Patent ID: 6018376
Filing Date: 2000-01-25
Classification: H04N

Abstract:
A synchronous reproduction apparatus for synchronously reproducing a video signal and an audio signal, and receiving a multiplexed bit stream in which the following data are packeted: video encoded data obtained by encoding video frames, each frame being a fundamental unit of reproduction of a video signal; video presentation time data showing a time to output a reproduced video signal of each video frame; audio encoded data obtained by encoding audio frames, each frame being a fundamental unit of reproduction of an audio signal; audio presentation time data showing a time to output a reproduced audio signal of each audio frame; and system time data:said apparatus comprising:system demultiplexing means for demultiplexing the multiplexed bit stream into the video encoded data, the audio encoded data, the video presentation time data, the audio presentation time data, and the system time data;video signal decoding means for decoding the video encoded data to produce a reproduced video signal;audio signal decoding means for decoding the audio encoded data to produce a reproduced audio signal;selecting means for selecting the system time separated from the multiplexed bit stream by the system demultiplexing means, during the starting operation wherein output of the reproduced video signal and the reproduced audio signal is started, while selecting the audio presentation time separated from the multiplexed bit stream by the system demultiplexing means, during the normal operation after the starting operation, wherein the reproduced video signal and the reproduced audio signal are successively output;an internal clock for setting its time with reference to the system time output from the selecting means during the starting operation and setting its time with reference to the audio presentation time output from the selecting means during the normal operation, and generating successive reference times;video presentation time comparing means for providing a difference between the video presentation time and the time of the internal clock, and outputting the difference as a video presentation time error during the starting operation and the normal operation;audio presentation time comparing means for providing a difference between the audio presentation time and the time of the internal clock, and outputting the difference as an audio presentation time error during the starting operation and the normal operation;video control means for controlling, during the starting operation, the video signal decoding means so that output of the reproduced video signal is started when the video presentation time error is within a prescribed range TH.sub.min (VS).about.TH.sub.max (VS) and, during the normal operation, controlling the video signal decoding means by advancing or delaying output of the reproduced video signal so that the video presentation time error is within a prescribed range TH.sub.min (VM).about.TH.sub.max (VM); andaudio control means for controlling, during the starting operation, the audio signal decoding means so that output of the reproduced audio signal is started when the audio presentation time error is within a prescribed range TH.sub.min (AS).about.TH.sub.max (AS) and, during the normal operation, controlling the audio signal decoding means by advancing or delaying output of the reproduced audio signal so that the video presentation time error is within a prescribed range TH.sub.min (AM).about.TH.sub.max (AM).