Android ChromeCast Coding – Passing MediaMetadata from Android to JS

Some commnents at Android Chromcast concept

Recently I was coding demo app including Chromecast support and custom reciever.
And, quite surprisingly, I had lot of problems passing metaData from Android part (sender) to JavaScript code (reciever).

Finnaly, after lot of googling and vasted time, I found out that
PROBLEM 1 : one can not create custom medaData, you have to use what Google prepared for you.
PROBLEM 2 : one can not pass any MediaMetadata field, because it is dependent on MediaMetadata type.
PROBLEM 3 : MediaMetadata naming is different at Android and JS part.

GENERAL

Google guide https://developer.android.com/reference/android/media/MediaMetadata
and https://developers.google.com/android/reference/com/google/android/gms/cast/MediaMetadata

There are 6 MediaMetadata types :
MEDIA_TYPE_GENERIC MEDIA_TYPE_PHOTO MEDIA_TYPE_MOVIE MEDIA_TYPE_TV_SHOW MEDIA_TYPE_MUSIC TRACK MEDIA_TYPE_USER

And various MediaMetadata fields :
// String movieMetadata.putString(MediaMetadata.KEY_TITLE, "TITLE"); movieMetadata.putString(MediaMetadata.KEY_SUBTITLE, "SUBTITLE"); movieMetadata.putString(MediaMetadata.KEY_ARTIST, "ARTIST"); movieMetadata.putString(MediaMetadata.KEY_ALBUM_ARTIST, "ALBUM_ARTIST"); movieMetadata.putString(MediaMetadata.KEY_ALBUM_TITLE, "ALBUM_TITLE"); movieMetadata.putString(MediaMetadata.KEY_COMPOSER, "COMPOSER"); movieMetadata.putString(MediaMetadata.KEY_SERIES_TITLE, "SERIES_TITLE"); movieMetadata.putString(MediaMetadata.KEY_STUDIO, "STUDIO"); movieMetadata.putString(MediaMetadata.KEY_LOCATION_NAME, "LOCATION_NAME");

// Date – java.util.Calendar
Calendar rightNow = Calendar.getInstance();
movieMetadata.putDate(MediaMetadata.KEY_CREATION_DATE, rightNow);
movieMetadata.putDate(MediaMetadata.KEY_BROADCAST_DATE, rightNow);
movieMetadata.putDate(MediaMetadata.KEY_RELEASE_DATE, rightNow);

// Int
movieMetadata.putInt(MediaMetadata.KEY_DISC_NUMBER, 1);
movieMetadata.putInt(MediaMetadata.KEY_TRACK_NUMBER, 2);
movieMetadata.putInt(MediaMetadata.KEY_SEASON_NUMBER,3);
movieMetadata.putInt(MediaMetadata.KEY_EPISODE_NUMBER, 4);
movieMetadata.putInt(MediaMetadata.KEY_WIDTH, 5);
movieMetadata.putInt(MediaMetadata.KEY_HEIGHT, 6);

// Double
movieMetadata.putDouble(MediaMetadata.KEY_LOCATION_LATITUDE, 11);
movieMetadata.putDouble(MediaMetadata.KEY_LOCATION_LONGITUDE, 12);

PROBLEM 1 : one can not create custom medaData, you have to use what Google prepared for you.
nothing to add here, you have to deal with it. If you need to pass your metaData – for example lenght, you can pass it using integer MediaMetadata fiel like KEY_DISC_NUMBER.

PROBLEM 2 : one can not pass any MediaMetadata field, because it is dependent on MediaMetadata type.
here comes the funny part. Google has restricted usage of MediaMetadata field for particular MediaMetadata types. So – for example – for type MEDIA_TYPE_MOVIE you can only pass fields :
– images (movieMetadata.addImage)
– Strings KEY_TITLE,KEY_STUDIO,KEY_SUBTITLE
– and Date KEY_RELEASE_DATE.
Nothing more.
See Googles table for details
https://developers.google.com/android/reference/com/google/android/gms/cast/MediaMetadata

PROBLEM 3 : MediaMetadata naming is different at Android and JS part, which is shocking for me.
This is really bad. One would expect for MediaMetadata fields name like „KEY_LOCATION_NAME“ at Android part will be recieved in JS part as something line „locationName“. No it is „location“. For „KEY_BROADCAST_DATE“ it is „originalAirdate“. Shame on you Google :).

Below details are based on my testing :
Android part (send as) / JavaScript part (recieved as) KEY_TITLE / title KEY_SUBTITLE / subtitle KEY_ARTIST / artist ALBUM_ARTIST / albumArtist ALBUM_TITLE / albumName COMPOSER / composer SERIES_TITLE / seriesTitle STUDIO / studio LOCATION_NAME / location KEY_CREATION_DATE / creationDateTime KEY_BROADCAST_DATE / originalAirdate KEY_RELEASE_DATE / releaseDate KEY_DISC_NUMBER / discNumber KEY_TRACK_NUMBER / trackNumber KEY_SEASON_NUMBER / season KEY_EPISODE_NUMBER / episode KEY_WIDTH / width KEY_HEIGHT / height KEY_LOCATION_LATITUDE / latitude KEY_LOCATION_LONGITUDE / longitude

CODING
As reference I am adding part of code so you can try it

1) Android (sender) part :
private MediaInfo buildMediaInfo() {

MediaMetadata movieMetadata = new MediaMetadata(MediaMetadata.MEDIA_TYPE_GENERIC);

movieMetadata.addImage(new WebImage(Uri.parse(mSelectedMedia.getImage(0))));
movieMetadata.addImage(new WebImage(Uri.parse(mSelectedMedia.getImage(1))));

// all available Keys – TEST / 20 in total

// String
movieMetadata.putString(MediaMetadata.KEY_TITLE, „TITLE“);
movieMetadata.putString(MediaMetadata.KEY_SUBTITLE, „SUBTITLE“);
movieMetadata.putString(MediaMetadata.KEY_ARTIST, „ARTIST“);
movieMetadata.putString(MediaMetadata.KEY_ALBUM_ARTIST, „ALBUM_ARTIST“);
movieMetadata.putString(MediaMetadata.KEY_ALBUM_TITLE, „ALBUM_TITLE“);
movieMetadata.putString(MediaMetadata.KEY_COMPOSER, „COMPOSER“);
movieMetadata.putString(MediaMetadata.KEY_SERIES_TITLE, „SERIES_TITLE“);
movieMetadata.putString(MediaMetadata.KEY_STUDIO, „STUDIO“);
movieMetadata.putString(MediaMetadata.KEY_LOCATION_NAME, „LOCATION_NAME“);

// Double
movieMetadata.putDouble(MediaMetadata.KEY_LOCATION_LATITUDE, 11);
movieMetadata.putDouble(MediaMetadata.KEY_LOCATION_LONGITUDE, 12);

return new MediaInfo.Builder(mSelectedMedia.getUrl())
.setStreamType(MediaInfo.STREAM_TYPE_BUFFERED)
.setContentType(„videos/mp4“)
.setMetadata(movieMetadata)
.setStreamDuration(mSelectedMedia.getDuration() * 1000)
.build();
}

2) JavaScript (reciever) part :

download whole code from view-source:http://vancura.cz/android/cast/reciever.html

// metaData sent by Android Sender part var senderMetadata = request.media.metadata;

// list keys in senderMetadata
var keys = Object.keys(senderMetadata);
console.log(‚senderMetadata contains ‚ + keys.length + ‚ keys: ‚+ keys);

// list values by keys
console.log(senderMetadata);

Then you will see in ChromeCast inspection log below MetaDate passed from Android to JS