Struct AVCaptureAudioDataOutput 

pub struct AVCaptureAudioDataOutput { /* private fields */ }

Available on crate features AVCaptureAudioDataOutput and AVCaptureOutputBase only.

AVCaptureAudioDataOutput is a concrete subclass of AVCaptureOutput that can be used to process uncompressed or compressed samples from the audio being captured.

Instances of AVCaptureAudioDataOutput produce audio sample buffers suitable for processing using other media APIs. Applications can access the sample buffers with the captureOutput:didOutputSampleBuffer:fromConnection: delegate method.

See also Apple’s documentation

Implementations

impl AVCaptureAudioDataOutput

pub unsafe fn init(this: Allocated<Self>) -> Retained<Self>

pub unsafe fn new() -> Retained<Self>

pub unsafe fn setSampleBufferDelegate_queue( &self, sample_buffer_delegate: Option<&ProtocolObject<dyn AVCaptureAudioDataOutputSampleBufferDelegate>>, sample_buffer_callback_queue: Option<&DispatchQueue>, )

Available on crate feature dispatch2 only.

Sets the receiver’s delegate that will accept captured buffers and dispatch queue on which the delegate will be called.

Parameter sampleBufferDelegate: An object conforming to the AVCaptureAudioDataOutputSampleBufferDelegate protocol that will receive sample buffers after they are captured.

Parameter sampleBufferCallbackQueue: A dispatch queue on which all sample buffer delegate methods will be called.

When a new audio sample buffer is captured it will be vended to the sample buffer delegate using the captureOutput:didOutputSampleBuffer:fromConnection: delegate method. All delegate methods will be called on the specified dispatch queue. If the queue is blocked when new samples are captured, those samples will be automatically dropped when they become sufficiently late. This allows clients to process existing samples on the same queue without having to manage the potential memory usage increases that would otherwise occur when that processing is unable to keep up with the rate of incoming samples.

Clients that need to minimize the chances of samples being dropped should specify a queue on which a sufficiently small amount of processing is being done outside of receiving sample buffers. However, if such clients migrate extra processing to another queue, they are responsible for ensuring that memory usage does not grow without bound from samples that have not been processed.

A serial dispatch queue must be used to guarantee that audio samples will be delivered in order. The sampleBufferCallbackQueue parameter may not be NULL, except when setting sampleBufferDelegate to nil otherwise -setSampleBufferDelegate:queue: throws an NSInvalidArgumentException.

Safety

sample_buffer_callback_queue possibly has additional threading requirements.

pub unsafe fn sampleBufferDelegate( &self, ) -> Option<Retained<ProtocolObject<dyn AVCaptureAudioDataOutputSampleBufferDelegate>>>

The receiver’s delegate.

The value of this property is an object conforming to the AVCaptureAudioDataOutputSampleBufferDelegate protocol that will receive sample buffers after they are captured. The delegate is set using the setSampleBufferDelegate:queue: method.

pub unsafe fn sampleBufferCallbackQueue( &self, ) -> Option<Retained<DispatchQueue>>

Available on crate feature dispatch2 only.

The dispatch queue on which all sample buffer delegate methods will be called.

The value of this property is a dispatch_queue_t. The queue is set using the setSampleBufferDelegate:queue: method.

pub unsafe fn audioSettings( &self, ) -> Retained<NSDictionary<NSString, AnyObject>>

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

The value of this property is an NSDictionary containing values for audio settings keys defined in AVAudioSettings.h. When audioSettings is set to nil, the AVCaptureAudioDataOutput vends samples in their device native format.

pub unsafe fn setAudioSettings( &self, audio_settings: Option<&NSDictionary<NSString, AnyObject>>, )

Setter for audioSettings.

This is copied when set.

Safety

audio_settings generic should be of the correct type.

pub unsafe fn spatialAudioChannelLayoutTag(&self) -> AudioChannelLayoutTag

Available on crate feature objc2-core-audio-types only.

The audio channel layout tag of the audio sample buffers produced by the audio data output.

