Synchronizing an audio-visual stream which is synchronized to a clock with the timebase of a video display device which is synchronized to a different clock

摘要

A DVD player that integrates a DVD device into a personal computer is provided. As such, the personal computer is able to output audio-visual works from a DVD CD-ROM. When integrating a DVD device with a personal computer, various problems must be overcome. For example, in a personal computer, the video display is controlled by a graphics controller, and in order to render an audio-visual stream in a personal computer, the audio-visual stream and the graphics controller must be synchronized. The synchronization problem arises because the graphics controller only displays data at the beginning of 33.4 millisecond time intervals. Thus, although the audio portion may be played almost immediately, the video portion may have to wait for up to 33.4 milliseconds before being displayed. In this manner, the audio portion and the video portion become unsynchronized which means that the audio portion plays before the corresponding video portion is displayed. The DVD player solves this problem by synchronizing the start of the audio-visual stream with the graphics controller so that the time at which a video sequence is displayed coincides with one of the graphics controller's 33.4 millisecond time intervals.