Class MediaProcessor

Media processor class holding and running insertable streams pipeline. The class should be created on the proper thread. Options are:

Application main thread when media processing wants to be performed in the main thread.
Worker thread when media processing wants to be performed in a Web worker thread.

Hierarchy

default<EventDataMap>
- MediaProcessor

Implements

MediaProcessorInterface

Index

Constructors

constructor

new MediaProcessor(): MediaProcessor
Returns MediaProcessor
Overrides Emittery<EventDataMap>.constructor

Properties

debug

debug: DebugOptions<EventDataMap>

Debugging options for the current instance.

`Static`isDebugEnabled

isDebugEnabled: boolean

Toggle debug mode for all instances.

Default: true if the DEBUG environment variable is set to emittery or *, otherwise false.

Example

import Emittery from 'emittery';

Emittery.isDebugEnabled = true;

const emitter1 = new Emittery({debug: {name: 'myEmitter1'}});
const emitter2 = new Emittery({debug: {name: 'myEmitter2'}});

emitter1.on('test', data => {
	// …
});

emitter2.on('otherTest', data => {
	// …
});

emitter1.emit('test');
//=> [16:43:20.417][emittery:subscribe][myEmitter1] Event Name: test
//	data: undefined

emitter2.emit('otherTest');
//=> [16:43:20.417][emittery:subscribe][myEmitter2] Event Name: otherTest
//	data: undefined

`Static` `Readonly`listenerAdded

listenerAdded: typeof listenerAdded

Fires when an event listener was added.

An object with listener and eventName (if on or off was used) is provided as event data.

Example

import Emittery from 'emittery';

const emitter = new Emittery();

emitter.on(Emittery.listenerAdded, ({listener, eventName}) => {
	console.log(listener);
	//=> data => {}

	console.log(eventName);
	//=> '🦄'
});

emitter.on('🦄', data => {
	// Handle data
});

`Static` `Readonly`listenerRemoved

listenerRemoved: typeof listenerRemoved

Fires when an event listener was removed.

An object with listener and eventName (if on or off was used) is provided as event data.

Example

import Emittery from 'emittery';

const emitter = new Emittery();

const off = emitter.on('🦄', data => {
	// Handle data
});

emitter.on(Emittery.listenerRemoved, ({listener, eventName}) => {
	console.log(listener);
	//=> data => {}

	console.log(eventName);
	//=> '🦄'
});

off();

Methods

anyEvent

anyEvent(): AsyncIterableIterator<
[keyof EventDataMap, WarnData | ErrorData | PipelineInfoData],
>

Get an async iterator which buffers a tuple of an event name and data each time an event is emitted.

Call return() on the iterator to remove the subscription.

In the same way as for events, you can subscribe by using the for await statement.

Returns AsyncIterableIterator<
[keyof EventDataMap, WarnData | ErrorData | PipelineInfoData],
>

Example

import Emittery from 'emittery';

const emitter = new Emittery();
const iterator = emitter.anyEvent();

emitter.emit('🦄', '🌈1'); // Buffered
emitter.emit('🌟', '🌈2'); // Buffered

iterator.next()
	.then(({value, done}) => {
		// done is false
		// value is ['🦄', '🌈1']
		return iterator.next();
	})
	.then(({value, done}) => {
		// done is false
		// value is ['🌟', '🌈2']
		// revoke subscription
		return iterator.return();
	})
	.then(({done}) => {
		// done is true
	});

bindMethods

bindMethods(
target: Record<string, unknown>,
methodNames?: readonly string[],
): void
Bind the given methodNames, or all Emittery methods if methodNames is not defined, into the target object.
Parameters
- target: Record<string, unknown>
- OptionalmethodNames: readonly string[]
Returns void
Example
```
import Emittery from 'emittery';

const object = {};

new Emittery().bindMethods(object);

object.emit('event');
```
Inherited from Emittery.bindMethods

clearListeners

clearListeners<Name extends keyof EventDataMap>(
eventName?: Name | readonly Name[],
): void
Clear all event listeners on the instance.

If eventName is given, only the listeners for that event are cleared.
Type Parameters
- Name extends keyof EventDataMap
Parameters
- OptionaleventName: Name | readonly Name[]
Returns void
Inherited from Emittery.clearListeners

destroy

destroy(): Promise<void>
Stops running the tranformation logic performed by the media processor instance.

