Exploring the Code

In this example, the app uses a custom video renderer to display a inverted color version of the video.

InvertedColorsVideoRenderer is a custom class that extends the BaseVideoRenderer class (defined in the Android SDK). The BaseVideoRenderer class lets you define a custom video renderer to be used by a Vonage Video publisher or subscriber:

The InvertedColorsVideoRenderer() constructor sets a renderer property to a GLSurfaceView object. The app uses this object to display the video using OpenGL ES 2.0. The renderer for this GLSurfaceView object is set to a MyRenderer object. MyRenderer is a custom class that extends GLSurfaceView.Renderer, and it is used to render the video to the GLSurfaceView object:

The onFrame() method of the video renderer is inherited from the BaseVideoRenderer class. The BaseVideoRenderer.onFrame() method is called when the publisher (or subscriber) renders a video frame to the video renderer.

The InvertedColorsVideoRenderer implementation of this method, it takes the frame's image buffer (YUV representation of the frame), passes it to the displayFrame method of the MyRenderer object and calls the requestRender() method of the GLSurfaceView object:

To render the video frames, the renderer class uses OpenGL shaders. In this sample shader produces the inverted color effect, more precisely this is achieved by this line which is inside the fragmentShaderCode string: