Quicktime File Format (2012-08-14).pdf

Media Data Atom TypesPanorama TracksQuickTime VR 2.2 does not require the original panoramic image to be rotated 90 degrees counterclockwise,as was the case in QuickTime VR 2.1. The rotated image is still diced into smaller frames, and each diced frameis then compressed and added to the video track as a video sample, as shown in Figure 4-27 (page 295).Figure 4-27Creating an image track for a panorama, with the image track oriented horizontallyOriginal panoramaDice the Image1 2 3 24Add samples to image trackImage track1 2 3 24In QuickTime 3.0, a panorama sample atom (which contains information about a single panorama) containsthe panoType field, which indicates whether the diced panoramic image is oriented horizontally or vertically.Cylindrical PanoramasThe primary change to cylindrical panoramas in QuickTime VR 2.2 is that the panorama, as stored in the imagetrack of the movie, can be oriented horizontally. This means that the panorama does not need to be rotated90 degrees counterclockwise, as required previously.To indicate a horizontal orientation, the field in the VRPanoSampleAtom data structure formerly calledreserved1 has been renamed panoType. Its type is OSType. The panoType field value for a horizontallyoriented cylinder is kQTVRHorizontalCylinder ('hcyl'), while a vertical cylinder is2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.295