How exactly the "Composite:Rotation" tag is created?

Started by 11august, April 28, 2020, 05:15:42 AM

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11august

April 28, 2020, 05:15:42 AM
Hi there!

I'm trying to figure out how the composite tag "Rotation" is generated from both "QuickTime:MatrixStructure" and "QuickTime:HandlerType". I've extracted using the -g option all the metadata from a bunch of videos and here's how it appears in my excel datasheet (see the screenshoot attached).

The "QuickTime:MatrixStructure" tag shows the same pattern: "100010001" and the "QuickTime:HandlerType" tag have only these five contents: "Metadata", "Video Track", "Audio Track", "Metadata Tags" or "Alias Data".

How the hell do "we" know with these tags that such or such video have either a "0", "90", 180" or "270" rotation applied? In other words, I can't figure out any logic behind the creation of the composite rotation tag using the two QuickTime tags, but I surely miss something!
Co-author and developper of the GEIPAN groupe image analysis software IPACO, part of the French Space Agency CNES

Phil Harvey

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April 28, 2020, 07:18:58 AM
The MatrixStructure is a rotation matrix.  And you should be looking at the video HandlerType to get the rotation of the video.

Google "rotation matrix" to learn more about rotation matrices.

- Phil
...where DIR is the name of a directory/folder containing the images.  On Mac/Linux/PowerShell, use single quotes (') instead of double quotes (") around arguments containing a dollar sign ($).
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