JPH0282885A - Picture coding switching method and picture coding changeover system - Google Patents

Abstract

PURPOSE:To prevent the transmission of a picture signal not normal to an opposite side by stopping the coding of a picture signal during the transmission while receiving a picture changeover request, confirming the end of the changeover of a picture signal input and coding and sending a switched picture signal after a prescribed time is awaited. CONSTITUTION:A picture input switching control section 2 switches an inputted picture signal into a picture signal by a command input from a picture signal during the transmission. A picture input state detection section 3 detects the input state of the said picture signal. A coding control section 6 in response to the said command input stops the coding of the picture signal during the transmission and counts it for a prescribed time and controls the coding after a prescribed time is counted. When the prescribed time is set to a time required to establish synchronization with respect to the input picture signal in a coder 8, for example, the coder can restart the coding processing in a proper timing in the case of the changeover of the picture signal.

Description

[Detailed Description of the Invention] [Summary] This invention relates to an image encoding switching method for switching an image signal that is being encoded and transmitted to another image signal, encoding it, and transmitting the image signal. In an image encoding system that selects one of a plurality of image signals, encodes it, and transmits it, the purpose is to enable the encoding device to restart the encoding process at an appropriate timing. The encoding of the image signal being transmitted is stopped, and after confirming that the switching of the image signal input is completed and waiting for a predetermined time, the switched image signal is encoded and transmitted.

[Industrial Application Field] The present invention relates to an image encoding switching method for switching an image signal that is being encoded and transmitted to another image signal, encoding, and transmitting it, and an image code that implements the method. Regarding the switching system.

For example, when transmitting images of a video conference, in addition to moving images such as images of people participating in the conference, still images such as charts are transmitted.

Furthermore, since image signals generally have a huge amount of data, they are usually compressed by encoding processing and the like before being transmitted.

By the way, the transmission of still images during a video conference as described above is performed in a time-division manner during the transmission of moving images. At this time, the encoding system needs to be able to switch to interrupting the encoding process for moving images and performing the encoding process for still images.

[Prior Art and Problems to be Solved by the Invention] FIG. 8 shows the overall configuration of an image encoding and decoding system used for transmitting video conference images.

As shown in FIG. 8, a moving image signal from a camera 71 that takes moving images of people, etc., and a still image signal from a camera 72 that takes still images such as tables, etc. are transmitted to the station controller. After one is selected in 73 and encoded in the encoding/decoding device C0DEC75,
Coding/decoding device C0DEC on the other side via the transmission path
77, where it is decoded and displayed.

Here, the above-mentioned image signal can be selected, for example, from the device input section 76 attached to the encoding/decoding device C0DEC75, or from the station controller 73 placed under the conference presenter or operator. This is done by manual input from a remote input unit 74 attached to the.

Conventionally, when attempting to transmit a still image in the middle of transmitting a moving image, an encoding device immediately stops the encoding process of the moving image that is being transmitted upon recognizing a request to transmit the still image. From that point on, the human input image signal was switched, and the encoding process was resumed after waiting a time deemed sufficient for the encoding device to establish synchronization with the switched input image signal.

For example, FIG. 9 shows the conventional timing of still image transmission during moving image transmission.

Up to time ■ in Figure 9, the moving image is encoded and transmitted, but at that time ■, when the operator presses the switch to instruct still image transmission (in this case, the device input button in Figure 8 76
), and this instruction is sent to the station controller 73 (S in FIG. 9) via a control signal line.
TCNT) (time ■), and switching of the input image signal from a moving image to a still image is started.

Furthermore, the encoding device 50 (in FIG. 9, C0DEC
At the time indicated by ), the encoding operation is stopped, and a request to freeze the moving image is placed on the frame header and transmitted to the other party (time ■).

Then, the input image signal switches to a still image (time ■
), and after waiting a time T that is considered sufficient for the encoding device to establish synchronization with the switched input image signal, the encoding process is resumed (time ■), encoding and transmitting the still image. (time ■).

In FIG. 9, the switching from a still image to a moving image shown from time ■ to [phase] starts from time ■ when encoding and transmission of the still image is started. The time after waiting TD, which is considered to be enough time for the transmission to end and switching back to the moving image again.
[phase], the encoding of the moving image is restarted.

However, in the conventional image coding switching method as described above, if the waiting time Tc or T is set too long, time will be wasted until the video transmission is restarted, and conversely, If the waiting time is too short, an incorrect image signal may be input before the switching from a moving image to a still image or from a still image to a moving image is completed, and the other party may receive an incorrect image signal. There was a problem in that it ended up being transmitted.

