How to detect true aspect ratio from a DVD?

[lyle waggoner]

I'm aware that you can use iMDb to look up the technical specs, but I sometimes find that from region to region, these specs can differ, particularly on ex-rental DVDs.

When converting DVDs to avis etc, it'd be great if there was a way to detect the actual aspect ratio of the DVD I'm converting - ie, 2:35:1, 1:85:1, etc (as opposed to just 16:9 vs 4:3 which is easy enough to identify by sight).

Is there any app that can do this, where VOB or IFO's or whatever on a DVD is concerned?

Thanks in advance for any help on this!

[FulciLives]

What exactly would you do with such information? In short I don't understand the question I guess because I can't figure out what it is you are trying to do with that information.

Anyways it usually isn't that hard to "eyeball" aspect ratios. Most movies are either 1.85:1 or 2.35:1 with a few being 1.66:1 ... and then of course you have full screen 1.33:1

You could always try loading a VOB into VirtualDubMod and cut the black out and see what you have left.

For instance a 4:3 WS DVD with a 2.35:1 aspect ratio will be approximately 720x272 once you cut out the black above and below the image.

A 16:9 WS DVD with a 2.35:1 aspect ratio will be approximately 720x360 once you cut out the black above and below the image.

A 4:3 WS DVD with a 1.85:1 aspect ratio will be roughtly 720x360 once you cut out the black above and below the image.

Not sure on the math for a 16:9 WS DVD with a 1.85:1 aspect ratio but it is probably something like 720x420 give or take.

These are all for NTSC DVD by the way.

- John "FulciLives" Coleman

[jagabo]

For a 4:3 encoded NTSC movie in a 720x480 frame divide 640 by the active picture height (ie, what's left after removing the black bars). For example 640/272 = 2.35.

For a 16:9 encoded NTSC movie in a 720x480 frame divide 853 by the active picture height.

[dphirschler]

A 16:9 WS DVD with a 2.35:1 aspect ratio will be approximately 720x360 once you cut out the black above and below the image.

A 4:3 WS DVD with a 1.85:1 aspect ratio will be roughtly 720x360 once you cut out the black above and below the image.

John, this is wrong.

2.35:1 aspect ratio after cutting all the black will be approx. 720x272 letterboxed and 720x363 anamorphic widescreen.

1.85:1 aspect ratio after cutting all the black will be approx. 720x345 letterboxed and 720x460 anamorphic widescreen.

1.78:1 (or 16x9 as we like to call it) will be 720x360 letterboxed and 720x480 anamorphic.

1.66:1 and 1.33:1 make no sence to go anamorphic, but letterbox for 1.66:1 would be approx. 720x385.

And all these numbers can vary slightly depending on how much black they decide to add to the sides of the image and how accurately they size their frame prior to encoding.


Darryl

[FulciLives]

@dphirschler

I do appreciate the correct info but hey I was close enough especially with the 2.35:1 aspect ratio numbers LOL

I still don't see the point of this ... I mean a movie has an aspect ratio and that's that ... who cares exactly what it is ... you can't change it.

I suppose this is good info for those that want to shoot with a camcorder and "mimc" an aspect ratio by cropping/masking the image ... as long as you frame for it while shooting.

I remember a low budget horror film that was shot on video that came out around 1992 and it was framed at 2.35:1 by simply masking the top and bottom with black which was kinda neato looking at the time for something shot on video.

- John "FulciLives" Coleman

[lyle waggoner]

What exactly would you do with such information? In short I don't understand the question I guess because I can't figure out what it is you are trying to do with that information.

Anyways it usually isn't that hard to "eyeball" aspect ratios. Most movies are either 1.85:1 or 2.35:1 with a few being 1.66:1 ... and then of course you have full screen 1.33:1

You could always try loading a VOB into VirtualDubMod and cut the black out and see what you have left.

I guess I don't yet have the feel/touch to eyeball aspect ratios yet - the reason I want the info is that I use DVDx to rip avis from my DVDs, and I have the option to autocrop and resize (unfortunately, it doesn't intuitively fill in the values, but it's the best tool for the job I've found). I have a chart for the values for each aspect ratio - everything works great providing I know for sure what the aspect ratio is, but for reasons stated above, this occasionally varies, and it'd be great if I could get extract the exact ratio from the disc itself, so my avi backups have an accurate AR.

I guess it could be done by cropping the black from a VOB, but I thought there might be a simple indicator on the DVD that would carry the info. I got a tip that Media Player Classic would do so if you hit the "5" key on th numeric keypad while a VOB was loaded, but all that seems to do is to report ALL widescreen films as 1.78:1. Is there any other way (standalone app or otherwise) to get the AR from the disc?

Thanks for the help...

[jagabo]

I got a tip that Media Player Classic would do so if you hit the "5" key on th numeric keypad while a VOB was loaded, but all that seems to do is to report ALL widescreen films as 1.78:1.

Yes, because they are all encoded as 16:9 (including the black bars).

Open your VOB files in VirtualDubMod. Add the Null Filter. Use the Cropping tool to crop off the top and bottom black borders. Look to see how many scanlines are left. Use the equations I gave earlier to calculate the aspect ratio.

Oh wait, you're in Australia so you need PAL equations. Hold on a minute...

4:3 PAL: divide 768 by the number of scanlines.
16:9 PAL: divide 1024 by the number of scanlines.

[lyle waggoner]

I got a tip that Media Player Classic would do so if you hit the "5" key on th numeric keypad while a VOB was loaded, but all that seems to do is to report ALL widescreen films as 1.78:1.

Yes, because they are all encoded as 16:9 (including the black bars).

Open your VOB files in VirtualDubMod. Add the Null Filter. Use the Cropping tool to crop off the top and bottom black borders. Look to see how many scanlines are left. Use the equations I gave earlier to calculate the aspect ratio.

Oh wait, you're in Australia so you need PAL equations. Hold on a minute...

4:3 PAL: divide 768 by the number of scanlines.
16:9 PAL: divide 1024 by the number of scanlines.

It feels like something of an inexact science though, cropping manually using the null filter in VirtualdubMOD. I guess I'm only a few pixels off at worst (just doing it now, after cropping I had 405 scanlines, which worked out to 2.53 - which I guess tells me it's approximate to 2.35:1...), but I'd have liked if it there was an exact report to be found somewhere on the media.

Anyhow, thanks for the PAL equations, much appreciated.

[dphirschler]

I do appreciate the correct info but hey I was close enough especially with the 2.35:1 aspect ratio numbers LOL

John, the only reason I posted the correction was that you showed two different aspect ratios if the result after cropping the black bars was 360.


Darryl