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james g. brown
Progressive of Fields?
on Oct 7, 2008 at 8:51:02 am

Hi,

I am in the UK so work in PAL and for years I have been working with footage that is all Upper Field First, and so have been authoring video with this interpretation in After Effects, Premiere etc and when I get to the Encore stage I burn the DVD with Upper Fields.

But recently I have had clients complaining about how they can see the fields and a reduced quality in aliasing when they play back my DVDs on PC screens and LCD TVs. I understand why and so I am thinking about changing everything I do to Progressive footage.

I just wanted to ask questions such as what happens when you play a progressive disc on an old analogue TV. Will it look awful?

Plus, do people think that generally LCD's and Plasma screens are used more nowadays than analogue TV's.

I just cant decide whether to make the switch or not and would value people opinions and ideas.

Thanks,

James


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Jeff Bellune
Re: Progressive of Fields?
on Oct 7, 2008 at 12:36:20 pm

[james g. brown] "I have had clients complaining about how they can see the fields and a reduced quality in aliasing when they play back my DVDs on PC screens and LCD TVs. I understand why and so I am thinking about changing everything I do to Progressive footage."

All video is stored on DVD-Video discs as interlaced, even progressive footage. When a DVD is displayed on a progressive display device like a computer monitor or an HDTV, it is up to either the DVD player or the display device to deinterlace the footage.

The quality that your clients are seeing from your interlaced DVDs on their computer monitors is solely as a result of the poor deinterlacing done by their software DVD players. Poor results on the HDTVs may well be due to a combination of poor deinterlacing *and* poor upscaling done by the TV itself.

Progressive footage that is stored as interlaced on a DVD has data flags set that allow certain DVD players to perfectly reconstruct the progressive frames of the original footage. Hollywood's DVDs are constructed this way. The number of hardware DVD players that have this capability is increasing as prices come down. So a decision to produce DVDs that contain progressive footage probably won't hurt the majority of your clients, and may help the ones having trouble.

However, unless your source footage (that footage that comes off of the camera) is progressive, you must ensure that you use high-quality deinterlacing to process the video for final export. If you use Premiere Pro, you must not use its native deinterlacing because the quality is horrible compared to almost anything else.

Realize that you only have a certain amount of control over the quality that your clients end up seeing. More and more the quality of the presentation is dependent on how the audience sets up their display chain, and less dependent upon the author's talent and technical skill. You can do everything just right, and still not be assured that your clients will get to see anything close to the original quality.

-Jeff

The Focal Easy Guide to Adobe Encore DVD 2.0


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james g. brown
Re: Progressive of Fields?
on Oct 7, 2008 at 1:27:48 pm

thanks alot for your help on this Jeff, what you say makes alot of sense. i don't really work with live footage, just rendered frames from 3ds max which are rendered out with fields.

i try as much as possible to speak to my clients and find out exactly what setup they will be showing the DVD's on but usually they just guess. it can get annoying.

one other thing, i always export my final project from after effects or premiere as an MPEG-2 with a constant bitrate of 7mbps, quality of 5. i have always been told that 7mbps is the highest I can go. Do you know otherwise? And is this the best way to get the highest quality MPEG2?

Cheers again,

James



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Jeff Bellune
Re: Progressive of Fields?
on Oct 7, 2008 at 1:55:44 pm

[james g. brown] "i don't really work with live footage, just rendered frames from 3ds max which are rendered out with fields."

This makes a transition to progressive output very easy. Just export frame-based progressive image sequences (or video) out of Max and edit them in a progressive Pr project and/or AE comp. Export to mpeg with No Fields (Progressive Scan). When Encore builds the final DVD, it will recognize the progressive video in the mpeg file, and set the appropriate flags for progressive playback, even though the video will be stored on disc as interlaced.

[james g. brown] "i always export my final project from after effects or premiere as an MPEG-2 with a constant bitrate of 7mbps, quality of 5"

Using a DVD burner with the latest firmware updates, and quality blank media (Taiyo Yuden or Verbatim), I've had very good success recently with one-pass VBR with a min bit rate of 3.5, a target bit rate of 6 and a max bit rate of 8. I've become a big fan of VBR over CBR, even if only one pass is used. However, 2 or more passes are recommended to squeeze that last bit of quality out of the transcoding process.

