JPH11331841A - Video transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To send compressed video data obtained by compressing the video signal of a selected necessary channel from a transmission side to a receiving side by avoiding the compressing processing of a disturbed video signal at the time of selecting switching the video signal of the necessary channel. SOLUTION: When a channel selecting signal 18 set outside while compress- processing a video signal 11 instructs the selection of a video signal 12, a microcomputer 3 does not output a switch instruction signal 15 selecting the signal 12 to a video signal switching part 1. Until the compressing processing of one frame of a compressing processing part input signal 13, which is presently under processing, is finished, the microcomputer 3 keeps a switch instructing signal 15 selecting the side of a contact (a) to prevent the disturbance of synchronization with a video signal compressed by a compressing part 2. At the time of detecting the finish of the compressing processing of one frame of the signal 13 at the part 2 from a compressing period display signal 17, the microcomputer 3 stops a compression instruction signal 16 outputting to the part 2 to stop the succeeding compression of the signal 13 after this with respect to the part 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of selecting and switching a video signal of a required channel from input video signals of a plurality of channels, performing signal compression processing, and transmitting video data obtained by compressing the video signal of the required channel. Video transmission device, in particular, even if the video signal of the required channel is selected and switched at an arbitrary timing from the video signals of multiple channels that are not synchronized, control is performed so that the video signal disturbed by the switching is not compressed, The present invention relates to a video transmission device capable of transmitting compressed video data obtained by compressing a video signal of a required channel.

[0002]

2. Description of the Related Art A prior art of a video transmission apparatus for selecting and switching a video signal of a required channel from video signals of a plurality of channels, compressing the video signal of the required channel and transmitting compressed video data will be described. The simplest is a video transmission device used for a simple television camera monitoring system or the like. For example, as shown in FIG. 4, a plurality of television cameras 41 and 42 and a video signal switch 4
3 and a video compression processing device 44. The video signal switch 43 of this television camera monitoring system is a video signal switch having a function of simply switching,
When the video signals of a plurality of channels captured by the plurality of television cameras 41 and 42 are switched by the video signal switch 43 and the video signal of the required channel is selected, a synchronization signal for driving the plurality of television cameras 41 and 42 is generated. Since each television camera is independent and the phase of the video signal of a plurality of channels is different, for example, when switching to a video signal of a required channel in the middle of the video signal period before switching (the switching position is undefined), the horizontal The video signal in which the vertical synchronizing signal greatly fluctuates is output to the video compression processor 44, and the distorted video signal is compressed.

As shown in FIG. 5, synchronous coupling (GEN
LOCK) function of a plurality of television cameras 51, 5
2, video signal switch 53, video compression processor 54
And a synchronizing signal generator 55 to provide a television camera monitoring system (transmitting side). The video signal switch 53 of this television camera monitoring system is a video signal switch having a function of simply switching, and is picked up by a plurality of television cameras 51 and 52 synchronously coupled with a synchronization signal generator 55. The video signals of a plurality of channels are switched by the video signal switch 53 and the video signals of the required channels are selected.
Synchronization signals for driving the channels 1 and 52 are synchronized, and the phases of the video signals of a plurality of channels are synchronized. When the signal is switched (the switching position is undefined), the video signal whose screen is switched halfway is output to the video compression processing device 54, and the video signal from the different television cameras is compressed at the top and bottom of the screen. For example, in the case of a system in which compressed video data is transmitted from a transmission side to a reception side via a low bit rate line,
Although the compressed video data of each frame is transmitted intermittently,
If the distorted video signal is compressed, the compressed video data is transmitted, decompressed by the receiving device of the system, and the video signal is output, until the compressed video data of the next frame is transmitted, There is a problem that a disturbed image is displayed on a video monitor for a long time, for example.

