Class EncodedVideoChunkPolyfill

src/encoded_video_chunk.ts:16–76

 * Corresponds to the WebCodecs EncodedVideoChunk API.
 */
export class EncodedVideoChunkPolyfill {
	/**
	 * Whether this chunk is a key frame ("key") or delta frame ("delta").
	 */
	readonly type: EncodedVideoChunkType;
	/**
	 * The timestamp in integer microseconds.
	 */
	readonly timestamp: number;
	/**
	 * The duration in integer microseconds, or null if not specified.
	 */
	readonly duration: number | null;
	/**
	 * The size of the encoded data in bytes.
	 */
	readonly byteLength: number;

	private data: Uint8Array;

	/**
	 * Creates a new EncodedVideoChunk.
	 */
	constructor(init: EncodedVideoChunkInit) {
		if (init.type !== 'key' && init.type !== 'delta') {
			throw new TypeError(`type must be 'key' or 'delta'.`);
		}
		if (!Number.isFinite(init.timestamp)) {
			throw new TypeError(`timestamp must be a finite number.`);
		}
		if (init.duration !== undefined && !Number.isFinite(init.duration)) {
			throw new TypeError(`duration must be a finite number if specified.`);
		}
		if (!(
			init.data instanceof ArrayBuffer
			|| (typeof SharedArrayBuffer !== 'undefined' && init.data instanceof SharedArrayBuffer)
			|| ArrayBuffer.isView(init.data))
		) {
			throw new TypeError(`data must be an ArrayBuffer, SharedArrayBuffer, or ArrayBufferView.`);
		}

		this.type = init.type;
		this.timestamp = Math.trunc(init.timestamp);
		this.duration = init.duration !== undefined
			? Math.trunc(init.duration)
			: null;
		this.byteLength = init.data.byteLength;
		this.data = toUint8Array(init.data).slice(); // Clone the data
	}

	/**
	 * Copies the encoded chunk data to a destination buffer.
	 */
	copyTo(destination: AllowSharedBufferSource) {
		if (destination.byteLength < this.data.byteLength) {
			throw new TypeError('Destination buffer is too small.');
		}