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

Media Data Atom TypesQuickTime VR File FormatImportant This section describes the file format supported by version 2.1 of the QuickTime VR Manager.All QuickTime VR movies contain a single QTVR track, a special type of QuickTime track that maintains a list ofthe nodes in the movie. Each individual sample in a QTVR track contains general information and hot spotinformation for a particular node.If a QuickTime VR movie contains any panoramic nodes, that movie also contains a single panorama track, andif it contains any object nodes, it also contains a single object track. The panorama and object tracks containinformation specific to the panoramas or objects in the movie. The actual image data for both panoramas andobjects is usually stored in standard QuickTime video tracks, hereafter referred to as image tracks. (An imagetrack can also be any type of track that is capable of displaying an image, such as a QuickTime 3D track.) Theindividual frames in the image track for a panorama make up the diced frames of the original single panoramicimage. The frames for the image track of an object represent the many different views of the object. Hot spotimage data is stored in parallel video tracks for both panoramas and objects.Single-Node Panoramic MoviesFigure 4-23 (page 285) illustrates the basic structure of a single-node panoramic movie. As you can see, everypanoramic movie contains at least three tracks: a QTVR track, a panorama track, and a panorama image track.Figure 4-23The structure of a single-node panoramic movie fileQTVR trackPanorama trackPanorama image trackFor a single-node panoramic movie, the QTVR track contains just one sample. There is a corresponding samplein the panorama track, whose time and duration are the same as the time and duration of the sample in theQTVR track. The time base of the movie is used to locate the proper video samples in the panorama imagetrack. For a panoramic movie, the video sample for the first diced frame of a node’s panoramic image is locatedat the same time as the corresponding QTVR and panorama track samples. The total duration of all the videosamples is the same as the duration of the corresponding QTVR sample and the panorama sample.A panoramic movie can contain an optional hot spot image track and any number of standard QuickTimetracks. A panoramic movie can also contain panoramic image tracks with a lower resolution. The video samplesin these low-resolution image tracks must be located at the same time and must have the same total durationas the QTVR track. Likewise, the video samples for a hot spot image track, if one exists, must be located at thesame time and must have the same total duration as the QTVR track.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.285