[HLS] Add CHANNELS attribute to #EXT-X-MEDIA

As specified in HLS spec (https://tools.ietf.org/html/rfc8216):

All audio EXT-X-MEDIA tags SHOULD have a CHANNELS attribute.  If a
Master Playlist contains two Renditions encoded with the same
codec but a different number of channels, then the CHANNELS
attribute is REQUIRED; otherwise, it is OPTIONAL.

Fixes #299

Change-Id: Ic2308c39b170178b11cb0d94c3a8083c8b5f3353

packager/app/test/testdata/bear-640x360-av-master-golden.m3u8

@@ -1,5 +1,5 @@
 #EXTM3U
 ## Generated with https://github.com/google/shaka-packager version <tag>-<hash>-<test>
-#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="audio",NAME="stream_0",URI="audio.m3u8"
+#EXT-X-MEDIA:TYPE=AUDIO,URI="audio.m3u8",GROUP-ID="audio",NAME="stream_0",CHANNELS="2"
 #EXT-X-STREAM-INF:BANDWIDTH=1217518,CODECS="avc1.64001e,mp4a.40.2",RESOLUTION=640x360,AUDIO="audio"
 video.m3u8

packager/app/test/testdata/bear-640x360-av-mp4-master-cenc-golden.m3u8

@@ -1,5 +1,5 @@
 #EXTM3U
 ## Generated with https://github.com/google/shaka-packager version <tag>-<hash>-<test>
-#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="audio",NAME="stream_0",URI="audio.m3u8"
+#EXT-X-MEDIA:TYPE=AUDIO,URI="audio.m3u8",GROUP-ID="audio",NAME="stream_0",CHANNELS="2"
 #EXT-X-STREAM-INF:BANDWIDTH=1111147,CODECS="avc1.64001e,mp4a.40.2",RESOLUTION=640x360,AUDIO="audio"
 video.m3u8

packager/app/test/testdata/bear-640x360-av-mp4-master-golden.m3u8

@@ -1,5 +1,5 @@
 #EXTM3U
 ## Generated with https://github.com/google/shaka-packager version <tag>-<hash>-<test>
-#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="audio",NAME="stream_0",URI="audio/audio.m3u8"
+#EXT-X-MEDIA:TYPE=AUDIO,URI="audio/audio.m3u8",GROUP-ID="audio",NAME="stream_0",CHANNELS="2"
 #EXT-X-STREAM-INF:BANDWIDTH=1105129,CODECS="avc1.64001e,mp4a.40.2",RESOLUTION=640x360,AUDIO="audio"
 video/video.m3u8

packager/hls/base/master_playlist.cc

@@ -20,6 +20,26 @@ namespace hls {
 
 namespace {
 
+void AppendMediaTag(const std::string& base_url,
+                    const std::string& group_id,
+                    const MediaPlaylist* audio_playlist,
+                    std::string* out) {
+  DCHECK(audio_playlist);
+  DCHECK(out);
+
+  out->append("#EXT-X-MEDIA:TYPE=AUDIO");
+  base::StringAppendF(out, ",URI=\"%s\"",
+                      (base_url + audio_playlist->file_name()).c_str());
+  base::StringAppendF(out, ",GROUP-ID=\"%s\"", group_id.c_str());
+  std::string language = audio_playlist->GetLanguage();
+  if (!language.empty())
+    base::StringAppendF(out, ",LANGUAGE=\"%s\"", language.c_str());
+  base::StringAppendF(out, ",NAME=\"%s\"", audio_playlist->name().c_str());
+  base::StringAppendF(out, ",CHANNELS=\"%d\"",
+                      audio_playlist->GetNumChannels());
+  out->append("\n");
+}
+
 void AppendStreamInfoTag(uint64_t bitrate,
                          const std::string& codecs,
                          uint32_t width,
@@ -81,21 +101,7 @@ bool MasterPlaylist::WriteMasterPlaylist(const std::string& base_url,
 
     uint64_t max_audio_bitrate = 0;
     for (const MediaPlaylist* audio_playlist : audio_playlists) {
-      base::StringAppendF(
+      AppendMediaTag(base_url, group_id, audio_playlist, &audio_output);
-          &audio_output,
-          "#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID=\"%s\",NAME=\"%s\",",
-          group_id.c_str(), audio_playlist->name().c_str());
-      std::string language = audio_playlist->GetLanguage();
-      if (!language.empty()) {
-        base::StringAppendF(
-            &audio_output,
-            "LANGUAGE=\"%s\",",
-            language.c_str());
-      }
-      base::StringAppendF(
-          &audio_output,
-          "URI=\"%s\"\n",
-          (base_url + audio_playlist->file_name()).c_str());
       const uint64_t audio_bitrate = audio_playlist->Bitrate();
       if (audio_bitrate > max_audio_bitrate)
         max_audio_bitrate = audio_bitrate;

