If you have audio that doesn't have a specific piece of album art, you can define a default image url using the "default_album_art" key. The value can be set on initialization or through a public method. You can also set the default playlist art for metadata. If you don't define a piece of album art for your playlist you can also set that on initialization through the "default_playlist_art" key or through a public method.
Amplitude.init({
"songs": [...],
"default_album_art": "/url/to/default.jpg"
});
Amplitude.setDefaultAlbumArt( "/url/to/default.jpg" );
Amplitude.init({
"songs": [...],
"playlists": {
...
},
"default_playlist_art": "/url/to/default.jpg"
});
Amplitude.setDefaultPlaylistArt( "/url/to/default.jpg" );