MediaPlayer example: Display track-specific metadata

Update the metadata information to show track-specific metadata for
the active tracks, besides the media's metadata.
Add a missing signal emmission on darwin's mediaplayer.

Change-Id: I0513d3ab0c2b62cf74ef060bc1367e2589f68bcd
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
(cherry picked from commit af3286225434fd995b4dfdcb6ebb379b6ffa741d)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 24 insertions, 8 deletions

diff --git a/examples/multimedia/video/mediaplayer/MetadataInfo.qml b/examples/multimedia/video/mediaplayer/MetadataInfo.qml
index aea0fd1df..5019c1759 100644
--- a/examples/multimedia/video/mediaplayer/MetadataInfo.qml
+++ b/examples/multimedia/video/mediaplayer/MetadataInfo.qml
@@ -57,14 +57,19 @@ Item {
     id: root
     implicitWidth: 200
 
+    function clear() {
+        elements.clear();
+    }
+
     function read(metadata) {
-        elements.clear()
-        for (var key of metadata.keys()) {
-            if (metadata.stringValue(key)) {
-                elements.append(
-                            { name: metadata.metaDataKeyToString(key)
-                            , value: metadata.stringValue(key)
-                            })
+        if (metadata) {
+            for (var key of metadata.keys()) {
+                if (metadata.stringValue(key)) {
+                    elements.append(
+                                { name: metadata.metaDataKeyToString(key)
+                                , value: metadata.stringValue(key)
+                                })
+                }
             }
         }
     }
diff --git a/examples/multimedia/video/mediaplayer/main.qml b/examples/multimedia/video/mediaplayer/main.qml
index 0bbf672ac..ea31ba2ed 100644
--- a/examples/multimedia/video/mediaplayer/main.qml
+++ b/examples/multimedia/video/mediaplayer/main.qml
@@ -73,6 +73,14 @@ Window {
 
     MediaPlayer {
         id: mediaPlayer
+
+        function updateMetadata() {
+            metadataInfo.clear();
+            metadataInfo.read(mediaPlayer.metaData);
+            metadataInfo.read(mediaPlayer.audioTracks[mediaPlayer.activeAudioTrack]);
+            metadataInfo.read(mediaPlayer.videoTracks[mediaPlayer.activeVideoTrack]);
+        }
+
         videoOutput: videoOutput
         audioOutput: AudioOutput {
             id: audio
@@ -81,7 +89,7 @@ Window {
         }
 
         onErrorOccurred: { mediaErrorText.text = mediaPlayer.errorString; mediaError.open() }
-        onMetaDataChanged: { metadataInfo.read(mediaPlayer.metaData) }
+        onMetaDataChanged: { updateMetadata() }
         onTracksChanged: {
             audioTracksInfo.read(mediaPlayer.audioTracks);
             audioTracksInfo.selectedTrack = mediaPlayer.activeAudioTrack;
@@ -89,7 +97,9 @@ Window {
             videoTracksInfo.selectedTrack = mediaPlayer.activeVideoTrack;
             subtitleTracksInfo.read(mediaPlayer.subtitleTracks);
             subtitleTracksInfo.selectedTrack = mediaPlayer.activeSubtitleTrack;
+            updateMetadata()
         }
+        onActiveTracksChanged: { updateMetadata() }
     }
 
     PlayerMenuBar {
diff --git a/src/multimedia/platform/darwin/mediaplayer/avfmediaplayer.mm b/src/multimedia/platform/darwin/mediaplayer/avfmediaplayer.mm
index 0b71880aa..311a87a31 100644
--- a/src/multimedia/platform/darwin/mediaplayer/avfmediaplayer.mm
+++ b/src/multimedia/platform/darwin/mediaplayer/avfmediaplayer.mm
@@ -1163,6 +1163,7 @@ void AVFMediaPlayer::setActiveTrack(QPlatformMediaPlayer::TrackType type, int in
     }
     for (int i = 0; i < t.count(); ++i)
         t.at(i).enabled = (i == index);
+    emit activeTracksChanged();
 }
 
 int AVFMediaPlayer::activeTrack(QPlatformMediaPlayer::TrackType type)