Multi-media jitter removal in an asynchronous digital home network

• US 7,366,206 B2
• Filed: 06/29/2001
• Issued: 04/29/2008
• Est. Priority Date: 07/26/2000
• Status: Expired due to Term

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Jones, Thomas Herbert, Lockridge, Terry Wayne, Horlander, Thomas Edward
• Primary Examiner(s): Ngo; Ricky Q.
• Assistant Examiner(s): Sinkantarakorn; Pao
• Application Number:
  US10/333,272
• Publication Number:
  US 20040010729A1
• Time in Patent Office: 2,496 Days
• Field of Search: 370/229, 370/232, 370/235, 370/304, 370/350, 370/412, 370/503, 370/535, 370/230, 370/508, 370/509, 370/516, 375/354, 375/359, 348/500, 379/219, 709/154, 709/155, 725 78- 82
• US Class Current: 370/509
• CPC Class Codes: H04J 3/0632 Synchronisation of packets and cells, e.g. transmission of voice via a packet network, circuit emulation service [CES] queuing arrangements in packet switching elements H04L49/90; synchronising systems for the synchronous transmission of a pulse code modulated video signal with one or more other pulse code modulated signals H04N7/56
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/0082 fields explicitly indicating existence of error in data being transmitted, e.g. so that downstream stations can avoid decoding erroneous packet; relays
• CPC Class Codes: H04L 12/2803 Home automation networks
• CPC Class Codes: H04L 12/2807 Exchanging configuration information on appliance services in a home automation network arrangements for maintenance or administration involving network analysis for automatically determining the actual topology of a network H04L41/12; hardware or software tools for network management using graphical user interfaces H04L41/22; address allocation H04L61/50
• CPC Class Codes: H04L 12/2834 Switching of information between an external network and a home network access arrangements H04L12/2856
• CPC Class Codes: H04L 12/2838 Distribution of signals within a home automation network, e.g. involving splitting/multiplexing signals to/from different paths adaptations of television systems for transmission by electric cable for domestic distribution H04N7/106; hybrid transport H04L12/6418; home network arrangements specially adapted for distribution of digital video signals H04N7/24
• CPC Class Codes: H04L 12/6418 Hybrid transport
• CPC Class Codes: H04L 2001/0097 Relays
• CPC Class Codes: H04L 2012/2841 Wireless
• CPC Class Codes: H04L 2012/2843 Mains power line
• CPC Class Codes: H04L 2012/2845 Telephone line
• CPC Class Codes: H04L 2012/2849 Audio/video appliances
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/4305 Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083
• CPC Class Codes: H04N 21/43072 of multiple content streams on the same device
• CPC Class Codes: H04N 21/43615 Interfacing a Home Network, e.g. for connecting the client to a plurality of peripherals home Audio Video Interoperability [HAVI] data switching networks H04L12/2805
• CPC Class Codes: H04N 21/64322 IP
• CPC Class Codes: H04N 5/04 : Synchronising for television systems using pulse code modulation H04N7/56
• CPC Class Codes: H04N 7/106 : for domestic distribution

Abstract

A method and an apparatus using a system level clocking scheme to remove jitter from multi-media packets distributed over an asynchronous network. The present invention overcomes the problems associated with jitter introduced in an asynchronous network by using various time stamps to synchronize a client device clock to a headend clock and to control the data flow in the client device to match the rate that the data is received by a broadband receiver coupled to the headend. The present invention allows the client device to synchronize to a selected one of a plurality of headend clock by including a clock adjustment factor along with the time stamps. The time stamps are added at the physical layer so that the time stamps correspond to the time the data packets are placed onto and received from the asynchronous network.

Claims

1. A server apparatus for receiving packetized multi-media data and transmitting the packetized multi-media data over an asynchronous network, the apparatus comprising:

an input for receiving the packetized multi-media data from a selected one of a plurality of remote signal sources each corresponding to one or more head-end networks, the packetized multi-media data including synchronizing information associated with the selected signal source;

a clock;

a controller, coupled to the input and the clock, for generating a clock adjustment factor for correlating the clock to a clock associated with the selected signal source in response to the synchronizing information, the controller generating data frames having the packetized multi-media data and the clock adjustment factor included therein;

an output, coupled to the asynchronous network, for transmitting the data frames to a client device;

a time stamping device, coupled to the controller, the clock and the output of the server apparatus, for placing a synchronizing time stamp in each data frame, the synchronizing time stamp being indicative of the time the respective data frame is placed onto the asynchronous network, whereby the synchronizing time stamp and the clock adjustment factor are used by the client device for synchronizing a clock associated with the client device with the clock associated with the selected signal source without changing the clock of the server apparatus.

2. The server apparatus according to claim 1, wherein the controller generates data flow time stamps in response to the receipt of the packetized multi-media data, each data flow time stamp being indicative of a time a respective multi-media data packet is received at the input, the data frame including the packetized multi-media and associated data flow time stamps, wherein the data flow time stamps and the clock adjustment factor are used by the client device to control a data flow rate in the client device to correspond to a rate that the packetized multi-media data is received at the input.

3. The server apparatus according to claim 2, wherein the data frame comprises a data frame header, time stamp data portion for accepting synchronizing time stamps, a clock adjustment portion for accepting the clock adjustment factor, and a data portion for accepting packetized multi-media data and their corresponding data flow time stamps.

