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-   Canon XL and GL Series DV Camcorders (https://www.dvinfo.net/forum/canon-xl-gl-series-dv-camcorders/)
-   -   24p questions (https://www.dvinfo.net/forum/canon-xl-gl-series-dv-camcorders/34265-24p-questions.html)

Donald Pittelli February 4th, 2005 04:46 PM

thanks Mr deLange and Mr Hurd
 
i thought it had to be 60i . the manual dose not say . heres what confused me i took some video of a machine in motion in 24p. the play back had that frame pulse look like 24p on the tv . i have yet to buy a lcd widescean . so i go to my neighbor who has hidef plasma. even though this is not hidef cam the picture shore looks good lots of detail .thanks dp

A. J. deLange February 5th, 2005 08:25 AM

You'll find this discussed at some length in http://www.dvinfo.net/conf/showthrea...threadid=36253 I have a post in this thread which will direct you to http://homepage.mac.com/ajdel/FileSharing7.html where you can download a dv file with 60i,30p and 24p (both pulldowns) cuts of a rotating fan (be sure to set Qucktime quality to high). Stepping through these one frame at a time is very helpful in seeing how the XL2 handles these modes.

Mel Williams February 15th, 2005 10:39 AM

timecode question - 24p in XL2, Movie Mode Normal in GL1?
 
Hi all,
I've got a question regarding timecode.

I'm shooting a corporate training video with my new XL2 and my old GL1.

I would like to shoot 24p (non-drop) with my XL2 and Movie Mode Normal with my GL1.

Would this produce unsightly differences between the two cameras?

Would I have any problems in postproduction with Final Cut Pro?

Can I use my GL1 to strip all my tapes and then record at 24p with the XL2?

Any recommendations in setup when using the XL2 with the GL1?

Please help, my shoot is tomorrow.

Thanks,
Mel

Pete Bauer February 15th, 2005 10:59 AM

Hi Mel and welcome to DVinfo!

I don't use FCP, but have a GL2 and XL2. I think a couple of aspects might give you fits in post:
- Mixing 24p and 30p. Care to match shutter speeds might minimize how visible the frame rate differences would be. But it would seem a lot simpler to stick with 30p throughout, as I'd think most people could perceive the difference in frame rate and/or cadence of the pull-up of the 24p footage.
- Substantial difference in widescreen resolution between the two cameras, if that's what you're shooting.
- Even in narrow screen, GL1 Movie Mode is going to have a little lower resolution than the XL2's true progressive scan images. But that's probably small enough to be overcome with sharpness settings and/or in post.

All that said, there's no substitute for real-world experience. I'd encourage you to shoot short test clips (even just 10 second samples from each camera) and then share your results with the community so we all REALLY know if it is viable to mix as you've asked about.

Scot Hampton February 26th, 2005 12:51 PM

24P Advanced & Camera Settings
 
Hi everyone,

We've recently bought an XL2 at work and I'm having some trouble figuring out 24P Advanced footage...I've tried several tests and I just seem to be getting footage with excessive noise. I know that 24P footage is supposed to have that film look, but I feel like I'm doing something wrong, because I've taken a look at test footage on this site, which seems to be a lot cleaner, and I feel like I don't have my export settings in Avid set right, or my settings on the XL2 set correctly for that matter. There's just a lot of flickering in larger areas (like a wall) or in areas of detail (like a carpet) and what seems to me to be way more noise than you'd see in normal 24P footage.

Specifics:

I'm shooting in 24P Advanced (2:3:3:2), then importing into a 23.976 project in Avid Xpress pro w/Mojo. I'm exporting as a quicktime, and then importing into After Effects 6.5.

I've searched this forum extensively and found some great advice and articles. If anyone has any more specific advice, or oculd point me to a thread regarding this topic, I would greatly appreciate your comments.

Best,
Scot

Chris Hurd February 26th, 2005 01:05 PM

Unless you're intending to transfer your video to 35mm film, I would recommend shooting in the basic 24P mode, with 2:3 pulldown. The "advanced" 2:3:3:2 option is better suited for 35mm film transfer, but is not ideal for distributing on video.

That said, any number of other factors could be contributing to your problem. Don't shoot in the Green Box (easy recording) program mode, and make sure you have Gain set to +0db and not Auto. Other considerations are your shutter speed and any Custom Presets you're using. Welcome to DV Info Net,

Andrew Oh February 26th, 2005 01:14 PM

Also, do you mean noise or aliasing on edges? If that's what you mean, you may want to turn down the sharpness a bit.

