much better than any deinterlaced video I can render out of Vegas?

I suspect the answer is that Media Player can refresh my display faster than 30 times per second, and thus "deinterlace" without losing temporal information. But if computer displays can do this, why does everyone deinterlace their video "for the web"?
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Samantha Pattison
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Post » Sat Jan 08, 2011 4:38 pm

Windows Media Player automatically deinterlaces during playback -- I think it uses a straight blend -- always looks a bit mushy to me.

VLC Player, on the other hand, does not deinterlace until you tell it to -- load your video, see how it looks interlaced, then play around with the several deinterlacing options available.

Rendering HDV for the web can be done beautifully in Handbrake, if you set the default decomb (not deinterlace) option.
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Post » Sat Jan 08, 2011 10:50 pm

I've tried Handbrake several times and was not that impressed with the output.
I now use Mike Crash's free Smart De-Interlacer followed by his Dynamic Noise Reduction. I do all of that in a project at source resolution then nest that in another project which handles the downscale to 720p and encode from that using the Sony AVC encoder at 6Mbps.
Getting the de-interlacer working right takes a little experimenting. Once I got everything working correctly I'm very happy with the outcome.
In the past the 720p playout from YouTube looked pretty good but most people don't bother to select 720p to view. The 360p playout looked like garbage, probably because YouTube's encoders were being swamped by hard to see noise and artifacts in the original.

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Siobhan Thompson
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Post » Sun Jan 09, 2011 12:35 am

I strongly agree that Mike Crash's Smart Deinterlacer works well IF you take the time to experiment first with the particular clip that needs to be deinterlaced. Yesterday I deinterlaced two Cineform 1440 interlaced files. For some unknown reason, the "fields and frames" gave the best results on one, but only the "fields only" preset would properly deinterlace the second.

Also, be sure the little triangle points to the left or else you may mess up pans and zooms (search this forum for "yellow triangle"). When done correctly, you'll not see loss of detail in the image (be sure to turn off all the automatic stuff, like "fit to window" in the preview, and set it to "best, full" or you won't really see the effects correctly)

I should mention that I'm rendering the deinterlaced material to 60fps Cineform (using the codec that came with NeoScene). I also render out to full 1920x1080 so that I won't have to worry about using the resulting file in other apps that may not like the 1440. Resulting files seem to play back very smoothly IF I play it from a fast SSD or RAID 0 disk array.

I render in 9c32 - it seems less likely to crash than 8c, and 9c-64 does not have any decent 64-bit plugin for deinterlacing AFAIK. What a pity.

Render times are slow. I had a 20-min. video that took hours to deinterlace. The other is 1 hr. 40 min. long, and it looks like its going to take nearly three days (I started it about this time yesterday and it is 40% done) on my Q6600 2.4gHz 8GB RAM Win7-64.

Edit: I believe that you'll need to go into project settings and change field order to None, Deinterlace method to "none" and Full-resolution rendering quality to "Best."
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Kayleigh Mcneil
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Post » Sun Jan 09, 2011 1:30 am

Keep in mind that often it's best to just leave the video in it's original format. Also, a mix of 60i and 30p looks great if it all flagged as 60i. WMP and VLC are getting really good at deinterlacing on the fly. Uploads to Youtube and Vimeo should be deinterlaced, but otherwise, you are often better leaving the original format intact.
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Matt Bee
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Post » Sat Jan 08, 2011 8:56 pm

I seem to have sparked a general discussion of various deinterlacers, and appreciate all the information. But I'm still interested in the question I actually asked. Let me try a more specific example.

I have an HDV 60i source clip that's a real challenge for deinterlacing - trees in the foreground and the camera is panning too fast. I render this twice with the Sony AVC encoder, first as progressive and then again as interlaced, keeping all other settings the same.

Viewing the results in Media Player, the progressive version is either smeary or jerky (depending on whether the project deinterlacing method is set to "blend fields" or "interpolate"). This much makes sense to me. But by comparison, the interlaced version looks sharp and smooth, not just by a small amount, but by a very large, obvious-to-anybody degree. If Media Player is deinterlacing the second file on the fly, with very good results, why can't Vegas do the same when it renders the progressive output? After all, Media Player has to work in real time and Vegas doesn't.

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Megan Stabler
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Post » Sat Jan 08, 2011 2:30 pm

I guess my first response was a little too subtle.

1) Don't use Windows Media Player to compare interlaced vs. non-interlaced video, because it deinterlaces by default.

2) VLC Player, unlike WMP, does not use deinterlacing as its default. However, it's deinterlace options include Discard (Interpolate), Blend, Mean, Bob, Linear, X, Yadif, and Yadif 2X. Gives you lots of options to which to compare your rendered versions.

3) The stock deinterlace options in Vegas are rudimentary, to say the very least. Blend and interpolate, that's it. Search the internet to find out the differences.
There is a primer here:

4) The other rendering options suggested to you are the Smart Deinterlace plugin for Vegas, Decomb (or deinterlace) in Handbrake, Smart Bob and Decomb (and several permutations thereof) from Donald Graft in Virtualdub and AviSynth. As is evident from this thread, people have different preferences; however sophisticated deinterlace / decomb solutions are not to be found natively in Vegas..

