A splicer for splicing nulllivenull bit streams such as those which carry video programs that have been encoded according to the MPEG-2 standard. The splicer controls the rate at which it outputs the spliced bit stream by means of a model of the receiver and can thereby prevent overflow or underflow in receivers receiving the spliced bit stream. The splicer also includes analyzers for reading the old bit stream and the new bit stream that is to be spliced to the new bit stream. The analyzers provide information to the receiver model and also permit the splicer to select IN and OUT points in the old and new bit streams that minimize the effect of the splice on the decoding of the bit stream done in the receiver. Where necessary, the splicer modifies the output bit stream to reduce interference with decoding. The splicer does not require splice parameters to select IN and OUT points or to determine the proper bit rate or the spliced bit stream. The splicer is further able to make non-seamless and seamless splices and greatly simplifies the making of undetectable splices. It is also able to splice in response to an external splice signal, to a splice command in a bit stream, or to the presence of the beginning or end of a bit stream in the splicer.