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Pixel Aspect Ratio - When 720x480 = 853x480
- Categorized in: Streaming quality control tools
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.
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.