Further, in order to prevent switching in the middle of a video signal as in the above-described television camera monitoring system, as shown in FIG. A video signal switch 63 for switching video signals of a plurality of channels using a vertical synchronization signal during a vertical blanking period of the synchronization signal.
TV camera monitoring system (transmitting side) composed of a video compression processing device 64 and a synchronization signal generator 65
There is. A video signal switch 63 of the television camera monitoring system has a function of switching a video signal using a vertical synchronization signal input from the synchronization signal generator 65 during a vertical blanking period of the synchronization signal. The video signals of a plurality of channels captured by the plurality of television cameras 61 and 62 that are synchronously coupled with the synchronization signal generator 65 are switched in a vertical blanking period (the blanking period is a synchronization without a video signal). (For example, a period during which processing is not performed on a video monitor).

[0005] As described above, the video signal switch 63 that switches during the vertical blanking period of the video signal performs the switching operation of the video signal at an arbitrary timing. Therefore, the video signal is switched to the video signal of the required channel in the middle of the video signal before the switching, and the operation of disturbing the video signal is not performed. Therefore, if video signals of a plurality of channels imaged by a plurality of television cameras 61 and 62 that are synchronously coupled are switched by a video signal switch 63 that switches in a vertical blanking period, for example, a required signal is required in the middle of the video signal period before switching. The video signal is not switched to the channel video signal, is continuously switched without any disturbance of the video signal, and can be input to the video compression processing device 64 to perform normal compression processing.

[0006]

In a video transmission apparatus according to the prior art, a video signal of a required channel is selected and switched by a video signal switcher from input video signals of a plurality of channels, and compressed by a video compression processor. When a video signal is transmitted from the transmission side to the reception side, in order to prevent a video signal whose synchronization has been disturbed due to switching by a video signal switcher from being compressed, images are taken by a plurality of television cameras having a synchronization coupling function and synchronous coupling is performed. The compressed video data is transmitted after being switched by a video signal switch that performs a switching operation during a vertical blanking period, and the compressed video data is transmitted. It is more expensive than a non-functional television camera. Further, in order to synchronously couple a plurality of television cameras having a synchronous coupling function, it is necessary to supply a reference synchronous signal from a reference synchronous signal generator to each television camera having a synchronous coupling function. However, this requires the installation of a coaxial cable for supplying a synchronization signal to each television camera, which increases costs. Further, a circuit or device for switching the timing of switching the video signal of the required video channel from the video signals of a plurality of channels in synchronization with the vertical blanking period of the synchronization signal is required, which further increases the cost.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and when a video signal of a required channel is selected and switched at an arbitrary timing from among video signals of a plurality of input channels that are not synchronously coupled, the switching is performed. It is an object of the present invention to provide a video transmission apparatus for transmitting compressed video data obtained by compressing a video signal of a selected required channel from a transmitting side to a receiving side so as not to perform a compression process on a video signal which is disturbed by the above.

[0008]

In order to achieve the above object, a video transmission apparatus according to the present invention selects and switches a video signal of a required channel from a plurality of externally input video signals, and switches the video signal. A video signal switching unit that outputs a video signal of a channel; a compression processing unit that compresses the video signal of the required channel input from the video signal switching unit and sends out compressed video data to a receiving side; A microcomputer that controls selection switching of the video signal of the required channel in the video signal switching unit and execution and stop of the compression processing of the video signal of the required channel in the compression processing unit based on the channel selection signal When the video signal of the required channel is selectively switched at an arbitrary timing, the compression process of the video signal disturbed by the switching is performed. Those who do not rope.

More specifically, the video signal switching section of the video transmission apparatus according to the present invention uses a switching command signal input from a microcomputer to output a video of a desired channel from video signals of a plurality of channels input from outside. Signals are selectively switched to output video signals of the required channels. Further, the compression processing section of the video transmission apparatus of the present invention compresses the video signal of the required channel input from the video signal switching section according to a compression command signal input from the microcomputer, and sends the compressed video data to the receiving side. And a compression period display signal to the microcomputer. Further, the microcomputer of the video transmission apparatus of the present invention outputs a switching command signal created by a channel selection signal input from the outside and a compression period display signal input from the compression processing unit to the video signal switching unit, The compression command signal generated from the compression period display signal input from the compression processing unit is output to the compression processing unit.

Further, the video transmission apparatus of the present invention selects and switches a video signal of a required channel from a plurality of video signals input from the outside according to a switching command signal input from a microcomputer. A video signal switching unit that outputs a video signal of the desired channel, and compresses the video signal of the required channel input from the video signal switching unit by a compression command signal input from the microcomputer, and sends the compressed video data to the receiving side. With
A compression processing unit that outputs a compression period display signal to the microcomputer; and a switching command signal created by a channel selection signal input from the outside and the compression period display signal input from the compression processing unit. And switching the selection of the video signal of the required channel to output to the
A microcomputer that outputs a compression command signal created based on the compression period display signal input from the compression processing unit to the compression processing unit and controls execution and stop of compression processing of the video signal of the required channel. Further, even when the selection of the video signal of the required channel is switched at an arbitrary timing, the compression processing of the video signal disturbed by the switching is not performed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a video transmission apparatus according to the present invention will be described with reference to FIGS. FIG. 1 shows a control of a microcomputer (microcomputer) when a video signal switching unit switches a video signal of a plurality of channels (not necessarily synchronized), for example, a video signal of two channels input from two television cameras. The compression process is temporarily stopped so that the video signal disturbed by the switching is not compressed, and the video signal of the required channel is switched by the video signal switching unit. FIG. 3 is a block diagram of a video transmission apparatus according to the present invention, in which a compression processing unit performs compression processing of a video signal of a required channel and transmits compressed video data obtained by compressing the video signal to a receiving side.

In FIG. 1, reference numeral 10 denotes a video transmission device, 1 denotes a video signal switching section which switches input video signals of a plurality of channels by a separately input switching command signal and selects and outputs a video signal of a required channel; , Video signal switching unit 1
Starts the compression processing of the video signal of the required channel at a timing with the video signal of the required channel selected and input from, and sends the compressed video data obtained by compressing the video signal to the other device on the receiving side, and transmits one frame. A compression processing unit 3 that outputs a compression period display signal indicating a period during which compression processing for one (or one field) is being performed is input with a channel selection signal that instructs selection of a video signal of a required channel. This shows a microcomputer that outputs a switching command signal to the video signal switching unit 1 and controls and outputs a compression command signal that is timed to a video signal of a required channel to the compression processing unit 2.

A timing chart (shown in FIG. 2) of various signals used in the video transmission apparatus of the present invention and a microcomputer 3
The operation of the video transmission apparatus according to the present invention will be described with reference to the operation flowchart of FIG. 3 (shown in FIG. 3). Note that FIG.
Converts a compression processing unit input signal (video signal of a required channel) 13 output from the contact c of the video signal switching unit 1 and input to the compression processing unit 2 into a video signal input to the contact a of the video signal switching unit 1 11, a video signal 12 input to the contact b
In the case of switching to, the input video signals 11 and 12 of a plurality of channels, the compression processing unit input signal 13, the switching command signal 15, the compression command signal 16, the compression period display signal 1
7, the timing of the channel selection signal 18 is shown.

The video transmission apparatus 10 receives a video signal of a plurality of channels (not necessarily synchronized), for example, a video signal 11 from two television cameras (not shown) (see signal waveform 21 in FIG. 2). ) Is the contact a of the video signal switching unit 1.
The video signal 12 (see signal waveform 22 in FIG. 2) is
Has been entered. The channel selection signal 18 (see the signal waveform 25 in FIG. 2 on the video signal 11 side) set externally has already instructed the microcomputer 3 to select the video signal 11, and a switching command from the microcomputer 3 based on this instruction. The signal 15 (see a side of the signal waveform 26 in FIG. 2) is output to the video signal switching unit 1. The video signal switching unit 1 selects the contact a under the control of the switching command signal 15 and converts the video signal 11 from the contact c to the compression processing unit input signal 13 (signal waveform 2 in FIG. 2).
3) to the compression processing unit 2.

