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Randy Mack
letterboxing 720x480 for 4:3 NTSC playback
on Sep 3, 2009 at 8:20:18 am

Hi folks,

I've spent all day googling and am about losing my mind. I have a simple situation and yet cannot reach my goal-- to letterbox 720x480 footage on a DVD.

The footage was shot at 720x480 and edited in FCP. Compressor'd to DVD Studio Pro. When I set it all to 4x3, the footage gets cut off on the sides when played on my stand-alone dvd player hooked up to a regular tv. When I re-encode the mp2 as 16x9, the aspect ratio becomes stretched horizontally AND it still cuts off the sides of the image (albeit not as much as in 4x3 mode).

I suspect something in the way I'm encoding the mp2 is wrong.

Here are my Compressor settings for the 16x9 export whose outcome is described above:
Description: 6.5Mbps,1-Pass VBR,16x9
File Extension: m2v
Estimated file size: 2.86 GB/hour of source
Type: MPEG-2 video elementary stream
Usage:SD DVD
Video Encoder
Format: M2V
Width and Height: Automatic
Pixel aspect ratio: Default
Crop to: Letterbox area of source
Padding: None
Frame rate: (100% of source)
Frame Controls: Automatically selected: Off
Start timecode from source
Aspect ratio: 16:9
Field dominance: Automatic
Average data rate: 6.5 (Mbps)
1 Pass VBR enabled
Maximum data rate: 8 (Mbps)
High quality
Best motion estimation
Closed GOP Size: 1/2 second, Structure: IBBP
DVD Studio Pro meta-data enabled

These are the 4x3 settings:
Description: 6.8Mbps,1-Pass VBR,4:3
File Extension: m2v
Estimated file size: 2.86 GB/hour of source
Type: MPEG-2 video elementary stream
Usage:SD DVD
Video Encoder
Format: M2V
Width and Height: Automatic
Pixel aspect ratio: Default
Crop: None
Padding: None
Frame rate: (100% of source)
Frame Controls: Automatically selected: Off
Start timecode from source
Aspect ratio: 4:3
Field dominance: Automatic
Average data rate: 6.5 (Mbps)
1 Pass VBR enabled
Maximum data rate: 8 (Mbps)
High quality
Best motion estimation
Closed GOP Size: 1/2 second, Structure: IBBP
DVD Studio Pro meta-data enabled

The fact I have 3:2 footage and my only choices are 4:3 or 16:9 kinda makes me feel like I'm in trapped in a Escherian labryinth overseen by Kafka, and the technical explanation I've read only strengthen the feeling.... So I guess I'm looking for something more like an algorithm than an explanation... ;-)

thanks much!
_Randy

Armak Productions
http://www.BurningAnnie.com
http://www.MorningsideLow.com/#top


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Noah Kadner
Re: letterboxing 720x480 for 4:3 NTSC playback
on Sep 3, 2009 at 12:13:46 pm

But what is the original footage? Is it 4:3 letterbox or 16:9 anamorphic? DVDs will happily display the proper aspect ratio of 16:9 anamorphic, 4:3 standard or 4:3 letterbox, provided you send the footage formatted properly.

Noah

Check out my book: RED: The Ultimate Guide to Using the Revolutionary Camera!. Unlock the secrets of the 24p, HD and Final Cut Studio.
Now featuring the Sony EX1 Guidebook, Panasonic HVX200, and Panasonic DVX100.
http://www.callboxlive.com


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Randy Mack
Re: letterboxing 720x480 for 4:3 NTSC playback
on Sep 3, 2009 at 5:47:01 pm

I don't understand the question-- the original footage is 720x480, which is 3:2... so, how can it be 16x9 or 4x3? It was shot on a Canon XL-2 if that's helpful info.

So far I've authored DVDs in both 16x9 and 4x3 letterbox modes, and both trim the image on the sides. I haven't tested it in anamorphic because we didn't shoot in anamorphic (but maybe 'anamorphic' means something different than it does with lenses?)...

_R


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Michael Sacci
Re: letterboxing 720x480 for 4:3 NTSC playback
on Sep 3, 2009 at 6:56:03 pm

The question is -

Is your footage 16:9 or 4:3 (3:2 is the same as 4:3 and just a different way of looking at the numbers, 3:2 is what 4:3 is if converted to square pixels)

There are explanations of aspect ratio all over the web. In SD NTSC both 16:9 and 4:3 have the same pixel count 720x480 (or 486), what is different is the aspect ratio of each, 16:9 is 1.2 so the pixel is wider than it is tall, where as 4:3 is .9 so the pixel is taller than it is wide.

True 16:9 footage as captured by higher end cameras is refered to as anamorphic, which means it captured 720x480 1.2 ratio.

So how was your footage shot, captured and edited, and finally encoded. If it is not 16:9 all the way through you will not have correct 16:9 on the DVD.

