Fail MP3 probe if AC3 or EC3 detected (#5695)

Related to #4958
video-dev · Jul 26, 2023 · b724bd3 · b724bd3
1 parent b8c3d36
commit b724bd3
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Showing 4 changed files with 46 additions and 29 deletions.
diff --git a/src/demux/audio/aacdemuxer.ts b/src/demux/audio/aacdemuxer.ts
@@ -41,7 +41,7 @@ class AACDemuxer extends BaseAudioDemuxer {
   }
 
   // Source for probe info - https://wiki.multimedia.cx/index.php?title=ADTS
-  static probe(data): boolean {
+  static probe(data: Uint8Array | undefined): boolean {
     if (!data) {
       return false;
     }

diff --git a/src/demux/audio/ac3-demuxer.ts b/src/demux/audio/ac3-demuxer.ts
@@ -1,5 +1,6 @@
 import BaseAudioDemuxer from './base-audio-demuxer';
 import { getID3Data, getTimeStamp } from '../id3';
+import { getAudioBSID } from './dolby';
 import type { HlsEventEmitter } from '../../events';
 import type { AudioFrame, DemuxedAudioTrack } from '../../types/demuxer';
 
@@ -55,7 +56,7 @@ export class AC3Demuxer extends BaseAudioDemuxer {
     }
   }
 
-  static probe(data): boolean {
+  static probe(data: Uint8Array | undefined): boolean {
     if (!data) {
       return false;
     }
@@ -66,33 +67,15 @@ export class AC3Demuxer extends BaseAudioDemuxer {
     }
 
     // look for the ac-3 sync bytes
-    let offset = id3Data.length;
+    const offset = id3Data.length;
     if (
       data[offset] === 0x0b &&
       data[offset + 1] === 0x77 &&
-      getTimeStamp(id3Data) !== undefined
-    ) {
+      getTimeStamp(id3Data) !== undefined &&
       // check the bsid to confirm ac-3
-      let bsid = 0;
-      let numBits = 5;
-      offset += numBits;
-      const temp = new Uint32Array(1); // unsigned 32 bit for temporary storage
-      const mask = new Uint32Array(1); // unsigned 32 bit mask value
-      const byte = new Uint8Array(1); // unsigned 8 bit for temporary storage
-      while (numBits > 0) {
-        byte[0] = data[offset];
-        // read remaining bits, upto 8 bits at a time
-        const bits = Math.min(numBits, 8);
-        const shift = 8 - bits;
-        mask[0] = (0xff000000 >>> (24 + shift)) << shift;
-        temp[0] = (byte[0] & mask[0]) >> shift;
-        bsid = !bsid ? temp[0] : (bsid << bits) | temp[0];
-        offset += 1;
-        numBits -= bits;
-      }
-      if (bsid < 16) {
-        return true;
-      }
+      getAudioBSID(data, offset) < 16
+    ) {
+      return true;
     }
     return false;
   }

diff --git a/src/demux/audio/dolby.ts b/src/demux/audio/dolby.ts
@@ -0,0 +1,21 @@
+export const getAudioBSID = (data: Uint8Array, offset: number): number => {
+  // check the bsid to confirm ac-3 | ec-3
+  let bsid = 0;
+  let numBits = 5;
+  offset += numBits;
+  const temp = new Uint32Array(1); // unsigned 32 bit for temporary storage
+  const mask = new Uint32Array(1); // unsigned 32 bit mask value
+  const byte = new Uint8Array(1); // unsigned 8 bit for temporary storage
+  while (numBits > 0) {
+    byte[0] = data[offset];
+    // read remaining bits, upto 8 bits at a time
+    const bits = Math.min(numBits, 8);
+    const shift = 8 - bits;
+    mask[0] = (0xff000000 >>> (24 + shift)) << shift;
+    temp[0] = (byte[0] & mask[0]) >> shift;
+    bsid = !bsid ? temp[0] : (bsid << bits) | temp[0];
+    offset += 1;
+    numBits -= bits;
+  }
+  return bsid;
+};
diff --git a/src/demux/audio/mp3demuxer.ts b/src/demux/audio/mp3demuxer.ts
@@ -2,7 +2,8 @@
  * MP3 demuxer
  */
 import BaseAudioDemuxer from './base-audio-demuxer';
-import * as ID3 from '../id3';
+import { getID3Data, getTimeStamp } from '../id3';
+import { getAudioBSID } from './dolby';
 import { logger } from '../../utils/logger';
 import * as MpegAudio from './mpegaudio';
 
@@ -29,7 +30,7 @@ class MP3Demuxer extends BaseAudioDemuxer {
     };
   }
 
-  static probe(data): boolean {
+  static probe(data: Uint8Array | undefined): boolean {
     if (!data) {
       return false;
     }
@@ -38,8 +39,20 @@ class MP3Demuxer extends BaseAudioDemuxer {
     // Look for MPEG header | 1111 1111 | 111X XYZX | where X can be either 0 or 1 and Y or Z should be 1
     // Layer bits (position 14 and 15) in header should be always different from 0 (Layer I or Layer II or Layer III)
     // More info http://www.mp3-tech.org/programmer/frame_header.html
-    const id3Data = ID3.getID3Data(data, 0) || [];
-    let offset = id3Data.length;
+    const id3Data = getID3Data(data, 0);
+    let offset = id3Data?.length || 0;
+
+    // Check for ac-3|ec-3 sync bytes and return false if present
+    if (
+      id3Data &&
+      data[offset] === 0x0b &&
+      data[offset + 1] === 0x77 &&
+      getTimeStamp(id3Data) !== undefined &&
+      // check the bsid to confirm ac-3 or ec-3 (not mp3)
+      getAudioBSID(data, offset) <= 16
+    ) {
+      return false;
+    }
 
     for (let length = data.length; offset < length; offset++) {
       if (MpegAudio.probe(data, offset)) {