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To deinterlace or not to deinterlace... that is the problem

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Simon Toro
To deinterlace or not to deinterlace... that is the problem
on Mar 4, 2011 at 9:39:56 pm

Hi, I guess this is the right topic to post this, although the question is a little more engrossing than just Encore. Actually it is a two-part question.
This is my story:

I shot a short documentary on a sony Z1, at 1080i50 (I'm in Europe). I edited it on Final Cut Pro and I used a Nattress filter called G Smart De-Interlace V2.5.1, to give it a more "cinematic" feel, because hdv gave it too much of a "tv" look, which the director allegedly was running away from. meh..
anyways, once I finished, I exported a quicktime movie using the same preset as captured from the camera: HDV 1080i50. So this is my first question:
Is my exported movie interlaced video, or progressive?
It shouldn't be interlaced, right? because of the deinterlacing filter I used on it, and because when you pause it during movement it looks like there is only one single picture in every frame, as opposed to when you pause the clips directly captured from the camera-- they looked interlaced. BUT, the preset I used for exporting is 1080i... so...? Is it interlaced or not? I haven´t got a clue.

ok... I gave this quicktime movie over to the guy who is to make the DVD authoring for the final client of the documentary, and he told me all he did was put it in a adobe encore timeline and make a DVD with it. Without applying any filters or process. And the burned DVD plays wonderfully except for very subtle lines which you can see on high-contrast areas or very bright colors in movement. Now, these lines, or stripes that you can see, are not the regular interlacing artifact that you normally see i.e.: they're not teeth, nor combing. They're just lines. Like darker lines that flicker a little.
oh, and CRT TVsets do not show this problem.
So this is my 2nd question:
Anyone got any advice on what to do, or what is going on here?

I would very much appreciate your help, since I have no one to turn to and am not really an expert on DVD authoring (as you can see, the guy doing the DVD isn't either... but he just doesn't really care:(

Thank you!
simon.


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Daniel Ludwig
Re: To deinterlace or not to deinterlace... that is the problem
on Mar 5, 2011 at 5:16:37 am

hi simon,
the simple answer is: your exported video is 1080i50 as your sequenz-setting is 1080i50. it doesn´t matter if you have deinterlaced your original source-clips or not, because the sequenz-settings has been setuped interlaced.

as you would like to have a progressive-DVD you need to have a progressive sequenz and a progressive encoding.

what you´ve done normally will be called 1080psf25 (progressive segmented frames), meaning:

you put progressive frames into an interlaced recording, the result will be an interlaced film with progressive content on every field, but this might go to much in detail.


now to your second question:
there could be several issues to get DVDs wrong. as that guy has no clue how DVD-authoring works, that could be the main problem. if he just put your movie-file into encore (which version of encore?), I would think of wrong field-dominance, or bad encoding-quality, or whatever.

as your film is HD you should downscale it to SD prior encoding. I would advice to use innobits purifier to do so. this has a 2nd advantage. purifier could reduce/delete HDV-digital-artefacts.

another point to think about: HDV has the nativ resolution 1440x1080, and it will scaled to 1920x1080 while playback. so there could be another issue.

where did you check this DVD? on a class A reference tube-monitor with a stand-alone-player?

if you need another guy to author your disc - it might be possible over here as well - I´m based in cologne, germany.

cheers

danny


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Simon Toro
Re: To deinterlace or not to deinterlace... that is the problem
on Mar 6, 2011 at 12:29:29 am

Thank you very much for the offer danny!
unfortunately, the DVD is due this next tuesday and I still have a couple of changes to do to the editing, so there's no time! :((

Still, I'm very interested on what you said about the correct way of recording the DVD. Should we put the movie into a progressive sequence and encoding on Encore, or an interlaced one?

Also, on this downscaling... would it be better to export the final edit to a MPEG-2 file and then putting that into encore?
If so, what size and bitrate would you recommend?

Once again, thank you very much!


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Daniel Ludwig
Re: To deinterlace or not to deinterlace... that is the problem
on Mar 6, 2011 at 3:21:26 am

Hi again,
I would stay interlaced for your DVD.

here is a workflow you should follow:

1.) edit your film
2.) export it as self-contained movie (HDV-codec)
3.) downscale it to SD-PAL (upper field first) using innobits purifier, MPEG Streamclip, or maybe After Effects
4.) do a bitbudgeting
(depending on the duration of your film you´ll have a different bitrate)
5.) encode your video to m2v and audio to dolby AC-3 using Adobe Media Encoder, create your own preset depending on your calculated bitbudget
6.) use the previous encoded assets for DVD-authoring

as you haven´t told us the duration of your film, I couldn´t tell you which bitrate you could use. should it be a single-layer DVD (DVD-5) or a DVD double layer (DVD-9)?

cheers

danny


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Simon Toro
Re: To deinterlace or not to deinterlace... that is the problem
on Mar 6, 2011 at 12:00:12 pm

Thanks a lot! I'll try that workflow as soon as I finish the last changes on the edit.