If you have 16:9 all the way through the encoding process. In DVDSP you set your asset to 16:9 Letterbox. Then if the dvd player is set up correctly for the TV it will display fullscreen on a 16:9 TV and letterboxed on a 4:3 screen.

If would help if you could an still image out of FCP and posted it, we could tell in a second how it is set up in the editing program.

How much are you losing, you always lose 10% on each edge.


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Noah Kadner
Re: letterboxing 720x480 for 4:3 NTSC playback
on Sep 3, 2009 at 10:40:50 pm

NTSC is *always* 720x480, it's a question is the material anamorphic or standard. This should help explain it a bit better for you:

http://www.thedigitalbits.com/articles/anamorphic/anamorphic185demo.html

Noah

Check out my book: RED: The Ultimate Guide to Using the Revolutionary Camera!. Unlock the secrets of the 24p, HD and Final Cut Studio.
Now featuring the Sony EX1 Guidebook, Panasonic HVX200, and Panasonic DVX100.
http://www.callboxlive.com


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Randy Mack
Re: letterboxing 720x480 for 4:3 NTSC playback
on Sep 4, 2009 at 1:11:59 am

The material is not anamorphic.

Here is footage from it--





NTSC is *always* 720x480

Huh. I thought NTSC was 640x480. If this is true, and my TV and dvd player are NTSC, why would it cut off the edges of my 720x480 image as if it was 640x480? And for that matter, why would the aspect ratio choice be 4x3 (vs 16x9) if NTSC is 3x2?

I haven't responded to Michael yet, but he says that somehow 4x3 = 3x2 which just defies mathematical law to me. I must be confused about something very fundamental about all this, such as what a pixel is.

_R

_Randy

BURNING ANNIE
***************
*
* * WINNER * BEST FEATURE * 2004 MassBay Int'l Film Festival * *
* * WINNER * BEST FEATURE * 2004 West Virginia Filmmakers Festival * *
*
* * http://www.BurningAnnie.com * *


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Michael Sacci
Re: letterboxing 720x480 for 4:3 NTSC playback
on Sep 4, 2009 at 1:41:16 am

Your problem is you are not listening or reading.

You have a 4:3 video, it is not 16:9 so no DVD with correctly letterbox your video, why because is is not 16:9.

If you want that look you can add a Letterbox mask in FCP but it will top of the top and bottom of your video which you have not framed for. You turn 4:3 video into 16:9 or just letterbox it you will lose about 35% of the image (split between the top and bottom.

Pixel is a dot, not all dot are the same shape. SD NTSC video is never square, but the pixel count is always 720x480, the shape will determine whether it is 16:9 or 4:3.

4:3 and 3:2 are same after you convert the 720x480 into a square pixel which would give you your 640x480. So I'm saying that 720x480 non-square pixel for 4:3 TV is the same as 640x480 square pixels for computer.

Now you need to know that TV cuts off 10% of the image all around. If you open your NLE turn on video guides (action safe) anything outside these lines will most likely NOT show up on a TV. So a mid shoot of say two guys walking down the street with 1/2 of one guys head already cut off will probably end up with his eyes cut off on a TV. Which I'm going to assume is the real problem you are having.



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Randy Mack
Re: letterboxing 720x480 for 4:3 NTSC playback
on Sep 4, 2009 at 4:20:58 am

thanx for your help


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Randy Mack
Re: letterboxing 720x480 for 4:3 NTSC playback
on Sep 4, 2009 at 1:34:51 am

3:2 is the same as 4:3 and just a different way of looking at the numbers, 3:2 is what 4:3 is if converted to square pixels

Ok, my head just exploded a little bit. The shape of pixels shouldn't make any difference to the pixel count, since the dimensions refer to pixels themselves. A picture of 720 rectangular pixels will appear longer or wider than a picture of 720 square pixels but both are images of 720 pixels. (Right?!)

My film is 720 pixels wide and I would like to see all of those on the 640-wide TV. I know it will require reducing the image slightly, hence the need for letterboxing. Yet none of the letterboxing options I've tried succeed in creating the simple 11% reduction required.* Instead, it cuts off 11% of the image (or so, like 5.5% on each edge).

*Math note: 720-640= 80, which is 1/9 (ie. ~11%) of 720)

Here is footage from the film--





you always lose 10% on each edge.

What! 10% off each edge is 20%, or 1/5 of the whole image. My previous film was shot in 1080p HD and when I authored the DVD the loss on the edges was minimal. And one of the reasons we made this current film in SD was that it would WYSIWYG all the way to the TV. I calculate that a loss of 10% on each edge would put the film at 576x480, which just isn't acceptable. Fortunately, the loss of image I've observed in my experiments isn't that big, closer to the 5.5% mentioned above. And that's why I'm here, to learn how to save the omitted part of the image.