When you set your audio data output’s associated AVCaptureDeviceInput/multichannelAudioMode property to AVCaptureMultichannelAudioModeFirstOrderAmbisonics, the AVCaptureSession allows up to two AVCaptureAudioDataOutput instances to be connected to the First-order Ambisonsics (FOA) input. If you connect a single AVCaptureAudioDataOutput instance, you must configure its AVCaptureAudioDataOutput/spatialAudioChannelLayoutTag property to produce either four channels of FOA audio or two channels of Stereo audio. If you connect two AVCaptureAudioDataOutput instances, you must configure one to output four channels of FOA audio and the other to output two channels of Stereo audio.

Thus, when you set your associated AVCaptureDeviceInput/multichannelAudioMode property to AVCaptureMultichannelAudioModeFirstOrderAmbisonics, you must set your connected AVCaptureAudioDataOutput instance’s AVCaptureAudioDataOutput/spatialAudioChannelLayoutTag property to either kAudioChannelLayoutTag_Stereo for stereo, or (kAudioChannelLayoutTag_HOA_ACN_SN3D | 4) for FOA (see <doc ://com.apple.documentation/documentation/coreaudiotypes/audiochannellayouttag>). When you set your associated AVCaptureDeviceInput/multichannelAudioMode to any other value, the AVCaptureSession only supports one AVCaptureAudioDataOutput, and you may only set AVCaptureAudioDataOutput/spatialAudioChannelLayoutTag to kAudioChannelLayoutTag_Unknown (the default value).

Your AVCaptureSession validates your app’s adherence to the the above rules when you call AVCaptureSession/startRunning: or AVCaptureSession/commitConfiguration and throws a NSInvalidArgumentException if necessary.

pub unsafe fn setSpatialAudioChannelLayoutTag( &self, spatial_audio_channel_layout_tag: AudioChannelLayoutTag, )

Available on crate feature objc2-core-audio-types only.

Setter for spatialAudioChannelLayoutTag.

pub unsafe fn recommendedAudioSettingsForAssetWriterWithOutputFileType( &self, output_file_type: &AVFileType, ) -> Option<Retained<NSDictionary<NSString, AnyObject>>>

Available on crate feature AVMediaFormat only.

Specifies the recommended settings for use with an AVAssetWriterInput.

Parameter outputFileType: Specifies the UTI of the file type to be written (see AVMediaFormat.h for a list of file format UTIs).

Returns: A fully populated dictionary of keys and values that are compatible with AVAssetWriter.

The value of this property is an NSDictionary containing values for compression settings keys defined in AVAudioSettings.h. This dictionary is suitable for use as the “outputSettings” parameter when creating an AVAssetWriterInput, such as,

[AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeAudio outputSettings:outputSettings sourceFormatHint:hint];

The dictionary returned contains all necessary keys and values needed by AVAssetWriter (see AVAssetWriterInput.h, -initWithMediaType:outputSettings: for a more in depth discussion). For QuickTime movie and ISO files, the recommended audio settings will always produce output comparable to that of AVCaptureMovieFileOutput.

Note that the dictionary of settings is dependent on the current configuration of the receiver’s AVCaptureSession and its inputs. The settings dictionary may change if the session’s configuration changes. As such, you should configure your session first, then query the recommended audio settings.

Methods from Deref<Target = AVCaptureOutput>

pub unsafe fn connections(&self) -> Retained<NSArray<AVCaptureConnection>>

Available on crate feature AVCaptureSession only.

The connections that describe the flow of media data to the receiver from AVCaptureInputs.

The value of this property is an NSArray of AVCaptureConnection objects, each describing the mapping between the receiver and the AVCaptureInputPorts of one or more AVCaptureInputs.

pub unsafe fn connectionWithMediaType( &self, media_type: &AVMediaType, ) -> Option<Retained<AVCaptureConnection>>

Available on crate features AVCaptureSession and AVMediaFormat only.

Returns the first connection in the connections array with an inputPort of the specified mediaType.

Parameter mediaType: An AVMediaType constant from AVMediaFormat.h, e.g. AVMediaTypeVideo.

This convenience method returns the first AVCaptureConnection in the receiver’s connections array that has an AVCaptureInputPort of the specified mediaType. If no connection with the specified mediaType is found, nil is returned.

pub unsafe fn transformedMetadataObjectForMetadataObject_connection( &self, metadata_object: &AVMetadataObject, connection: &AVCaptureConnection, ) -> Option<Retained<AVMetadataObject>>

Available on crate features AVCaptureSession and AVMetadataObject only.

