How PsF video from the V1 is different than "p" or "F" video

[Steve Mullen]

Originally Posted by Odile Patra

... horizontal lines ares still "flicking", and I have to set sharpness lower ( 3) to fully avoid it.

You can't "avoid" line flicker with 1080i50 (or 1080i60 video). It's inherent in the "i" system. All you are doing is creating a vertical smear that makes a single pixel line "thicker" than 1 video line -- hence no flicker. That smear is killing the fine detail in your image.

Whoever at Sony Service Europe told folks to set Shapness at "3" clearly has zero understanding of what line flicker IS and zero understanding of how 1080i is different than 720p or 1080 "F."

Line flicker is inherent in any display system that presents video as a series of FIELDs. It makes no difference if the display is interlaced or progressive. As long as the video enters the display as a series of fields that are then presented sequentially -- whenever there are single pixel high "lines" they will appear in one field presentation but not in the other field presntation. Therefore, the line(s) will flicker at 25Hz or 30Hz. (The former will be far more visible and annoying.)

It doesn't matter if the sensors use progressive or interlace scanning. The V1 is capturing 24p, 25p, or 30p! The issue is not IN the "camera."

Once a progressive scanned image is converted to INTERLACE video -- as it is with the V1 -- the video becomes Progressive segmented Frames -- PsF. The same as CineAlta -- except not 1080/48PsF.

From this point forward, ALL video equipment will treat it as "interlace video with no motion artifacts." Thus, when displayed it will have line flicker just as does ALL interlace video.

You need to always read 24p as 24PsF, 25p as 25PsF, and 30p as 30PsF.

The way to eliminate line flicker is to correctly use the V1's progressive video:

1) After editing at 25fps, convert each video frame to a film frame or 25p DVD. (DVD video "should" be displayed as progressive video, but unless the viewer has the correct equipment it will not be.)

2) After editing at 25fps, record to 1080p25 D-5. The transcode will accumulate pairs of fields into a video frame before recording. But, if broadcast using any 1080i50 channel, the video will now be interlace and you'll see line flicker. This is why the IBC wants either 720p50 or 1080p50.

3) Remove 2-3 pulldown (24fps) and edit. Doing so removes the FIELDs. Then transfer to 24p DVD, 1080p24 D-5, or film. Obviously film and D-5 will be progressive "recordings."

If broadcast by ABC, FOX, ESPN, the D-5 will have 2-3 pulldown added, but will remain progressive. But, if broadcast using any 1080i60 channel -- despite the addition of 2-3 pulldown, the video will now be interlace and you'll see line flicker. DVD video "should" be displayed as progressive video, but unless the viewer has the correct equipment it will not be.

As long as you view 1080PsF or 1080i video -- you may see line flicker on very thin horizontal lines/edges.

[Craig Irving]

Great post, but that reminds me of a question.
Is there an advantage to putting 24pA into a 24fps timeline and authoring your DVD as a 24P DVD as opposed to just keeping it 60i and making a 60i DVD?

The only reason I mention this is because I know my TV is only going to be displaying 60i anyway, so what's the difference between having my TV doing that conversion back to 60i and just leaving it at 60i in the first place and editing on a standard timeline?

I'm just saying, if people are primarily showing their equipment on regular TVs...which do you think is best?

[Bob Grant]

Having spent more time than was reasonable dealing with line twitter from high resolution stills when made into SD DVDs I'd have to disagree with some of that.

The problems were never visible on display devices that were progressive, didn't try plasma but LCDs were clean. CRTs were a nightmare, on several stills I had an issue where the whole frame would flicker yet it was rock solid on a LCD.

I've seen the same thing in OTA SD broadcasts. Source is probably F950, the downconverted SD can have line flicker very badly but again watching the same thing on a LCD it's completely clean.

With the hires stills I got around the problem by applying a Very small amount of gaussian blur in the vertical direction only while monitoring on a CRT. For shots that warranted the effort I'd mask the problem areas and apply the blur to that area only.

[Steve Mullen]

Originally Posted by Bob Grant

The problems were never visible on display devices that were progressive, didn't try plasma but LCDs were clean. CRTs were a nightmare, on several stills I had an issue where the whole frame would flicker yet it was rock solid on a LCD.

Most LCD and plasma displays will switch to "weave" for stills, which causes both fields to be combined into one 1080-line frame that is presented twice -- so no flicker.

You got "lucky" because you were using stills. With motion video, weave is very rarely used. Thus, two fields will not be combined. If bob is used -- consider why this deinterlacing technique got its name. :(

Note: EDTVs -- now mostly found in Region 50 for displaying PAL DVDs, will flicker even on stills. That's because they don't combine fields since an EDTVs' vertical resolution is so limited. EDTV's simply display one field after the other. That may be why line twitter is reported in the PAL areas.

By the way, scaling-up each field from 540 to say 768-lines can cause the image to be be blurred vertically. Given MPEG-2's 4:2:0 chroma, if the chroma is not scaled correctly -- which is likely in these cheaper EDTVs -- the result could be smeared color.

[Greg Boston]

Originally Posted by Craig Irving

Is there an advantage to putting 24pA into a 24fps timeline and authoring your DVD as a 24P DVD as opposed to just keeping it 60i and making a 60i DVD?

The only reason I mention this is because I know my TV is only going to be displaying 60i anyway, so what's the difference between having my TV doing that conversion back to 60i and just leaving it at 60i in the first place and editing on a standard timeline?

I'm just saying, if people are primarily showing their equipment on regular TVs...which do you think is best?

It may not help with the visual quality of the end result except that authoring a true 24P dvd vs. 60i will allow you to fit more material on the dvd. You can make use of longer time at the same quality, or settle for the same amount of run time with higher data rates (less compression) for better visual quality.

-gb-

[Piotr Wozniacki]

Originally Posted by Steve Mullen

The way to eliminate line flicker is to correctly use the V1's progressive video:

1) After editing at 25fps, convert each video frame to a film frame or 25p DVD. (DVD video "should" be displayed as progressive video, but unless the viewer has the correct equipment it will not be.)

2) After editing at 25fps, record to 1080p25 D-5. The transcode will accumulate pairs of fields into a video frame before recording. But, if broadcast using any 1080i50 channel, the video will now be interlace and you'll see line flicker. This is why the IBC wants either 720p50 or 1080p50.

OK Steve, I'll have a V1E back for a short testing, so I'd like - for this test sake - to do exactly what you're proposing here and post the results. Even though I might argue here about the Canon 25F not needing "special treatment" to look great, I won't:)

But please give me a step-by-step instruction on what I should do with a 25p clip from the V1E, in order to watch it without flicker with default sharpness. I'm using Sony Vegas 7.0d (have also access to Edius 4.13 as well as Premiere Pro 2.0) and only have a 1920x1200 LCD (either as a PC monitor using DVI-D, or as an HD monitor using component). If it is possible to be done (ie. avoid line flicker while maintaining sharpness), your theory will be self-defending (and very useful actually; otherwise it'll just remain... well, just another arguable theory).

PS. I have no idea whether my LCD is weaving or bobbing - all I know is that both 1080i from all cameras I tried AND 1080/25F from Canon A1 look terrific...

[Steve Mullen]

Originally Posted by Piotr Wozniacki

I'm using Sony Vegas 7.0d (have also access to Edius 4.13 as well as Premiere Pro 2.0) and only have a 1920x1200 LCD (either as a PC monitor using DVI-D, or as an HD monitor using component).

1) I've only used Vegas and Edius to work with 24p -- so you'll have to figure-out how to capture 50i and get it into a 25fps timeline.

2) For a real test you need to export keeping resolution. If you export in PAL, you'll be scaling down the images and smoothing it.

3) You also need to export at 25p.

5) I burn 720p30 and 720p60 to red-laser at 1280x720 using MPEG-2 ar 27Mbps. Then I play these on my Toshiba HD DVD player into my native 1280x720 HDTV. This keeps the path progressive and HD.

Unless you can do this -- you can export an MPEG-2 1080/25p file and play with VLC via your computer's DVI port. I'm assuming that VLC will do nothing more than display each frame twice.

If you use Vegas and your computer has a second DVI port -- you can use the External Monitor function to view the timeline. It "should" output 50p. Check at the Vegas forum.

[Bob Grant]

Vegas has no 1080 25p template however I've been told that by simply changing the project properties to Field Order = None you'll be set to go.

I'm not so certain just what it might do though with the DVI feed to the secondary preview device, that goes through the graphics card and from memory depending on the setting might be doing an adaptive de-interlace. Need to check this one out.

The internal preview monitor certainly doesn't but it can get pretty funky to know just what you're seeing, particulalry with PAL.

[Steve Mullen]

Originally Posted by Bob Grant

Vegas has no 1080 25p template however I've been told that by simply changing the project properties to Field Order = None you'll be set to go.

I'm not so certain just what it might do though with the DVI feed to the secondary preview device, that goes through the graphics card and from memory depending on the setting might be doing an adaptive de-interlace. Need to check this one out.

The internal preview monitor certainly doesn't but it can get pretty funky to know just what you're seeing, particulalry with PAL.

I agree. When I tried using my HDTV's PC port it didn't work very well. So now I send out from my MBP via DVI port into HDMI. This works OK, but not perfectly with motion. I use it only for CC.

I'm going to burn 24p via 60i red laser HD tonight.

My real question is will I be able to get 1080/24p to HD DVD. We are on the real bleeding edge.

[Piotr Wozniacki]

Originally Posted by Steve Mullen

1) I've only used Vegas and Edius to work with 24p -- so you'll have to figure-out how to capture 50i and get it into a 25fps timeline.

2) For a real test you need to export keeping resolution. If you export in PAL, you'll be scaling down the images and smoothing it.

3) You also need to export at 25p.

5) I burn 720p30 and 720p60 to red-laser at 1280x720 using MPEG-2 ar 27Mbps. Then I play these on my Toshiba HD DVD player into my native 1280x720 HDTV. This keeps the path progressive and HD.

Unless you can do this -- you can export an MPEG-2 1080/25p file and play with VLC via your computer's DVI port. I'm assuming that VLC will do nothing more than display each frame twice.

