Method for bidirectionally transmitting digital video signal and digital video signal bidirectional transmission system

• US 5,978,651 A
• Filed: 04/14/1997
• Issued: 11/02/1999
• Est. Priority Date: 12/28/1993
• Status: Expired due to Term

• Current Assignee: GFM GmbH (GFM-Holding AG)
• Original Assignee: Hitachi Denshi Kabushiki Kaisha
• Inventors: Tanabe, Kazuhiro, Nisikawa, Hiroyuki, Murata, Nobuo, Eto, Yoshizumi
• Primary Examiner(s): Miller, John W.
• Application Number:
  US08/839,489
• Time in Patent Office: 932 Days
• Field of Search: 455/5.1, 455/3.1, 455/4.1, 455/4.2, 455/6.1, 455/6.2, 455/6.3, 348/12, 348/13, 348/14, 348/15, 348/16, 348/17, 348/6, 348/143, 348/211, 348/212, 348/423, 370/521, 370/451, 370/458
• US Class Current: 348/14.13
• CPC Class Codes: H04N 21/2381 Adapting the multiplex stream to a specific network, e.g. an Internet Protocol [IP] network transmission of MPEG streams over ATM H04L12/5601
• CPC Class Codes: H04N 21/4223 Cameras H04N23/00 takes precedence
• CPC Class Codes: H04N 21/4381 Recovering the multiplex stream from a specific network, e.g. recovering MPEG packets from ATM cells transmission of MPEG streams over ATM H04L12/5601
• CPC Class Codes: H04N 23/66 Remote control of cameras or camera parts, e.g. by remote control devices
• CPC Class Codes: H04N 7/141 between two video terminals, e.g. videophone telephonic communication systems combined with television receiver for reception of entertainment or information matter H04M11/085
• CPC Class Codes: H04N 7/142 Constructional details of the terminal equipment, e.g. arrangements of the camera and the display
• CPC Class Codes: H04N 7/147 Communication arrangements, e.g. identifying the communication as a video-communication, intermediate storage of the signals selecting H04Q
• CPC Class Codes: H04N 7/181 for receiving images from a plurality of remote sources
• CPC Class Codes: H04N 7/183 for receiving images from a single remote source

Abstract

In a video signal transmission method and system wherein a signal containing a video signal is bidirectionally transmitted and received in a substantially real time in video appliances coupled via a transmission path to each other, a digital signal containing a digital video signal is time-compressed, and a transmission operation is controlled in such a manner that a transmission period and a no transmission period are alternately produced in a preselected period. Then, the time-compressed digital signal is transmitted to the transmission path during the transmission period, whereas another digital signal transmitted via the transmission path from the video appliance on the counter side is received during the no transmission period. Then, the received digital signal is time-expanded to reproduce the original signal.

Claims

1. A first video appliance for use with a second video appliance, said first video appliance being coupled to said second video appliance via a transmission path when said first video appliance is being used with said second video appliance to enable digital signals containing at least digital video signals and digital audio signals to be bidirectionally transmitted and received in substantially real time between said first video appliance and said second video appliance via said transmission path, said first video appliance and said second video appliance each including a transmitting and receiving apparatus, said first video appliance comprising:

means for producing a first digital signal by time-division multiplexing at least a first digital video signal and a first digital audio signal;

means for compressing a first information amount of said first digital video signal in said first digital signal to produce a first compressed digital signal, dividing said first compressed digital signal into a plurality of predetermined periods, and time-axis compressing said first compressed and divided digital signal in order to produce a first compressed, divided, and time-axis compressed digital signal repeating a signal period and a no signal period alternately;

means for transmitting said first compressed, divided, and time-axis compressed digital signal to said second video appliance through said transmission path;

means for controlling said transmitting and receiving apparatus of said first video appliance to generate a first transmission period and a second transmission period alternately on said transmission path, said first transmission period being longer than said second transmission period, and controlling said transmitting means of said first video appliance so that said first compressed, divided, and time-axis compressed digital signal of said first video appliance is synchronized with said first transmission period and transmitted to said second video appliance in said first transmission period of said transmission path;

means for receiving a second compressed, divided, and time-axis compressed digital signal from said second video appliance;

means for time-axis expanding said second compressed, divided, and time-axis compressed digital signal to reproduce a second digital signal; and

means for separating said time-axis expanded second digital signal to reproduce at least a second digital video signal and a second digital audio signal.