4. The server apparatus according to claim 3, wherein the time stamp data portion includes a first time stamp data portion for accepting the synchronizing time stamp and a second time stamp data portion for accepting a second synchronizing time stamp added by the client device.

5. The server apparatus according to claim 2, wherein the asynchronous network is an Ethernet network.

6. The server apparatus according to claim 2, wherein the asynchronous network is an HPNA network.

7. The server apparatus according to claim 2, wherein the asynchronous network is a PLC network.

8. The server apparatus according to claim 2, wherein the asynchronous network is a wireless network.

9. A method for transmitting packetized multi-media data over an asynchronous network, the method comprising:

receiving the packetized multi-media data from a selected one of a plurality of remote signal sources each corresponding to one or more head-end networks, the packetized multi-media data having synchronizing information associated with the selected signal source;

generating a clock adjustment factor for correlating a server clock to a clock associated with the selected signal source in response to the synchronizing information;

generating data frames having the packetized multi-media data and the clock adjustment factor included therein;

placing the data frames on the asynchronous network to transmit the data frames to a client device, wherein a synchronizing time stamp is generated and placed in each data frame, each synchronizing time stamp being indicative of the time the respective data frame is place in the asynchronous network, wherein the synchronizing time stamps and the clock adjustment factor are used by the client devices to synchronize a clock associated with the client device to the clock associated with the selected signal source without changing the server clock.

10. The method according to claim 9, further comprising the steps of generating data flow time stamps upon receipt of the packetized multi-media data, each data flow time stamp being indicative of a time a corresponding multi-media data packet is received, and the step of generating data frames includes generating data frames having the packetized multi-media data and the data flow time stamps included therein, whereby the client device can control a data flow rate in the client device to correspond to the rate the packetlzed multi-media data is received in response to the data flow time stamps and the clock adjustment factor.

11. An apparatus for processing packetized multi-media data received over an asynchronous network, the packetized multi-media data comprising data frames having first synchronizing time stamps indicative of the time respective data frames are placed on the asynchronous network, and a clock adjustment factor that correlates a server clock with a clock associated with a signal source, the apparatus comprising;

an input, coupled to the asynchronous network, for receiving the data frames transmitted by a server device operatively coupled to a selected one of a plurality of remote signal sources each corresponding to one or more head-end networks;

a time stamp device, coupled to the input, for generating a second synchronizing time stamp indicative of the time the data frame is received at the input;

a clock;

a controller, coupled to the clock and the time stamp device, for synchronizing the clock to a clock associated with the selected one of a plurality of remote signal sources in response to the first synchronizing time stamps, the clock adjustment factor and the second synchronizing time stamps and without changing the server clock.

12. The apparatus according to claim 11, wherein the data frames further include data flow time stamps associated with the packetized multi-media data, the data flow time stamps being indicative of the time each multi-media data packet is received by the server device, and further comprising a buffer for storing the packetized multi-media data, and a decoder, wherein the controller controls the rate that the packetized multi-media data is transferred to the decoder to correspond to the rate that the packetized multi-media data is received at the server device in response to the data flow time stamps and the clock adjustment factor.

13. The apparatus according to claim 12, wherein the controller generates an error signal indicative of the difference between the clock and the clock associated with the signal source in response to the first synchronizing time stamps, the clock adjustment factors, and the second synchronizing time stamps, and frequency locks the clock to the signal source clock in response to the error signal.

14. The apparatus according to claim 12, wherein the asynchronous network is an Ethernet network.

15. The apparatus according to claim 12, wherein the asynchronous network is an HPNA network.

16. The apparatus according to claim 12, wherein the asynchronous network is a PLC network.

17. The apparatus according to claim 12, wherein the asynchronous network is a wireless network.

18. A method for controlling a client device in response to a receipt of data frames received over an asynchronous network, each of the data frames including packetized multi-media data, a first synchronizing time stamp indicative of the time the data frame is placed on the asynchronous network, and a clock adjustment factor indicative of a correlation between a sever clock and a signal source clock, the method comprising;

receiving the data frames transmitted by a server device operatively coupled to a selected one of a plurality of remote signal sources each corresponding to one or more head-end networks;

generating second synchronizing time stamps upon receipt of the data frames, each second time stamp being indicative of the time a respective data frame is received by the client device; and

synchronizing a clock in the client device to the signal source clock in response to the first synchronizing time stamps, the clock adjustment factor and the second synchronizing time stamps and without changing the server clock.

19. The method according to claim 18, wherein the synchronizing step includes generating an error signal indicative of the difference between the client device clock and the signal source clock in response to the first synchronizing time stamps, the clock adjustment factors, and the second synchronizing time stamps, and frequency locking the client device clock to the signal source clock in response to the error signal.

20. The method according to claim 18, wherein the data frames further include data flow time stamps, each data flow time stamp being indicative of a time a corresponding multi-media data packet is received by the server device, further comprising the step of:

controlling a rate at which the packetized multi-media data is transferred from a buffer to a decoder to correspond to the rate at which the packetized multi-media data is received at the server device in response to the data flow time stamps and the clock adjustment factor.