#7064: Check integrity of MPEG-TS video stream.

Author: mstyura

api-extractor/report/hls.js.api.md

@@ -4778,6 +4778,7 @@ export interface TransmuxerResult {
 // @public (undocumented)
 export type TSDemuxerConfig = {
     forceKeyFrameOnDiscontinuity: boolean;
+    handleMpegTsVideoIntegrityErrors: 'process' | 'skip';
 };
 
 // Warning: (ae-missing-release-tag) "UriReplacement" is part of the package's API, but it is missing a release tag (@alpha, @beta, @public, or @internal)

docs/API.md

@@ -110,6 +110,7 @@ See [API Reference](https://hlsjs-dev.video-dev.org/api-docs/) for a complete li
   - [`stretchShortVideoTrack`](#stretchshortvideotrack)
   - [`maxAudioFramesDrift`](#maxaudioframesdrift)
   - [`forceKeyFrameOnDiscontinuity`](#forcekeyframeondiscontinuity)
+  - [`handleMpegTsVideoIntegrityErrors`](#handlempegtsvideointegrityerrors)
   - [`abrEwmaFastLive`](#abrewmafastlive)
   - [`abrEwmaSlowLive`](#abrewmaslowlive)
   - [`abrEwmaFastVoD`](#abrewmafastvod)
@@ -470,6 +471,7 @@ var config = {
   stretchShortVideoTrack: false,
   maxAudioFramesDrift: 1,
   forceKeyFrameOnDiscontinuity: true,
+  handleMpegTsVideoIntegrityErrors: 'process',
   abrEwmaFastLive: 3.0,
   abrEwmaSlowLive: 9.0,
   abrEwmaFastVoD: 3.0,
@@ -1471,6 +1473,17 @@ Setting this parameter to false can also generate decoding weirdness when switch
 
 parameter should be a boolean
 
+### `handleMpegTsVideoIntegrityErrors`
+
+(default: `'process'`)
+
+Controls how corrupted video data is handled based on MPEG-TS integrity checks.
+
+- `'process'` (default): Continues processing corrupted data, which may lead to decoding errors.
+- `'skip'`: Discards corrupted video data to prevent potential playback issues.
+
+This parameter accepts a string with possible values: `'process'` | `'skip'`.
+
 ### `abrEwmaFastLive`
 
 (default: `3.0`)

src/config.ts

@@ -269,6 +269,7 @@ export type TimelineControllerConfig = {
 
 export type TSDemuxerConfig = {
   forceKeyFrameOnDiscontinuity: boolean;
+  handleMpegTsVideoIntegrityErrors: 'process' | 'skip';
 };
 
 export type HlsConfig = {
@@ -413,6 +414,7 @@ export const hlsDefaultConfig: HlsConfig = {
   stretchShortVideoTrack: false, // used by mp4-remuxer
   maxAudioFramesDrift: 1, // used by mp4-remuxer
   forceKeyFrameOnDiscontinuity: true, // used by ts-demuxer
+  handleMpegTsVideoIntegrityErrors: 'process', // used by ts-demuxer
   abrEwmaFastLive: 3, // used by abr-controller
   abrEwmaSlowLive: 9, // used by abr-controller
   abrEwmaFastVoD: 3, // used by abr-controller

src/demux/tsdemuxer.ts

@@ -72,6 +72,7 @@ class TSDemuxer implements Demuxer {
   private aacOverFlow: AudioFrame | null = null;
   private remainderData: Uint8Array | null = null;
   private videoParser: BaseVideoParser | null;
+  private videoIntegrityChecker: PacketsIntegrityChecker | null = null;
 
   constructor(
     observer: HlsEventEmitter,
@@ -182,6 +183,7 @@ class TSDemuxer implements Demuxer {
 
     this._videoTrack = TSDemuxer.createTrack('video') as DemuxedVideoTrack;
     this._videoTrack.duration = trackDuration;
+    this.videoIntegrityChecker = new PacketsIntegrityChecker(this.logger);
     this._audioTrack = TSDemuxer.createTrack(
       'audio',
       trackDuration,
@@ -227,6 +229,8 @@ class TSDemuxer implements Demuxer {
     let pes: PES | null;
 
