US 5,565,923 A · Apparatus for formatting a digital signal to include multiple time stamps for system synchronization

Abstract

Apparatus for developing synchronization of an intermediate layer of signal such as the transport or multiplex layer of a multi-layered compressed video signal, includes at the encoding end of the system apparatus for including a time stamp reference, such as a count value from a modulo K counter, and provision for a differential time stamp related to time stamps of a further compressed signal or differential transit times of respective transport packets. Flags are included in transport packets of signal to indicate the presence or absence of the time stamps or differential time stamps. At the receiving end of the system, circuitry examines respective packets for the condition of the flags to locate specific information such as the time stamps and differential time stamps. A counter is responsive to a controlled receiver clock signal and the count value of this counter is sampled at the arrival of transport packets including a flag indicating the presence of a time stamp. Circuitry is described for using the time stamps and the sampled count values of the receiver counter to provide a signal for controlling the frequency of the receiver clock signal.

Claims8

Dependent claims

Apparatus for providing a compressed video signal comprising:

a source of compressed video signal;
counter circuitry for generating time stamps;
a transport processor for a) dividing said compressed video signal into segments of data no larger than a predetermined size;
b) forming transport headers including data fields identifying at least in part the contents of respective transport packets;
c) forming auxiliary information provisionally including first and second data blocks for containing one of said time stamps and a further time stamp respectively, said further time stamp being related to a further compressed video signal;
and providing first and second flags respectively exhibiting respective first states to indicate the presence of said first and second data blocks;
d) including said one time stamp in said first data block only for said first flag exhibiting its respective first state and including said further time stamp in said second data block only for said second flag exhibiting its first state;
and e) forming transport packets respectively including a header and a payload, wherein said payload includes a segment of compressed video signal, and ones of said payloads include said auxiliary information.

5 more elements

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 ones of which have provision for including auxiliary information, which auxiliary information may include clock references and further clock references, said further clock references being related to clock references of a further compressed video signal, and first and second flags indicating the presence or absence of said clock references and said further clock references, said apparatus comprising:

a source of transport packets of compressed video signal;
a controlled oscillator, responsive to a control signal E, for providing a receiver system clock;
a receiver counter arranged to count pulses of said receiver system clock;
detector circuitry coupled to said source of transport packets for detecting said first and second flags, and if said flags are detected, determining the presence or absence of said clock reference and said further clock reference;
and
clock control circuitry, responsive to at least said clock reference when available, for generating said control signal E.

3 more elements

Dependencies are inferred from the claim text.

Apparatus for formatting a digital signal to include multiple time stamps for system synchronization

Life of this patent

Apparatus for formatting a digital signal to include multiple time stamps for system synchronization

Life of this patent

Abstract

Claims8