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Is there a way to calculate aspect ratio in pixels?

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ryan elder
Is there a way to calculate aspect ratio in pixels?
on Sep 21, 2018 at 1:19:35 am

I was thinking of editing some scenes in my current project with an aspect ratio of 2.20:1, but is there anyway on Premiere Pro to do that? Premiere Pro wants to know the exact number of pixels for the project. I tried googling what formula to use to calculate a pixel aspect ratio out of 2.20:1, but couldn't find any. There are sights that say how many pixels in HD, that 2.35:1 would come out to, or 1.85:1, but I couldn't find any for 2.20:1 specifically. Does anyone know?


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Brent Marginet
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 21, 2018 at 2:54:22 am

It's very simple math. Let's base the width of the video as 1920 because that's an easy standard to work with. So 1920/2.2 = 872.7272.... so use either 873 or 872 as your height. You could even round up to 874 to make things nice and even.

It's very simple to calculate for any aspect ratio.

"MY MEDIA/PROJECT MOTTO: If you think three copies of your Media or Projects are enough. Take a moment to place a value on them and then maybe add two more. Hard Drives are now stupidly cheap. A RE-SHOOT AND YOUR TIME AREN'T."


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Ann Bens
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 21, 2018 at 2:11:53 pm

I would pick 872 as it can be divide by 4.

-----------------------------------------------
Adobe Certified Expert Premiere Pro CS2/CS6/CC
Adobe Community Professional


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Jeff Pulera
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 21, 2018 at 3:17:17 pm

And perhaps you want to use the standard 1920x1080 sequence and just letterbox the video content at desired aspect rather than inventing some new dimensions and creating a video in a non-standard format. Just sayin'.

And what Ann said, that is because some encoders like H.264 encode the video in blocks of pixels and odd numbers don't work out and may cause an export failure. If you do decide to at some unique resolution, try the entire workflow to delivery format first before committing so you avoid these problems.

Thanks

Jeff Pulera
Safe Harbor Computers


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ryan elder
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 21, 2018 at 10:27:46 pm

Oh okay thanks. What pixels aspect ratio in the actual pixels should I choose then? I've been doing square pixels this whole time, but is that right?

As for choosing 873 cause it can be divided by 4, what does dividing by 4 have to do with it?


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Chris Wright
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 22, 2018 at 12:00:01 am

1. HDTV is always square pixels(that's the standard). You don't need to worry about PAR unless making graphics, text, in non- standard resolutions with anamorphic lenses or SDTV/DV.

2.PAR only works if the NLE or playback device supports it. I like to think of it like color management; it only works if its interpreted correctly.

3. some older video codecs may not support odd number pixel resolutions. that's just a programming deficiency, not a rule. and Jeff is right, burning in black padding is the safest and most common form of broadcast widescreen, but it won't work on streaming sites like vimeo or when creating a DCP.


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ryan elder
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 22, 2018 at 12:19:01 am

Okay thanks. When you say burning in black padding, you mean the black bars on the top and bottom, like putting them in permanently?


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Chris Wright
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 22, 2018 at 12:36:22 am

yes, the black becomes the signal as there's no alpha channel. it's called padding.


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ryan elder
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 22, 2018 at 7:48:50 am

Oh okay then thanks.

So is there any reason to export at 1920 x 1080 with black bars, rather than just export at 1920 x 872? I mean it was said that it is better for TVs right, but I play blu ray movies on my computer, and when I open them in windows media player, there are no black bars cause windows media player makes the shape of the movie aspect ratio. So it seems that blu rays don't even have black bars, and are just exported at whatever aspect ratio the movie was shot and edited in, unless I am wrong?


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Brent Marginet
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 22, 2018 at 8:19:49 am
Last Edited By Brent Marginet on Sep 22, 2018 at 8:22:59 am

If a video was done at any aspect ratio other than 1.78:1 like, 1.85, 2.35 or 2.39 and Windows Media Player is not playing it back with black bars (i.e. Letterboxed) then Windows Media Player is not playing it back properly. This would also mean that everything you watch at these aspect ratios will either be stretched and people will all look tall and skinny or the left and right portions of the video will be cropped off.

In the end who are you delivering this to, if it’s a broadcaster then they will want it as 1920x1080 Letterboxed. If not get you will need to get the delivery specs from whoever is going to receive the video in the end. Lastly many times the recipient of the video will take something like a 1920x872 video and place it into a 1920x1080 frame so it will get padded (i.e. Letterboxed) anyway.

Let’s face it TV’s are 1.78:1 so any of these aspect ratios will need to be padded with black and played back letterboxed. Again what is the final destination for this video and what are their delivery specs.

"MY MEDIA/PROJECT MOTTO: If you think three copies of your Media or Projects are enough. Take a moment to place a value on them and then maybe add two more. Hard Drives are now stupidly cheap. A RE-SHOOT AND YOUR TIME AREN'T."


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ryan elder
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 22, 2018 at 8:27:44 am

Oh okay thanks, I thought that the TVs were just playing movies exported in 1920 x 802 for movies that were shot in 2.35:1.

Perhaps windows media player can sense the black bars and get rid of them and make a shape of just the movie then?

So if distributors want 1920 x1080 then, then I will have to come up with a math formula to calculate how much percent the black bars should be at. Is there a formula for calculating that percentage?


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Brent Marginet
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 22, 2018 at 8:36:58 am

Yes there should be but I do not know what the formula is in Premiere, I primarily use Avid so therefore I know what it is in Avid. Don’t refer to them as “Black Bars” you are adding a “Mask” over top of your video to chop off the top and bottom portions.

So take a look at the Mask Tool in Premiere and see if there is an easy way to calculate this, there usually is.

"MY MEDIA/PROJECT MOTTO: If you think three copies of your Media or Projects are enough. Take a moment to place a value on them and then maybe add two more. Hard Drives are now stupidly cheap. A RE-SHOOT AND YOUR TIME AREN'T."


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Brent Marginet
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 22, 2018 at 8:42:25 am

It could be as simple as 872/1080=0.8074 and you would enter that into the Mask Tool.

"MY MEDIA/PROJECT MOTTO: If you think three copies of your Media or Projects are enough. Take a moment to place a value on them and then maybe add two more. Hard Drives are now stupidly cheap. A RE-SHOOT AND YOUR TIME AREN'T."


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Brent Marginet
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 22, 2018 at 1:42:44 am
Last Edited By Brent Marginet on Sep 22, 2018 at 1:43:31 am

That would be 872 and the reason for the division by 4 is because macro blocks in video are always either 2x2, 4x4, 8x8 or 16x16 in size. All of which are divisible by 4, this comes into play especially when you compress video into something like an mp4, H.264, H.265 etc.

Please someone give me crap if I got any of this wrong.

"MY MEDIA/PROJECT MOTTO: If you think three copies of your Media or Projects are enough. Take a moment to place a value on them and then maybe add two more. Hard Drives are now stupidly cheap. A RE-SHOOT AND YOUR TIME AREN'T."


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Chris Wright
Re: Is there a way to calculate aspect ratio in pixels?
on Sep 21, 2018 at 10:51:48 am

aspect ratio and pixel aspect ratio are two completely different things although they are related.

pixel aspect ratio is the pixels being schmooshed like anamorphic lenses. they are also known as the PAR of non-square values not 1:1.

Aspect ratio is a combination of all three factors.

Aspect Ratio = (Horizontal Resolution / Vertical Resolution) × Pixel Aspect Ratio

see
https://forums.creativecow.net/thread/3/1005853


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