Converts an AVMetadataObject’s visual properties to the receiver’s coordinates.

Parameter metadataObject: An AVMetadataObject originating from the same AVCaptureInput as the receiver.

Parameter connection: The receiver’s connection whose AVCaptureInput matches that of the metadata object to be converted.

Returns: An AVMetadataObject whose properties are in output coordinates.

AVMetadataObject bounds may be expressed as a rect where {0,0} represents the top left of the picture area, and {1,1} represents the bottom right on an unrotated picture. Face metadata objects likewise express yaw and roll angles with respect to an unrotated picture. -transformedMetadataObjectForMetadataObject:connection: converts the visual properties in the coordinate space of the supplied AVMetadataObject to the coordinate space of the receiver. The conversion takes orientation, mirroring, and scaling into consideration. If the provided metadata object originates from an input source other than the preview layer’s, nil will be returned.

If an AVCaptureVideoDataOutput instance’s connection’s videoOrientation or videoMirrored properties are set to non-default values, the output applies the desired mirroring and orientation by physically rotating and or flipping sample buffers as they pass through it. AVCaptureStillImageOutput, on the other hand, does not physically rotate its buffers. It attaches an appropriate kCGImagePropertyOrientation number to captured still image buffers (see ImageIO/CGImageProperties.h) indicating how the image should be displayed on playback. Likewise, AVCaptureMovieFileOutput does not physically apply orientation/mirroring to its sample buffers – it uses a QuickTime track matrix to indicate how the buffers should be rotated and/or flipped on playback.

transformedMetadataObjectForMetadataObject:connection: alters the visual properties of the provided metadata object to match the physical rotation / mirroring of the sample buffers provided by the receiver through the indicated connection. I.e., for video data output, adjusted metadata object coordinates are rotated/mirrored. For still image and movie file output, they are not.

pub unsafe fn metadataOutputRectOfInterestForRect( &self, rect_in_output_coordinates: CGRect, ) -> CGRect

Available on crate feature objc2-core-foundation only.

Converts a rectangle in the receiver’s coordinate space to a rectangle of interest in the coordinate space of an AVCaptureMetadataOutput whose capture device is providing input to the receiver.

Parameter rectInOutputCoordinates: A CGRect in the receiver’s coordinates.

Returns: A CGRect in the coordinate space of the metadata output whose capture device is providing input to the receiver.

AVCaptureMetadataOutput rectOfInterest is expressed as a CGRect where {0,0} represents the top left of the picture area, and {1,1} represents the bottom right on an unrotated picture. This convenience method converts a rectangle in the coordinate space of the receiver to a rectangle of interest in the coordinate space of an AVCaptureMetadataOutput whose AVCaptureDevice is providing input to the receiver. The conversion takes orientation, mirroring, and scaling into consideration. See -transformedMetadataObjectForMetadataObject:connection: for a full discussion of how orientation and mirroring are applied to sample buffers passing through the output.

pub unsafe fn rectForMetadataOutputRectOfInterest( &self, rect_in_metadata_output_coordinates: CGRect, ) -> CGRect

Available on crate feature objc2-core-foundation only.

Converts a rectangle of interest in the coordinate space of an AVCaptureMetadataOutput whose capture device is providing input to the receiver to a rectangle in the receiver’s coordinates.

Parameter rectInMetadataOutputCoordinates: A CGRect in the coordinate space of the metadata output whose capture device is providing input to the receiver.

Returns: A CGRect in the receiver’s coordinates.

AVCaptureMetadataOutput rectOfInterest is expressed as a CGRect where {0,0} represents the top left of the picture area, and {1,1} represents the bottom right on an unrotated picture. This convenience method converts a rectangle in the coordinate space of an AVCaptureMetadataOutput whose AVCaptureDevice is providing input to the coordinate space of the receiver. The conversion takes orientation, mirroring, and scaling into consideration. See -transformedMetadataObjectForMetadataObject:connection: for a full discussion of how orientation and mirroring are applied to sample buffers passing through the output.

pub unsafe fn isDeferredStartSupported(&self) -> bool

A BOOL value that indicates whether the output supports deferred start.