Returns Promise<void>
Implementation of MediaProcessorInterface.destroy

emit

emit<Name extends never>(eventName: Name): Promise<void>
Trigger an event asynchronously, optionally with some data. Listeners are called in the order they were added, but executed concurrently.
Type Parameters
- Name extends never
Parameters
- eventName: Name
Returns Promise<void>
A promise that resolves when all the event listeners are done. Done meaning executed if synchronous or resolved when an async/promise-returning function. You usually wouldn't want to wait for this, but you could for example catch possible errors. If any of the listeners throw/reject, the returned promise will be rejected with the error, but the other listeners will not be affected.

Inherited from Emittery.emit
emit<Name extends keyof EventDataMap>(
eventName: Name,
eventData: EventDataMap[Name],
): Promise<void>
Trigger an event asynchronously, optionally with some data. Listeners are called in the order they were added, but executed concurrently.
Type Parameters
- Name extends keyof EventDataMap
Parameters
- eventName: Name
- eventData: EventDataMap[Name]
Returns Promise<void>
A promise that resolves when all the event listeners are done. Done meaning executed if synchronous or resolved when an async/promise-returning function. You usually wouldn't want to wait for this, but you could for example catch possible errors. If any of the listeners throw/reject, the returned promise will be rejected with the error, but the other listeners will not be affected.

Inherited from Emittery.emit

emitSerial

emitSerial<Name extends never>(eventName: Name): Promise<void>
Same as emit(), but it waits for each listener to resolve before triggering the next one. This can be useful if your events depend on each other. Although ideally they should not. Prefer emit() whenever possible.

If any of the listeners throw/reject, the returned promise will be rejected with the error and the remaining listeners will not be called.
Type Parameters
- Name extends never
Parameters
- eventName: Name
Returns Promise<void>
A promise that resolves when all the event listeners are done.

Inherited from Emittery.emitSerial
emitSerial<Name extends keyof EventDataMap>(
eventName: Name,
eventData: EventDataMap[Name],
): Promise<void>
Same as emit(), but it waits for each listener to resolve before triggering the next one. This can be useful if your events depend on each other. Although ideally they should not. Prefer emit() whenever possible.

If any of the listeners throw/reject, the returned promise will be rejected with the error and the remaining listeners will not be called.
Type Parameters
- Name extends keyof EventDataMap
Parameters
- eventName: Name
- eventData: EventDataMap[Name]
Returns Promise<void>
A promise that resolves when all the event listeners are done.

Inherited from Emittery.emitSerial

events

events<Name extends keyof EventDataMap>(
eventName: Name | readonly Name[],
): AsyncIterableIterator<EventDataMap[Name]>

Get an async iterator which buffers data each time an event is emitted.

Call return() on the iterator to remove the subscription.

Type Parameters

Name extends keyof EventDataMap

Parameters

eventName: Name | readonly Name[]

Returns AsyncIterableIterator<EventDataMap[Name]>

Example

import Emittery from 'emittery';

const emitter = new Emittery();
const iterator = emitter.events('🦄');

emitter.emit('🦄', '🌈1'); // Buffered
emitter.emit('🦄', '🌈2'); // Buffered

iterator
	.next()
	.then(({value, done}) => {
		// done === false
		// value === '🌈1'
		return iterator.next();
	})
	.then(({value, done}) => {
		// done === false
		// value === '🌈2'
		// Revoke subscription
		return iterator.return();
	})
	.then(({done}) => {
		// done === true
	});

In practice you would usually consume the events using the for await statement. In that case, to revoke the subscription simply break the loop.

Example

import Emittery from 'emittery';

const emitter = new Emittery();
const iterator = emitter.events('🦄');

emitter.emit('🦄', '🌈1'); // Buffered
emitter.emit('🦄', '🌈2'); // Buffered

// In an async context.
for await (const data of iterator) {
	if (data === '🌈2') {
		break; // Revoke the subscription when we see the value `🌈2`.
	}
}

It accepts multiple event names.

Example

import Emittery from 'emittery';

const emitter = new Emittery();
const iterator = emitter.events(['🦄', '🦊']);

emitter.emit('🦄', '🌈1'); // Buffered
emitter.emit('🦊', '🌈2'); // Buffered

iterator
	.next()
	.then(({value, done}) => {
		// done === false
		// value === '🌈1'
		return iterator.next();
	})
	.then(({value, done}) => {
		// done === false
		// value === '🌈2'
		// Revoke subscription
		return iterator.return();
	})
	.then(({done}) => {
		// done === true
	});

listenerCount

listenerCount<Name extends keyof EventDataMap>(
eventName?: Name | readonly Name[],
): number
The number of listeners for the eventName or all events if not specified.
Type Parameters
- Name extends keyof EventDataMap
Parameters
- OptionaleventName: Name | readonly Name[]
Returns number
Inherited from Emittery.listenerCount

off

off<Name extends (keyof EventDataMap) | (keyof OmnipresentEventData)>(
    eventName: Name | readonly Name[],
    listener: (
        eventData: (EventDataMap & OmnipresentEventData)[Name],
    ) => void | Promise<void>,
): void

Remove one or more event subscriptions.