The movie is 47 minutes long. But the DVD will also include a 3'30'' videoclip from the band and a short (15'' or so) menu animation. I don't exactly know how to input that into the bitbudgeting calculation, but I'll figure it out. -I've never used a bitbudget app before. Now that you mentioned it, I looked it up and found a free one at Ken Stone's final cut pro website. Hope it works!
Thanks,
simon.


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Daniel Ludwig
Re: To deinterlace or not to deinterlace... that is the problem
on Mar 6, 2011 at 3:21:57 pm

hey simon,
there is a little app one of my german collegues have been written. it´s a bit slow but have a great interface. it´s called simple bitbudget, you can find it over here:

http://truevision-video.de/index.php?article_id=31&clang=1

PS: for DVD-R/+R I would mention not to work with higher bitrates than 7.8MBit/s for you video, and allways use dolby digital audio.

cheers

danny


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Simon Toro
Re: To deinterlace or not to deinterlace... that is the problem
on Mar 6, 2011 at 3:29:55 pm

Awesome! Thanks a lot, the app looks great, I'll make sure to donate! ;)


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Angelo Lorenzo
Re: To deinterlace or not to deinterlace... that is the problem
on Mar 5, 2011 at 11:57:31 pm

To clarify, is your deliverable a DVD or Blu-Ray disc? If you're shooting and editing 1080i50, take the interlace filter off it as its exporting to interlace and you're probably creating some kind of resampling artifact when it's resized.

If you are delivering a DVD, de-interlacing is redundant as all legal dvd videos (PAL and NTSC) are interlaced. "Progressive" DVD players use hardware pulldown during the disc read.

If you have any decent grasp of video, reading the Wikipedia article on DVD video will help http://en.wikipedia.org/wiki/Dvd_video


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Simon Toro
Re: To deinterlace or not to deinterlace... that is the problem
on Mar 6, 2011 at 12:18:51 am

Yeah, I'm not deinterlacing to try and turn the video into a progressive video; I ony applied the deinterlacing filter to get rid of a little of that TV feel. So ultimately I don't mind the video still being interlaced. What bugs me is if wether the filter is causing the lines?
What do you think?


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Angelo Lorenzo
Re: To deinterlace or not to deinterlace... that is the problem
on Mar 6, 2011 at 3:13:36 am

I would say the first suspected cause of the lines are the deinterlace filter. Depending on how it blends/resamples frames, artifacts may be visible on high contrast monitors.

Overall, in my experience though, I think the "film look" being based solely on 24p is bullocks. To tone down the video look, we've had more success with using slower (wider degree) shutters, adding a grain overlay to the video to increase visual accutance, and by using more aggressive color grading and luma curve adjustment. Shooting on cameras with 2/3" sensors or larger really helps as well as part of it is depth of field. It's a "total package" thing.


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Simon Toro
Re: To deinterlace or not to deinterlace... that is the problem
on Mar 6, 2011 at 11:35:10 am

You're absolutely right. The bigger sensor camera thing is not possible for this project unfortunately, but all the other things we've taken care of. We shot using a little zoom whenever possible to force a shallower depth of field on the subjects, and we've treated the image with levels, saturation, contrast and grain filters so as to achieve a more "cinematic" look. Still, without the deinterlacing, it looked more like a color-corrected soap opera than a film. I'm not saying we're fooling anyone as it is, but at least it looks more like what the director wanted.

About the deinterlacing filter being responsible for the lines, here's a new discovery we've made: The other video that is included in the DVD, a music video from the same band, also shows the same lines during fade-ins and other hi-contrast moments. This video does not have (to my knowledge) any deinterlacing filter or weird process. It has been broadcasted on tv and seen in many places with no lines at all, so there must be something wrong with the DVD encoding! what do you think it could be?
Here's a screengrab of the music video showing the lines during a fade-in:


As I said, the 'lines' are not the typical combing deinterlacing artifact, but to me they look like they're interlace-related. What do you think?

thanks,
simon.


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eric pautsch
Re: To deinterlace or not to deinterlace... that is the problem
on Mar 7, 2011 at 1:16:06 am

Off Topic but thats the coolest Bit Budget tool Ive ever seen. I tried it a couple years ago but too bad its in German - for me anyway :(



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Maurito Zarate
Re: To deinterlace or not to deinterlace... that is the problem
on Mar 29, 2011 at 2:42:06 pm

Hallo guys,
I can't understand why I can see very good a new DVD, just bought in a shop, in TV AND in PC or Flat Screen... normally we have to deinterlace for DVD issue? I think ist better NOT deinterlace and you'll see very good in evry player sistem (Old TV, Flat, Web Computer screen,...)


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