Some digital picture frames have built-in speakers that can play MP3 and WAV audio files, which can be useful for displaying photographs. A digital picture frame may show M-JPEG, WMA, AVI, and MPEG-1, 2, and 4 video data. Certain digital photo frames include clock, calendar, and alarm features, allowing you to replace your old alarm clock with a digital photo frame that also serves as an alarm clock. Digital picture frames, according to the manufacturer, can also be used as secondary computer monitors.