2. A first video appliance as claimed in claim 1, wherein said second video appliance which said first video appliance is for use with includes:

means for producing said second digital signal by multiplexing at least said second digital video signal and said second digital audio signal;

means for compressing a second information amount of said second digital video signal in said second digital signal to produce a second compressed digital signal in such a manner that said second information amount of said second digital video signal after compression is smaller than said first information amount of said first video signal after compression, dividing said second compressed digital signal into a plurality of predetermined periods, and time-axis compressing said second compressed and divided digital signal in order to produce said second compressed, divided, and time-axis compressed digital signal repeating a signal period and a no signal period, alternately;

means for transmitting said second compressed, divided, and time-axis compressed digital signal to said transmission path;

means for controlling said transmitting and receiving apparatus of said second video appliance and said transmitting means of said second video appliance so that said second compressed, divided, and time-axis compressed digital signal is synchronized with said second transmission period and transmitted to said first video appliance in said second transmission period of said transmission path;

means for receiving said first compressed, divided, and time-axis compressed digital signal from said first video appliance;

means for time-axis expanding said first compressed, divided, and time-axis compressed digital signal to reproduce said first digital signal; and

means for separating said time-axis expanded first digital signal to reproduce said first digital video signal and said first digital audio signal.

3. A first video appliance as claimed in claim 1, wherein said first video appliance is a television camera;

and

wherein said second video appliance is a television camera controlling apparatus.

4. A first video appliance as claimed in claim 3, wherein said transmission path includes a triple coaxial cable.

5. A video signal transmission system as claimed in claim 1, wherein said transmission path includes a triple coaxial cable.

6. A first video appliance as claimed in claim 5, wherein said first video appliance is a television camera;

and

wherein said second video appliance is a television camera controlling apparatus.

7. A video signal transmission system wherein digital signals containing at least digital video signals and digital audio signals are bidirectionally transmitted and received in substantially real time in first and second video appliances coupled via a transmission path, said first and second video appliances each including a transmitting and receiving apparatus, said first video appliance comprising:

means for producing a first digital signal by time-division multiplexing at least a first digital video signal and a first digital audio signal;

means for compressing a first information amount of said first digital video signal in said first digital signal to produce a first compressed digital signal, dividing said first compressed digital signal into a plurality of predetermined periods, and time-axis compressing said first compressed and divided digital signal in order to produce a first compressed, divided, and time-axis compressed digital signal repeating a signal period and a no signal period alternately;

means for transmitting said first compressed, divided, and time-axis compressed digital signal to said second video appliance through said transmission path;

means for controlling said transmitting and receiving apparatus of said first video appliance to generate a first transmission period and a second transmission period alternately on said transmission path, said first transmission period being longer than said second transmission period, and controlling said transmitting means of said first video appliance so that said first compressed, divided, and time-axis compressed digital signal of said first video appliance is synchronized with said first transmission period and transmitted to said second video appliance in said first transmission period of said transmission path;

means for receiving a second compressed, divided, and time-axis compressed digital signal from said second video appliance;

means for time-axis expanding said second compressed, divided, and time-axis compressed digital signal to reproduce a second digital signal; and

means for separating said time-axis expanded second digital signal to reproduce at least a second digital video signal and a second digital audio signal;

wherein said second video appliance comprises;

means for producing said second digital signal by multiplexing at least said second digital video signal and said second digital audio signal;

means for compressing a second information amount of said second digital video signal in said second digital signal to produce a second compressed digital signal in such a manner that said second information amount of said second digital video signal after compression is smaller than said first information amount of said first video signal after compression, dividing said second compressed digital signal into a plurality of predetermined periods, and time-axis compressing said second compressed and divided digital signal in order to produce said second compressed, divided, and time-axis compressed digital signal repeating a signal period and a no signal period, alternately;

means for transmitting said second compressed, divided, and time-axis compressed digital signal to said transmission path;

means for controlling said transmitting and receiving apparatus of said second video appliance and said transmitting means of said second video appliance so that said second compressed, divided, and time-axis compressed digital signal is synchronized with said second transmission period and transmitted to said first video appliance in said second transmission period of said transmission path;

means for receiving said first compressed, divided, and time-axis compressed digital signal from said first video appliance;

means for time-axis expanding said first compressed, divided, and time-axis compressed digital signal to reproduce said first digital signal; and

means for separating said time-axis expanded first digital signal to reproduce said first digital video signal and said first digital audio signal.

8. A video signal transmission system as claimed in claim 7, wherein said first video appliance is a television camera;

and

wherein said second video appliance is a television camera controlling apparatus.

9. A video signal transmission system as claimed in claim 8, wherein said transmission path includes a triple coaxial cable.