The compression processing unit 2 compresses the input compression processing unit input signal 13 (video signal 11) and transmits the compressed video data 14 (for example, as serial data) to another device on the receiving side. Sending out. This state is maintained until the video signal switching unit 1 outputs the video signal 1 until the newly selected channel selection signal 18 is input to the microcomputer 3.
1 is selected and input to the compression processing unit 2 as a compression processing unit input signal 13, where the compressed video data 14 of the video signal 11 is transmitted to the receiving side. At this time, the compression processing unit 2 performs compression processing on the input compression processing unit input signal 13 and sends out the compressed video data 14 to another device on the receiving side, while displaying the compression period display signal 17 (see FIG. 2). Signal waveform 24
To the microcomputer 3).

Next, for example, during the compression processing of the video signal 11, when the channel selection signal 18 set externally instructs the microcomputer 3 to select the video signal 12 (the switching instruction of the signal waveform 25 in FIG. The microcomputer 3 immediately receives the video signal 1 (see the signal 12 side and step 31 in FIG. 3).
2 is not output to the video signal switching unit 1. (In FIG. 2, even if the channel selection signal 18 gives a switching instruction, the switching command signal 15 is still on the a side.) The microcomputer 3 sets the channel selection signal 18 and the compression processing unit 2
Is compared with the compression period display signal 17 input from the CPU, and the switching command signal 15 is contacted until the compression processing of one frame of the compression processing unit input signal 13 (video signal 11) currently being compressed is completed. Hold so that it becomes the selection of the a side,
Control is performed so that synchronization with the video signal compressed by the compression processing unit 2 is not disturbed (see step 32 in FIG. 3). Microcomputer 3
When it is detected from the compression period display signal 17 input from the compression processing unit 2 that the compression processing of one frame of the compression processing unit input signal 13 in the compression processing unit 2 is completed,
The compression command signal 16 output to the compression processing unit 2 is stopped (see the stop of the signal waveform 27 in FIG. 2 and step 33 in FIG. 3), and the compression processing unit input signal 13 Is stopped.

After the compression command signal 16 is stopped, the microcomputer 3 sets the switching command signal 15 (the switching command of the signal waveform 26 shown in FIG. Reference to the b side, and steps 34 and 3 in FIG.
5 and 36) to the video signal switching unit 1. The video signal switching unit 1 switches the contact from the contact a to the contact b when the switching command signal 15 is input, and outputs the video signal 12 to the compression processing unit 2 as the compression processing input signal 13. The video signal 12 is input to the compression processing unit 2 in place of the video signal 11 as the compression processing unit input signal 13. Since the phase of the video signal 11 is different from that of the video signal 11, the compression processing unit input signal 13 Will fluctuate greatly. Therefore, if the compression processing unit 2 performs the compression processing in a state of a large fluctuation, the compression processing unit 2 cannot follow the fluctuation, and the compression processing unit input signal 13
However, since the compression processing unit 2 has already stopped the compression by the compression command signal 16, the compressed video signal is not compressed. Microcomputer 3
Waits for the compression processing unit 2 to recover synchronization with the compression processing unit input signal 13 (for example, after switching the compression processing unit input signal 13, the compression processing unit 2 normally compresses the switched video signal. The time until it can be obtained is determined in advance by an experiment or the like, and the microcomputer 3 monitors whether the time has elapsed (see step 37 in FIG. 3). 2 and execution reference from the stop of the signal waveform 27, and step 38 in FIG. 3) are output.

The compression processing section 2 compresses the input compression processing section input signal 13 (video signal 12) and sends out the compressed video data 14 for transmission to another device on the receiving side.
In this state, the video signal 12 is selected by the video signal switching unit 1 and input to the compression processing unit 2 as the compression processing unit input signal 13 until the channel selection signal 18 newly set externally is input to the microcomputer 3. The compressed video data 14 of the video signal 12 is transmitted to the receiving side. In addition,
During the period when the compression processing is stopped in the compression processing unit 2, the compressed video data 14 is not transmitted from the compression processing unit 2, so that a period of no signal occurs on the receiving side as it is. In order to prevent the occurrence of this period of no signal, the compression processing unit 2 includes a memory device, for example, a memory device for one frame of compressed video data, and always writes and reads out the compressed video data to be transmitted once. I have. The control of writing and reading of the compressed video data in this memory device is performed by a compression command signal 16 input from the microcomputer.
When the compression command signal 16 instructs stop while writing and reading of one piece of compressed video data is being performed, the memory device stops writing and only reads out the stored one frame of compressed video data. Become like Next, when the compression command signal 16 instructs execution at the timing when the synchronization is restored, the memory device resumes writing, and starts writing and reading out the compressed video data of the switched video signal 12.

