Struct AVAudioCompressedBuffer

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pub struct AVAudioCompressedBuffer { /* private fields */ }

Available on crate feature AVAudioBuffer only.

Expand description

A subclass of AVAudioBuffer for use with compressed audio formats.

Implementations§

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impl AVAudioCompressedBuffer

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pub unsafe fn initWithFormat_packetCapacity_maximumPacketSize( this: Allocated<Self>, format: &AVAudioFormat, packet_capacity: AVAudioPacketCount, maximum_packet_size: NSInteger, ) -> Retained<Self>

Available on crate features AVAudioFormat and AVAudioTypes only.

Initialize a buffer that is to contain compressed audio data.

Parameter format: The format of the audio to be contained in the buffer.

Parameter packetCapacity: The capacity of the buffer in packets.

Parameter maximumPacketSize: The maximum size in bytes of a compressed packet. The maximum packet size can be obtained from the maximumOutputPacketSize property of an AVAudioConverter configured for encoding this format.

An exception is raised if the format is PCM.

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pub unsafe fn initWithFormat_packetCapacity( this: Allocated<Self>, format: &AVAudioFormat, packet_capacity: AVAudioPacketCount, ) -> Retained<Self>

Available on crate features AVAudioFormat and AVAudioTypes only.

Initialize a buffer that is to contain constant bytes per packet compressed audio data.

Parameter format: The format of the audio to be contained in the buffer.

Parameter packetCapacity: The capacity of the buffer in packets.

This fails if the format is PCM or if the format has variable bytes per packet (format.streamDescription->mBytesPerPacket == 0).

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pub unsafe fn packetCapacity(&self) -> AVAudioPacketCount

Available on crate feature AVAudioTypes only.

The number of compressed packets the buffer can contain.

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pub unsafe fn packetCount(&self) -> AVAudioPacketCount

Available on crate feature AVAudioTypes only.

The current number of compressed packets in the buffer.

You may modify the packetCount as part of an operation that modifies its contents. The packetCount must be less than or equal to the packetCapacity.

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pub unsafe fn setPacketCount(&self, packet_count: AVAudioPacketCount)

Available on crate feature AVAudioTypes only.

Setter for packetCount.

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pub unsafe fn maximumPacketSize(&self) -> NSInteger

The maximum size of a compressed packet in bytes.

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pub unsafe fn data(&self) -> NonNull<c_void>

Access the buffer’s data bytes.

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pub unsafe fn byteCapacity(&self) -> u32

The buffer’s capacity in bytes

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pub unsafe fn byteLength(&self) -> u32

The current number of valid bytes in the buffer.

Can be changed as part of an operation that modifies the contents.

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pub unsafe fn setByteLength(&self, byte_length: u32)

Setter for byteLength.

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pub unsafe fn packetDescriptions(&self) -> *mut AudioStreamPacketDescription

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

Access the buffer’s array of packet descriptions, if any.

If the format has constant bytes per packet (format.streamDescription->mBytesPerPacket != 0), then this will return nil.

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pub unsafe fn packetDependencies( &self, ) -> *mut AudioStreamPacketDependencyDescription

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

Access the buffer’s array of packet dependencies, if any.

If the format doesn’t employ packet dependencies, this will be nil.

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impl AVAudioCompressedBuffer

Methods declared on superclass NSObject.

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

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

Methods from Deref<Target = AVAudioBuffer>§

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pub unsafe fn format(&self) -> Retained<AVAudioFormat>

Available on crate feature AVAudioFormat only.

The format of the audio in the buffer.

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pub unsafe fn audioBufferList(&self) -> NonNull<AudioBufferList>

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

The buffer’s underlying AudioBufferList.

For compatibility with lower-level CoreAudio and AudioToolbox API’s, this method accesses the buffer implementation’s internal AudioBufferList. The buffer list structure must not be modified, though you may modify buffer contents.

The mDataByteSize fields of this AudioBufferList express the buffer’s current frameLength.

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pub unsafe fn mutableAudioBufferList(&self) -> NonNull<AudioBufferList>

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

A mutable version of the buffer’s underlying AudioBufferList.

Some lower-level CoreAudio and AudioToolbox API’s require a mutable AudioBufferList, for example, AudioConverterConvertComplexBuffer.

The mDataByteSize fields of this AudioBufferList express the buffer’s current frameCapacity. If they are altered, you should modify the buffer’s frameLength to match.

Methods from Deref<Target = NSObject>§

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

Handle messages the object doesn’t recognize.

See Apple’s documentation for details.

Methods from Deref<Target = AnyObject>§

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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());

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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.

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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`
    }
}