10. A video signal transmission system as claimed in claim 7, wherein said transmission path includes a triple coaxial cable.

11. A video signal transmission system as claimed in claim 10, wherein said first video appliance is a television camera;

and

wherein said second video appliance is a television camera controlling apparatus.

12. A video signal transmission method wherein digital signals including at least digital video signals are bidirectionally transmitted and received in substantially real time between first and second video appliances coupled via a transmission path, said first and second video appliances each including a transmitting and receiving apparatus, said method comprising the steps of:

compressing a first information amount of a first digital video signal in a first digital signal of said first video appliance to produce a first compressed digital signal, dividing said first compressed digital signal into a plurality of predetermined periods, and time-axis compressing said first compressed and divided digital signal to produce a first compressed, divided, and time-axis compressed digital signal repeating a signal period and a no signal period alternately, said first compressed, divided, and time-axis compressed digital signal being transmitted on said transmission path;

controlling said transmitting and receiving apparatus of said first video appliance to generate a first transmission period and a second transmission period alternately on said transmission path, said first transmission period being longer than said second transmission period, so that said first compressed, divided, and time-axis compressed digital signal of said first video appliance is synchronized with said first transmission period and transmitted to said second video appliance in said first transmission period of said transmission path;

receiving said first compressed, divided, and time-axis compressed digital signal from said first video appliance at said second video appliance;

time-axis expanding said first compressed, divided, and time-axis compressed digital signal to reproduce said first digital signal at said second video appliance;

compressing a second information amount of a second digital video signal in a second digital signal of said second video appliance to produce a second compressed digital video signal in such a manner that said second information amount of said second digital video signal after compression is smaller than said first information amount of said first digital video signal after compression, dividing said second compressed digital signal of said second video appliance into a plurality of predetermined periods, and time-axis compressing said second compressed and divided digital signal to produce a second compressed, divided, and time-axis compressed digital signal repeating a signal period and a no signal period alternately;

controlling said transmitting and receiving apparatus of said second video appliance so that said second compressed, divided, and time-axis compressed digital signal of said second video appliance is synchronized with said second transmission period and transmitted to said first video appliance in said second transmission period of said transmission path;

receiving said second compressed, divided, and time-axis compressed digital signal from said second video appliance at said first video appliance; and

time-axis expanding said second compressed, divided, and time-axis compressed digital signal to reproduce said second digital signal at the first video appliance.

13. A video signal transmission method as claimed in claim 12, wherein said first digital signal is a first time-division multiplex signal in which at least said first digital video signal and a first digital audio signal are multiplexed;

and

wherein said second digital signal is a second time-division multiplex signal in which at least said second digital video signal and a second digital audio signal are multiplexed.

14. A video signal transmission method as claimed in claim 12, wherein after said first transmission period in which said first compressed, divided, and time-axis compressed digital signal from said first video appliance is transmitted ends, said second transmission period in which said second compressed, divided, and time-axis compressed digital signal from said second video appliance is transmitted begins;

and

wherein after said second transmission period in which said second compressed, divided, and time-axis compressed digital signal from said second video appliance is transmitted ends, said first transmission period in which said first compressed, divided, and time-axis compressed digital signal from said first video appliance is transmitted begins.

15. A video signal transmission method as claimed in claim 12, wherein after a predetermined delay time elapses since transmission of said first compressed, divided, and compressed digital signal from said first video appliance transmitted in said first transmission period ends, said second transmission period in which said second compressed, divided, and compressed digital signal from said second video appliance is transmitted begins.

16. A video signal transmission method as claimed in claim 15, wherein said predetermined delay time is set to be longer than a transmission delay time generated when said first and second compressed, divided, and time-axis compressed digital signals are transmitted on said transmission path.

17. A video signal transmission method as claimed in claim 15, wherein said predetermined delay time is based on a transmission delay time appearing in the digital signal transmitted in said transmission path.

18. A video signal transmission method as claimed in claim 17, wherein said predetermined delay time is equal to or longer than said transmission delay time.

19. A video signal transmission method as claimed in claim 12, wherein a ratio of said first transmission period to said second transmission period is selected to be 2:

1.

20. A video signal transmission method as claimed in claim 19, wherein said first transmission period and said second transmission period correspond to twelve scanning line periods and six scanning line periods, respectively, of a video signal.

21. A video signal transmission method as claimed in claim 12, wherein a time duration of said first compressed, divided, and time-axis compressed digital signal of said first video appliance is made shorter than said first transmission period;

and

wherein a time duration of said second compressed, divided, and time-axis compressed digital signal of said second video appliance is made shorter than said second transmission period.