As another means, a memory device provided in the compression processing section 2 on the transmission side of the video transmission apparatus is provided on the reception side of the video transmission apparatus in order to prevent a period of no signal from occurring. You may. The compressed video data 14 transmitted and transmitted from the compression processing unit 2 on the transmission side is written to and read from the memory device provided on the reception side. The stored compressed video data 14 is read. FIG. 7 shows a case where a memory device, for example, a one-frame memory device is replaced with a video transmission device in order to prevent a period in which no signal is generated during a period in which compression processing is stopped in the compression processing unit 2 on the transmission side. It is a block diagram which shows the example at the time of providing on the receiving side. Compression processing unit 2 on the transmission side of video transmission device
The compressed video data 14 transmitted and transmitted from is received and input to the decompression processing unit 71 on the receiving side. The decompression processing unit 71 performs a decompression process on the input compressed video data 14 and outputs the decompressed video data to the memory device 72. The memory device 72 temporarily writes and reads the video data input from the decompression processing unit 71 and outputs the video data to the video encoder 73. When the compressed video data 14 of the next frame is decompressed by the decompression processing unit 71, the decompressed new video data is overwritten on the video data written in the memory device 72. During this period, the video data of the previous frame is kept held. The video encoder 73 converts the video data input from the memory device 72 into an analog video signal 75,
The converted video signal 75 is output to another device. As described above, if the video signal of the required channel is selected by the video transmission device of the present invention and the timing of switching the video signal and the period of the compression process are simply controlled by the microcomputer, the compression process of the disturbed video signal can be performed. It is possible to avoid even if the input video signals of a plurality of channels are asynchronous, so that there is no need to prepare equipment for synchronous coupling, so that the system can be reduced in size and cost can be reduced. Can be realized.

[0020]

According to the present invention, when a video signal of a required channel is selected and switched at an arbitrary timing from the video signals of a plurality of input channels which are not synchronously coupled, the switching is disturbed. It is possible to provide a video transmission apparatus that does not perform video signal compression processing and that transmits compressed video data obtained by compressing a video signal of a selected required channel from a transmission side to a reception side.

[Brief description of the drawings]

FIG. 1 is a block diagram of a video transmission device according to the present invention.

FIG. 2 is a timing chart of various signals used in the video transmission device of the present invention.

FIG. 3 is a flowchart of a microcomputer used in the video transmission device of the present invention.

FIG. 4 is an explanatory diagram of conventional video signal switching and transmission.

FIG. 5 is an explanatory diagram of conventional video signal switching and transmission.

FIG. 6 is an explanatory diagram of conventional video signal switching and transmission.

FIG. 7 is an explanatory diagram of a receiving-side circuit for preventing occurrence of a no-signal period due to suspension of compression processing.

[Explanation of symbols]

Reference Signs List 1 video signal switching unit 2 compression processing unit 3 microcomputer 10 video transmission device 41, 42, 51, 52, 61, 62 television camera 43, 53, 63 video signal switching device 44, 54, 64 video compression device 55, 65 synchronization Signal generator 71 Decompression processing unit 72 Memory device 73 Video encoder. 11 video signal 12 video signal 13 compression processing unit input signal 14 compressed video data 15 switching command signal 16 compression command signal 17 compression period display signal 18 channel selection signal.

