EP0624982A2
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EP
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Clock apparatus for a compressed video signal
Assignee: Technicolor USA Inc
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Filing: 1994-05-04
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Granted: —
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Expires: 2014-05-04
Abstract
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 a modulo K counter (23) which is clocked responsive to a system clock (22), and the count valued is embedded (13) in the signal at the transport layer according to a predetermined schedule. At the receiving end of the system a similar counter is responsive to a controlled receiver clock signal (26) and the count value of this counter is sampled (18) at the arrival of the count values embedded in the transport layer. The differences of successive sampled count values of the receiver counter are compared with the differences of corresponding successive values of the embedded count values in the transport layer to provide a signal to control (27) the receiver clock signal.
Inventors
- 👤 Michael Scott Deiss
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 08:11
CPC Classifications
H; H04; H04N; H04N19/00; H04N19/60; H04N19/61; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/085; H03L7/16; H03L7/18; H03L7/181; H04N21/00; H04N21/20; H04N21/23; H04N21/236; H04N21/23608; H04N21/23614; H04N21/40; H04N21/43; H04N21/4302; H04N21/4305; H04N21/434; H04N21/4348; H04N19/70
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
155 words
Video signal compression apparatus characterized by: a source (10) of video signal; a source (22) of a clock signal; a counter (23) for counting said clock signal modulo N, where N is an integer; means (24) for selecting ones of count values provided by said counter as Presentation Time references, which Presentation Time references are associated with predetermined segments of said video signal; compression means (11,12) for compressing said video signal and hierarchically formatting compressed video data with said Presentation Time references included; means (13,25) for periodically selecting further count values provided by said counter as Program Clock References; a transport processor (13) coupled to receive formatted compressed video data including said Presentation Time references from said compression means, for segmenting said compressed video data into transport packets including transport headers and wherein said Program Clock References are included in ones of said transport packets; and means (14,15) for conditioning said transport packets for transmission.
Claim 2
Dependent Claim
36 words
The apparatus set forth in Claim 1, characterized in that said transport processor includes means for determining instances when said Program Clock References are to be selected by said means for periodically selecting further count values.
Claim 3
Dependent Claim
45 words
The apparatus set forth in Claim 1, characterized in that said transport processor forms transport packets of compressed video data and auxiliary transport packets including said Program Clock References, and includes means for interspersing said auxiliary transport packets with transport packets of compressed video data.
Claim 4
Dependent Claim
177 words
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 periodically obtained from a counter arranged to count modulo M, pulses of an encoding system clock where M is an integer, said apparatus characterized by: a source (17) of transport packets including compressed video transport packets and transport packets which include said count values; a controlled oscillator (37), responsive to a control signal, for providing a receiver system clock; a receiver counter (36) arranged to count pulses of said receiver system clock modulo M; means (31,55), responsive to the occurrence of transport packets which include said count values, for storing count values output by said receiver counter; and means (38,39) 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.
Claim 5
Dependent Claim
73 words
The apparatus set forth in claim 4, characterized in that said means for generating said control signal, E, includes means for calculating said control signal, E, proportional to: E =f( |PCR n - PCR n-1 | - |IRCV n - RCV n-1 |) where PCR n and PCR n-1 are successive count values occurring in transport packets and RCV n and RCV n-1 are corresponding stored count values output by said receiver clock.
Claim 6
Dependent Claim
88 words
The apparatus set forth in claim 5, characterized in that said means for generating said control signal, E, further includes: means for storing count values PCR₀ and RCV₀ 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( |PCR n - PCR₀| - |RCV n - RCV₀|) means for selectively providing said signals E or E' as control signals for controlling said controlled oscillator.
References Cited (Backward Citations)
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