Pixel Aspect Ratio - When 720x480 = 853x480

I recently taught a couple of seminars in Los Angeles at StreamingMedia West. You can find links to the presentations at the link in the previous sentance.

I just got an email from a student asking:

At Streaming Media West you introduced the session to MediaInfo, a very handy tool, thank you. Quick question, on one video I notice that OSX "get info" gives me a different dimension than Media info does.  And a screen shot shows that it is 853x480 Do you know why that might be?

Here's the pic, with OSX on the left, MediaInfo on the right. 

mediainfoosx.jpg

Here's my response.

Let me tell you what I know, and you can tell me if it's relevant - if you send me a short file I could confirm.

If this was a 16:9 DV file (I know it's not), the true pixel resolution - or the actual pixels stored in the file -- would be 720x480 - that's what DV is. When displayed, though, because the pixels are stored at a pixel aspect ratio of 1.2 - you multiply the horizontal resolution by 1.2 to get the actual pixels the video consumes onscreen. 1.2 x 720 is 864, which for some reason, gets rounded down to 853.

It's a very confusing area because of how the different products analyze and present the analysis. Bottom line is that there are 720x480 pixels in the file, but when displayed, it's 853x480.

Here's the response back:

Ok so another one of those square pixel, rectangular pixel situations.  Ok I just got my head around that with illustrator and titling/overlays. Thanks, appreciate the quick reply.

Which is exactly correct.

 

 

 

 

 

 

 

 

 

 


Comments (4)

david
Said this on 7-11-2011 At 03:17 am

it's because the image of video is anamorphic. when video is displayed in panoramic mode, the image stretches to reach the 1.78 ratio, keeping its vertical resolution (480).

853:480 = 16:9 (1.78)

Said this on 7-11-2011 At 07:49 am
Exactly!

Thanks for chiming in.

Jan
david
Said this on 7-11-2011 At 05:53 pm

You're welcome

Pablo Kahale
Said this on 1-31-2012 At 12:46 pm

Hello Jan, I'm confused about PAR (Pixel Aspect Ratio), SAR (Storage AR) and DAR (Display AR). Can you give me some directions or where to get information related to this theme?
Here is an example of what I'm testing: 
I have a video source file with 720x576 pixels, DAR: 4:3. My target is configured the same way: 720x576 pixels, DAR: 4:3. I am using Rhozet Carbon Coder, and when I set up the transcoding, the PAR is changed automaticaly to 16:15.
The result is an image on screen that is a little bit wide than the video source file. Aparently about 15 pixels wider.
Can you help me, please?
Best regards.
Pablo

Hello Jan, I'm confused about PAR (Pixel Aspect Ratio), SAR (Storage AR) and DAR (Display AR). Can you give me some directions or where to get information related to this theme?


Here is an example of what I'm testing: 

I have a video source file with 720x576 pixels, DAR: 4:3. My target is configured the same way: 720x576 pixels, DAR: 4:3. I am using Rhozet Carbon Coder, and when I set up the transcoding, the PAR is changed automaticaly to 16:15.
The result is an image on screen that is a little bit wide than the video source file. Aparently about 15 pixels wider.

Can you help me, please?
Best regards.
Pablo

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