Clock recovery apparatus as for a compressed video signal

Apparatus for synchronizing, at least a portion of a compressed video signal receiving system which processes a compressed video signal occurring in transport packets of compressed video signal interspersed with transport packets which include count values (PCR's) periodically obtained asynchronously with said video signal, from a counter arranged to count modulo M, (M greater than 2.sup.10) pulses of an encoding system clock, said apparatus comprising:

• a source of transport packets including compressed video transport packets and transport packets which include said count values (PCR's);
• a controlled oscillator, responsive to a control signal, for providing a receiver system clock;
• a receiver counter arranged to count pulses of said receiver system clock modulo M;
• means, responsive to the occurrence of transport packets which include said count values, for storing count values output by said receiver counter;
• and
• means responsive to the differences of count values in successively occurring transport packets which include said count values, and differences in corresponding successively stored count values output by said receiver counter for generating a control signal, E, for controlling said controlled oscillator.

Apparatus for synchronizing at least a portion of a compressed video signal receiving system which processes a compressed video signal occurring in transport packets of compressed video signal interspersed with transport packets which include count values (PCR's) periodically obtained asynchronously with said video signal, from a counter arranged to count modulo M, (M greater than 2.sup.10) pulses of an encoding system clock, said apparatus comprising;

• a source of transport packets including compressed video transport packets and transport packets which include said count values (PCR's);
• a controlled oscillator, responsive to a control signal, for providing a receiver system clock;
• a receiver counter arranged to count pulses of said receiver system clock modulo M;
• means, responsive to the occurrence of transport packets which include said count values, for storing count values output by said receiver counter;
• means responsive to the differences of count values in successively occurring transport packets which include said count values, and differences in corresponding successively stored count values output by said receiver counter for generating a control signal, E, for controlling said controlled oscillator;
• means for storing count values PCR.sub.0 and RCV.sub.0 which correspond to a count value occurring in a transport packet occurring at system start up and a corresponding receiver count value respectively;
• means for calculating a control signal, E', proportional to:
• E'=f(.vertline.PCR.sub.n -PCR.sub.0 .vertline.-.vertline.RCV.sub.n -RCV.sub.0 .vertline.)
• where PCR.sub.n is a count value occurring in current transport packet and RCV.sub.n is a corresponding stored count value output by said receiver clock;
• and
• means for selectively providing said signals E or E' as control signals for controlling said controlled oscillator.

Apparatus for providing a compressed signal including a plurality of components, comprising:

• a source of said signal including a plurality of components;
• compression means coupled to said source for providing compressed signal components including descriptive headers and data representing pixel information formatted according to a predetermined protocol;
• a system clock for providing clock pulses;
• a counter for counting said clock pulses modulo M, where M is a value greater than 2.sup.10 ;
• means for periodically storing count values (PCR's) provided by said counter which are asynchronous with and independent of said plurality of signal components;
• a transport processor coupled to receive formatted compressed, for dividing said compressed signal into segments of predetermined amounts of data, and for forming transport headers, said transport processor concatenating respective transport headers with payloads consisting of respective segments of said compressed signal to form respective transport packets, said transport processor also including means for forming auxiliary transport packets, distinguishable from said transport packets, and including at least said count values, and interspersing said auxiliary transport packets with compressed signal transport packets;
• and
• means for conveying said compressed video signal transport packets interspersed with said auxiliary transport packets.

Video signal compression apparatus comprising:

• a source of video signal;
• a source of a clock signal;
• a counter for counting said clock signal modulo N, where N is an integer greater than 2.sup.5 ;
• means for capturing count values provided by said counter as Presentation Time references, which Presentation Time references are synchronized with predetermined segments of said video signal;
• Compression means for compressing said video signal and hierarchically formatting compressed video data with said Presentation Time references included;
• means for periodically selecting, asynchronously with said video signal, further count values provided by said counter as Program Clock References;
• a transport processor coupled to receive formatted compressed video data including said Presentation Time references from said compression means, or segmenting said compressed video data into transport packets including payloads of said compressed video data and Presentation Time references concatenated with transport headers, and wherein said Program Clock References are included in payloads of ones of said transport packets;
• and
• means for conditioning said transport packets for transmission.