Merge remote-tracking branch 'origin/main' into mpeg-ts

src/matroska/ebml.ts

@@ -7,7 +7,7 @@
  */
 
 import { MediaCodec } from '../codec';
-import { assertNever, textDecoder, textEncoder } from '../misc';
+import { assert, assertNever, textDecoder, textEncoder } from '../misc';
 import { FileSlice, readBytes, Reader, readF32Be, readF64Be, readU8 } from '../reader';
 import { Writer } from '../writer';
 
@@ -470,6 +470,10 @@ export const MIN_HEADER_SIZE = 2; // 1-byte ID and 1-byte size
 export const MAX_HEADER_SIZE = 2 * MAX_VAR_INT_SIZE; // 8-byte ID and 8-byte size
 
 export const readVarIntSize = (slice: FileSlice) => {
+	if (slice.remainingLength < 1) {
+		return null;
+	}
+
 	const firstByte = readU8(slice);
 	slice.skip(-1);
 
@@ -484,10 +488,19 @@ export const readVarIntSize = (slice: FileSlice) => {
 		mask >>= 1;
 	}
 
+	// Check if we have enough bytes to read the full varint
+	if (slice.remainingLength < width) {
+		return null;
+	}
+
 	return width;
 };
 
 export const readVarInt = (slice: FileSlice) => {
+	if (slice.remainingLength < 1) {
+		return null;
+	}
+
 	// Read the first byte to determine the width of the variable-length integer
 	const firstByte = readU8(slice);
 
@@ -503,6 +516,11 @@ export const readVarInt = (slice: FileSlice) => {
 		mask >>= 1;
 	}
 
+	if (slice.remainingLength < width - 1) {
+		// Not enough bytes
+		return null;
+	}
+
 	// First byte's value needs the marker bit cleared
 	let value = firstByte & (mask - 1);
 
@@ -563,39 +581,58 @@ export const readElementId = (slice: FileSlice) => {
 		return null;
 	}
 
+	if (slice.remainingLength < size) {
+		return null; // It don't fit
+	}
+
 	const id = readUnsignedInt(slice, size);
 	return id;
 };
 
-export const readElementSize = (slice: FileSlice) => {
-	let size: number | null = readU8(slice);
+/** Returns `undefined` to indicate the EBML undefined size. Returns `null` if the size couldn't be read. */
+export const readElementSize = (slice: FileSlice): number | undefined | null => {
+	// Need at least 1 byte to read the size
+	if (slice.remainingLength < 1) {
+		return null;
+	}
 
-	if (size === 0xff) {
-		size = null;
-	} else {
-		slice.skip(-1);
-		size = readVarInt(slice);
+	const firstByte = readU8(slice);
 
-		// In some (livestreamed) files, this is the value of the size field. While this technically is just a very
-		// large number, it is intended to behave like the reserved size 0xFF, meaning the size is undefined. We
-		// catch the number here. Note that it cannot be perfectly represented as a double, but the comparison works
-		// nonetheless.
-		// eslint-disable-next-line no-loss-of-precision
-		if (size === 0x00ffffffffffffff) {
-			size = null;
-		}
+	if (firstByte === 0xff) {
+		return undefined;
+	}
+
+	slice.skip(-1);
+	const size = readVarInt(slice);
+
+	if (size === null) {
+		return null;
+	}
+
+	// In some (livestreamed) files, this is the value of the size field. While this technically is just a very
+	// large number, it is intended to behave like the reserved size 0xFF, meaning the size is undefined. We
+	// catch the number here. Note that it cannot be perfectly represented as a double, but the comparison works
+	// nonetheless.
+	// eslint-disable-next-line no-loss-of-precision
+	if (size === 0x00ffffffffffffff) {
+		return undefined;
 	}
 
 	return size;
 };
 
 export const readElementHeader = (slice: FileSlice) => {
+	assert(slice.remainingLength >= MIN_HEADER_SIZE);
+
 	const id = readElementId(slice);
 	if (id === null) {
 		return null;
 	}
 
 	const size = readElementSize(slice);
+	if (size === null) {
+		return null;
+	}
 
 	return { id, size };
 };
@@ -720,8 +757,8 @@ export const CODEC_STRING_MAP: Partial<Record<MediaCodec, string>> = {
 	'webvtt': 'S_TEXT/WEBVTT',
 };
 
-export function assertDefinedSize(size: number | null): asserts size is number {
-	if (size === null) {
+export function assertDefinedSize(size: number | undefined): asserts size is number {
+	if (size === undefined) {
 		throw new Error('Undefined element size is used in a place where it is not supported.');
 	}
 };

src/matroska/matroska-demuxer.ts

@@ -193,6 +193,7 @@ type InternalTrack = {
 	codecId: string | null;
 	codecPrivate: Uint8Array | null;
 	defaultDuration: number | null;
+	defaultDurationNs: number | null;
 	name: string | null;
 	languageCode: string;
 	decodingInstructions: DecodingInstruction[];
@@ -346,7 +347,7 @@ export class MatroskaDemuxer extends Demuxer {
 				} else if (id === EBMLId.Segment) { // Segment found!
 					await this.readSegment(dataStartPos, size);
 
-					if (size === null) {
+					if (size === undefined) {
 						// Segment sizes can be undefined (common in livestreamed files), so assume this is the last
 						// and only segment
 						break;
@@ -364,7 +365,7 @@ export class MatroskaDemuxer extends Demuxer {
 					// doesn't contain any of the clusters that follow it. In the case, we apply the following logic: if
 					// we find a top-level cluster, attribute it to the previous segment.
 
