import AudioNodeSubgraph from './AudioNodeSubgraph';
import Device from './Device';
/**
 * A device that applies some transform to another device, returning a device and optional
 * `AudioNode` for use by the device controller.
 *
 * The results are applied by the device controller in two stages:
 *
 * 1. The transform device is used to retrieve the constraints that identify an inner media stream.
 *    This will be managed by the controller.
 * 2. The transform device provides a Web Audio node that will be connected between the input and
 *    the output of the device controller's audio graph. This is returned as a pair, `(start, end)`,
 *    to allow an arbitrary subgraph of nodes to be returned.
 *
 * The application should call `stop` when the device will no longer be used. This method is
 * defined on this interface to establish that convention.
 */
export default interface AudioTransformDevice {
    /**
     * Called when `realtimeMuteLocalAudio` is called on the `RealtimeController`. Implement this
     * callback to avoid doing expensive processing when the audio output is disabled.
     */
    mute(muted: boolean): Promise<void>;
    /**
     * `stop` should be called by the application to free any resources associated
     * with the device (e.g., workers).
     *
     * After this is called, the device should be discarded.
     */
    stop(): Promise<void>;
    /**
     * Return the inner {@link Device} that the device controller should select as part
     * of the application of this `AudioTransformDevice`.
     */
    intrinsicDevice(): Promise<Device>;
    /**
     * Optionally return a pair of `AudioNode`s that should be connected to the applied inner
     * device. The two nodes can be the same, indicating the smallest possible subgraph.
     *
     * @param context The `AudioContext` to use when instantiating the nodes.
     */
    createAudioNode?(context: AudioContext): Promise<AudioNodeSubgraph | undefined>;
}
/**
 * `isAudioTransformDevice` is a type guard for {@link AudioTransformDevice}.
 *
 * @param device the value to check.
 */
export declare function isAudioTransformDevice(device: any): device is AudioTransformDevice;