Method and apparatus for preserving synchronization of audio and video presentation when splicing transport streams

A method for preserving lip sync during a splicing operation where a plurality of data streams is multiplexed into an output stream, where each of the data streams contains an audio stream having a plurality of audio access units and a video stream having a plurality of video access units that are in lip sync, said method comprising the steps of:

• (a) splicing a portion of a first data stream into the output stream;
• (b) splicing a portion of a second data stream into the output stream;
• (c) determining at a splice point whether an overlap condition exists between a last video access unit from said first data stream and a first video access unit from said second data stream;
• and
• (d) deleting either said last video access unit or said first video access unit if an overlap condition exists.

An apparatus for preserving lip sync during a splicing operation where a plurality of data streams is multiplexed into an output stream, where each of the data streams contains a first substream having a plurality of access units and a second substream having a plurality of access units, said apparatus comprising:

• a splicer for splicing a portion of a first data stream and a portion of a second data stream into the output stream;
• a means, coupled to said splicer, for determining at a splice point whether an overlap condition exists between said access units from said first data stream and said second data stream;
• and
• a means, coupled to said determining means, for deleting one or more of said access units if an overlap condition exists.