Start work on demuxing

src/isobmff/isobmff-boxes.ts

@@ -9,8 +9,10 @@ import {
 	TRANSFER_CHARACTERISTICS_MAP,
 	MATRIX_COEFFICIENTS_MAP,
 	colorSpaceIsComplete,
+	IDENTITY_MATRIX,
+	rotationMatrix,
 } from '../misc';
-import { AudioCodec, SubtitleCodec, VideoCodec } from '../source';
+import { AudioCodec, SubtitleCodec, VideoCodec } from '../codec';
 import { formatSubtitleTimestamp } from '../subtitles';
 import { Writer } from '../writer';
 import {
@@ -208,21 +210,6 @@ const lastPresentedSample = (samples: Sample[]) => {
 	return result;
 };
 
-const rotationMatrix = (rotationInDegrees: number): TransformationMatrix => {
-	const theta = rotationInDegrees * (Math.PI / 180);
-	const cosTheta = Math.cos(theta);
-	const sinTheta = Math.sin(theta);
-
-	// Matrices are post-multiplied in ISOBMFF, meaning this is the transpose of your typical rotation matrix
-	return [
-		cosTheta, sinTheta, 0,
-		-sinTheta, cosTheta, 0,
-		0, 0, 1,
-	];
-};
-
-const IDENTITY_MATRIX = rotationMatrix(0);
-
 const matrixToBytes = (matrix: TransformationMatrix) => {
 	return [
 		fixed_16_16(matrix[0]), fixed_16_16(matrix[1]), fixed_2_30(matrix[2]),

src/isobmff/isobmff-reader.ts

@@ -0,0 +1,118 @@
+import { Reader } from '../reader';
+
+export class IsobmffReader {
+	pos = 0;
+
+	constructor(public reader: Reader) {}
+
+	readRange(start: number, end: number) {
+		const { view, offset } = this.reader.getViewAndOffset(start, end);
+		return new Uint8Array(view.buffer, offset, end - start);
+	}
+
+	readU8() {
+		const { view, offset } = this.reader.getViewAndOffset(this.pos, this.pos + 1);
+		this.pos++;
+
+		return view.getUint8(offset);
+	}
+
+	readU16() {
+		const { view, offset } = this.reader.getViewAndOffset(this.pos, this.pos + 2);
+		this.pos += 2;
+
+		return view.getUint16(offset, false);
+	}
+
+	readU24() {
+		const { view, offset } = this.reader.getViewAndOffset(this.pos, this.pos + 3);
+		this.pos += 3;
+
+		const high = view.getUint16(offset, false);
+		const low = view.getUint8(offset + 2);
+		return high * 0x100 + low;
+	}
+
+	readS32() {
+		const { view, offset } = this.reader.getViewAndOffset(this.pos, this.pos + 4);
+		this.pos += 4;
+
+		return view.getInt32(offset, false);
+	}
+
+	readU32() {
+		const { view, offset } = this.reader.getViewAndOffset(this.pos, this.pos + 4);
+		this.pos += 4;
+
+		return view.getUint32(offset, false);
+	}
+
+	readI32() {
+		const { view, offset } = this.reader.getViewAndOffset(this.pos, this.pos + 4);
+		this.pos += 4;
+
+		return view.getInt32(offset, false);
+	}
+
+	readU64() {
+		const high = this.readU32();
+		const low = this.readU32();
+		return high * 0x100000000 + low;
+	}
+
+	readF64() {
+		const { view, offset } = this.reader.getViewAndOffset(this.pos, this.pos + 8);
+		this.pos += 8;
+
+		return view.getFloat64(offset, false);
+	}
+
+	readFixed_16_16() {
+		return this.readS32() / 0x10000;
+	}
+
+	readFixed_2_30() {
+		return this.readS32() / 0x40000000;
+	}
+
+	readAscii(length: number) {
+		const { view, offset } = this.reader.getViewAndOffset(this.pos, this.pos + length);
+		this.pos += length;
+
+		let str = '';
+		for (let i = 0; i < length; i++) {
+			str += String.fromCharCode(view.getUint8(offset + i));
+		}
+		return str;
+	}
+
+	readIsomVariableInteger() {
+		let result = 0;
+
+		for (let i = 0; i < 4; i++) {
+			result <<= 7;
+			const nextByte = this.readU8();
+			result |= nextByte & 0x7f;
+
+			if ((nextByte & 0x80) === 0) {
+				break;
+			}
+		}
+
+		return result;
+	}
+
+	readBoxHeader() {
+		let totalSize = this.readU32();
+		const name = this.readAscii(4);
+		let headerSize = 8;
+
+		const hasLargeSize = totalSize === 1;
+		if (hasLargeSize) {
+			totalSize = this.readU64();
+			headerSize = 16;
+		}
+
+		return { name, totalSize, headerSize, contentSize: totalSize - headerSize };
+	}
+}