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

Profile Atom GuidelinesUniversal Featuresfeature-code'vvfp'feature-valueUnsigned int(32) holding the value 0 if the frame rate is constant or the value 1 if the frame durationsvaryFeature ValuesThe feature value holds one of the following two values: 0 if all video samples have the same display duration,or 1 if any video samples vary in duration.Writer ResponsibilitiesA writer of the Video Variable Frame Rate Indication feature should compare the video track sample durations.If all considered durations have the same value, the value 0 indicating constant frame rate should be recorded.If any durations differ, the value 1 should be recorded for the feature. No other value should be recorded.Feature Value AlgorithmIf the Time to Sample table records a constant duration for all samples, then record 0, else record 1.Reader ResponsibilitiesA reader of this feature code should only expect the values 0 or 1.Audio Sample Rate for a Sample EntryContaining profile atomTrack (sound), moviepart-ID0x20202020 (universal feature)feature-code'ausr'feature-valueUnsigned int(32) holding the audio sample rate in units per second (for example, 44100 for 44.1 kHz)Feature ValuesThis feature value is an unsigned 32-bit integer holding the audio sample rate in units per seconds (cycles persecond). The value should be rounded up to the nearest integer if it has a fractional portion.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.417