JP2001157178A - Image transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To learn how much the delay quantity of an output video signal is by outputting the quantity of delay caused by compressing/expanding and transmitting an image on the receiving side. SOLUTION: On the transmission side, a time signal and a video signal are composited and compressing/expanding processing is performed while compositing them. On the reception side, the composited time signal is extracted and a difference from present time is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an image transmission device.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a block diagram showing a conventional image transmission apparatus.

In FIG. 2, 1 is a video signal, 4 is an image compression processing unit, 5 is an interface unit with a transmission line of a transmission unit, 6 is a transmission line, 7 is a transmission line interface unit of a reception unit, and 8 is an image decompression process. Reference numeral 14 denotes a video signal output. The video signal 1 is image-compressed by the compression processing unit 4 and then input to the interface unit 5 with the transmission path. The output signal passes through the transmission path 6 and is input to the transmission path interface unit 7 of the receiving unit. The original video signal is returned to the original video signal by the image expansion processing unit 8 and is output from the receiving unit as the video signal output 14. The video signal output from the receiving side is subjected to the compression processing time (t
1), the expansion processing time (t2) of the expansion processing unit 8 and the propagation delay (t3) generated in the transmission path 6 cause a delay time of t1 + t2 + t3 for the video signal 1. In particular, at times t1 and t2, a video signal having an enormous data amount is subjected to a process of compressing the data amount by utilizing the redundancy of human visual characteristics and the correlation between images and a decompression process of returning to an original image. The processing time is several hundred ms to several seconds, which causes a large delay. Further, even when the transmission path 6 has a long distance, it also causes a delay (t3) that cannot be ignored. In addition, this delay is not constant due to fluctuations in the compression / expansion processing time due to differences in captured images, and fluctuations in propagation delay due to differences in transmission routes and transmission methods (differences in error correction functions, storage amount during storage transmission, etc.). There is. Therefore, since it is not constant how much the video signal from the transmitting side is delayed on the receiving side, when the received video signal is confirmed and the control signal is sent to the transmitting side, there is a disadvantage that the timing is not constant. For example, in the case of a conventional video display device, since video input is almost real-time from video input to video output, a device that displays time, such as a clock, is photographed.
Since the time is c to msec or less, there is almost no difference from the current time and the viewer can watch the video without any discomfort. However, when the compression and decompression of the image causes a delay time of several hundred msec, the time at the time of viewing and the video output are output. Because the time difference between the clocks is large,
Viewers may feel uncomfortable.

[0004]

SUMMARY OF THE INVENTION In order to solve these drawbacks, the present invention outputs the difference between the time taken on the transmitting side and the time taken on the receiving side on the receiving side, and how much the amount of delay of the output video signal is reduced. It is to make it understand.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention synthesizes a display indicating time in a photographed video signal, and compresses and decompresses the video signal, and delays the video signal due to propagation delay in a transmission path. Is output on the receiving side. As a result, even if the delay due to the compression / expansion processing, the fluctuation in the compression / expansion processing time due to the difference in video, and the propagation delay due to the difference in the transmission route / transmission method fluctuate, the delay amount of the output image can be known on the receiving side. There are advantages. Therefore, when sending a control signal to the transmission side while watching the received video, the reception side knows how long the delay time is, and therefore, there is an advantage that it is possible to know how early the control signal should be sent to the transmission side.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing one embodiment of the present invention. 1 is a video signal, 2 is a time generation unit of a transmission unit, 3
Denotes a synthesizing unit of the time display signal and the video signal (hereinafter abbreviated as a synthesizing unit), 4 denotes an image compression processing unit, 5 denotes an interface unit with a transmission line of a transmission unit, 6 denotes a transmission line, and 7 denotes a transmission line of a reception unit An interface unit, 8 is an image decompression processing unit, 9 is a circuit for extracting time data from the time display unit in the decompressed image data (hereinafter abbreviated as a time extraction circuit), and 10 is a time from the transmission unit and a time on the reception side. A circuit for calculating a time difference from the generation unit (hereinafter abbreviated as a time difference calculation circuit), 11 is a time difference output circuit, 12 is a reception-side time generation unit, 13 is a time difference output signal, and 14 is a video signal output. The time signal output from the time generating unit 2 is synthesized with the video signal 1 by the synthesizing unit 3. At this time, the position of the time signal to be synthesized with the video signal and the signal format of the time signal extract time data on the receiving side. The position of the time and the signal format should be matched. The time of the time generator 2 of the transmitting unit is set to the same time as that of the time generator 13 of the receiving unit. The video signal combined with the time signal is image-compressed by the compression processing unit 4, passes through the interface unit 5 with the transmission line of the transmission unit, passes through the transmission line 6, and passes through the transmission line interface unit 7 of the reception unit. The original video signal is returned to the original video signal by the expansion unit 8 and output from the reception unit as the video signal output 14. On the other hand, the expanded video signal 14 also includes a time signal synthesized by the transmission unit. Since the position and signal format of the time signal in the video signal are matched between the transmitting side and the receiving side, the time extracting circuit 9 can extract only the time signal from the transmitting unit. Since the current time of the extracted time signal is matched in advance between the transmitting side and the receiving side, the extracted time signal has a value delayed on the receiving side by the amount of delay caused in the compression / decompression and the transmission path. For the delayed value, the time difference between the time signal extracted by the time difference calculation circuit 10 and the time signal from the time generation unit 13 of the receiving unit is obtained, and the time difference is converted into a required signal format by the output circuit 11 and then output. It is output as signal 13. The time difference output may be superimposed on the video signal output 14 as necessary, or may be displayed on another display device (not shown).

