Patent ID: 6993081
Filing Date: 2006-01-31
Classification: H04N

Abstract:
1. A method for splicing two MPEG encoded digital video streams to provide a single decodable video stream for transport at an MPEG transport level, said decodable video stream comprising video frames for temporary storage at a receiver decode buffer, the method comprising the steps of: a) determining a splice outpoint of a first stream and a splice inpoint of a second stream to establish a splice point for both streams; b) for each said first stream and said second stream, calculating a decoder_buffer_delay characterized as a time period between the first byte of the video frame entering into the decoder buffer until it is removed from the buffer at a decoding time, said first stream having an associated first decoder_buffer_delay (decoder_buffer_delay c) transmitting the first stream up to the determined splice outpoint onto an output transport stream; d) comparing said first buffer delay and second buffer delay to generate a buffer delay difference and adjusting the decoder buffer occupancy level according to said buffer delay difference, said adjusting including inserting video null packets between said first and second streams at the splice point, to precisely compensate any mismatch of decoder_buffer_delays between the first and second streams, further including the step of delaying the decoding time of the second stream to match said first buffer and second buffer delays of the respective first and second streams to be spliced at the splicing point and further including the step of adding replacement frames comprising video packets to said first stream, an amount of video null packets to transmit calculated according to:  where N is the smallest integer that makes the result of the equation positive and represents the number of replacement frames to be inserted; and e) transmitting the second stream starting from the determined inpoint through said output transport stream.