Michael Galvan February 26th, 2005 07:25 PM

Hi Scot,

I don't know about Avid as I work with Final Cut Pro, but I would recommend always shooting in 2:3:3:2 as it gives you more options than regular 3:2 pulldown. True, 3:2 pulldown allows you to edit on a 29.97 timeline and is meant for final viewing on NTSC but by using 2:3:3:2, you can revert the footage back to true 23.98fps and edit in that timeline. When finished with your edit, you can simply reapply the 3:2 pulldown to conform it back to 29.97 NTSC or make a progressive scan DVD.

As for your footage, check all obvious things like gain and iris levels. It could also be due to your multiple exporting ... make sure you use the appropriate DV codecs throughout your conversions.

Hope this helps,

Richard Hunter February 26th, 2005 08:51 PM

Hi Scot. When you shoot in progressive scan mode, and then view the results on an interlaced monitor, you will often see flickering of the fine details. You can try setting the Vertical Detail to Low (in custom preset) to reduce this effect.

Richard

Scot Hampton February 26th, 2005 08:58 PM

Thanks Richard, Chris and Michael...I've been reviewing some of Adam Wilts materials on the subject...and I found some really good help files (pdfs) on 24p.com.

I think the problem was the interlaced monitor, as well as perhaps my gain settings, I think i had them set on auto for my prelim tests...Am going to go back next week and do some more thorough tests, with better settings.

Joseph Andolina February 28th, 2005 08:11 PM

Adam Wilts
 
Where do I find the PDF files by Adam Wilts?

Any help would be appreciated.

Chris Hurd February 28th, 2005 08:23 PM

Two separate things...

Adam Wilt (a DV guru) is at www.adamwilt.com.

Various 24P docs in PDF format are at www.24p.com.

Hope this helps,

Nico van Tonder March 1st, 2005 04:47 AM

Hi Scott,

I am shooting with a PAL XL2 and in the beginning I had bugs crawling all over my footage - to such an extend that I thought something was wrong with the XL2. I removed the UV filter, etc., but nothing helped.

I captured the footage on an old Compaq laptop while I was building a proper XT PC.

I gave that laptop to my grandson and bought a new HP Compaq nw800 Mobile Workstation with much faster RAM and a very fast 60GB hard drive - and quess what? The bugs dissapeared like magic.

I'm not saying that is your problem - but the PC plays a very important role when capturing. Ask me!!

Alvaro Duran March 24th, 2005 10:31 PM

XL2 ISO value at 24p
 
Hello everyone

I read this info in one of yoir messages:

If I have 60i, 16:9 Mode, 1/60th second shutter speed, 0db Gain the effective ASA of the XL2 is 400.

Considering this info may I assume that 24p, 16:9, 1/24th shutter speed, 0db gain is equal to an effective ISO of 160?

Mike Minor April 2nd, 2005 08:23 PM

Motion lines on 24p 16:9 Footage
 
Hello. When looking at some footage i shot on FCP (and also when i export it to DVD and watch it on a tv) i notice a lot of "motion lines" for lack of a better term. When theres moving on screen little lines occur around whatevers moving. Anyone experienced this/know a fix? thanks.


if you guys dont know what i'm talking about, i could post a short clip if need be.

Douglas Robbins April 3rd, 2005 02:06 AM

You will only see them in the browser and the viewer. They go away when you export the project.

Douglas

Richard Hunter April 3rd, 2005 02:56 AM

Hi Mike. I'm not sure whether you are seeing motion blur due to slow shutter or some other effect. Posting a sample clip would be the best bet.

Richard

Rob Lohman April 3rd, 2005 03:16 AM

Hello Alvaro, welcome aboard DVInfo.net!

ISO is very difficult "thing" in the world of digital video. You cannot
really compare it to film. I have no idea if your numbers are sound
or not. May I ask why you would need the ISO info?

