Depending on the type of media file, ELAN automatically displays three Viewers (Video, Waveform and Timeline Viewer). Furthermore one can choose an additional viewer in the tabs on the right /left(For more info on how to choose the viewers in left / right of video see Figure 4.29) of the video Viewer: a text viewer, a grid viewer, a subtitle viewer, a lexicon viewer , a audio recognizer, a video recognizer or a metadata viewer. Note that it is not possible to activate both the Timeline and the Interlinear Viewer at the same time. To select which viewers you want and which viewers should be visible see Section 4.5.20.

	Note
	If a media file is not available (e.g., the *.mpg/*.mov file in case of audio data, or the *.wav file in case of some video data), the corresponding Viewer is not available either.