Splicing compressed, local video segments into fixed time slots in a network feed
View Patent ↗A method for seamlessly splicing a local commercial segment into an existing network time slot, without decoder buffer overflow or underflow. The vbv_delay of the commercial segment is manipulated (e.g., for a minimum delay or a maximum delay). The pictures from the commercial segment are output for at least a portion of the associated network time slot duration. A determination is made regarding the number of pictures remaining in a stored portion of the incoming network feed or the commercial segment and the output rate is adjusted as required. The vbv_delay of the stored network feed or the vbv_delay of the local commercial segment is adjusted to match the vbv_delay of the incoming network feed.
1. A method of splicing a stream of a commercial time slot into a network time slot of an incoming network stream, said commercial time slot and network time slot each having an in-point and an out-point and a duration, the method comprising:
multiplexing the commercial stream into the network stream such that the commercial slot in-point is aligned with the network slot out-point;
during the commercial stream, adjusting the vbv_delays of said stream such that the duration of the commercial stream has a maximum duration that is longer than the duration of the network time slot, any difference in durations being equal to a network feed extra;
at the network stream in-point, multiplexing any remaining portion of the commercial stream at a higher stream rate, and storing any network feed extra; and
at the commercial stream out-point, multiplexing any stored network feed extra into the network stream while adjusting the vbv_delays of the stored network feed extra until the vbv_delays in the network feed extra match that in the incoming network feed.
2. A method of splicing as recited in claim 1 , wherein the duration of the commercial time slot is 30.5 seconds.
3. The method of claim 2 ,
wherein the duration of the network time slot is based on a Decode Time Stamp and a network time slot duration time tolerance; and
wherein any stored feed extra is at least as large as the difference between the 30.5 seconds and the network time slot duration.
4. A method of splicing a stream of a commercial time slot into a network time slot of an incoming network stream, said commercial time slot and network time slot each having an in-point and an out-point and a duration, the method comprising:
multiplexing the commercial stream into the network stream such that the commercial slot in-point is aligned with the network slot out-point;
while multiplexing the commercial stream into the network stream, computing an expected completion time of the network time slot by monitoring the network feed, and adjusting the vbv_delays of the commercial stream such that the duration of the commercial stream has a minimum duration that is shorter than the duration of the network time slot;
between a presecribed point prior to the out-point of the commercial time slot and the out-point of the commercial time slot, multiplexing the remaining portion of the commercial stream at a slower stream rate by adjusting the vbv_delays to meet the expected completion time; and
at the network in-point, multiplexing the incoming network feed into the network stream.
5. The method of claim 4 , wherein the minimum duration is 29.5 seconds.
6. The method of claim 5 ,
wherein the network time slot duration is based on a Decode Time Stamp and a network time slot duration time tolerance and the prescribed point is 29 seconds, the remaining portion of the commercial time slot including 15 pictures; and
wherein the slower stream rate for the remaining portion of the commercial stream is based on taking the difference between the duration of the network time slot and 29.5 seconds.
7. A method of splicing as recited in claim 4 , wherein computing the expected completion time includes:
computing a difference between the number of pictures in the network slot and the number of pictures that have passed in the network stream since the commercial in-point; and
multiplying the difference by the picture rate.