Patent ID: 7924929
Filing Date: 2011-04-12
Classification: G11B,H04N

Abstract:
1. A method of testing audio/video synchronization of a decoder device for receiving a digital stream, said digital stream containing system time clock fields, program clock reference fields, audio decoding time stamp fields, audio presentation time stamp fields, video decoding time stamp fields and video presentation time stamp fields, comprising: recovering at least two sequential program clock references from said program clock reference fields; calculating a frequency of a device used to encode said digital stream based on said sequential program clock references and decoder time stamps of when said sequential program clock references were recovered; generating an audio elementary stream and a video elementary stream from said digital stream; recovering from said audio elementary stream at least one audio decoding time stamp from said audio decoding time stamp fields and calculating a first time difference between said audio decoding time stamp and a first decoder time stamp of when an audio unit corresponding to said audio decoding time stamp was decoded; recovering from said audio elementary stream at least one audio presentation time stamp from said audio presentation time stamp fields and calculating a second time difference between said audio presentation time stamp and a second decoder time stamp of when an audio unit corresponding to said audio presentation time stamp was presented; recovering from said video elementary stream at least one video decoding time stamp from said video decoding time stamp fields and calculating a third time difference between said video decoding time stamp and a third decoder time stamp of when a video frame corresponding to said video decoding time stamp was decoded; and recovering from said video elementary stream at least one video presentation time stamp from said video presentation time stamp fields and calculating a fourth time difference between said video presentation time stamp and a fourth decoder time stamp of when said a video frame corresponding to said video presentation time stamp was presented.