Support AES-128 Encrypted Low-Latency HLS Parts (#5214)

Author: robwalch

src/controller/base-stream-controller.ts

@@ -581,6 +581,9 @@ export default class BaseStreamController
       keyLoadingPromise = this.keyLoader.load(frag).then((keyLoadedData) => {
         if (!this.fragContextChanged(keyLoadedData.frag)) {
           this.hls.trigger(Events.KEY_LOADED, keyLoadedData);
+          if (this.state === State.KEY_LOADING) {
+            this.state = State.IDLE;
+          }
           return keyLoadedData;
         }
       });

src/crypt/decrypter.ts

@@ -58,13 +58,6 @@ export default class Decrypter {
   public flush(): Uint8Array | null {
     const { currentResult, remainderData } = this;
     if (!currentResult || remainderData) {
-      logger.error(
-        `[softwareDecrypt] ${
-          remainderData
-            ? 'overflow bytes: ' + remainderData.byteLength
-            : 'no result'
-        }`
-      );
       this.reset();
       return null;
     }

src/demux/transmuxer.ts

@@ -112,11 +112,16 @@ export default class Transmuxer {
       if (decrypter.isSync()) {
         // Software decryption is progressive. Progressive decryption may not return a result on each call. Any cached
         // data is handled in the flush() call
-        const decryptedData = decrypter.softwareDecrypt(
+        let decryptedData = decrypter.softwareDecrypt(
           uintData,
           keyData.key.buffer,
           keyData.iv.buffer
         );
+        // For Low-Latency HLS Parts, decrypt in place, since part parsing is expected on push progress
+        const loadingParts = chunkMeta.part > -1;
+        if (loadingParts) {
+          decryptedData = decrypter.flush();
+        }
         if (!decryptedData) {
           stats.executeEnd = now();
           return emptyResult(chunkMeta);

src/loader/m3u8-parser.ts

@@ -258,19 +258,7 @@ export default class M3U8Parser {
         if (Number.isFinite(frag.duration)) {
           frag.start = totalduration;
           if (levelkeys) {
-            frag.levelkeys = levelkeys;
-            const { encryptedFragments } = level;
-            if (
-              frag.levelkeys &&
-              Object.keys(frag.levelkeys).some(
-                (format) => frag.levelkeys![format].isCommonEncryption
-              ) &&
-              (!encryptedFragments.length ||
-                encryptedFragments[encryptedFragments.length - 1].levelkeys !==
-                  levelkeys)
-            ) {
-              encryptedFragments.push(frag);
-            }
+            setFragLevelKeys(frag, levelkeys, level);
           }
           frag.sn = currentSN;
           frag.level = id;
@@ -512,6 +500,9 @@ export default class M3U8Parser {
       assignProgramDateTime(frag, prevFrag);
       frag.cc = discontinuityCounter;
       level.fragmentHint = frag;
+      if (levelkeys) {
+        setFragLevelKeys(frag, levelkeys, level);
+      }
     }
     const fragmentLength = fragments.length;
     const firstFragment = fragments[0];
@@ -661,3 +652,22 @@ function setInitSegment(
   }
   frag.initSegment = null;
 }
+
+function setFragLevelKeys(
+  frag: Fragment,
+  levelkeys: { [key: string]: LevelKey },
+  level: LevelDetails
+) {
+  frag.levelkeys = levelkeys;
+  const { encryptedFragments } = level;
+  if (
+    (!encryptedFragments.length ||
+      encryptedFragments[encryptedFragments.length - 1].levelkeys !==
+        levelkeys) &&
+    Object.keys(levelkeys).some(
+      (format) => levelkeys![format].isCommonEncryption
+    )
+  ) {
+    encryptedFragments.push(frag);
+  }
+}