5) Different types of video benefit differently from different types of deinterlacing. High detail video might look great with bob, while high-motion footage might actually look best with Interpolate (which actually throws away half the information!). Experiment!
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Anne marie
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Post » Sat Jan 08, 2011 6:12 pm

The reason is because Media Player is probably doing a bob deinterlace which you are seeing at sixty frames per second. The first sixtieth of a second it is showing the odd field interpolated up, the second sixtieth of a second it is showing the even field interpolated up. Vegas can't do this because it isn't fast enough to work with HD video at 60 fps. Nothing against Vegas. It's not alone there.

That is why you a further ahead to just work at 60i unless you need 30p for a specific use like uploading to Vimeo or Youtube.

You want to see spectacular deinterlacing? Render to 1080i mxf and play it back with the free Sony mxf player. Wow!
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laila hassan
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Post » Sat Jan 08, 2011 6:59 pm

The reason is because Media Player is probably doing a bob deinterlace

The visual comparison tests I ran a couple of years ago suggest (but do not prove) that WMP may use a simple blend to deinterlace, Native progressive footage looks as crappy in WMP as native interlaced. If WMP was using bob, I think it would be sharper and there would be tiny, but discernable shears on motion diagonals from interlaced source.

I'm going to try your last suggestion re MXF. Sounds interesting!
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Post » Sat Jan 08, 2011 12:12 pm

"I have an HDV 60i source clip that's a real challenge for deinterlacing - trees in the foreground and the camera is panning too fast. I render this twice with the Sony AVC encoder, first as progressive and then again as interlaced, keeping all other settings the same."

I deinterlace HDV files often, and I get the best results from Smart Deinterlace IF I want to do it in Vegas (I've experimented with V-dub & Handbrake and others, but not enough to make firm conclusions). If you want to stay in Vegas, then try this;

1. Open Project Media and right click the clip; choose Media FX (if you apply FX as Media FX, you won't have to worry about the direction triangles point even if you re-size - there are no triangles in Media FX because you are treating the media with the FX before anything else is done to it).

2. Choose Smart Deinterlace (you'll of course have to install it first)

3. Choose Field-only differencing - it seems to always work. Check the "compare color channels. I also check Use cubic, and Motion map denoising. Instead of the suggested 15-35, choose 5 for Motion threshold.

You should set project properties to (edited) Field Order: none; DEinterlace method: None; Rendering quality: best; with the size you want for your final output (1920x1080, in my case). To see how it's going to look, set Preview window to full/best, and uncheck "resize to fit preview window size (or whatever it says)."

If re-sizing your clip(s), perhaps you'll need to keep the default smart resample, although I don't remember seeing much difference when I disable resampling. You may need to experiment with this.

(edit:) I ran another test, and I can't see any advantage even on fast pans when I enable resampling and resize from 1440 to 1920. I just finished a deinterlace job with it set to "none" and it looks pristine.

Then render to the new size, if re-sizing is desired, and choose a codec that can provide progressive as an option. To test: Select a short section of the timeline that has lots of motion and then play in VLC just to be sure that it looks good - motion should be smooth as silk, and both vertical and horiz. resolution should be great (no visible loss at all). When satisfied, render the entire timeline.

But remember, if you use a codec such as Cineform that creates huge files, you'll need to put them on a really fast hard disk if you want smooth playback (RAID 0 or SSD preferred).

Incidentally, HDV is a lossy codec with a relatively low data rate for MPG2-based compression, and can't handle too much detail and motion without giving a soft picture. If panning too fast across leaves on trees, you may just have to live with a soft picture, for the data rate of HDV really isn't good enough for such a challenge. That's one reason why my new TM700 gives so much better detail when panning than was possible with my HDV cams. It uses an MP4 variant that provides much more efficient compression, with a data rate of 28mb/s

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No Name
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Post » Sat Jan 08, 2011 6:08 pm

As a rule I never ever shoot interlaced, I wish that option was removed from my camera so I can't ever accidently switch on.

Yea I know that this has been discussed sooooo many times already but no one has convinced me that it is the way to go.

Did I mention already that I never shoot interlaced ?)
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Vincent Joe
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Post » Sat Jan 08, 2011 3:27 pm

I usually shoot 30p but I'll still shoot 60i for things like sports or fast run and gun hand held stuff. Also I shoot 60i for things that I know I'll slow down. Weddings are a good thing to shoot 60i because you are likely to use slow motion a lot in the edit (hokey but still loved by brides and their mothers everywhere).
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Brιonα Renae
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Post » Sun Jan 09, 2011 12:27 am

>The visual comparison tests I ran a couple of years ago suggest (but do not prove) that WMP may use a simple blend to deinterlace...

A couple of years ago WMP was just using a simple blend deinterlace. It looks a heck of a lot better now than it used to.
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Isaac Saetern
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Post » Sat Jan 08, 2011 11:47 pm

OK.... silly question.

How do I install the de-interlace plugin? (I'd like to play with it)

I downloaded it (Mike Crash's, right?) Ran the executable, which installed the .dll in the filters folder. When I go to vid fx, I expected to see it, or see it in a different folder (user fx?).

I'm, using 9d-64. Is that the issue? WIll the plug-in not work on -64 bit?

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Josephine Gowing
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Post » Sat Jan 08, 2011 5:06 pm

It won't work with VP9 x64. If not already done, you have to install the 32 bit version of Vegas.
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Cheville Thompson
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