A video signal is processed in a video device (50). The video signal transfers video data representing either three dimensional video [3D] content formatted according to a 3D format or 2D content formatted according to a 2D format. The video signal has a 2D frame and a control structure of a 2D format for being compatible with existing distribution systems. The device has a processor (52) for providing a 3D status signal indicative of the format of the video signal. The processor determines a respective format score for at least one of the possible 3D formats by processing the video data according to respective predetermined format properties for deriving and comparing respective 3D subframes, and sets the 3D status signal based on an assessment of the format score to indicate the format of the video signal. Advantageously the 3D format is detected automatically and a 3D display can be controlled accordingly.