Video Streaming (RPC v4.5+)

In order to stream video from an SDL app, we only need to manage a few things. For the most part, the library will handle the majority of logic needed to perform video streaming.

SDL Remote Display

The SdlRemoteDisplay base class provides the easiest way to start streaming using SDL. The SdlRemoteDisplay is extended from Android's Presentation class with modifications to work with other aspects of the SDL Android library.

Note

It is recommended that you extend this as a local class within the service that has the SdlManager instance.

Extending this class gives developers a familiar, native experience to handling layouts and events on screen.

public static class MyDisplay extends SdlRemoteDisplay{
    public MyDisplay(Context context, Display display) {
        super(context, display);
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.stream);

        Button button = findViewById(R.id.button);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                DebugTool.logInfo(TAG, "Button Clicked");
            }
        });
    }

    //onViewResized is added in SDL v5.1+
    @Override
    public void onViewResized(int width, int height) {
        DebugTool.logInfo(TAG, "Remote view new width and height ("+ width + ", " + height + ")");
    }
}

Note

If you are obfuscating the code in your app, make sure to exclude your class that extends SdlRemoteDisplay. For more information on how to do that, you can check Proguard Guidelines.

Managing the Stream

The VideoStreamManager can be used to start streaming video after the SdlManager has successfully been started. This is performed by calling the method startRemoteDisplayStream(Context context, final Class<? extends SdlRemoteDisplay> remoteDisplay, final VideoStreamingParameters parameters, final boolean encrypted, VideoStreamingRange supportedLandscapeStreamingRange, VideoStreamingRange supportedPortraitStreamingRange).

public static class MyDisplay extends SdlRemoteDisplay {

    public MyDisplay(Context context, Display display) {
        super(context, display);
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.stream);

        String videoUri = "android.resource://" + context.getPackageName() + "/" + R.raw.sdl;
        VideoView videoView = findViewById(R.id.videoView);
        videoView.setVideoURI(Uri.parse(videoUri));
        videoView.start();
    }

    //onViewResized is added in SDL v5.1+
    @Override
    public void onViewResized(int width, int height) {
        DebugTool.logInfo(TAG, "Remote view new width and height ("+ width + ", " + height + ")");
    }
}

//...

if (sdlManager.getVideoStreamManager() != null) {
    sdlManager.getVideoStreamManager().start(new CompletionListener() {
        @Override
        public void onComplete(boolean success) {
            if (success) {
                sdlManager.getVideoStreamManager().startRemoteDisplayStream(getApplicationContext(), MyDisplay.class, null, false, null, null);
            } else {
                DebugTool.logError(TAG, "Failed to start video streaming manager");
            }
        }
    });
}

Ending the Stream

When the HMIStatus is back to HMI_NONE it is time to stop the stream. This is accomplished through a method stopStreaming().

Map<FunctionID, OnRPCNotificationListener> onRPCNotificationListenerMap = new HashMap<>();
onRPCNotificationListenerMap.put(FunctionID.ON_HMI_STATUS, new OnRPCNotificationListener() {
    @Override
    public void onNotified(RPCNotification notification) {
        OnHMIStatus status = (OnHMIStatus) notification;
        if (status != null && status.getHmiLevel() == HMILevel.HMI_NONE) {

            //Stop the stream
            if (sdlManager.getVideoStreamManager() != null && sdlManager.getVideoStreamManager().isStreaming()) {
                sdlManager.getVideoStreamManager().stopStreaming();
            }

        }
    }
});
builder.setRPCNotificationListeners(onRPCNotificationListenerMap);

Handling HMI Scaling (RPC v6.0+)

If the HMI scales the video stream, you will have to handle scaling the projected view, touches and haptic rectangles yourself (this is all handled for you behind the scenes in the VideoStreamManager API). To find out if the HMI scales the video stream, you must for query and check the VideoStreamingCapability for the scale property. Please check the Adaptive Interface Capabilities section for more information on how to query for this property using the system capability manager.

