fix: Fix ENCA box parsing (#6298)

lib/media/segment_utils.js

@@ -349,7 +349,7 @@ shaka.media.SegmentUtils = class {
         // This signals an encrypted sample, which we can go inside of to
         // find the codec used.
         // Note: If encrypted, you can only have audio or video, not both.
-        .box('enca', Mp4Parser.visualSampleEntry)
+        .box('enca', Mp4Parser.audioSampleEntry)
         .box('encv', Mp4Parser.visualSampleEntry)
         .box('sinf', Mp4Parser.children)
         .box('frma', (box) => {

lib/util/mp4_parser.js

@@ -271,6 +271,63 @@ shaka.util.Mp4Parser = class {
   }
 
 
+  /**
+   * A callback that tells the Mp4 parser to treat the body of a box as a audio
+   * sample entry.  A audio sample entry has some fixed-sized fields
+   * describing the audio codec parameters, followed by an arbitrary number of
+   * appended children.  Each child is a box.
+   *
+   * @param {!shaka.extern.ParsedBox} box
+   * @export
+   */
+  static audioSampleEntry(box) {
+    // The "reader" starts at the payload, so we need to add the header to the
+    // start position.  The header size varies.
+    const headerSize = shaka.util.Mp4Parser.headerSize(box);
+
+    // 6 bytes reserved
+    // 2 bytes data reference index
+    box.reader.skip(8);
+    // 2 bytes version
+    const version = box.reader.readUint16();
+    // 2 bytes revision (0, could be ignored)
+    // 4 bytes reserved
+    box.reader.skip(6);
+
+    if (version == 2) {
+      // 16 bytes hard-coded values with no comments
+      // 8 bytes sample rate
+      // 4 bytes channel count
+      // 4 bytes hard-coded values with no comments
+      // 4 bytes bits per sample
+      // 4 bytes lpcm flags
+      // 4 bytes sample size
+      // 4 bytes samples per packet
+      box.reader.skip(48);
+    } else {
+      // 2 bytes channel count
+      // 2 bytes bits per sample
+      // 2 bytes compression ID
+      // 2 bytes packet size
+      // 2 bytes sample rate
+      // 2 byte reserved
+      box.reader.skip(12);
+    }
+
+    if (version == 1) {
+      // 4 bytes samples per packet
+      // 4 bytes bytes per packet
+      // 4 bytes bytes per frame
+      // 4 bytes bytes per sample
+      box.reader.skip(16);
+    }
+
+    while (box.reader.hasMoreData() && !box.parser.done_) {
+      box.parser.parseNext(box.start + headerSize, box.reader, box.partialOkay);
+    }
+  }
+
+
   /**
    * Create a callback that tells the Mp4 parser to treat the body of a box as a
    * binary blob and to parse the body's contents using the provided callback.