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

Media Data Atom TypesVideo MediaThe video media sample description adds the following fields to the general sample description.VersionA 16-bit integer indicating the version number of the compressed data. This is set to 0, unless a compressorhas changed its data format.Revision levelA 16-bit integer that must be set to 0.VendorA 32-bit integer that specifies the developer of the compressor that generated the compressed data.Often this field contains 'appl' to indicate Apple Computer, Inc.Temporal qualityA 32-bit integer containing a value from 0 to 1023 indicating the degree of temporal compression.Spatial qualityA 32-bit integer containing a value from 0 to 1024 indicating the degree of spatial compression.WidthA 16-bit integer that specifies the width of the source image in pixels.HeightA 16-bit integer that specifies the height of the source image in pixels.Horizontal resolutionA 32-bit fixed-point number containing the horizontal resolution of the image in pixels per inch.Vertical resolutionA 32-bit fixed-point number containing the vertical resolution of the image in pixels per inch.Data sizeA 32-bit integer that must be set to 0.Frame countA 16-bit integer that indicates how many frames of compressed data are stored in each sample. Usuallyset to 1.Compressor nameA 32-byte Pascal string containing the name of the compressor that created the image, such as "jpeg".DepthA 16-bit integer that indicates the pixel depth of the compressed image. Values of 1, 2, 4, 8 ,16, 24, and32 indicate the depth of color images. The value 32 should be used only if the image contains an alphachannel. Values of 34, 36, and 40 indicate 2-, 4-, and 8-bit grayscale, respectively, for grayscale images.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.157