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5:4 Aspect ratio? pixel aspect ratio 59:54? 4×3 vs 5:4
Hello
I need some help discerning the old problematic PAR (pixel aspect ratio)
I got to do some reediting on some old work done in 2010 by another editor that i just can’t reach.
I have to work on one of this 2 master files with the specs: (info from quicktime inspector)
Please don’t worry about the sound (i have an aiff master track)
MASTER A
FORMAT: Apple ProRes 422 HQ (up to 12-bit) 5.1(L R C LFE Ls Rs), AC3, 48000 HZ
RESOLUTION: 720X576 (5:4)
ENCODED FPS: 25
CURRENT SIZE: 720X576 (Actual size)
MASTER B
FORMAT: COMPONENT Y’CbCr 10-bit 4:2:2 (5-1-6)
RESOLUTION: 720X576 (768X576), 4:3 (pixel aspect ratio 59:54)
CURRENT SIZE: 768X576 (Actual size)
When i open each of them on quicktime i get 2 diferent aspect ratios. On A i have a 5:4 video and on the B a 4×3 video.
On A people are slimmer and taller than on B.
1. Which one should i do the reeditng?
A- How can i check if the pixels are square or rectangular on this file? Was this file made with the right export settings? Does it have a PAR (pixel aspect ratio) that quicktime doesn´t recognize? If so how can i check? If i use a media player and projector will i get a video with the aspect ratio of 5×4 or 4×3?
B- How can i check if the pixels are square or rectangular on this file? Was this file made with the right export settings? Is this PAR (pixel aspect ratio) of 59:54 right? If so how can i check? If i use a media player and projector
will i get a video with the aspect ratio of 5×4 or 4×3?i have attached 2 screen shots of the quicktime inspector info
thanxxx
Miguel
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5 Replies
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You seem to have two versions of the same 720×576 video (with unsquare pixels), differing only in their metadata. The metadata says what shape the unsquare pixels have, but metadata can easily go wrong as the file passes through programs that “interpret” it idiosyncratically. And metadata is easily corrected. I alter pixel aspect ratio in .mov files by using Jon Chappell’s excellent program QT Edit.
Now to the mess. 59/54 is the correct pixel ratio for DV-PAL. When the DV-PAL camera takes a picture of a circle, it will really cover 59/54 times as many pixels vertically as horizontally. That funny ratio (≈ 1.0926) arose from TV standards. The DV-PAL frame consists of 720×576 pixels; do the arithmetic. 59/54*720 = 786.666… . So when converted to square pixels the DV-PAL should be nearly 787×576 square pixels. Surprise, this is not 4:3! The DV-PAL image is not 4:3, it is about 1.366:1. Programs that make DV-PAL into 768×576 pixels (4:3) distort it a bit. Can you see the difference between 1.366:1 and 1.333:1? Maybe. Everyone’s a little skinnier. Or maybe it’s mentally “corrected”, as watching a movie from a side seat in the theater is. Albert Einstein famously wrote a letter to Maurice Pirenne wondering about this.
So, should you declare 59/54 (or 1.0926) the pixel aspect ratio in the metadata, or should you take it easy and declare a false pixel aspect ratio 16/15 (or 1.0666) which makes the 720×576 pixels come out as 768×576 square pixels, 4:3? I converted my DV-PAL material to 787×576 square pixels, because I want circles to be circular, don’t want to crop off image, and don’t care if 4:3 is someone’s old standard. My 787×576 video will probably be pillarboxed into 1024×576 (HD shape) downstream anyhow. Decide based on the use of your material.
The mentioned crop is a “horribility” chosen by some pseudo-purists. They crop off 8 pixels from one side, 9 pixels from the other side of the 720×576 video and then transform that sad 703×576 remainder using the honest 59/54 pixel aspect ratio to 768×576 square pixels. They regard those cropped 17 pixels (8+9 or 9+8?) as non-image, like over-scan in TV or like image invading perforations in film. Nonsense.
DC
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Thank you so much!
I would love to read that letter from Einstein.
One year later (my bad)
Thank you for such a beautiful response
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Also do you know of any good substitution program for that QT edit?
thank you
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Why substitute? QT Edit is up-to-date OS-wise. It’s a component of Pro Media Tools, the latest version of which requires High Sierra or higher: https://www.digitalrebellion.com/promedia/ . If it’s freeware you seek, there’s JES Extensifier https://macdownload.informer.com/jes-extensifier/ which might serve your needs.
digitalrebellion.com
Pro Media Tools - Digital Rebellion
Media and workflow management for video professionals
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For the 1955 Einstein letter see M.H. Pirenne, “Optics, Painting and Photography”, pages 99-100.
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