Furthermore, for the station controller 73,
There may be cases where a still image signal is not input, but conventional image coding switching methods cannot detect such a situation, and even in such cases, an abnormal image signal may be sent to the other party. There was a problem in that it ended up being transmitted.

The present invention has been made in view of the above-mentioned problems, and allows the encoding device to restart the encoding process at an appropriate timing when switching image signals, and also enables the encoding device to restart the encoding process at an appropriate timing, and also to enable the encoding device to restart the encoding process at an appropriate timing when switching image signals. It is an object of the present invention to provide an image encoding switching method that can also confirm whether or not the image encoding switching method is input, and an image encoding switching system that implements the image encoding switching method.

[Means to solve the problem]

As shown in FIG. 1, the image encoding switching method of the present invention is applied to an image encoding system in which one of a plurality of image signals is selected, encoded, and transmitted.
In response to this, the encoding of the image signal being transmitted is stopped at step S3, and after confirming that the manual switching of the image signal has been completed at step S5 and waiting for a predetermined time, at step S6, the encoded image signal is encoded and the image signal is encoded at step S3.
7 transmission.

FIG. 2 is a basic configuration diagram of a first embodiment of an image encoding switching system of the present invention that implements the above-mentioned image encoding switching method. In this figure, 1 is a transmission image instruction input section, 2 is an image input switching control section, 3 is an image input state detection section, 5 is an encoding section, 6 is an encoding control section, 7 is a clock section, and 8 is a It is an encoding device.

The encoding device 8 includes an encoding section 5 that encodes and transmits one of a plurality of image signals.

The transmission image instruction input unit l selects one of the plurality of image signals.
This is the part where you input instructions to select one, encode it, and transmit it.

The image input switching control section 2 switches the input image signal from the image signal being transmitted to the image signal based on the instruction input.

The image input state detection section 3 detects the input state of the image signal.

An encoding control unit 6 and a clock unit 7 are provided in the encoding device 8, and the clock unit 7 measures a predetermined time after receiving the input state information. , in response to the instruction input, controls the encoding unit 5 to stop encoding the image signal being transmitted, and to start encoding after measuring the predetermined time.

FIG. 3 is a basic configuration diagram of a second embodiment of the image encoding and switching system of the present invention that implements the image encoding switching method. In this figure, the encoding device 8 includes a central control unit 9
The central control section 9 includes the encoding control section 6 and the clock section 7.

Further, the central control section 9 controls the image input state detection section 3.
When it is recognized by the output that the inputted image signal is not input for a predetermined period of time after the instruction input, the encoding of the image signal being transmitted is started again.

[Function] According to the image encoding switching method of the present invention, after confirming in 1111 that the manual switching of the image signal has been completed, and after waiting for a predetermined time, encoding of the switched image signal is started. If this predetermined time is set, for example, to the time required for the encoding device 8 to establish synchronization with the input image signal, the encoding device will perform the encoding process at an appropriate timing when switching image signals. It can be restarted.

Further, according to the basic configuration of the first embodiment of the image encoding switching system of the present invention shown in FIG. It can be confirmed whether or not. Therefore, upon receiving this information, if the input image signal is switched in accordance with the instruction input, the encoding device 8 measures the aforementioned predetermined time in the clock section 7, and determines when the predetermined time has elapsed. After,
The encoding control section 6 is controlled to start encoding.

In this way, the encoding process is restarted at an appropriate timing to encode the input image signal switched by the instruction input.

Furthermore, according to the basic configuration of the second form of the image encoding switching system of the present invention shown in FIG.
When the central control unit 9 recognized by the output of the image input state detection unit 3 that there is no input of the input image signal for a predetermined period of time after the input of the instruction, the central control unit 9 detects the transmission again. control to encode and transmit the image signal inside. In this way, it is possible to check whether the image signal requested for transmission is being input.
Even if there is a transmission request and the image signal is not input,
Normal image transmission can continue.

[Example] A schematic hardware configuration of an example of the present invention is, for example,
It is shown in FIG. The configuration shown in FIG. 5 is obtained by applying the configuration shown in FIG. 3 described above to the teleconference image transmission system shown in FIG. 8 described above.

In FIG. 5, 41 is a video/still image switching control unit;
2 is a video/still image switching detection unit; 43 and 51 are peripheral interface adapters; 44 and 52 are CPUs;
45 and 53 are asynchronous interface adapters;
46 and 54 are drivers/receivers. and,
55 corresponds to the encoding unit 5 in the configuration shown in FIGS. 2 and 3, 40 corresponds to the station controller 73 in FIG. 8, and 50 corresponds to the code in the configuration shown in FIGS. 2 and 3. The first still image transmission request switch 4 is connected to the encoding device 8 or the encoding/decoding device 75 having the configuration shown in FIG.
7 is connected to the remote input section 74 having the configuration shown in FIG.
The still image transmission request switch 56 corresponds to the device input section 76 in FIG.

