A little guidance on aspect ratios pls

U

USLatin

Panamaniac
I am wondering why someone would mark the HVX for 1:1.85 since it is so close to the camera's ratio... and I am also wondering if this may have to do with the tiny amount of cropping that happens when I watch my last project on my widescreen TV regardless of what I do to try to avoid it

Anyways... some knowledgeable explanations and other important points concerning this area would be very helpful to me. Thanks in advance!
 
The cropping is part of the overscan -- even HD TVs still have it. I suspect in another decade or so when everything is all digital and we watch all-new HD content, that may finally become a historical anecdote.
 
So it is some sort of safety-crop so there is no black along the edges due to many different ratios being out there?
 
The overscan serves two purposes.

In the days of interlaced analog displays, the cathode ray gun would sweep from one edge of the display to the other once it hit the overscan area. Because the edge was somewhat fuzzy and unattractive, it was covered up by a bezel, and content was shot with this bezel in mind -- it's like a physical cropping of the display. Typically 10% of the display area was lost this way. Also, as displays aged, the CRT calibration would drift, often causing the picture to shrink.

Secondly, it is possible to carry out-of-band data in the signal that falls in the overscan area. Time codes, synchronization signals and content protection signals like Macrovision can and do utilize the overscan area.

The SMPT dictates that digital displays observe a slight cropping (I think it's 16 pixels), which is why your TV still cuts off a little bit of the image.
 
Excellent post... thanks for that info.

A few questions emerge then...

The 10% is easy to work with since you have the 90% safety guide in the HVX but how much should I worry about this kind of loss nowadays? It sounds like the 10% is no longer a problem but just 16-pixels?

How could I possibly mark for 16 pixels, I guess you just ignore such a minute sliver or simply remember it when framing.

Should I add black bars to my product?

Sorry about the million questions... I guess what I am asking altogether is: What to do for today's overscan?
 
I would not let anything important to your work get so close to the edge of the image that it risks being cropped. Your audience won't be looking there anyway.

I haven't done the math, but 16 pixels is probably around one or two lines of the HVX's LCD -- why would you even want to try to mask that?
 
yea... I thought it might translate to one pixel...
On regards to the over-scan I guess I should just deal with it and know I will lose some of the image... I just HATE not having an exact guide for my framing...

One last twist since you might have these numbers in your head:
How does 720p translate to 2.35 SD? Is it big enough to offer pixel to pixel? Or will that only be attainable with 1080p?
 
so let me see if I got it right...

720 being the with of SD, your final product's height so it fits on an SD TV will only be

480 / 2.35 = 204.25

then your with would be the full 720 of the TV set, so your 720p with in relation to the output is

1280 / 720 = 170%

and the height you need in relation to the height of 720p is

720 / 204.25 = 352%

so you have a boat load more rez than what you need... aghhh... duh... I mean if your set can only display 480 then you can shoot 480 and crop it to make it look like 2.35...

What the crap was I asking then... hummm...???

I hope there was some sort of intelligent thought behind my post but I can't remember what I was trying to figure out...

Maybe I wondered if 720 was enough for 1080 2.35??? No.... that makes no sense either...


ok... so... to get 2.35 you need to shoot whatever format you want to end up with and crop it, right?


OH!!! I know! I was confused but I must have been wondering if you'd end up with the same amount of data... meaning will a 2.35 crop of 720 be as big as SD... and the answer is

720 x 480 = 345,600

720 / 2.35 = 306

306 x 1280 = 391,680

YES! and 13% additional pixels.

That is sweet... but sorta dumb... cause now I need my audience to have a 720p monitor and Blue-Ray/HD-DVD to show them a 2.35 movie that has the same (a bit more) info than what they are used to... and even dummer since you have extra resolution that your better TV could display and you actually already shot!

I guess I was looking for a way to distribute the pixels in a more human-sight sort of way but not lose any information... it sorta feels nice to be able to offer 13% more info AND have a better aspect all while harnessing the cameras full capabilities since you are shooting in 720p and have access to all frame-rates...

Now if what you said is that 720p can offer you a 2.35 output with 480 plus horizontal lines then I guess your math was not right cause

720 / 2.35 = 306

So you don't have 480 vertical though that doesn't matter cause the total pixel count will be significantly 13% larger anyway because if you have a 720p TV you can use the full with and get

306 x 1280 = 391,680



If you have time, and the patience, lol, then please look over the post to tell me if I messed up somewhere but otherwise I will STFU for now :D
 
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I assumed what you wanted was to shoot 2.35 and deliver something that's 480 pixels high. The only way to do that right now would be on the web, or using HD DVD or Blu-Ray. You could center crop the 1280x720 image from the camera and get the required 1128x480 pixels with no scaling or interpolation.

If you are restricted to SD DVD, then as you said you would wind up with 204 vertical pixels in the image.
 
you are right... I messed up my math somewhere about not eing able to do a 480 2.35 out of 720... but like you said 480 x 2.35 is only 1128 so by just cropping a bit on the top and bottom you would get that 480 vertical 2.35 ratio that I sounded like I was asking for.

Thanks for the posts... I think I got a good idea of what's out there and how to do it.

And just to talk about it, the 720 x 204 image is tiny... you only get 146,880 pixels which is 42.5% the pixels of SD... yet I see a lot of these super wide aspects in commercials and some SD DVDs get quite wide too...

Is there no way to lower the level of compression for an SD DVD?
Since the image is smaller it would add a bit of wiggle room for a less compressed stream for the hardware so this has to be possible in terms of the hardware... but is it possible in terms of how an SD DVD is supposed to be encoded?
 
You can't lower the compression level past the maximum bitrate permitted by the DVD standard, and even that isn't always safe. I would not venture beyond 8000Kbps for the video, some older DVD players have trouble with high bitrates.

However, keep in mind that if you have a letterboxed 2.35 image, the black bars at the top and bottom will compress extremely well, which allows the remaining bandwidth to be used to encode a relatively small image. You should get a very detailed image from a 8000Kbps bitrate.
 
Oh... I see... if you are compressing the whole image your NLE will compress the black bars like crazy since there is all the same value and have a ton of bandwith left over... good point.

One more thing... since we are on the subject, sort of... then again this might be a question I might want to ask in the Vegas/FCP sections:

Should I add bars for a 4:3 or is there something I need to do so it fits on 16:9 TVs automatically... so far I have only burnt 16:9 versions of my projects since I was in control of the screenings but I should learn the right way to do things if there is one.
 
For DVDs, the DVD player will handle the aspect ratio conversion -- it just needs to be told the aspect ratio of the TV.

If the aspect ratio of the TV and the DVD disk don't match, the DVD player will letterbox or pillarbox the output.

It is possible to author DVDs that contain both 16:9 and 4:3 versions of the content, and letting the user choose when they play the disk. But since a DVD player will handle any conversion anyway, I don't see the value of doing this.

I think the automatic aspect ratio conversion is also what has made the separate 4:3 and 16:9 editions of DVDs a thing of the past -- virtually every disk coming out of Hollywood today is in widescreen format, and it can still be enjoyed without cropping on 4:3 TVs.
 
I like 1.85:1, because it allows for more vertical action as well as horizontal. It's wider than 16:9, but not too wide.
 
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