You can only set the deferredStartEnabled property value to true if the output supports deferred start.

pub unsafe fn isDeferredStartEnabled(&self) -> bool

A BOOL value that indicates whether to defer starting this capture output.

When this value is true, the session does not prepare the output’s resources until some time after AVCaptureSession/startRunning returns. You can start the visual parts of your user interface (e.g. preview) prior to other parts (e.g. photo/movie capture, metadata output, etc..) to improve startup performance. Set this value to false for outputs that your app needs for startup, and true for the ones it does not need to start immediately. For example, an AVCaptureVideoDataOutput that you intend to use for displaying preview should set this value to false, so that the frames are available as soon as possible.

By default, for apps that are linked on or after iOS 26, this property value is true for AVCapturePhotoOutput and AVCaptureFileOutput subclasses if supported, and false otherwise. When set to true for AVCapturePhotoOutput, if you want to support multiple capture requests before running deferred start, set AVCapturePhotoOutput/responsiveCaptureEnabled to true on that output.

If deferredStartSupported is false, setting this property value to true results in the system throwing an NSInvalidArgumentException.

• Note: Set this value before calling AVCaptureSession/commitConfiguration as it requires a lengthy reconfiguration of the capture render pipeline.

pub unsafe fn setDeferredStartEnabled(&self, deferred_start_enabled: bool)

Setter for isDeferredStartEnabled.

Methods from Deref<Target = NSObject>

pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>

pub fn class(&self) -> &'static AnyClass

Dynamically find the class of this object.

Panics

May panic if the object is invalid (which may be the case for objects returned from unavailable init/new methods).

Example

Check that an instance of NSObject has the precise class NSObject.

use objc2::ClassType;
use objc2::runtime::NSObject;

let obj = NSObject::new();
assert_eq!(obj.class(), NSObject::class());

pub unsafe fn get_ivar<T>(&self, name: &str) -> &T

where T: Encode,

👎Deprecated: this is difficult to use correctly, use Ivar::load instead.

Use Ivar::load instead.

Safety

The object must have an instance variable with the given name, and it must be of type T.

See Ivar::load_ptr for details surrounding this.

pub fn downcast_ref<T>(&self) -> Option<&T>

where T: DowncastTarget,

Attempt to downcast the object to a class of type T.

This is the reference-variant. Use Retained::downcast if you want to convert a retained object to another type.

Mutable classes

Some classes have immutable and mutable variants, such as NSString and NSMutableString.

When some Objective-C API signature says it gives you an immutable class, it generally expects you to not mutate that, even though it may technically be mutable “under the hood”.

So using this method to convert a NSString to a NSMutableString, while not unsound, is generally frowned upon unless you created the string yourself, or the API explicitly documents the string to be mutable.

See Apple’s documentation on mutability and on isKindOfClass: for more details.

Generic classes

Objective-C generics are called “lightweight generics”, and that’s because they aren’t exposed in the runtime. This makes it impossible to safely downcast to generic collections, so this is disallowed by this method.

You can, however, safely downcast to generic collections where all the type-parameters are AnyObject.

Panics

This works internally by calling isKindOfClass:. That means that the object must have the instance method of that name, and an exception will be thrown (if CoreFoundation is linked) or the process will abort if that is not the case. In the vast majority of cases, you don’t need to worry about this, since both root objects NSObject and NSProxy implement this method.

Examples

Cast an NSString back and forth from NSObject.

use objc2::rc::Retained;
use objc2_foundation::{NSObject, NSString};

let obj: Retained<NSObject> = NSString::new().into_super();
let string = obj.downcast_ref::<NSString>().unwrap();
// Or with `downcast`, if we do not need the object afterwards
let string = obj.downcast::<NSString>().unwrap();

Try (and fail) to cast an NSObject to an NSString.

use objc2_foundation::{NSObject, NSString};

let obj = NSObject::new();
assert!(obj.downcast_ref::<NSString>().is_none());

Try to cast to an array of strings.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);
// This is invalid and doesn't type check.
let arr = arr.downcast_ref::<NSArray<NSString>>();

This fails to compile, since it would require enumerating over the array to ensure that each element is of the desired type, which is a performance pitfall.