As for the quality slider, you only really need to use 5 when your video has lots of motion or lots of tiny details (like leaves on trees in a forest scene). Otherwise, a slider setting of 2 or 3 will produce good results in far less time than a setting of 5. And you always have the option of transcoding different parts of the video with different settings, depending on the content in those parts. Again, that is how Hollywood does it.

-Jeff

The Focal Easy Guide to Adobe Encore DVD 2.0


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james g. brown
Re: Progressive of Fields?
on Oct 7, 2008 at 3:46:17 pm

so does the blank media you burn to make a difference? I had never thought of that aspect before!

I may have a go with vbr and compare the two. The time it takes to transcode is not an issue really, I just want the best possible because I see all these cgi retail DVD's and the quality of mine never compares. The 3d renders are just as good (i dont actually do them, a company does) but the final DVD stage of the production is never quite as crisp and perfect as I would like it to be which gets me frustrated.

Does Hollywood use some software/hardware that I am unaware of and is totally out of reach?

Thanks again for your responses Jeff. They are very helpful.

James



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Jeff Bellune
Re: Progressive of Fields?
on Oct 7, 2008 at 4:26:38 pm

[james g. brown] "Does Hollywood use some software/hardware that I am unaware of and is totally out of reach?"

Yes and Most Emphatically Yes. They also use an army of video engineers who do nothing except transcode to DVD-compliant mpeg video all day long. They are experts, they are using (in most cases) software that is custom designed for them, and they encode frame-by-frame if they have to.

As in all things, some are better at it than others, which is why some DVDs are reference quality and others are merely ordinary.

-Jeff

The Focal Easy Guide to Adobe Encore DVD 2.0


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David Burch
Re: Progressive of Fields?
on Oct 30, 2008 at 4:56:11 am

You said all video on a DVD is stored as interlaced. Are you sure about that? I was under the impression that 24p video was actually stored on the disc as 24p, which is why it takes less room and can result in less compression for the same amount of footage. From what I have heard the DVD player does the opposite of what you said...instead of removing the 2:3 pulldown from interlaced footage flagged as progressive it adds it to progressive footage when it is outputting to a TV or monitor that can't support progressive scan. This is what I have always read to be the case anyway...



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Jeff Bellune
Re: Progressive of Fields?
on Oct 30, 2008 at 12:10:03 pm

David,

It is as I said.

The space savings with 24p occur because there are fewer frames of video than 60i.

For display on an interlaced TV, the flags in the encoded mpeg2 stream tell DVD players which fields to show and when to show them, and which fields to repeat and when to repeat them. For NTSC video that has been inverse telecined, the repeat_first_field flag is set on every fifth frame.

Progressive video is encoded into mpeg2 as paired fields when encoding for DVD-Video. Capable progressive-scan DVD players can perfectly re-create the progressive frames from the paired fields.

My reference is pp 3-48 to 3-50 of DVD Demystified, Third Edition by Jim Taylor, Mark R. Johnson and Charles G. Crawford. Jim Taylor is widely recognized as a leading authority on the DVD Specification and the technology behind it. More info and more technical references are available at http://www.dvddemystified.com/

-Jeff

The Focal Easy Guide to Adobe Encore DVD 2.0


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David Burch
Re: Progressive of Fields?
on Oct 31, 2008 at 1:37:55 am

Ok, correct me if I'm wrong on this, but this is what I think you are saying: 24p video is encoded on a dvd as paired fields but is still 24 frames per second? That would make sense, as a set of paired fields from a progressive source would still appear progressive when viewed together, and would allow for an easy 2:3 pulldown to be applied during playback. Adding fields would only occur when adding a pulldown from 24 to 30 fps, as far as I understand it. Going the other way around would require removing fields. Am I understanding this correctly?



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Jeff Bellune
Re: Progressive of Fields?
on Oct 31, 2008 at 1:43:46 am

[David Burch] "a set of paired fields from a progressive source would still appear progressive when viewed together, and would allow for an easy 2:3 pulldown to be applied during playback. Adding fields would only occur when adding a pulldown from 24 to 30 fps"

Correct. And the only time the player would need to add fields at 30 fps is when outputting to an interlaced display.

-Jeff

The Focal Easy Guide to Adobe Encore DVD 2.0


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