Instance Property


A Boolean value that indicates whether the export session can perform multiple passes over the source media to achieve better results.


var canPerformMultiplePassesOverSourceMediaData: Bool { get set }


When the value for this property is true, the export session can produce higher quality results at the expense of longer export times. Setting this property to true may also require the export session to write temporary data to disk during the export. To control the location of temporary data, use the property directoryForTemporaryFiles.

The default value is false. Not all export session configurations can benefit from performing multiple passes over the source media. In these cases, setting this property to true has no effect.

This property cannot be set after the export has started.

See Also

Configuring Output

var outputURL: URL?

The URL of the export session’s output.

var supportedFileTypes: [AVFileType]

An array containing the types of files the session can write.

var outputFileType: AVFileType?

The type of file written by the session.

var fileLengthLimit: Int64

The file length that the output of the session should not exceed.

var timeRange: CMTimeRange

The time range exported from the source.

var metadata: [AVMetadataItem]?

The metadata written to the output file by the export session.

var metadataItemFilter: AVMetadataItemFilter?

Specifies a filter object used during export to determine which metadata items to transfer from the source asset.

var audioMix: AVAudioMix?

The parameters for audio mixing and an indication whether to enable nondefault audio mixing for export.

var audioTimePitchAlgorithm: AVAudioTimePitchAlgorithm

A processing algorithm used to manage audio pitch for scaled audio edits.

var shouldOptimizeForNetworkUse: Bool

A Boolean value that indicates whether to optimize the movie should for network use.

var videoComposition: AVVideoComposition?

The instructions for video composition, and indicates whether video composition is enabled for export.

var customVideoCompositor: AVVideoCompositing?

The custom video compositor instance used, if any.

var directoryForTemporaryFiles: URL?

A directory that is suitable for containing temporary files generated during the export process.