QuickTime development mailing list: http://lists.apple.com/mailman/listinfo/quicktime-api
While Quartz (a.k.a. CoreGraphics) is Apple's 2D media library and OpenGL is Apple's chosen 3D media library, QuickTime is Apple's 4D (time-based) media library. While QuickTime's API is based on Carbon, it can largely be accessed by Cocoa apps for things like playing movies, loading graphic files, and playing MP3s via the QTKit framework.
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