media3/docs/retrieving-metadata.md

title
Retrieving metadata

During playback

Media metadata can be retrieved during playback in multiple ways, depending on the exact needs. Possible options are to listen to onTracksChanged, to listen to onStaticMetadataChanged or to add a MetadataOutput to the player.

Without playback

If playback is not needed, it is more efficient to use the [MetadataRetriever][] to extract media metadata because it avoids having to create and prepare a player.

ListenableFuture<TrackGroupArray> trackGroupsFuture =
   MetadataRetriever.retrieveMetadata(context, mediaItem);
Futures.addCallback(
   trackGroupsFuture,
   new FutureCallback<TrackGroupArray>() {
     @Override
     public void onSuccess(TrackGroupArray trackGroups) {
       handleMetadata(trackGroups);
     }

     @Override
     public void onFailure(Throwable t) {
       handleFailure(t);
     }
   },
   executor);

{: .language-java}

Motion photos

It is also possible to extract the metadata of a motion photo, containing the image and video offset and length for example. The supported formats are:

• JPEG motion photos recorded by Google Pixel and Samsung camera apps. This format is playable by ExoPlayer and the associated metadata can therefore be retrieved with a player or using the MetadataRetriever.
• HEIC motion photos recorded by Google Pixel and Samsung camera apps. This format is currently not playable by ExoPlayer and the associated metadata should therefore be retrieved using the MetadataRetriever.

For motion photos, the TrackGroupArray obtained with the MetadataRetriever contains a TrackGroup with a single Format enclosing a [MotionPhotoMetadata][] metadata entry.

for (int i = 0; i < trackGroups.length; i++) {
 TrackGroup trackGroup = trackGroups.get(i);
 Metadata metadata = trackGroup.getFormat(0).metadata;
 if (metadata != null && metadata.length() == 1) {
   Metadata.Entry metadataEntry = metadata.get(0);
   if (metadataEntry instanceof MotionPhotoMetadata) {
     MotionPhotoMetadata motionPhotoMetadata = (MotionPhotoMetadata) metadataEntry;
     handleMotionPhotoMetadata(motionPhotoMetadata);
   }
 }
}

{: .language-java}

[MetadataRetriever]: {{ site.exo_sdk }}/MetadataRetriever.html [MotionPhotoMetadata]: {{ site.exo_sdk }}/metadata/mp4/MotionPhotoMetadata.html