     const videoTrack = this._videoTrack as DemuxedVideoTrack;
+    const videoIntegrityChecker = this
+      .videoIntegrityChecker as PacketsIntegrityChecker;
     const audioTrack = this._audioTrack as DemuxedAudioTrack;
     const id3Track = this._id3Track as DemuxedMetadataTrack;
     const textTrack = this._txtTrack as DemuxedUserdataTrack;
@@ -290,7 +294,12 @@ class TSDemuxer implements Demuxer {
         switch (pid) {
           case videoPid:
             if (stt) {
-              if (videoData && (pes = parsePES(videoData, this.logger))) {
+              if (
+                videoData &&
+                (!videoIntegrityChecker.isCorrupted ||
+                  this.config.handleMpegTsVideoIntegrityErrors === 'process') &&
+                (pes = parsePES(videoData, this.logger))
+              ) {
                 if (this.videoParser === null) {
                   switch (videoTrack.segmentCodec) {
                     case 'avc':
@@ -309,7 +318,9 @@ class TSDemuxer implements Demuxer {
               }
 
               videoData = { data: [], size: 0 };
+              videoIntegrityChecker.reset(videoPid);
             }
+            videoIntegrityChecker.handle_packet(data.subarray(start));
             if (videoData) {
               videoData.data.push(data.subarray(offset, start + PACKET_LENGTH));
               videoData.size += start + PACKET_LENGTH - offset;
@@ -597,6 +608,8 @@ class TSDemuxer implements Demuxer {
       this._id3Track =
       this._txtTrack =
         undefined;
+
+    this.videoIntegrityChecker = null;
   }
 
   private parseAACPES(track: DemuxedAudioTrack, pes: PES) {
@@ -1057,4 +1070,77 @@ function parsePES(stream: ElementaryStreamData, logger: ILogger): PES | null {
   return null;
 }
 
+// See FFMpeg for reference: https://github.com/FFmpeg/FFmpeg/blob/e4c8e80a2efee275f2a10fcf0424c9fc1d86e309/libavformat/mpegts.c#L2811-L2834
+class PacketsIntegrityChecker {
+  private readonly logger: ILogger;
+
+  private pid: number = 0;
+  private lastContinuityCounter = -1;
+  private integrityState: 'ok' | 'tei-bit' | 'cc-failed' = 'ok';
+
+  constructor(logger: ILogger) {
+    this.logger = logger;
+  }
+
+  public get isCorrupted(): boolean {
+    return this.integrityState !== 'ok';
+  }
+
+  public reset(pid: number) {
+    this.pid = pid;
+    this.lastContinuityCounter = -1;
+    this.integrityState = 'ok';
+  }
+
+  public handle_packet(data: Uint8Array) {
+    if (data.byteLength < 4) {
+      return;
+    }
+
+    const pid = parsePID(data, 0);
+    if (pid !== this.pid) {
+      this.logger.debug(`Packet PID mismatch, expected ${this.pid} got ${pid}`);
+      return;
+    }
+
+    const adaptationFieldControl = (data[3] & 0x30) >> 4;
+    if (adaptationFieldControl === 0) {
+      return;
+    }
+    const continuityCounter = data[3] & 0xf;
+
+    const lastContinuityCounter = this.lastContinuityCounter;
+    this.lastContinuityCounter = continuityCounter;
+
+    const hasPayload = (adaptationFieldControl & 0b01) != 0;
+    const hasAdaptation = (adaptationFieldControl & 0b10) != 0;
+    const isDiscontinuity =
+      hasAdaptation && data[4] != 0 && (data[5] & 0x80) != 0;
+
+    if (isDiscontinuity) {
+      return;
+    }
+    if (lastContinuityCounter < 0) {
+      return;
+    }
+
+    const expectedContinuityCounter = hasPayload
+      ? (lastContinuityCounter + 1) & 0x0f
+      : lastContinuityCounter;
+    if (continuityCounter !== expectedContinuityCounter) {
+      this.logger.warn(
+        `MPEG-TS Continuity Counter check failed for PID='${pid}', CC=${continuityCounter}, Expected-CC=${expectedContinuityCounter} Last-CC=${lastContinuityCounter}`,
+      );
+      this.integrityState = 'cc-failed';
+      return;
+    }
+
+    if ((data[1] & 0x80) !== 0) {
+      this.logger.warn(`MPEG-TS Packet had TEI flag set for PID='${pid}'`);
+      this.integrityState = 'tei-bit';
+      return;
+    }
+  }
+}
+
 export default TSDemuxer;