US 6,118,498 A · Channel scanning and channel change latency reduction in an ATSC television receiver

Abstract

A method and apparatus for masking program selection latency in an MPEG-like information stream receiver, such as an ATSC or DVB television receiver. An information stream receiver receives VSB- or QAM-modulated signals comprising an MPEG-like system streams including program transport streams. In a channel scanning mode of operation, a plurality of identified program transport streams (i.e., channels) are sequentially retrieved from one or more system streams. A portion of each retrieved program transport stream, such as an intra-frame encoded video frame within an included elementary video stream, is extracted and stored in a memory. In a channel changing mode of operation, if a desired channel is one of the sequentially scanned channels, then the stored I-frame is retrieved and coupled to a decoder while the desired channel is re-acquired by tuning, demodulating, and demultiplexing operations. In this manner, the inherent latency of the tuning, demodulating, and demultiplexing operations are somewhat masked. Moreover, by storing tuning and demodulation parameters associated with an anticipated "next" channel, the actual time required to retrieve that channel is reduced.

Claims22

Dependent claims

A method for masking program selection latency in an MPEG-like information stream receiver, comprising the steps of:

retrieving, using a first tuner/demodulator pair, a selected information stream, said selected information stream being coupled to a decoder;
retrieving, in a scanning mode of operation using a second tuner/demodulator pair, at least a portion of each of a plurality of predefined information streams, each information stream being associated with a program;
storing, in said scanning mode of operation, each of said retrieved portions of said plurality of predefined information streams in a memory;
comparing, in a program selection mode of operation, identification indicium of a desired information stream to identification indicia of said plurality of predefined information streams;
and
in the case of a favorable comparison of said indicia:
initiating an information stream selection process, said selection process producing, after a delay time, said desired information stream;
retrieving, from said memory, the stored portion of the information stream comparing favorably to the desired information stream;
coupling, to said decoder, said retrieved information stream portion;
and
coupling, to said decoder, said desired information stream resulting from said information stream selection process.

8 more elements

In a television receiver, apparatus for rapidly changing channels comprising:

a first channel selector, for selecting a first channel from a plurality of available channels;
a decoder, coupled to said first channel selector, for decoding an information stream associated with said selected first channel to produce a decoded information stream;
a second channel selector, for sequentially selecting each of a plurality of identified channels within a list of channels to be scanned, each of said plurality of identified channels being associated with a respective information stream, a channel identifier and a channel tuning parameter;
and
a processor, coupled to said second channel selector and said decoder, for storing in a memory and retrieving at least a portion of said respective information streams associated with said sequentially selected channels;
wherein, in a channel changing mode of operation:
said processor, in response to a desired new channel comprising one of said plurality of listed channels, coupling to said decoder said stored portion of said information stream associated with said one listed channel;
said first channel selector selects said desired channel as said first channel;
and
said decoder, in response to said information stream associated with said desired channel being valid, begins decoding said first information stream.

7 more elements

In a receiver, apparatus for changing channels comprising:

a first tuner/demodulator pair, for tuning a desired RF carrier frequency and demodulating an information stream modulated onto said RF carrier frequency to produce a first system stream;
a second tuner/demodulator pair, for tuning a desired RF carrier frequency and demodulating an information stream modulated onto said RF carrier frequency to produce a second system stream;
a main demultiplexer, selectively coupled to one of said first and second tuner/demodulator pairs, for extracting and coupling to an output a video stream associated with a main channel from one of said first and second system streams;
an auxiliary demultiplexer, selectively coupled to one of said first and second tuner/demodulator pairs, for repetitively extracting and storing a portion a video stream associated with at least one auxiliary channel from one of said first and second system streams;
and
a video decoder, selectively coupled to one of said main and auxiliary demultiplexers, for decoding video information provided by one of said main and auxiliary demultiplexers to produce an output video stream;
wherein
in a channel scanning mode of operation:
said video decoder is coupled to said main demultiplexer;
and
in a channel change mode of operation:
said tuner/demodulator pair producing said system stream associated with said main channel is adjusted to produce a system stream associated with a desired channel,
said auxiliary demultiplexer retrieves, if available, and couples to an output, a portion a video stream associated with said desired channel, and
said video decoder is coupled to said auxiliary demultiplexer until said main demultiplexer begins producing a valid video information stream associated with said desired channel.

11 more elements

Dependencies are inferred from the claim text.

Channel scanning and channel change latency reduction in an ATSC television receiver

Life of this patent

Channel scanning and channel change latency reduction in an ATSC television receiver

Life of this patent

Abstract

Claims22