Camera2 adding black frames to a video

[UrielFrankel]

Hello
I am trying to manipulate the video that I get from the camera by making it black when the user presses a button. Since I attach the encoder surface directly to the Camera2 by using addTarget, I don't have the ability to alter the camera input. Is there a way to black the input? Like telling the Camera2 to give me black frames, or to be able to alter the encoder input? thanks
p.s. I saw BigFlake CameraToMpegTest it was too much OpenGL :)