If you use Vegas and your computer has a second DVI port -- you can use the External Monitor function to view the timeline. It "should" output 50p. Check at the Vegas forum.

Steve,

ad 1. OK - I can capture the 25p just fine;
ad 2. I don't get what you mean;
ad 3. Exporting in 25p is somewhat tricky in Vegas as there's no 1080-25p template ready, so - for the sake of true compatibility of results - please send me your suggested settings (and there are plenty of them in the "video" and "advanced video" sections of custom template - changing 23,97 into 25 fps in the 1080-24p Blue Print template is not enough as it results in error during render)
ad 5. I don't do HD DVDs or Blue Rays at the moment, so a 1080/25p MPG-2 file on disk is the only option. Yes I can play it either from Vegas timeline or with VLC and yes I can use the DVI or component (as a second monitor to my ATI card) - but as I mentioned in my original post, I have no idea what my monitor does on input, except that it can play a beautiful picture from all interlaced HDV sources PLUS the progressive 1080/25F from Canon.

Well, so far you haven't said anything that would change my current workflow to an extent that would make me anticipate a "new look" of the V1E' 25p... Please, try to be more specific!

[Steve Mullen]

Originally Posted by Piotr Wozniacki

Well, so far you haven't said anything that would change my current workflow to an extent that would make me anticipate a "new look" of the V1E' 25p... Please, try to be more specific!

YOU are the the person who is shooting 25p and I've got to assume you know how to capture 25p, edit 25p, and export in HD 25p. If not -- what are you doing with your 25p HD video?

I'm in 24p land and Vegas supports 24p from the V1, so I've no way to solve PAL land problems with Vegas. Check our Vegas forum for help with 25p if you need it.

My points are simple:

1) Using Sharpness below "5" is removing fine detail from your HD video. If you don't care -- that's fine by me.

2) Unless you create HD DVDs -- the only HD media option you've got is 1440x1080 MPEG-2 at 25p. You can view this using VLC via DVI to your monitor.

Bottom line -- if you are shooting progressive and want to avoid seeing interlace artifacts (line flicker), the entire path to your monitor must be progressive from the point of capture.

[Piotr Wozniacki]

Originally Posted by Steve Mullen

2) Unless you create HD DVDs -- the only HD media option you've got is 1440x1080 MPEG-2 at 25p. You can view this using VLC via DVI to your monitor.

Bottom line -- if you are shooting progressive and want to avoid seeing interlace artifacts (line flicker), the entire path to your monitor must be progressive from the point of capture.

Steve, I really wanted to follow your steps and recreate your workflow, but now I can see it all boils down to what I have been always doing: watching a 1080/25p MPEG-2. From your previous elaboration, I thought you meant something more to it....

[Steve Mullen]

Originally Posted by Piotr Wozniacki

... now I can see it all boils down to what I have been always doing: watching a 1080/25p MPEG-2.

If you are watching video played from the camera itself, you are not watching 1080/25p MPEG-2. You are watching 1080/25PsF MPEG-2. This is really 1080/50i.

You must export 1080/25p from an NLE to get true progressive HD video.

You've never said what you are doing when you view V1 video.

[Piotr Wozniacki]

Originally Posted by Steve Mullen

You must export 1080/25p from an NLE to get true progressive HD video.

That's what I've always done. I only meant that while it's easy with Premiere, my Vegas 7.0d cannot export a 1080/25p MPEG-2 by just changing the frame rate in the 1080/24p "Blue Print" template; I'll try to go through advanced video settings in order to make it work as soon as I have captured 25p material from the "fixed" V1E that I've just got an hour ago.

One thing I can tell you already after having hooked the camera to the component input of my monitor: while I haven't spotted any softness (it was obvious in my previous V1E), the prog scan introduces a lot of line flicker - especially visible with nearly horizontal, contrasty edges (such as a white book - say the camera's own manual - lying on my desk and filmed more or less horizontally). I'm not even going to reduce sharpness like Prime Support advices; it either is in a 1080/25p produced by an NLE or not. Should the latter be true, well - it would mean the V1 is a truly progressive camera, and you were right in saying that the flicker was introduced by the way we all were watching the 25PsF.

[Steve Mullen]

Originally Posted by Piotr Wozniacki

... the prog scan introduces a lot of line flicker -- especially visible with nearly horizontal, contrasty edges... .

... it would mean the V1 is a truly progressive camera, and you were right in saying that the flicker was introduced by the way we all were watching the 25PsF.

By definition -- progressive video cannot have line flicker. You need FIELDs to have flicker. So Progressive scan cannot "introduce" flicker because it has frames and does not have fields. And, by construction -- the V1 is a progressive scanning CAMERA. There is no "truly" about it. It simply is.

Fields are created AFTER the camera section only for the purpose of recording. Which makes it a "PsF" CAMCORDER. This is not the same as a 24p or 24F camcorder. The recorded video is interlaced -- meaning it has fields. This is why you can see flicker.

You have to convert interlace fields to progressive frames to get back to what the camera captured. Once there are no fields and only frames, by definition there can be no flicker -- on a progressive display.