import VideoFrameProcessor from './VideoFrameProcessor';
import VideoFrameProcessorPipelineObserver from './VideoFrameProcessorPipelineObserver';
/**
 * [[VideoFrameProcessorPipeline]] facilitates video processing by transforming a input `MediaStream`
 * with an array of {@link VideoFrameProcessor} to another `MediaStream`.
 * It invokes the execution of {@link VideoFrameProcessor} in interval specified by `framerate`.
 */
export default interface VideoFrameProcessorPipeline {
    /**
     * Sets the input for the pipeline. An active `MediaStream` will start the processing steps.
     * To stop the pipeline, `null` can be passed.
     * To switch `MediaSteam`, the pipeline must be stopped first.
     */
    setInputMediaStream(mediaStream: MediaStream): Promise<void>;
    /**
     * Returns the current input `MediaStream`.
     */
    getInputMediaStream(): Promise<MediaStream | null>;
    /**
     * Returns an active output stream.
     */
    getActiveOutputMediaStream(): MediaStream;
    /**
     * Stops the pipeline.
     */
    stop(): void;
    /**
     * Destroys the pipeline, processors, intermediate buffers and input stream.
     */
    destroy(): void;
    /**
     * Adds {@link VideoFrameProcessorPipelineObserver} observer to receive lifecycle and performance callback.
     */
    addObserver(observer: VideoFrameProcessorPipelineObserver): void;
    /**
     * Removes {@link VideoFrameProcessorPipelineObserver} observer.
     */
    removeObserver(observer: VideoFrameProcessorPipelineObserver): void;
    /**
     * Lists of processors to execute to produce output media stream.
     */
    processors: VideoFrameProcessor[];
    /**
     * The desired output frame rate.
     */
    framerate: number;
    /**
     * The output `MediaStream` as a result of processor executions.
     * It is possible, but unlikely, that this accessor will throw.
     */
    readonly outputMediaStream: MediaStream;
}