packager/hls/base/master_playlist_unittest.cc

@@ -128,6 +128,7 @@ TEST_F(MasterPlaylistTest, WriteMasterPlaylistVideoAndAudio) {
   MockMediaPlaylist english_playlist(kVodPlaylist, "eng.m3u8", "english",
                                      "audiogroup");
   EXPECT_CALL(english_playlist, GetLanguage()).WillRepeatedly(Return("en"));
+  EXPECT_CALL(english_playlist, GetNumChannels()).WillRepeatedly(Return(2));
   english_playlist.SetStreamTypeForTesting(
       MediaPlaylist::MediaPlaylistStreamType::kPlayListAudio);
   english_playlist.SetCodecForTesting(audio_codec);
@@ -142,6 +143,7 @@ TEST_F(MasterPlaylistTest, WriteMasterPlaylistVideoAndAudio) {
   MockMediaPlaylist spanish_playlist(kVodPlaylist, "spa.m3u8", "espanol",
                                      "audiogroup");
   EXPECT_CALL(spanish_playlist, GetLanguage()).WillRepeatedly(Return("es"));
+  EXPECT_CALL(spanish_playlist, GetNumChannels()).WillRepeatedly(Return(5));
   spanish_playlist.SetStreamTypeForTesting(
       MediaPlaylist::MediaPlaylistStreamType::kPlayListAudio);
   spanish_playlist.SetCodecForTesting(audio_codec);
@@ -162,15 +164,17 @@ TEST_F(MasterPlaylistTest, WriteMasterPlaylistVideoAndAudio) {
       "#EXTM3U\n"
       "## Generated with https://github.com/google/shaka-packager version "
       "test\n"
-      "#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID=\"audiogroup\",NAME=\"english\","
+      "#EXT-X-MEDIA:TYPE=AUDIO,URI=\"http://playlists.org/eng.m3u8\","
-      "LANGUAGE=\"en\",URI=\"http://playlists.org/eng.m3u8\"\n"
+      "GROUP-ID=\"audiogroup\",LANGUAGE=\"en\",NAME=\"english\","
-      "#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID=\"audiogroup\",NAME=\"espanol\","
+      "CHANNELS=\"2\"\n"
-      "LANGUAGE=\"es\",URI=\"http://playlists.org/spa.m3u8\"\n"
+      "#EXT-X-MEDIA:TYPE=AUDIO,URI=\"http://playlists.org/spa.m3u8\","
-      "#EXT-X-STREAM-INF:BANDWIDTH=360000,CODECS=\"sdvideocodec,audiocodec\""
+      "GROUP-ID=\"audiogroup\",LANGUAGE=\"es\",NAME=\"espanol\","
-      ",RESOLUTION=800x600,AUDIO=\"audiogroup\"\n"
+      "CHANNELS=\"5\"\n"
+      "#EXT-X-STREAM-INF:BANDWIDTH=360000,CODECS=\"sdvideocodec,audiocodec\","
+      "RESOLUTION=800x600,AUDIO=\"audiogroup\"\n"
       "http://playlists.org/sd.m3u8\n"
-      "#EXT-X-STREAM-INF:BANDWIDTH=760000,CODECS=\"hdvideocodec,audiocodec\""
+      "#EXT-X-STREAM-INF:BANDWIDTH=760000,CODECS=\"hdvideocodec,audiocodec\","
-      ",RESOLUTION=800x600,AUDIO=\"audiogroup\"\n"
+      "RESOLUTION=800x600,AUDIO=\"audiogroup\"\n"
       "http://playlists.org/hd.m3u8\n";
 