Mike Minor April 3rd, 2005 04:12 AM

Hey, they still existed when I exported them...so i uploaded a VERY short clip to show what i'm dealing with. It's short, but its full resolution so you can see the lines around any motion.

www.sodesune.com/sample.mov

A. J. deLange April 3rd, 2005 08:10 AM

When you shoot 24p the camera takes 24 complete pictures per second and splits each into two fields. Calling the fields from the first picture A and A', from the second B and B' and so on the camera writes them to tape as AA' BB' B'C CC' DD' EE' FF' F'G GG' HH' and so on if 2:3:3:2 pulldown is selected. If 2:3 pulldown is selected the sequence is AA' BB' B'C CD' D'D EE' FF' FG. Each pair defines a TV frame with the two fields as given by the letters. Thus in 2:3:3:2 the first and second frames as seen on the TV are composed of the two fields from the first and second pictures taken by the camera but the third has its first field taken from picture B and its second from picture C. The next four frames are "pure" but the fifth is mixed and so on. Thus in 2:3:3:2 every 5th frame is a combination of fields from 2 different pictures. If you look at this on a progressive device (such as a computer monitor) you are shown both fields simultaneously with two pictures superposed in the mixed frames and that is what you are seeing except that in the sequence you posted you have 2 pure frames followed by 2 mixed. This, as the second sequence above shows, is to be expected with 2:3 pulldown which is what I assume you used.

The way around this problem is to shoot 30p. Only use 24p if you are definitely going to film and then use 2:3:3:2 pulldown because, as you can see from the sequences above, the individual original frames are easily recovered from 2:3:3:2 whereas they are not from 2:3. If you feel you must shoot 24p (I think the biggest beneficiaries of 24p are Canon's marketing department) then use 2:3:3:2 because only 1 in 5 frames is mixed as opposed to 2 in 4. Another solution is to view the footage on an interlaced monitor.

At http://homepage.mac.com/ajdel/FileSharing7.html you can download a sequence, "Fan" illustrating the points made above. Be sure to set high quality mode if viewing with QT (because if you dont only half the fields are shown) and look at the clip on both a computer monitor and an interlaced monitor if you possibly can. Step through 1 frame at a time to see what's happening.

Mike Minor April 3rd, 2005 01:29 PM

Thanks for the response AJ your response made a lot of sense. Unfortunatly sounds like theres not much to be done at this stage.

also, i recorded in 2:3 not 2:3:3:2.

A. J. deLange April 3rd, 2005 02:45 PM

Alvaro,

No, the ISO rating stays the same as long as you don't touch the gain control. Just as the ISO rating of a film stays constant as you vary shutter speed and aperture so does the sensitivity of the CCD.

There is nothing inherently wrong in speaking about the ISO sensitivity of a CCD sensor - it is done all the time in the still camera world. The main difference is that you don't have a control labeled "gain" in a still digital camera. It is labeled ISO but it is exactly the same thing - a gain control.

If you expose an 18% gray card with an XL2 such that the light meter in the viewfinder reads at the center of its range (so that all the pixels fall in the middle of a luminance histogram (i.e. around 128 counts) then the ISO value which makes an INCIDENT light meter read the same combination of shutter speed and aperture (or any combination of equivalent exposure) is the "speed" of the camera. If I do this with tungsten lighting, 30p, 16:9, gain 0, tungsten balance and a shutter speed of 1/30th then it takes an f/4 on a 105 mm Nikkor to center the lightmeter in the camera. A Sekonic in front of the card set to ISO 200 gives me 1/30th at an f/4 so my measurement shows the speed of the camera as ISO 200 (and running around outside with the Sekonic confirms that this seems to be about right). Perhaps the biggest danger is that different people will measure it different ways! BTW I'm not saying that my reading is better than whoever posted 400. It was done pretty quickly and my method may not be what was used previously. This is why the ISO standard was written.

There is no reason that I can think of that someone couldn't take accurate measurements of the speed of the CCD (using whatever modifications to the ISO standard apply to CCDs) and publish this number. We could then subsequently take all our light readings with an incident meter using the published ISO number. We'd all figure out pretty quickly what our "working" ISO was exactly as still photographers do. I'm not advocating this as a way to go, just pointing out that it should be doable.

Kevin Chao April 3rd, 2005 05:08 PM

it either looks like compression artifacts... or a dirty head...

Mike Minor April 3rd, 2005 05:17 PM

Thanks Kevin. If they're compression artifacts, how can I get rid of them?

