A decoder is disclosed. A video decoder extracts, when receiving a video stream, video output time information attached to each video frame. Thereafter, a difference value calculator calculates a difference value between an occurrence time of a synchronizing signal and the video output time information. Further, an audio output time corrector corrects, using the difference value, audio output time information attached to each audio frame. Then, a video source outputs video represented by a video frame in synchronization with a synchronizing signal. An audio source outputs, when a value of reference time information and a corrected value of the audio output time information are synchronized, audio represented by an audio frame with the synchronized audio output time information.