Struct AVPlayerItemMetadataOutput

Source

#[repr(C)]
pub struct AVPlayerItemMetadataOutput { /* private fields */ }

Available on crate feature AVPlayerItemOutput only.

Expand description

A subclass of AVPlayerItemOutput that vends collections of metadata items carried in metadata tracks.

Setting the value of suppressesPlayerRendering on an instance of AVPlayerItemMetadataOutput has no effect.

Implementations§

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impl AVPlayerItemMetadataOutput

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pub unsafe fn initWithIdentifiers( this: Allocated<Self>, identifiers: Option<&NSArray<NSString>>, ) -> Retained<Self>

Creates an instance of AVPlayerItemMetadataOutput.

Parameter identifiers: A array of metadata identifiers indicating the metadata items that the output should provide.

See AVMetadataIdentifiers.h for publicly defined metadata identifiers. Pass nil to receive all of the timed metadata from all enabled AVPlayerItemTracks that carry timed metadata.

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pub unsafe fn delegate( &self, ) -> Option<Retained<ProtocolObject<dyn AVPlayerItemMetadataOutputPushDelegate>>>

The receiver’s delegate.

The delegate is held using a zeroing-weak reference, so this property will have a value of nil after a delegate that was previously set has been deallocated. This property is not key-value observable.

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pub unsafe fn advanceIntervalForDelegateInvocation(&self) -> NSTimeInterval

Permits advance invocation of the associated delegate, if any.

If it is possible, an AVPlayerItemMetadataOutput will message its delegate advanceIntervalForDelegateInvocation seconds earlier than otherwise. If the value you provide is large, effectively requesting provision of samples earlier than the AVPlayerItemMetadataOutput is prepared to act on them, the delegate will be invoked as soon as possible.

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pub unsafe fn setAdvanceIntervalForDelegateInvocation( &self, advance_interval_for_delegate_invocation: NSTimeInterval, )

Setter for advanceIntervalForDelegateInvocation.

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impl AVPlayerItemMetadataOutput

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 = AVPlayerItemOutput>§

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pub unsafe fn itemTimeForHostTime( &self, host_time_in_seconds: CFTimeInterval, ) -> CMTime

Available on crate features objc2-core-foundation and objc2-core-media only.

Convert a host time, expressed in seconds, to item time.

Converts a host time value (for example a CADisplayLink timestamp, or the value returned by CACurrentMediaTime()) to the equivalent time on the item’s timebase.

Note: The Core Animation CADisplayLink timestamp property expresses the most recent, or previous, screen refresh time. You need to increment this timestamp by the CADisplayLink’s duration property to find the next appropriate item time.

Parameter hostTimeInSeconds: The timestamp value to convert to item time.

Returns: The equivalent item time.

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pub unsafe fn itemTimeForMachAbsoluteTime( &self, mach_absolute_time: i64, ) -> CMTime

Available on crate feature objc2-core-media only.

Convenience method to convert a Mach host time to item time.

Converts Mach host time to the equivalent time on the item’s timebase. mach_absolute_time() returns time awake since boot in system-specific rational units that can be queried by calling mach_timebase_info().

Parameter machAbsoluteTime: The Mach host time to convert to item time.

Returns: The equivalent item time.

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pub unsafe fn itemTimeForCVTimeStamp(&self, timestamp: CVTimeStamp) -> CMTime

Available on crate features objc2-core-media and objc2-core-video only.

Convenience method to convert a CoreVideo timestamp to the equivalent time on the item’s timebase.

Note: A CVDisplayLink provides a parameter inOutputTimestamp that expresses a future screen refresh time. You can use this value directly to find the next appropriate item time. Use itemTimeForHostTime if you were using this method previously to find the item time and have to switch over due to CVDisplayLink deprecation.

Parameter timestamp: The CoreVideo timestamp value to convert to item time.

Returns: The equivalent item time.

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pub unsafe fn suppressesPlayerRendering(&self) -> bool

Indicates whether the output, when added to an AVPlayerItem, will be used in addition to normal rendering of media data by the player or instead of normal rendering.

The default value is NO, indicating that the output will be used in addition to normal rendering. If you want to render the media data provided by the output yourself instead of allowing it to be rendered as in normally would be by AVPlayer, set suppressesPlayerRendering to YES.

Whenever any output is added to an AVPlayerItem that has suppressesPlayerRendering set to YES, the media data supplied to the output will not be rendered by AVPlayer. Other media data associated with the item but not provided to such an output is not affected. For example, if an output of class AVPlayerItemVideoOutput with a value of YES for suppressesPlayerRendering is added to an AVPlayerItem, video media for that item will not be rendered by the AVPlayer, while audio media, subtitle media, and other kinds of media, if present, will be rendered.

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pub unsafe fn setSuppressesPlayerRendering( &self, suppresses_player_rendering: bool, )

Setter for suppressesPlayerRendering.

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.

§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`
    }
}