US 2002/0154694 A1 · BIT STREAM SPLICER WITH VARIABLE-RATE OUTPUT

Abstract

A splicer for splicing “live” 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.

Claims45

Dependent claims

A splicer for receiving an old bit stream and a new bit stream, producing a varying bit-rate output stream with a splice between the old bit stream and the new bit stream, and providing the output stream to a receiver, the splicer having the improvement comprising:

a bit rate determiner for determining a bit rate for the output stream around the splice such that a buffer in the receiver which receives the output stream will neither overflow nor underflow;
and
an output controller for providing the output bit stream at the determined bit rate.

A splicer for receiving an old MPEG-2 bit stream and a new MPEG-2 bit stream, producing a varying-rate MPEG-2 output stream with a splice between the old bit stream and the new bit stream, and providing the output stream to a receiver with a decoder for MPEG-2 bit streams, the splicer having the improvement comprising:

a bit rate determiner which uses a VBV model of the decoder to determine a bit rate for the output stream around the splice such that the decoder will neither overflow nor underflow;
and
an output controller for providing the output bit stream at the determined bit rate.

Dependencies are inferred from the claim text.

Bit stream splicer with variable-rate output

Life of this patent

Bit stream splicer with variable-rate output

Life of this patent

Abstract

Claims45