AVCaptureAudioFileOutput Class Reference

Inherits from
Conforms to
Framework
/System/Library/Frameworks/AVFoundation.framework
Availability
Available in OS X v10.7 and later.
Declared in
AVCaptureOutput.h

Overview

AVCaptureMovieFileOutput is a concrete sub-class of AVCaptureFileOutput that writes captured audio to any audio file type supported by CoreAudio.

AVCaptureAudioFileOutput implements the complete file recording interface declared by AVCaptureFileOutput for writing media data to audio files. In addition, you can configure options specific to the audio file formats, including writing metadata collections to each file and specifying audio encoding options. AVCaptureAudioFileOutput does not, however, support startRecordingToOutputFileURL:recordingDelegate:—use startRecordingToOutputFileURL:outputFileType:recordingDelegate: instead.

Tasks

Discovering Supported Types

Starting a Recording

Configuration

Properties

audioSettings

The settings used to decode or re-encode audio before it is output by the receiver.

@property(nonatomic, copy) NSDictionary *audioSettings
Discussion

The value of this property is a dictionary containing values for audio settings keys defined in AVAudioSettings.h. If you set the value of this property to nil, the output vends samples in their device native format.

Availability
  • Available in OS X v10.7 and later.
Declared In
AVCaptureOutput.h

metadata

A collection of metadata to be written to the receiver's output files.

@property(nonatomic, copy) NSArray *metadata
Discussion

The value of this property is an array of AVMetadataItem objects representing the collection of top-level metadata to be written in each output file. Only ID3 v2.2, v2.3, or v2.4 style metadata items are supported.

Availability
  • Available in OS X v10.7 and later.
Declared In
AVCaptureOutput.h

Class Methods

availableOutputFileTypes

Returns array containing UTIs identifying the file types AVCaptureAudioFileOutput can write.

+ (NSArray *)availableOutputFileTypes
Return Value

An array containing UTIs identifying the file types AVCaptureAudioFileOutput can write.

Availability
  • Available in OS X v10.7 and later.
Declared In
AVCaptureOutput.h

Instance Methods

startRecordingToOutputFileURL:outputFileType:recordingDelegate:

Tells the receiver to start recording to a new file of the specified format, and specifies a delegate that will be notified when recording is finished.

- (void)startRecordingToOutputFileURL:(NSURL *)outputFileURL outputFileType:(NSString *)fileType recordingDelegate:(id < AVCaptureFileOutputRecordingDelegate >)delegate
Parameters
outputFileURL

The URL of the output file.

This method throws an NSInvalidArgumentException if the URL is not a valid file URL.

If a file at the given URL already exists when capturing starts, recording to the new file will fail.

fileType

A UTI indicating the format of the file to be written.

UTIs for common audio file types are declared in AVMediaFormat.h.

delegate

An object conforming to the AVCaptureFileOutputRecordingDelegate protocol.

You must specify a delegate to be notified when recording is finished.

Discussion

You do not need not to call stopRecording before calling this method while another recording is in progress. If this method is invoked while an existing output file was already being recorded, no media samples will be discarded between the old file and the new file.

When recording is stopped—by calling stopRecording, by changing files using this method, or because of an error—the remaining data that needs to be included to the file will be written in the background. Therefore, you must specify a delegate that will be notified when all data has been written to the file using the captureOutput:didFinishRecordingToOutputFileAtURL:fromConnections:error: method. The recording delegate can also optionally implement methods that inform it when data starts being written, when recording is paused and resumed, and when recording is about to be finished.

On OS X, if this method is called within the captureOutput:didOutputSampleBuffer:fromConnection: delegate method, the first samples written to the new file are guaranteed to be those contained in the sample buffer passed to that method.

Availability
  • Available in OS X v10.7 and later.
Declared In
AVCaptureOutput.h