Claims (7)

[Claims] 1. A video signal of a required channel is selected and switched from a plurality of video signals input from the outside, and
A video signal switching unit that outputs the video signal of the required channel; a compression processing unit that compresses the video signal of the required channel input from the video signal switching unit and sends out compressed video data to a receiving side; Based on the input channel selection signal, the video signal switching unit controls the selection switching of the video signal of the required channel and the compression processing unit controls execution and stop of the compression processing of the video signal of the required channel. A video transmission device comprising a microcomputer, wherein when the video signal of the required channel is selectively switched at an arbitrary timing, the video signal disturbed by the switching is not compressed. 2. A video signal of a desired channel is selected and switched from a plurality of video signals input from the outside, and
A video signal switching unit for outputting the video signal of the required channel; a video signal of the required channel input from the video signal switching unit being subjected to compression processing to obtain compressed video data; A compression processing unit having a memory device for transmitting the video signal; and a video signal switching unit for selectively switching the video signal of the required channel based on a channel selection signal input from the outside. And a microcomputer for controlling the execution and stop of the video signal compression processing, and when the video signal of the required channel is selectively switched at an arbitrary timing, the compression processing of the video signal disturbed by the switching is performed. And the compressed video data before switching from the memory device to the receiving side even when the compression process is stopped. Video transmission apparatus being characterized in that so as to output. 3. The video transmission device according to claim 1, wherein the video signal switching unit selects a video signal from a plurality of externally input video signals according to a switching command signal input from a microcomputer. A video transmission device for selectively switching a video signal of a channel and outputting a video signal of the required channel. 4. The video transmission apparatus according to claim 1, wherein the compression processing section performs a compression process on a video signal of a required channel input from the video signal switching section in accordance with a compression command signal input from the microcomputer. A video transmission device for transmitting video data to a receiving side and outputting a compression period display signal to the microcomputer. 5. The video transmission device according to claim 1, wherein the microcomputer has a switching command signal generated based on a channel selection signal input from the outside and a compression period display signal input from the compression processing unit. And a compression instruction signal generated by the compression period display signal input from the compression processing unit, and outputs the compression command signal to the compression processing unit. 6. A video signal for selecting and switching a video signal of a required channel from a plurality of video signals input from the outside by a switching command signal input from a microcomputer, and outputting the video signal of the required channel. A switching unit; compressing the video signal of the required channel input from the video signal switching unit with a compression command signal input from the microcomputer, transmitting compressed video data to a receiving side, and compressing the compressed video data to the microcomputer; A compression processing unit that outputs a display signal; and a switching command signal created by a channel selection signal input from the outside and the compression period display signal input from the compression processing unit. Selection switching of a video signal of a required channel and display of the compression period input from the compression processing unit And a microcomputer for controlling the execution and stop of the compression processing of the video signal of the required channel by outputting the compression command signal generated by the signal to the compression processing unit, and the video signal of the required channel at an arbitrary timing. A video signal transmission apparatus which does not perform a compression process on a video signal disturbed by the switching even when the selection is switched. 7. A video signal for selecting and switching a video signal of a required channel from a plurality of video signals input from outside by a switching command signal input from a microcomputer, and outputting the video signal of the required channel. A switching unit; compressing the video signal of the required channel input from the video signal switching unit with a compression command signal input from the microcomputer, transmitting compressed video data to a receiving side, and compressing the compressed video data to the microcomputer; A compression processing unit that outputs a display signal; and a switching command signal created by a channel selection signal input from the outside and the compression period display signal input from the compression processing unit. Selection switching of a video signal of a required channel and display of the compression period input from the compression processing unit And a microcomputer for controlling the execution and stop of the compression processing of the video signal of the required channel by outputting the compression command signal generated by the signal to the compression processing unit, and the video signal of the required channel at an arbitrary timing. When the selection switch of
A transmitting side that does not perform a compression process on the video signal disturbed by the switching, receives the compressed video data transmitted from the transmitting side, and performs a decompression process on the compressed video data to perform decompression. A decompression processing unit that outputs video data, a memory device that temporarily stores the video data input from the decompression processing unit, reads and outputs the video data, and processes the video data input from the memory device.
A receiving side having a video encoder that converts the video signal of the required channel into an analog video signal and outputs the video signal of the required channel to another device,
A video transmission device, wherein the video data before the channel switching is read from the memory device during a period in which the compression-processed video signal from the transmission side is absent.