Class: AVMutableVideoCompositionLayerInstruction

Inherits:
AVVideoCompositionLayerInstruction show all

Overview

AVMutableVideoCompositionLayerInstruction is a mutable subclass of AVVideoCompositionLayerInstruction that you use to modify the transform and opacity ramps to apply to a given track in an AV composition.

Instance Attribute Summary (collapse)

Class Method Summary (collapse)

Instance Method Summary (collapse)

Methods inherited from AVVideoCompositionLayerInstruction

#getOpacityRampForTime:startOpacity:endOpacity:timeRange:, #getTransformRampForTime:startTransform:endTransform:timeRange:

Methods inherited from NSObject

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Constructor Details

This class inherits a constructor from NSObject

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class NSObject

Instance Attribute Details

- (CMPersistentTrackID) trackID

The trackID of the source track to which the compositor will apply the instruction.

Returns:

  • (CMPersistentTrackID)

Class Method Details

+ (Object) videoCompositionLayerInstruction

Returns a new mutable video composition layer instruction.

Returns:

  • (Object) —

    A new mutable video composition layer instruction with no transform or opacity ramps and trackID initialized to kCMPersistentTrackID_Invalid.

+ (Object) videoCompositionLayerInstructionWithAssetTrack(track)

Returns a new mutable video composition layer instruction for the given track.

Parameters:

  • track (AVAssetTrack) —

    The asset track to which to apply the instruction.

Returns:

  • (Object) —

    A new mutable video composition layer instruction with no transform or opacity ramps and trackID initialized to the track ID of track.

Instance Method Details

- (Object) setOpacity(opacity, atTime:time)

Sets a value of the opacity at a time within the time range of the instruction. Sets a fixed opacity to apply from the specified time until the next time at which an opacity is set; this is the same as setting a flat ramp for that time range. Before the first time for which an opacity is set, the opacity is held constant at 1.0; after the last specified time, the opacity is held constant at the last value.

Parameters:

  • opacity (Float) —

    The opacity to be applied at time. The value must be between 0.0 and 1.0.

  • time (CMTime) —

    A time value within the time range of the composition instruction.

Returns:

- (Object) setOpacityRampFromStartOpacity(startOpacity, toEndOpacity:endOpacity, timeRange:timeRange)

Sets an opacity ramp to apply during a specified time range. During an opacity ramp, opacity is computed using a linear interpolation. Before the first time for which an opacity is set, the opacity is held constant at 1.0; after the last specified time, the opacity is held constant at the last value.

Parameters:

  • startOpacity (Float) —

    The opacity to be applied at the start time of timeRange. The value must be between 0.0 and 1.0.

  • endOpacity (Float) —

    The opacity to be applied at the end time of timeRange. The value must be between 0.0 and 1.0.

  • timeRange (CMTimeRange) —

    The time range over which the value of the opacity will be interpolated between startOpacity and endOpacity.

Returns:

- (Object) setTransform(transform, atTime:time)

Sets a value of the transform at a time within the time range of the instruction. Sets a fixed transform to apply from the specified time until the next time at which a transform is set. This is the same as setting a flat ramp for that time range. Before the first specified time for which a transform is set, the affine transform is held constant at the value of CGAffineTransformIdentity; after the last time for which a transform is set, the affine transform is held constant at that last value.

Parameters:

  • transform (CGAffineTransform) —

    The transform to be applied at time.

  • time (CMTime) —

    A time value within the time range of the composition instruction.

Returns:

- (Object) setTransformRampFromStartTransform(startTransform, toEndTransform:endTransform, timeRange:timeRange)

Sets a transform ramp to apply during a given time range. During a transform ramp, the affine transform is interpolated between the values set at the ramp's start time and end time. Before the first specified time for which a transform is set, the affine transform is held constant at the value of CGAffineTransformIdentity; after the last time for which a transform is set, the affine transform is held constant at that last value.

Parameters:

  • startTransform (CGAffineTransform) —

    The transform to be applied at the starting time of timeRange.

  • endTransform (CGAffineTransform) —

    The transform to be applied at the end time of timeRange.

  • timeRange (CMTimeRange) —

    The time range over which the value of the transform will be interpolated between startTransform and endTransform.

Returns: