Develop Reference

Implementing Android Auto voice command support

I am working on implementing voice commands for Android Auto using media player callback methods. I am having trouble getting Auto to recognize that I am asking to play a title on my application: “Play [x] on MyApp”. I understand that it takes a few days after being published for this command to work, but I should still be able to say “Play [x]” while the media session is already running and it should use onPrepareFromSearch and onPlayFromSearch methods to search for and play content.
When I say “Play [x] on MyApp” I get the response “I looked for [x] on MyApp on Google Play Music but it either isn’t available or it can’t be played right now”.
When I say “Play [x]” while my media service is running it will usually redirect me to Google Play Music.
I am able to pause, resume, skip forward and skip backward using voice commands and I see those being logged but when I try to perform a voice search neither onPrepareFromSearch nor onPlayFromSearch are called.
Things I have tried:
Added an <intent-filter> for MEDIA_PLAY_FROM_SEARCH to an activity in my application as to mark my application available to search for media
Implemented onPrepareFromSearch and onPlayFromSearch in my MediaSessionCompat.Callback
Added ACTION_PLAY_FROM_SEARCH and ACTION_PREPARE_FROM_SEARCH as supported actions.
Set the media session flags FLAG_HANDLES_MEDIA_BUTTONS and FLAG_HANDLES_TRANSPORT_CONTROLS
Added support for Android Auto as per the documentation here: https://developer.android.com/training/cars/media/auto
Is there a step I am missing in order to get this to work?

Google ChromeCast Playlist from Android Device

I'm using a sample app for the RemotePlaybackClient from #commonsware to play a video from a url to Google ChromeCast dongle, the app works like a charm but I would like to implement a playlist, any idea how to send a playlist to ChromeCast from an Android device?
As usual, I don't need code, just links, tutorials, etc... Tks.

Are you using a custom receiver?
If so, you can pass a json to such receiver with your playlist and manage that list with a playback state.

you might try looking at "mediaList" object here. Thats your playlist object.
This is a totally different project (not mediaRouter api but ccl instead) that i used because i wanted to implement a playlist and wanted to NOT take on my own receiver app. I wanted to see whether the default receiver could collaborate with an existing github sender sample - altered slightly to manipulate both a playList implemented in the "mediaList" AND to send appropriate and successive PLAY instructions to the default recieiver app when that app's state as relayed in normal "consumer" message traffic indicated state=ready.
D/ccl_VideoCastManager(31057): onApplicationStatusChanged() reached: Ready To Cast
So, when the default receiver fires the "ready" message, the senderApp can just call getNext to return an entry from "mediaList" and then send a "play(mediaInfo.entry)" to the default receiver.
onApplicationStatusChanged() is the interface used by the ccl to commmunicate/ sync player state between the local/remote players. When the default-remote-state changes to "ready to cast" you can use "VideoCastManager" and its base class to select the next MediaInfo entry and format a message for the remote to play it...
this.startCastControllerActivity(this.mContext, nextMediaInfo, 0, true);
code above from sender/ccl base tells the receiver to play the item that the sender has determine is next from list.
Note : i was advised to implement the playlist on a custom receiver app that i would write. Im not that ambitious and found a very simple hack on the sender/ccl classes that was reliable enough for me.

Casting video to ChromeCast by Youtube app

I tried using a Android phone to cast to Chromecast device by Youtube app. I added some Videos to queue, then I used another phone to cast to Chromecast device. The second one automatically knows the videos added to queue on the first one.
I don't know how Youtube app can do this?
EDIT I guess Youtube app uses one custom data channel besides Media channel. When Video is added to queue, sender app will send somethings (eg: videoId) to receiver. Receiver will save it in array of video ID. When another phone connects to Chromecast device, It'll receiver array of video ID from the receiver. Can anyone give other solutions? Thanks

I guess what you are asking is how you can create a play list, potentially shared by multiple devices. If that is the case, you have a couple of choices:
keep the playlist in the receiver: this is the simplest option. This will be a simple array on the receiver, kept in memory, which will go away when application ends. A custom receiver is required and it can implement the methods such as "append, insert, get, clear, ... to provide what the senders need. When each sender connects, it can ask (calling 'get' for example) for the current "queue" and then can modify the queue by other methods such as 'clear', 'append', 'insert', .... Note that there is no long-term persistence on the receiver (local storage is available but will be cleared as son as the app is gone).
keep the playlist in the cloud: you need to do most of the things that you do in the previous option but you also persist the playlist to the cloud; the advantage is that playlist lasts beyond the life of a session (this may or may not be desired). In addition, sender apps can potentially get the playlist fro the cloud directly, if needed.
The important thing is that the main storage for your playlist is not your sender devices; they don't know (and shouldn't know) abut the presence of other senders in the eco-system.
On the receiver side, we recently published a simple sample that sows how the notion of (local) playlist can be implemented; that is a simplified example but is enough to show that with minimal work, you can take advantage of the Media Channel; for more sophisticated handling of a shared queue, you definitely need an out-of-bound channel/namespace to handle all the additional api's that I mentioned above.

accessing one app from another app

Can someone explain me how to control one application from another application? I'm running a music player in an app1 using service class. And I want to stop that music player from another app.,i.e app2. But, I'm fallin short o the concept.

Depends what you need to do.
Opening another activity (or sending messages) is by using Intents:
Intent intent = new Intent();
intent.setAction(android.content.Intent.ACTION_VIEW);
// ...
startActivity(intent);
Starting service is by using startService()
What you are trying to do can also be done using Intent broadcasts but only if your target app supports and listens to specific actions on the broadcast. You need to see if there is such an ACTION supported.

I'd like to continue this question a bit.
In my case, I'm developing the target app and I need to implement few simple procedure calls for the main app. Basically 'start', 'stop' and 'sendData'. As I wrote, I'm developing the target app so I can support whatever I want. Which would you say is the easiest way to handle.
The whole situation a bit more explained. Main app would like my app to start it's work, and if needed they'll request that I turn myself off and when the main app is closing it would request me to send my data forward.
I'm quite new to android development, so code snippets are preferable. Thank you.

Receiving MP3 play actions in a BroadcastReceiver in Android

I am trying to build an Android Service that should get notified when the user starts playing an MP3. I checked LogCat when I start playing a song and saw that the following Intent is logged:
Intent { act=com.android.music.PLAYBACK_VIEWER flg=0x4000000 cmp=com.android.music/.MediaPlaybackActivity }
I couldn't figure out how to write an IntentFilter to let my Service know that this event has occurred and let me know the name of the song that will be played. I searched Android reference but could not find anything on PLAYBACK_VIEWER.
Thanks,
C

I would do neither. First, none of this is part of the SDK and so may change at any point. Second, this will only work for the built-in media player application, not any third-party or OEM-supplied media players, and I expect more people to gravitate to those.