[0007]

As described above, according to the present invention, it is possible to output the time lag of the video signal due to the compression and decompression and the propagation delay of the transmission path on the receiving side. For this reason, even if the compression / expansion processing time varies due to the difference in the captured video, and the propagation delay varies due to the difference in the transmission route and transmission method, the receiving side has the effect of knowing the amount of delay of the output image data. . Therefore, when transmitting the control signal to the transmission side after confirming the received video, the reception side knows how long the delay time is, so that it is possible to know how early the control signal should be transmitted to the transmission side. . For example, in a surveillance camera device, when it is desired to view an image at 0 minutes and 0 seconds every hour on the receiving side, which is the monitor side, the total transmission delay is reduced from 0 minutes and 0 seconds by a route (not shown) from the receiving side. If an image request signal to the surveillance camera is sent before the time, an image of exactly 0 minutes and 0 seconds can be obtained. Also, several hundred m
As described above, in a system having a delay time of several seconds to several seconds, when a time display such as a clock is photographed and output as a video, a large delay time occurs due to the compression and expansion of the image, and a large delay time occurs during viewing. The difference between the time and the time of the clock that outputs the video becomes large. For this reason, an uncomfortable feeling is given to the viewer. Even in such a case, the present invention superimposes a display such as "the current image is an image two seconds ago by digital processing" on the screen,
The viewer can be notified in advance that the image is not the image at the current time, so that the viewer does not feel uncomfortable. Further, when a plurality of videos having a delay time of several hundred msec are synthesized at the same time due to the image compression / expansion process, video delay processing is added based on each time difference data to perform a video synthesis process in the same country. You can also.

Thus, the present invention has a number of advantages.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram of a conventional system.

[Explanation of symbols]

1: a video signal, 2: a time generation section of a transmission section, 3: a synthesis section of a time display signal and a video signal, 4: an image compression processing section, 5:
Interface section with transmission path of transmission section, 6: transmission path,
7: Transmission path interface unit of the receiving unit, 8: Image expansion processing unit, 9: Circuit for extracting time data from the time display unit in the expanded image data, 10: Time generation from the transmission unit and generation of time on the receiving side Circuit for calculating the time difference from the unit, 1
1: time difference output circuit, 12: reception-side time generation unit, 1
3: Time difference output signal, 14: Video signal output.

Claims (2)

[Claims] 1. An image transmission apparatus for transmitting a video signal, comprising: a time generating unit; a synthesizing circuit for synthesizing a time signal from the time generating unit and a video signal to be transmitted to obtain a synthesized video signal; An image transmission apparatus comprising: an image compression processing unit that performs a compression processing unit on the combined video signal; and an interface that sends the combined compressed video signal compressed by the image compression processing unit to a transmission path. 2. An image transmitting apparatus on the receiving side having a time generating unit, comprising: an interface for receiving a signal from the image transmitting apparatus via a transmission line; and a compressed and synthesized video signal from the interface. A time signal extraction circuit for extracting a time signal from a composite video signal output from the image expansion processing unit; a time signal from the time generation unit; and a time signal from the time extraction circuit. An image transmission apparatus comprising: a time difference calculation circuit that calculates a time difference from the time difference; and an output circuit that outputs a time difference signal based on a result calculated by the time difference calculation circuit.