Charles Papert April 3rd, 2005 05:44 PM

The issue is that the curve of video is different than film, so that readings taken in the shadows will not expose the same as one would "expect"...i.e. a virtually non-existent reading may be quite visible on screen. Thus a light meter, or classic definition of ISO is not as transferable to digital as it might seem. Thus, what appears to make sense as a 400 ASA rating for the camera may act more like a 640 or 800 ASA rating when examining values in the toe.

A. J. deLange April 3rd, 2005 08:54 PM

That's quite true and the shoulder is different too - no grace with respect to over exposure in digital. And it's also true of still digital cameras which use ISO ratings as a matter of course. An exposure meter doesn't know about gamma or latitude. All it knows is how to get Zone V correctly exposed given the amount of light available regardless of whether the "film" is reversal or negative or CCD. The skilled wet photographer learns how to tweak the ISO setting for his combination of film, camera developer and paper. The skilled still digital photographer does the same and there is no reason why a videographer can't do it too. Whether we are aware of it or not the camera's meter has an "ISO" setting - so many watt seconds per square cm gives 50 IRE and the camera will, in automatic mode, adjust iris and/or shutter to get that many and if the subject is an 18% gray card or the scen is average, all is well. If it isn't, that's what the AE shift control is for and why those of us who use manual don't always center the "needle".

A. J. deLange April 4th, 2005 06:25 AM

While surfing about looking for details on the ISO standard I found http://www.spectracine.com/determini...o.htm#plancha1 which is a short article describing the means for determination of the ISO rating of a professional video camera. They suggest the same method I described except that they want the "crossover chip" which is, I guess, one on the test target used by pro videographers set to 55 IRE. I don't know whether this chip is at 19% but I'll bet it's close. They then go on at great length explaining why using an incident meter is a far better way to set exposure than using a monitor. Now I've got nothing to gain by pushing this technique except that maybe I'll discover that these guys are right and get better video (there certainly are some advantages to incident light metering) but these guys sell light meters to Hollywood so you may conclude that they aren't as dispassionate as I.

Steve Brady April 4th, 2005 06:42 AM

No, AJ's right, it's a pulldown issue.

Like AJ said, every four 24fps frames get distributed among 5 30i video frames like so: AA BB BC CD DD... The first, second and fifth video frames are "Whole" frames, because both fields contain the same 24fps frame, and the third and fourth video frames are "Split" frames, because each field contains a different 24fps frame. So the video sequence is WWSSW. However, you can start capturing the video at any frame. If you start capturing at the third video frame in the repeating sequence, for example, then your app needs to know that the pulldown on the clip is SSWWW. I don't use FCP, so I can't tell you how to set that up, I'm afraid.

Also, a word about 2:3 vs 2:3:3:2. It's fairly widely put about that this is a marketing gimmick, but the real point of it is that if your final material is going to be delivered at 24fps (not just film, but progressive DVD like you seem to be doing here, or web video, or whatever) then you'll get better picture quality, because rather than having to reconstruct two of the 24p frames from separate video frames, each 24p frame is stored in it's own video frame (you just throw out the split frame in the middle of each sequence of five). The only reason to shoot 2:3 rather than 2:3:3:2 is if there's a possibility that the footage will need to be viewed as 60i video without undergoing the conversion to 2:3.

A. J. deLange April 4th, 2005 07:33 AM

Mike,

There is something that can be done but you may not like the results. If you "deinterleave" i.e. throw away all the high or all the low fields the motion blur will go away. To see what this looks like view the footage in QT with out setting quality to High. What you may not like is that half your vertical resolution goes out the window with the motion lines. If this is acceptable then there is probably some way to do the deinterleaving in FCP but I don't know what it is.

Ed Bicker April 4th, 2005 01:40 PM

Hello AJ,

FIrst, I have two questions. I have an XL2, 20X
When you refer to QT, what do you mean??

Second, I shot a nature scene last week and I can not remember, what frame rate I was in. It was either 24p or 60i, but the problem that I saw was that I had horizontal rectangles forming as I moved the camera across the landscape. It was not there earlier in the video, but I was going through the process of shooting at various frame rates and all of a sudden, as I was playing this back these rectangles began to form and , of course, they destroyed the quality of the image. ANy idea why they would have formed when I panned to the right or left??? I do not remember them being there in the view finder.

Matthew Nayman April 4th, 2005 01:52 PM

Sound like you have a dirty head in there... send a cleaning tape through it..