Type Parameters

Name extends (keyof EventDataMap) | (keyof OmnipresentEventData)

Parameters

eventName: Name | readonly Name[]
listener: (eventData: (EventDataMap & OmnipresentEventData)[Name]) => void | Promise<void>

Returns void

Example

import Emittery from 'emittery';

const emitter = new Emittery();

const listener = data => {
	console.log(data);
};

emitter.on(['🦄', '🐶', '🦊'], listener);
await emitter.emit('🦄', 'a');
await emitter.emit('🐶', 'b');
await emitter.emit('🦊', 'c');
emitter.off('🦄', listener);
emitter.off(['🐶', '🦊'], listener);
await emitter.emit('🦄', 'a'); // nothing happens
await emitter.emit('🐶', 'b'); // nothing happens
await emitter.emit('🦊', 'c'); // nothing happens

offAny

offAny(
    listener: (
        eventName: keyof EventDataMap,
        eventData: WarnData | ErrorData | PipelineInfoData,
    ) => void | Promise<void>,
): void
Remove an onAny subscription.
Parameters
- listener: (
  eventName: keyof EventDataMap,
  eventData: WarnData | ErrorData | PipelineInfoData,
  ) => void | Promise<void>
Returns void
Inherited from Emittery.offAny

on

on<Name extends (keyof EventDataMap) | (keyof OmnipresentEventData)>(
    eventName: Name | readonly Name[],
    listener: (
        eventData: (EventDataMap & OmnipresentEventData)[Name],
    ) => void | Promise<void>,
    options?: { signal?: AbortSignal },
): UnsubscribeFunction
Subscribe to one or more events.

Using the same listener multiple times for the same event will result in only one method call per emitted event.
Type Parameters
- Name extends (keyof EventDataMap) | (keyof OmnipresentEventData)
Parameters
- eventName: Name | readonly Name[]
- listener: (eventData: (EventDataMap & OmnipresentEventData)[Name]) => void | Promise<void>
- Optionaloptions: { signal?: AbortSignal }
Returns UnsubscribeFunction
An unsubscribe method.
Example
```
import Emittery from 'emittery';

const emitter = new Emittery();

emitter.on('🦄', data => {
	console.log(data);
});

emitter.on(['🦄', '🐶'], data => {
	console.log(data);
});

emitter.emit('🦄', '🌈'); // log => '🌈' x2
emitter.emit('🐶', '🍖'); // log => '🍖'
```
Inherited from Emittery.on

onAny

onAny(
    listener: (
        eventName: keyof EventDataMap,
        eventData: WarnData | ErrorData | PipelineInfoData,
    ) => void | Promise<void>,
    options?: { signal?: AbortSignal },
): UnsubscribeFunction
Subscribe to be notified about any event.
Parameters
- listener: (
  eventName: keyof EventDataMap,
  eventData: WarnData | ErrorData | PipelineInfoData,
  ) => void | Promise<void>
- Optionaloptions: { signal?: AbortSignal }
Returns UnsubscribeFunction
A method to unsubscribe.

Inherited from Emittery.onAny

once

once<Name extends (keyof EventDataMap) | (keyof OmnipresentEventData)>(
    eventName: Name | readonly Name[],
    predicate?: (
        eventData: (EventDataMap & OmnipresentEventData)[Name],
    ) => boolean,
): EmitteryOncePromise<(EventDataMap & OmnipresentEventData)[Name]>
Subscribe to one or more events only once. It will be unsubscribed after the first event that matches the predicate (if provided).
Type Parameters
- Name extends (keyof EventDataMap) | (keyof OmnipresentEventData)
Parameters
- eventName: Name | readonly Name[]
  The event name(s) to subscribe to.
- Optionalpredicate: (eventData: (EventDataMap & OmnipresentEventData)[Name]) => boolean
  Optional predicate function to filter event data. The event will only be emitted if the predicate returns true.
Returns EmitteryOncePromise<(EventDataMap & OmnipresentEventData)[Name]>
The promise of event data when eventName is emitted and predicate matches (if provided). This promise is extended with an off method.
Example
```
import Emittery from 'emittery';

const emitter = new Emittery();

emitter.once('🦄').then(data => {
	console.log(data);
	//=> '🌈'
});

emitter.once(['🦄', '🐶']).then(data => {
	console.log(data);
});

// With predicate
emitter.once('data', data => data.ok === true).then(data => {
	console.log(data);
	//=> {ok: true, value: 42}
});

emitter.emit('🦄', '🌈'); // Logs `🌈` twice
emitter.emit('🐶', '🍖'); // Nothing happens
emitter.emit('data', {ok: false}); // Nothing happens
emitter.emit('data', {ok: true, value: 42}); // Logs {ok: true, value: 42}
```
Inherited from Emittery.once

