Function parseFrameMetadata

apps/desktop/src/utils/frame-worker.ts:222–294

(bytes: Uint8Array)

const NV12_FULL_MAGIC = 0x4e563146;

function parseFrameMetadata(bytes: Uint8Array): FrameMetadata | null {
	if (bytes.byteLength < 24) return null;

	if (bytes.byteLength >= 28) {
		const formatOffset = bytes.byteOffset + bytes.byteLength - 4;
		const formatView = new DataView(bytes.buffer, formatOffset, 4);
		const formatFlag = formatView.getUint32(0, true);

		if (formatFlag === NV12_VIDEO_MAGIC || formatFlag === NV12_FULL_MAGIC) {
			const metadataOffset = bytes.byteOffset + bytes.byteLength - 28;
			const meta = new DataView(bytes.buffer, metadataOffset, 28);
			const yStride = meta.getUint32(0, true);
			const height = meta.getUint32(4, true);
			const width = meta.getUint32(8, true);
			const frameNumber = meta.getUint32(12, true);
			const targetTimeNs = meta.getBigUint64(16, true);

			if (!width || !height || !yStride) return null;

			const ySize = yStride * height;
			const uvSize = yStride * Math.floor(height / 2);
			const totalSize = ySize + uvSize;

			if (bytes.byteLength - 28 < totalSize) {
				return null;
			}

			return {
				format: "nv12",
				width,
				height,
				yStride,
				fullRange: formatFlag === NV12_FULL_MAGIC,
				frameNumber,
				targetTimeNs,
				ySize,
				uvSize,
				totalSize,
			};
		}
	}

	const metadataOffset = bytes.byteOffset + bytes.byteLength - 24;
	const meta = new DataView(bytes.buffer, metadataOffset, 24);
	const strideBytes = meta.getUint32(0, true);
	const height = meta.getUint32(4, true);
	const width = meta.getUint32(8, true);
	const frameNumber = meta.getUint32(12, true);
	const targetTimeNs = meta.getBigUint64(16, true);

	if (!width || !height) return null;

	const expectedRowBytes = width * 4;
	const availableLength = strideBytes * height;

	if (
		strideBytes === 0 ||
		strideBytes < expectedRowBytes ||