Patent ID: 6975363
Filing Date: 2005-12-13
Classification: H04N

Abstract:
1. In a digital receiver that is configured to receive a digital video signal representing a plurality of digital video packets and a digital audio signal representing a plurality of digital audio packets, a method of independently timing the presentation of the video information of the digital video packets with respect to the timing of the presentation of the audio information of the digital audio packets so that the video information and the audio information may be accurately timed even if they are from different unrelated programs, the method comprising the following: an act of receiving a digital video signal and a digital audio signal; an act of extracting a plurality of digital video packets from the digital video signal; assigning timestamps at a relatively constant time period to the digital video and audio packets after being received and prior to implementation of a variable time process to the digital packets; an act of using a video clock to control the timing of the presentation of the video information represented by the plurality of digital video packets; an act of using an audio clock to control the timing of the presentation of the audio information represented by the plurality of digital audio packets, wherein the audio clock operates separately and independently of the video clock; and wherein at least one of the video clock or the audio clock speed up or slow down in response to a comparison of a program clock reference within at least one of the digital video packets or digital audio packets, respectively, with a local time at the digital receiver as determined by the timestamp, wherein the comparison occurs after the variable time process, and such that the assignment of the timestamps at the relatively constant time period to the digital packets after being received and prior to implementation of a variable time process enables a determination as to whether the video clock or the audio clock should be sped up or slowed down notwithstanding any affects of the variable time process.