setTrackExpectedRate

setTrackExpectedRate(trackExpectedRate: number): void
Sets the expected rate of the track per second. The media processor will use this number for calculating drops in the rate. This could happen when the transformation will take more time than expected. This will not cause an error, just warning to the client. Mostly: Video: 30 frames per second Audio: 50 audio data per second for OPUS In case of increased frame dropping rate a warning will be emitted according to info here. This is an optional method.
Parameters
- trackExpectedRate: number
  number holds the predicted track rate.
Returns void

setTransformers

setTransformers(transformers: Transformer<any, any>[]): Promise<void>
Sets an array of transfromer instances that will be hold and ran by the media processor instance. See example here
Parameters
- transformers: Transformer<any, any>[]
  An array of transformer instances.
Returns Promise<void>

transform

transform(readable: ReadableStream, writable: WritableStream): Promise<void>
Starts running the tranformation logic performed by the media processor instance. When running an instance of this class on a Web worker thread the call for this function should be made by the user. See example here. When running an instance of this class on the application main thread there is no need to call this method given it will be called by the MediaProcessorConnector instance.
Parameters
- readable: ReadableStream
  Readable stream associated to the media source being processed.
- writable: WritableStream
  Writable stream associated to the resulting media once processed.
Returns Promise<void>
Implementation of MediaProcessorInterface.transform
transform(track: MediaStreamTrack): Promise<MediaStreamTrack>
Starts running the tranformation logic performed by the media processor instance. Special case of transform for browsers implementing the proposed standard, which only works inside webworkers. Only Webkit for now..
Parameters
- track: MediaStreamTrack
  Track to be processed.
Returns Promise<MediaStreamTrack>
New track to be used.

Implementation of MediaProcessorInterface.transform

`Static`mixin

mixin(
emitteryPropertyName: string | symbol,
methodNames?: readonly string[],
): <T extends new (...arguments_: readonly any[]) => any>(klass: T) => T
In TypeScript, it returns a decorator which mixins Emittery as property emitteryPropertyName and methodNames, or all Emittery methods if methodNames is not defined, into the target class.
Parameters
- emitteryPropertyName: string | symbol
- OptionalmethodNames: readonly string[]
Returns <T extends new (...arguments_: readonly any[]) => any>(klass: T) => T
Example
```
import Emittery from 'emittery';

@Emittery.mixin('emittery')
class MyClass {}

const instance = new MyClass();

instance.emit('event');
```
Inherited from Emittery.mixin

Class MediaProcessor

Hierarchy

Implements

Index

Constructors

Properties

Methods

Constructors

constructor

Returns MediaProcessor

Properties

debug

StaticisDebugEnabled

Example

Static ReadonlylistenerAdded

Example

Static ReadonlylistenerRemoved

Example

Methods

anyEvent

Returns AsyncIterableIterator< [keyof EventDataMap, WarnData | ErrorData | PipelineInfoData],>

Example

bindMethods

Parameters

Returns void

Example

clearListeners

Type Parameters

Parameters

Returns void

destroy

Returns Promise<void>

emit

Type Parameters

Parameters

Returns Promise<void>

Type Parameters

Parameters

Returns Promise<void>

emitSerial

Type Parameters

Parameters

Returns Promise<void>

Type Parameters

Parameters

Returns Promise<void>

events

Type Parameters

Parameters

Returns AsyncIterableIterator<EventDataMap[Name]>

Example

Example

Example

listenerCount

Type Parameters

Parameters

Returns number

off

Type Parameters

Parameters

Returns void

Example

offAny

Parameters

Returns void

on

Type Parameters

Parameters

Returns UnsubscribeFunction

Example

onAny

Parameters

Returns UnsubscribeFunction

once

Type Parameters

Parameters

Returns EmitteryOncePromise<(EventDataMap & OmnipresentEventData)[Name]>

Example

setTrackExpectedRate

Parameters

`Static`isDebugEnabled

`Static` `Readonly`listenerAdded

`Static` `Readonly`listenerRemoved

Returns AsyncIterableIterator<
[keyof EventDataMap, WarnData | ErrorData | PipelineInfoData],
>

`Static`mixin