Video Streaming Parameters (SDL v5.1+)

Starting with SDL version 5.1+ the VideoStreamingParameters you provide will automatically be aligned with the VideoStreamingCapabilities provided by the HMI.
If the HMI provides the scale or resolution in the VideoStreamingCapabilities the video stream will use that scale or resolution. Otherwise, the scale or resolution you defined in the VideoStreamingParameters will be used.
If the HMI provides the bitrate or preferred frame rate in the VideoStreamingCapabilities and they are also defined in the VideoStreamingParamerters you provided, the smaller bitrate or preferred frame rate will be used.

Video Framerate

Starting with SDL v5.1, the video stream manager works behind the scene to create a consistent video stream that matches the framerate set in VideoStreamingParameters. This is the now the default behavior but you have the option to revert to the old behavior by setting the stableFrameRate flag to false in the VideoStreamingParameters.

VideoStreamingParameters params = new VideoStreamingParameters();
//Turn on use of stable frame rate
params.setStableFrameRate(true);
//Set the frame rate that you would wish to stream at
params.setFrameRate(30);

Supporting Different Video Streaming Window Sizes (RPC v7.1+)

Some HMIs support multiple view sizes and may resize your SDL app's view during video streaming (i.e. to a collapsed view, split screen, preview mode or picture-in-picture). By default, your app will support all the view sizes and the VideoStreamManager will resize the video stream when the HMI notifies the app of the updated screen size.
If you you wish to support only some screen sizes, you can configure the two VideoStreamingRange parameters when starting your video stream using the startRemoteDisplay method. One range is for landscape orientations and one range is for portrait orientations.
In these VideoStreamingRange parameters you can define different view sizes that you wish to support in the event that the HMI resizes the view during the stream.
In the VideoStreamingRange you will define a minimum and maximum resolution, minimum diagonal, and a minimum and maximum aspect ratio. Any values you do not wish to use should be set to null.
If you want to support all possible landscape or portrait sizes you can simply pass null for supportedLandscapeStreamingRange, supportedPortraitStreamingRange, or both.
If you wish to only support landscape orientation or only support portrait orientation you "disable" the range by passing a VideoStreamingRange with all 0 values set.

//This VideoStreamingRange represents a disabled Range and can be passed if you do not wish to support landscape orientation or portrait orientation
final VideoStreamingRange disabledRange = new VideoStreamingRange(new Resolution(0, 0), new Resolution(0, 0), 0.0, 0.0, 0.0);

//This VideoStreamingRange represents that we will support any resolution between 500x200 and 800x400 no matter the diagonal size or aspect ratio
final VideoStreamingRange landscapeRange = new VideoStreamingRange(new Resolution(500, 200), new Resolution(800, 400), null, null, null);

//This VideoStreamingRange represents that we will support any aspect ratio between 1.0 and 2.5 no matter the resolution or diagonal size
final VideoStreamingRange portraitRange = new VideoStreamingRange(null, null, null, 1.0, 2.5);

if (sdlManager.getVideoStreamManager() != null) {
    sdlManager.getVideoStreamManager().start(new CompletionListener() {
        @Override
        public void onComplete(boolean success) {
            if (success) {
                sdlManager.getVideoStreamManager().startRemoteDisplayStream(getApplicationContext(), MyDisplay.class, null, false, landscapeRange, portraitRange);
            } else {
                DebugTool.logError(TAG, "Failed to start video streaming manager");
            }
        }
    });
}

Note

If you disable both the supportedLandscapeStreamingRange and supportedPortraitStreamingRange, video will not stream.

If the HMI resizes the view during the stream, the video stream will automatically restart with the new size and the onViewResized method you defined in your presentation class will be notified of the new screen size.

public static class MyDisplay extends SdlRemoteDisplay{
    public MyDisplay(Context context, Display display) {
        super(context, display);
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        //...
    }

    //onViewResized is added in SDL v5.1+
    @Override
    public void onViewResized(int width, int height) {
        DebugTool.logInfo(TAG, "Remote view new width and height ("+ width + ", " + height + ")");
        //Update presentation based on new resolution
    }
}

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