Is there a way to calculate aspect ratio in pixels?

[Brent Marginet]

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.\”

[Chris Wright]

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

[Ann Bens]

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

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[Jeff Pulera]

And perhaps you want to use the standard 1920×1080 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

[Ryan Elder]

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?

[Chris Wright]

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.

[Ryan Elder]

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

[Chris Wright]

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

[Brent Marginet]

That would be 872 and the reason for the division by 4 is because macro blocks in video are always either 2×2, 4×4, 8×8 or 16×16 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.\”

[Ryan Elder]

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?