fix: convencience method for setting clip in MP

src/atem.ts

@@ -21,6 +21,7 @@ import { InputChannel } from './state/input'
 import { DownstreamKeyerGeneral, DownstreamKeyerMask } from './state/video/downstreamKeyers'
 import * as DT from './dataTransfer'
 import { Util } from './lib/atemUtil'
+import * as Enums from './enums'
 
 export interface AtemOptions {
 	address?: string,
@@ -247,6 +248,13 @@ export class Atem extends EventEmitter {
 		return this.sendCommand(command)
 	}
 
+	setMediaPlayerSource (newProps: Partial<{ sourceType: Enums.MediaSourceType, stillIndex: number, clipIndex: number }>, player = 0) {
+		const command = new Commands.MediaPlayerSourceCommand()
+		command.mediaPlayerId = player
+		command.updateProps(newProps)
+		return this.sendCommand(command)
+	}
+
 	setMediaClip (index: number, name: string, frames = 1) {
 		const command = new Commands.MediaPoolSetClipCommand()
 		command.updateProps({ index, name, frames })