diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index 0f0af429d2..685026cdb3 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -4,6 +4,7 @@
 
 * Fix the start of audio getting truncated when transitioning to a new
   item in a playlist of opus streams.
+* Fix detection of Dolby Atmos in HLS to match the HLS authoring specification.
 
 ### 2.10.6 (2019-10-17) ###
 
diff --git a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistParser.java b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistParser.java
index 030520f8cb..7ccbaf5d59 100644
--- a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistParser.java
+++ b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistParser.java
@@ -445,7 +445,15 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
                   ? Util.getCodecsOfType(variant.format.codecs, C.TRACK_TYPE_AUDIO)
                   : null;
           sampleMimeType = codecs != null ? MimeTypes.getMediaMimeType(codecs) : null;
-          int channelCount = parseChannelsAttribute(line, variableDefinitions);
+          String channelsString =
+              parseOptionalStringAttr(line, REGEX_CHANNELS, variableDefinitions);
+          int channelCount = Format.NO_VALUE;
+          if (channelsString != null) {
+            channelCount = Integer.parseInt(Util.splitAtFirst(channelsString, "/")[0]);
+            if (MimeTypes.AUDIO_E_AC3.equals(sampleMimeType) && channelsString.endsWith("/JOC")) {
+              sampleMimeType = MimeTypes.AUDIO_E_AC3_JOC;
+            }
+          }
           format =
               Format.createAudioContainerFormat(
                   /* id= */ formatId,
@@ -819,13 +827,6 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
     return roleFlags;
   }
 
-  private static int parseChannelsAttribute(String line, Map<String, String> variableDefinitions) {
-    String channelsString = parseOptionalStringAttr(line, REGEX_CHANNELS, variableDefinitions);
-    return channelsString != null
-        ? Integer.parseInt(Util.splitAtFirst(channelsString, "/")[0])
-        : Format.NO_VALUE;
-  }
-
   @Nullable
   private static SchemeData parseDrmSchemeData(
       String line, String keyFormat, Map<String, String> variableDefinitions)