Downcast when processing each element instead.

use objc2_foundation::{NSArray, NSObject, NSString};

let arr = NSArray::from_retained_slice(&[NSObject::new()]);

for elem in arr {
    if let Some(data) = elem.downcast_ref::<NSString>() {
        // handle `data`
    }
}

Trait Implementations

impl AsRef<AVCaptureAudioDataOutput> for AVCaptureAudioDataOutput

fn as_ref(&self) -> &Self

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<AVCaptureOutput> for AVCaptureAudioDataOutput

fn as_ref(&self) -> &AVCaptureOutput

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<AnyObject> for AVCaptureAudioDataOutput

fn as_ref(&self) -> &AnyObject

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<NSObject> for AVCaptureAudioDataOutput

fn as_ref(&self) -> &NSObject

Converts this type into a shared reference of the (usually inferred) input type.

impl Borrow<AVCaptureOutput> for AVCaptureAudioDataOutput

fn borrow(&self) -> &AVCaptureOutput

Immutably borrows from an owned value.

impl Borrow<AnyObject> for AVCaptureAudioDataOutput

fn borrow(&self) -> &AnyObject

Immutably borrows from an owned value.

impl Borrow<NSObject> for AVCaptureAudioDataOutput

fn borrow(&self) -> &NSObject

Immutably borrows from an owned value.

impl ClassType for AVCaptureAudioDataOutput

const NAME: &'static str = "AVCaptureAudioDataOutput"

The name of the Objective-C class that this type represents.

type Super = AVCaptureOutput

The superclass of this class.

type ThreadKind = <<AVCaptureAudioDataOutput as ClassType>::Super as ClassType>::ThreadKind

Whether the type can be used from any thread, or from only the main thread.

fn class() -> &'static AnyClass

Get a reference to the Objective-C class that this type represents.

fn as_super(&self) -> &Self::Super

Get an immutable reference to the superclass.

impl Debug for AVCaptureAudioDataOutput

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Deref for AVCaptureAudioDataOutput

type Target = AVCaptureOutput

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl Hash for AVCaptureAudioDataOutput

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Message for AVCaptureAudioDataOutput

fn retain(&self) -> Retained<Self>

where Self: Sized,

Increment the reference count of the receiver.

impl NSObjectProtocol for AVCaptureAudioDataOutput

fn isEqual(&self, other: Option<&AnyObject>) -> bool

where Self: Sized + Message,

Check whether the object is equal to an arbitrary other object.

fn hash(&self) -> usize

where Self: Sized + Message,

An integer that can be used as a table address in a hash table structure.

fn isKindOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of the class, or one of its subclasses.

fn is_kind_of<T>(&self) -> bool

where T: ClassType, Self: Sized + Message,

👎Deprecated: use isKindOfClass directly, or cast your objects with AnyObject::downcast_ref

Check if the object is an instance of the class type, or one of its subclasses.

fn isMemberOfClass(&self, cls: &AnyClass) -> bool

where Self: Sized + Message,

Check if the object is an instance of a specific class, without checking subclasses.

fn respondsToSelector(&self, aSelector: Sel) -> bool

where Self: Sized + Message,

Check whether the object implements or inherits a method with the given selector.

fn conformsToProtocol(&self, aProtocol: &AnyProtocol) -> bool

where Self: Sized + Message,

Check whether the object conforms to a given protocol.

fn description(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object.

fn debugDescription(&self) -> Retained<NSObject>

where Self: Sized + Message,

A textual representation of the object to use when debugging.

fn isProxy(&self) -> bool

where Self: Sized + Message,

Check whether the receiver is a subclass of the NSProxy root class instead of the usual NSObject.

fn retainCount(&self) -> usize

where Self: Sized + Message,

The reference count of the object.

impl PartialEq for AVCaptureAudioDataOutput

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl RefEncode for AVCaptureAudioDataOutput

const ENCODING_REF: Encoding = <AVCaptureOutput as ::objc2::RefEncode>::ENCODING_REF

The Objective-C type-encoding for a reference of this type.

impl DowncastTarget for AVCaptureAudioDataOutput

impl Eq for AVCaptureAudioDataOutput