Add FLAC support

src/controller/buffer-controller.ts

@@ -2,6 +2,7 @@ import { Events } from '../events';
 import { logger } from '../utils/logger';
 import { ErrorDetails, ErrorTypes } from '../errors';
 import { BufferHelper } from '../utils/buffer-helper';
+import { getCodecCompatibleName } from '../utils/codecs';
 import { getMediaSource } from '../utils/mediasource-helper';
 import { ElementaryStreamTypes } from '../loader/fragment';
 import type { TrackSet } from '../types/track';
@@ -262,7 +263,11 @@ export default class BufferController implements ComponentAPI {
             '$1'
           );
           if (currentCodec !== nextCodec) {
-            const mimeType = `${container};codecs=${levelCodec || codec}`;
+            let trackCodec = levelCodec || codec;
+            if (trackName.slice(0, 5) === 'audio') {
+              trackCodec = getCodecCompatibleName(trackCodec);
+            }
+            const mimeType = `${container};codecs=${trackCodec}`;
             this.appendChangeType(trackName, mimeType);
             logger.log(
               `[buffer-controller]: switching codec ${currentCodec} to ${nextCodec}`
@@ -747,7 +752,12 @@ export default class BufferController implements ComponentAPI {
           );
         }
         // use levelCodec as first priority
-        const codec = track.levelCodec || track.codec;
+        let codec = track.levelCodec || track.codec;
+        if (codec) {
+          if (trackName.slice(0, 5) === 'audio') {
+            codec = getCodecCompatibleName(codec);
+          }
+        }
         const mimeType = `${track.container};codecs=${codec}`;
         logger.log(`[buffer-controller]: creating sourceBuffer(${mimeType})`);
         try {

src/controller/level-controller.ts

@@ -16,7 +16,7 @@ import {
 import { HdcpLevel, HdcpLevels, Level } from '../types/level';
 import { Events } from '../events';
 import { ErrorTypes, ErrorDetails } from '../errors';
-import { isCodecSupportedInMp4 } from '../utils/codecs';
+import { isCodecSupportedInMp4, getCodecCompatibleName } from '../utils/codecs';
 import BasePlaylistController from './base-playlist-controller';
 import { PlaylistContextType, PlaylistLevelType } from '../types/loader';
 import type Hls from '../hls';
@@ -122,6 +122,10 @@ export default class LevelController extends BasePlaylistController {
         }
       }
 
+      if (levelParsed.audioCodec) {
+        levelParsed.audioCodec = getCodecCompatibleName(levelParsed.audioCodec);
+      }
+
       const {
         AUDIO,
         CODECS,

src/controller/stream-controller.ts

@@ -1227,7 +1227,12 @@ export default class StreamController
         }
       }
       // HE-AAC is broken on Android, always signal audio codec as AAC even if variant manifest states otherwise
-      if (ua.indexOf('android') !== -1 && audio.container !== 'audio/mpeg') {
+      if (
+        audioCodec &&
+        audioCodec.indexOf('mp4a.40.5') !== -1 &&
+        ua.indexOf('android') !== -1 &&
+        audio.container !== 'audio/mpeg'
+      ) {
         // Exclude mpeg audio
         audioCodec = 'mp4a.40.2';
         this.log(`Android: force audio codec to ${audioCodec}`);

src/remux/passthrough-remuxer.ts

@@ -256,6 +256,12 @@ function getParsedTrackCodec(
   if (parsedCodec === 'avc1' || type === ElementaryStreamTypes.VIDEO) {
     return 'avc1.42e01e';
   }
+  if (parsedCodec === 'fLaC') {
+    return 'fLaC';
+  }
+  if (parsedCodec === 'Opus') {
+    return 'Opus';
+  }
   return 'mp4a.40.5';
 }
 export default PassThroughRemuxer;

src/utils/codecs.ts

@@ -14,6 +14,9 @@ const sampleEntryCodesISO = {
     dtsh: true,
     'ec-3': true,
     enca: true,
+    fLaC: true, // MP4-RA listed codec entry for FLAC
+    flac: true, // legacy browser codec name for FLAC
+    FLAC: true, // some manifests may list "FLAC" with Apple's tools
     g719: true,
     g726: true,
     m4ae: true,
@@ -83,3 +86,41 @@ export function isCodecSupportedInMp4(codec: string, type: CodecType): boolean {
     `${type || 'video'}/mp4;codecs="${codec}"`
   );
 }
+
+interface CodecNameCache {
+  flac?: string;
+  opus?: string;
+}
+
+const CODEC_COMPATIBLE_NAMES: CodecNameCache = {};
+
+type LowerCaseCodecType = 'flac' | 'opus';
+
+function getCodecCompatibleNameLower(
+  lowerCaseCodec: LowerCaseCodecType
+): string {
+  if (CODEC_COMPATIBLE_NAMES[lowerCaseCodec]) {
+    return CODEC_COMPATIBLE_NAMES[lowerCaseCodec]!;
+  }
+
+  const codecsToCheck = {
+    flac: ['fLaC', 'flac', 'FLAC'],
+    opus: ['Opus', 'opus'],
+  }[lowerCaseCodec];
+
+  for (let i = 0; i < codecsToCheck.length; i++) {
+    if (isCodecSupportedInMp4(codecsToCheck[i], 'audio')) {
+      CODEC_COMPATIBLE_NAMES[lowerCaseCodec] = codecsToCheck[i];
+      return codecsToCheck[i];
+    }
+  }
+
+  return lowerCaseCodec;
+}
+
+const AUDIO_CODEC_REGEXP = /flac|opus/i;
+export function getCodecCompatibleName(codec: string): string {
+  return codec.replace(AUDIO_CODEC_REGEXP, (m) =>
+    getCodecCompatibleNameLower(m.toLowerCase() as LowerCaseCodecType)
+  );
+}