Matt

A. J. deLange April 4th, 2005 03:34 PM

QT refers to QuickTime - Apple's way of handling video. All Apple computers come with Quick Time Player and it is available free for Windows platforms as well. Many other programs are based on QT such as Final Cut Pro.

Rectangles appearing erratically throughout DV video are an indication that bits have been dropped. The most likely cause is indeed a dirty head.

Mike Minor April 4th, 2005 04:55 PM

How do you alter the quicktime quality setting? I poked around in preferences and couldnt find anything.

Also, anyone how to Deinterleave footage on a mac thats ultimately going to dvd?

A. J. deLange April 4th, 2005 06:16 PM

In QT: Movie > Get Movie Properties will open a window with two pull down menus. Use the left one to select the video track. Now use the right one to select Quality. Check the "High Quality Enabled" box and you are set.

In the FCP browser window: Effects > Video Filters > Video > Deinterlace brings up a filter which allows you to select the field you want to retain.

Mike Minor April 4th, 2005 10:53 PM

you're the man AJ! Thanks!

Bruce S. Yarock April 13th, 2005 08:14 AM

24p confusion
 
I've read a number of posts on this topic, and still have some questions.
I want to be able to get a more filmic look with my xl2, but don't plan to transfer to film. We out put everything we do to dvd.
1- Do I use the 2:3 pulldown in this case?
2-If I use the 2:3, do I edit on a 24 tmeline or 30? ( were just trying out Premiere pro, and itlooks like the only option offered is what it calls "Panasonic 24p...2:3:3:2").
3- Is Vegas any better for 24p editing?
4-If you edit on a 30 timeline, do you still retain the 24p look?
Thanks
Bruce Yarock

Pete Bauer April 13th, 2005 11:17 AM

Hi Bruce,

I don't have PPro in front of me right now so unable to be very specific. I assume you want to shoot 24fps and end up with a 24fps DVD?

FYI, there are some bugs and problems with PPro and 24p handling, so unless 24p is specifically important to you and you're ready to do a fair amount of reading and fiddling around to deal with these issues, it might be a whole lot easier to shoot 30p -- after all, frame rate isn't the only determinant of "film look."

Anyway, 24p certainly is a confusing topic. As best I understand so far, the short answer is:

- If you choose to use a 24fps timeline in PPro, you can shoot either 24p (2:3) or 24pA (2:3:3:2). From the 24p timeline, you can capture or import using either pull-down method. I can't remember exactly how to access the dialog box, but there is one that allows you to choose between the pull-down / pull-up methods...can't remember if it is the Interpret Footage dialog, or in the project settings somewhere.

- If you choose to use a 30fps timeline in PPro, use 24p (2:3).

From a 24p timeline, regardless of how the footage got there, export either using a native 24fps file format for further transcoding, or using 24p (2:3). The cadence of 2:3:3:2 doesn't work with 30fps projects and DVDs, so you wouldn't want to export that.

Bruce S. Yarock April 13th, 2005 11:38 AM

Thanks Pete3, I'll try shooting at 2:3 and import to pro . Then I'll edit in 24p timeline and try to burn to dvd.
Bruce Yarock

David Lach April 13th, 2005 11:43 AM

Pete, what are these bugs you're talking about? I recently edited a 24p project without any glitch. Have I been lucky or you've been unlucky?

Bruce, it's all about the timeline. If you edit in a 30fps timeline, use 3:2. If editing will be done in a 24fps timeline, use 2:3:3:2.

3:2 is not reversible, so it will give you the film look you're after, but you will never be able to get your true 24p sequence back without quality loss due to recompression.

2:3:3:2 means you discard the fake frames introduced by the XL2 to comply with the DV 60i standard to get your true 24p sequence back and edit it as such. You can then burn a 24p DVD. The DVD player will do the 3:2 pulldown on the fly to see it on an NTSC TV.

Notable advantages of editing and outputing to DVD in 24p is less rendering time (less frames to render) and potentially better image quality (needs less compression per frame on the DVD).

David Lach April 13th, 2005 11:46 AM

<<<-- Originally posted by Bruce S. Yarock : Thanks Pete3, I'll try shooting at 2:3 and import to pro . Then I'll edit in 24p timeline and try to burn to dvd.
Bruce Yarock -->>>

Don't. If you capture in 3:2, you need to edit your footage in a 30fps timeline.


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