I appreciate the help so far,
_R


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Noah Kadner
Re: letterboxing 720x480 for 4:3 NTSC playback
on Sep 4, 2009 at 3:47:12 am

I'm sorry but you need to go off and do some more reading on your own this is basic stuff. NTSC is always 720x480 not 640x480.



Check out my book: RED: The Ultimate Guide to Using the Revolutionary Camera!. Unlock the secrets of the 24p, HD and Final Cut Studio.
Now featuring the Sony EX1 Guidebook, Panasonic HVX200, and Panasonic DVX100.
http://www.callboxlive.com


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Jeff Pulera
Re: letterboxing 720x480 for 4:3 NTSC playback
on Sep 8, 2009 at 3:10:40 pm

Hi Randy,

It sounds like you are attempting to fix a "problem" that doesn't actually exist. If you shot and edited in 4:3 mode, and created a 4:3 DVD, nothing is getting cut off from your video - you are just not seeing all the way to the edges. Forget about pixels and aspect ratios, NTSC is NTSC.

Think of framed artwork - you don't see the very edge of the painting, the frame covers a little. It would be distracting to actually see the edge of the canvas, so it goes behind the frame a little.

Television has always worked the same way, especially years ago. Each TV was calibrated a little differently, so broadcasters had no way of knowing if the viewer's images would be shown a little smaller or larger than intended. That is why TV sets had the bezel around the glass screen and the image would go behind the bezel, to make sure no one would see the edge of the video.

To ensure that none of your subject gets body parts cut off, you must leave a little room between them and the edge of the picture when shooting, since the amount of image getting chopped on the viewer's display varies.

I often see cable commercials (local stuff) where titles go off the edge of the screen and I can't read the whole thing. Amateur mistake, since titlers in NLEs have Safe Area guides on screen that one should stay within when designing titles.

So what I am saying is, if you shot regular 4:3 NTSC video, and edited in a 4:3 NTSC project, and then Export as 4:3 DVD, and your subjects are getting cut off when viewing the results, is that it simply was not SHOT properly.

When editing in your NLE, the preview window will show the entire frame, including the "overscan" area that is normally unseen on a TV. Never expect to see the entire same image area in the end result. Yes, the whole frame is recorded on the DVD, but if it was all displayed, some viewers might see black edges beyond the picture on their particular set.

Moral of the story - don't frame so tight when shooting and the end result should then look more pleasing.

Jeff Pulera
Safe Harbor Computers


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Randy Mack
Re: letterboxing 720x480 for 4:3 NTSC playback
on Sep 8, 2009 at 6:50:20 pm

I appreciate the detailed response. That confirms my suspicion. I'm still mystified as to why 720x480 is referred to as 4x3 in violation of math, but it's good to know that it has no bearing on why the image is being cut off at the sides.

Thanks again,
_R


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Jeff Pulera
Re: letterboxing 720x480 for 4:3 NTSC playback
on Sep 8, 2009 at 8:18:52 pm

Hi Randy,

As others tried to explain, Pixel Aspect Ratio is the key. NTSC with square pixels would be 640 x 480. DV video uses rectangular pixels with a PAR of 0.9, thus the 720 x 480 image is still a 4:3 aspect ratio when viewed.

You may be aware that HD is 16:9 and uses 1920x1080 square pixels. HDV uses 1440x1080 rectangular pixels, but is still a 16:9 image that fills the screen, because the PAR = 1.333, and 1440 x 1.333 = 1920! To further confuse the issue, DVCPROHD is 1280 x 1080 with a 1.5 PAR, and 1280 x 1.5 = 1920, so HD, HDV and DVCPROHD are ALL 16:9 formats and all fill the same screen real estate in the end, at 16:9, using different pixel shapes and pixel counts.

So draw a box on paper with 4:3 dimensions, then fill it with little squares, 640 x 480 of them. Now take that same box, and draw in 720 x 480 little rectangles (0.9 aspect) and they will also fit the 4:3 box. Starting to make sense?

Jeff Pulera
Safe Harbor Computers


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Bob Bascelli
Re: letterboxing 720x480 for 4:3 NTSC playback
on Sep 11, 2009 at 3:49:22 pm

As others have said, 4:3 is 1.33:1, 720 x 480 is 1.5:1. Further, 16:9 is 1.77:1. All NTSC DVDs are set to display 720x480 regardless of the source aspect ratio. There's a flag in the DVD coding that's set to either 16:9 or 4:3.

Check this solution to the cutoff problem (which I've encountered):

If shot in, captured and edited in 4:3 and there is cutoff, the pixel aspect may be incorrect in the conversion from the editor into the file used to create the DVD. The Pixel Ratio should be D1. You might have to play a bit. Try exporting a small section.

Keep 'em flying.


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