   ASSERT_EQ(expected, actual);
@@ -198,6 +202,7 @@ TEST_F(MasterPlaylistTest, WriteMasterPlaylistMultipleAudioGroups) {
   MockMediaPlaylist eng_lo_playlist(kVodPlaylist, "eng_lo.m3u8", "english_lo",
                                     "audio_lo");
   EXPECT_CALL(eng_lo_playlist, GetLanguage()).WillRepeatedly(Return("en"));
+  EXPECT_CALL(eng_lo_playlist, GetNumChannels()).WillRepeatedly(Return(1));
   eng_lo_playlist.SetStreamTypeForTesting(
       MediaPlaylist::MediaPlaylistStreamType::kPlayListAudio);
   eng_lo_playlist.SetCodecForTesting(audio_codec_lo);
@@ -212,6 +217,7 @@ TEST_F(MasterPlaylistTest, WriteMasterPlaylistMultipleAudioGroups) {
   MockMediaPlaylist eng_hi_playlist(kVodPlaylist, "eng_hi.m3u8", "english_hi",
                                     "audio_hi");
   EXPECT_CALL(eng_hi_playlist, GetLanguage()).WillRepeatedly(Return("en"));
+  EXPECT_CALL(eng_hi_playlist, GetNumChannels()).WillRepeatedly(Return(8));
   eng_hi_playlist.SetStreamTypeForTesting(
       MediaPlaylist::MediaPlaylistStreamType::kPlayListAudio);
   eng_hi_playlist.SetCodecForTesting(audio_codec_hi);
@@ -232,15 +238,17 @@ TEST_F(MasterPlaylistTest, WriteMasterPlaylistMultipleAudioGroups) {
       "#EXTM3U\n"
       "## Generated with https://github.com/google/shaka-packager version "
       "test\n"
-      "#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID=\"audio_hi\",NAME=\"english_hi\","
+      "#EXT-X-MEDIA:TYPE=AUDIO,URI=\"http://anydomain.com/eng_hi.m3u8\","
-      "LANGUAGE=\"en\",URI=\"http://anydomain.com/eng_hi.m3u8\"\n"
+      "GROUP-ID=\"audio_hi\",LANGUAGE=\"en\",NAME=\"english_hi\","
-      "#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID=\"audio_lo\",NAME=\"english_lo\","
+      "CHANNELS=\"8\"\n"
-      "LANGUAGE=\"en\",URI=\"http://anydomain.com/eng_lo.m3u8\"\n"
+      "#EXT-X-MEDIA:TYPE=AUDIO,URI=\"http://anydomain.com/eng_lo.m3u8\","
-      "#EXT-X-STREAM-INF:BANDWIDTH=400000,CODECS=\"videocodec,audiocodec_hi\""
+      "GROUP-ID=\"audio_lo\",LANGUAGE=\"en\",NAME=\"english_lo\","
-      ",RESOLUTION=800x600,AUDIO=\"audio_hi\"\n"
+      "CHANNELS=\"1\"\n"
+      "#EXT-X-STREAM-INF:BANDWIDTH=400000,CODECS=\"videocodec,audiocodec_hi\","
+      "RESOLUTION=800x600,AUDIO=\"audio_hi\"\n"
       "http://anydomain.com/video.m3u8\n"
-      "#EXT-X-STREAM-INF:BANDWIDTH=350000,CODECS=\"videocodec,audiocodec_lo\""
+      "#EXT-X-STREAM-INF:BANDWIDTH=350000,CODECS=\"videocodec,audiocodec_lo\","
-      ",RESOLUTION=800x600,AUDIO=\"audio_lo\"\n"
+      "RESOLUTION=800x600,AUDIO=\"audio_lo\"\n"
       "http://anydomain.com/video.m3u8\n";
 
   ASSERT_EQ(expected, actual);

packager/hls/base/media_playlist.cc

@@ -434,6 +434,10 @@ std::string MediaPlaylist::GetLanguage() const {
   return LanguageToShortestForm(lang);
 }
 
+int MediaPlaylist::GetNumChannels() const {
+  return media_info_.audio_info().num_channels();
+}
+
 bool MediaPlaylist::GetDisplayResolution(uint32_t* width,
                                          uint32_t* height) const {
   DCHECK(width);

packager/hls/base/media_playlist.h

@@ -155,6 +155,9 @@ class MediaPlaylist {
   ///         form.  May be an empty string for video.
   virtual std::string GetLanguage() const;
 
+  /// @return number of channels for audio. 0 is returned for video.
+  virtual int GetNumChannels() const;
+
   /// @return true if |width| and |height| have been set with a valid
   ///         resolution values.
   virtual bool GetDisplayResolution(uint32_t* width, uint32_t* height) const;

packager/hls/base/media_playlist_unittest.cc

@@ -432,6 +432,22 @@ TEST_F(MediaPlaylistMultiSegmentTest, GetLanguage) {
   EXPECT_EQ("apa", media_playlist_.GetLanguage());  // no short form exists
 }
 
+TEST_F(MediaPlaylistMultiSegmentTest, GetNumChannels) {
+  MediaInfo media_info;
+  media_info.set_reference_time_scale(kTimeScale);
+
+  // Returns 0 by default if not audio.
+  EXPECT_EQ(0, media_playlist_.GetNumChannels());
+
+  media_info.mutable_audio_info()->set_num_channels(2);
+  ASSERT_TRUE(media_playlist_.SetMediaInfo(media_info));
+  EXPECT_EQ(2, media_playlist_.GetNumChannels());
+
+  media_info.mutable_audio_info()->set_num_channels(8);
+  ASSERT_TRUE(media_playlist_.SetMediaInfo(media_info));
+  EXPECT_EQ(8, media_playlist_.GetNumChannels());
+}
+
 TEST_F(MediaPlaylistMultiSegmentTest, InitSegment) {
   valid_video_media_info_.set_reference_time_scale(90000);
   valid_video_media_info_.set_init_segment_name("init_segment.mp4");

packager/hls/base/mock_media_playlist.h

@@ -43,6 +43,7 @@ class MockMediaPlaylist : public MediaPlaylist {
   MOCK_CONST_METHOD0(GetLongestSegmentDuration, double());
   MOCK_METHOD1(SetTargetDuration, void(uint32_t target_duration));
   MOCK_CONST_METHOD0(GetLanguage, std::string());
+  MOCK_CONST_METHOD0(GetNumChannels, int());
   MOCK_CONST_METHOD2(GetDisplayResolution,
                      bool(uint32_t* width, uint32_t* height));
 };