A mutable track in a composition object that you use to insert, remove, and scale track segments without affecting their low-level representation.


@interface AVMutableCompositionTrack : AVCompositionTrack


AVCompositionTrack defines constraints for the temporal alignment of the track segments. If you set the array of track segments in a mutable composition (see segments), you can test whether the segments meet the constraints using validateTrackSegments:error:.


Configuring Track Properties


The language associated with the track, as an ISO 639-2/T language code.


The language tag associated with the track, as an RFC 4646 language tag.


The time scale in which time values for the track can be operated upon without extraneous numerical conversion.


The preferred transformation of the visual media data for display purposes.


The preferred volume of the audible media data.

Associating Tracks

- addTrackAssociationToTrack:type:

Establishes a track association of a specific type between two tracks.

- removeTrackAssociationToTrack:type:

Removes a specific association type between two tracks.


Constants for identifying how other tracks are associated with a track.

Managing Time Ranges

- insertEmptyTimeRange:

Adds or extends an empty time range within the receiver.

- insertTimeRange:ofTrack:atTime:error:

Inserts a time range of a source track into a track of a composition.

- insertTimeRanges:ofTracks:atTime:error:

Inserts the time ranges of multiple source tracks into a track of a composition.

- removeTimeRange:

Removes a specified time range from the receiver.

- scaleTimeRange:toDuration:

Changes the duration of a time range in the receiver.


The track segments from a composition track.

Validating Segments

- validateTrackSegments:error:

Returns a Boolean value that indicates whether a given array of track segments conform to the timing rules for a composition track.

Instance Properties


Inherits From

See Also

Media Composition


An object that combines media data from multiple file-based sources to present or process media data from multiple sources.


A track in a composition object, consisting of a media type, a track identifier, and track segments.


A segment of a track, consisting of a URL, a track identifier, and a time mapping from the source track to the composition track.


A mutable object used to create a new composition from existing assets.