-					if (size === null) {
+					if (size === undefined) {
 						// Just in case this is one of those weird sizeless clusters, let's do our best and still try to
 						// determine its size.
 						const nextElementPos = await searchForNextElementId(
@@ -389,7 +390,7 @@ export class MatroskaDemuxer extends Demuxer {
 		})();
 	}
 
-	async readSegment(segmentDataStart: number, dataSize: number | null) {
+	async readSegment(segmentDataStart: number, dataSize: number | undefined) {
 		this.currentSegment = {
 			seekHeadSeen: false,
 			infoSeen: false,
@@ -406,7 +407,7 @@ export class MatroskaDemuxer extends Demuxer {
 			cuePoints: [],
 
 			dataStartPos: segmentDataStart,
-			elementEndPos: dataSize === null
+			elementEndPos: dataSize === undefined
 				? null // Assume it goes until the end of the file
 				: segmentDataStart + dataSize,
 			clusterSeekStartPos: segmentDataStart,
@@ -483,7 +484,7 @@ export class MatroskaDemuxer extends Demuxer {
 				break; // Stop at the first cluster
 			}
 
-			if (size === null) {
+			if (size === undefined) {
 				break;
 			} else {
 				currentPos = dataStartPos + size;
@@ -536,6 +537,13 @@ export class MatroskaDemuxer extends Demuxer {
 			this.currentSegment.timestampFactor = 1e9 / 1e6;
 		}
 
+		// Compute default duration for all tracks now that we have the timestamp factor
+		for (const track of this.currentSegment.tracks) {
+			if (track.defaultDurationNs !== null) {
+				track.defaultDuration = (this.currentSegment.timestampFactor * track.defaultDurationNs) / 1e9;
+			}
+		}
+
 		// Put default tracks first
 		this.currentSegment.tracks.sort((a, b) => Number(b.disposition.default) - Number(a.disposition.default));
 
@@ -606,7 +614,7 @@ export class MatroskaDemuxer extends Demuxer {
 		let size = elementHeader.size;
 		const dataStartPos = headerSlice.filePos;
 
-		if (size === null) {
+		if (size === undefined) {
 			// The cluster's size is undefined (can happen in livestreamed files). We'd still like to know the size of
 			// it, so we have no other choice but to iterate over the EBML structure until we find an element at level
 			// 0 or 1, indicating the end of the cluster (all elements inside the cluster are at level 2).
@@ -908,9 +916,7 @@ export class MatroskaDemuxer extends Demuxer {
 	}
 
 	readContiguousElements(slice: FileSlice, stopIds?: number[]) {
-		const startIndex = slice.filePos;
-
-		while (slice.filePos - startIndex <= slice.length - MIN_HEADER_SIZE) {
+		while (slice.remainingLength >= MIN_HEADER_SIZE) {
 			const startPos = slice.filePos;
 			const foundElement = this.traverseElement(slice, stopIds);
 
@@ -996,6 +1002,7 @@ export class MatroskaDemuxer extends Demuxer {
 					codecId: null,
 					codecPrivate: null,
 					defaultDuration: null,
+					defaultDurationNs: null,
 					name: null,
 					languageCode: UNDETERMINED_LANGUAGE,
 					decodingInstructions: [],
@@ -1005,6 +1012,11 @@ export class MatroskaDemuxer extends Demuxer {
 
 				this.readContiguousElements(slice.slice(dataStartPos, size));
 
+				// Check if track was disabled during parsing (e.g., by FlagEnabled being 0)
+				if (!this.currentTrack) {
+					break;
+				}
+
 				if (this.currentTrack.decodingInstructions.some((instruction) => {
 					return instruction.data?.type !== 'decompress'
 						|| instruction.scope !== ContentEncodingScope.Block
@@ -1149,7 +1161,6 @@ export class MatroskaDemuxer extends Demuxer {
 
 				const enabled = readUnsignedInt(slice, size);
 				if (!enabled) {
-					this.currentSegment!.tracks.pop();
 					this.currentTrack = null;
 				}
 			}; break;
@@ -1204,9 +1215,7 @@ export class MatroskaDemuxer extends Demuxer {
 
 			case EBMLId.DefaultDuration: {
 				if (!this.currentTrack) break;
-
-				this.currentTrack.defaultDuration
-					= this.currentTrack.segment.timestampFactor * readUnsignedInt(slice, size) / 1e9;
+				this.currentTrack.defaultDurationNs = readUnsignedInt(slice, size);
 			}; break;
 
 			case EBMLId.Name: {
@@ -2223,7 +2232,7 @@ abstract class MatroskaTrackBacking implements InputTrackBacking {
 				}
 			}
 
-			if (size === null) {
+			if (size === undefined) {
 				// Undefined element size (can happen in livestreamed files). In this case, we need to do some
 				// searching to determine the actual size of the element.