The moving image/still image switching control section 41 corresponds to the image input switching control section 2 in the configurations of FIGS. 2 and 3, and the moving image/still image switching detecting section 42 corresponds to the image input state detecting section 3. The moving image/still image switching control section 41 and the moving image/still image switching detecting section 42 are, for example, composed of relay switches that operate in conjunction with each other. Which image signal is selected and thereby which image signal is input to the station controller 40 can be detected by the moving image/still image switching detection section 42.

Information indicating the state of the input image signal detected by the moving image/still image switching detection section 42 is sent to the encoding/decoding device 50 via the asynchronous interface adapter 45 and driver/receiver 46 under the control of the CPU 44. and in the encoding/decoding device 50, the CP
U52 receives this via driver/receiver 54 and asynchronous interface adapter 53, and performs the same control as that performed by central control unit 9 of the configuration of FIG. 3 described above.

First and second still image transmission request switches 47 and 5
Reference numeral 6 also corresponds to the transmission image instruction input unit 1 in FIG. An instruction input from the second still image transmission request switch 56 is transmitted to the CPU 44 via the peripheral interface adapter 51. When an instruction is input from the first still image transmission request switch 47, the still image transmission request is sent to the CPU.
44 , it is further transmitted to the CPU 52 of the encoding/decoding device 50 via the asynchronous interface adapter 45 and the driver/receiver 46 .

In response to the still image transmission request as described above, the CPU 52
Like the central control unit 9 in FIG.
The still image switching control unit 41 is controlled by an asynchronous interface adapter 53 45 and a driver/receiver 5.
4.46.

FIG. 4 shows the procedure of an embodiment of the present invention having the above-described configuration.

First, in step 301, when a still image transmission request is input from the still image transmission request switch 47 or 56 in FIG.
0 CPU 52 (step 302).

Further, in step 303, the encoding process in the encoding unit 55 of the encoding device 50 is stopped, and the moving image is placed in a frozen state.

In step 304, it is determined whether or not a still image signal is input to the station controller 40. If it is input, the moving image/still image switching control section 41 switches the still image signal to the station controller 40. Then, the still image encoding operation is started (step 305).

When the still image encoding operation in step 305 is completed, the CPU 52 of the encoding device 50 issues a video switching request in step 307 to return to video transmission, and in step 308 starts video transmission. As soon as the presence or absence of the moving image signal is determined and moving image transmission is started, encoding of the moving image signal is restarted in step 309.

If the still image signal is not input in step 304, it is determined in step 306 whether or not the state in which the still image signal is not input continues for a predetermined period of time, and if the still image signal is not input, If the predetermined period of time has elapsed, the process proceeds to step 309 and the encoding of the moving image signal is restarted.

FIGS. 6 and 7 show the timing of the steps in the embodiment of the invention described above in more detail.

6 and 7 show the timing of the embodiment of the present invention in correspondence with the procedure of FIG. 9 showing the timing of the conventional method described above, and FIG. In steps 304 and 306, input of a still image signal is started before the predetermined time elapses, and FIG. 7 shows a case where the predetermined time elapses without a still image signal being input. This shows the case where

In FIG. 6, the moving image is encoded and transmitted until time ■; however, at time ■, when the operator presses the still image transmission request switch, this instruction is sent to the encoding device 50.
(indicated by C0DEC in FIGS. 6 and 7) to the station controller 40 (indicated by C0DEC in FIGS. 6 and 7).
ST CNT in the figures and FIG. At the same time, a request to freeze the moving image is placed on the frame header and transmitted to the other party (not shown as it is the same as in Fig. 9).
. In response to this, on the receiving side, the moving image transmitted from the encoding device 50 immediately before the above time ■' is displayed in a frozen state (■).

Here, the time indicated by ■ in FIG.
This is the time required for the controller 40 to switch the input image from a moving image to a still image.

According to the present invention, when the switching of the input image from a moving image to a still image is completed at time ⑥, the station controller 40 requests the encoding device 50 to complete the switching (start transmitting the still image). Information indicating the information is transmitted. When the CPU 52 of the encoding device 50 receives information indicating the completion of the switching, the CPU 52 of the encoding device 50
, a predetermined time T required from the start of reception of the still image signal to the establishment of synchronization is measured, and at a time (3) when the predetermined time T has elapsed, the still image is encoded and transmitted. (time ■).

At time ■, when the encoding and transmission of the still image described above is completed, the encoding device 50 transmits a request to switch the input image signal to a moving image to the station controller 40 (time ■). .

Corresponding to the completion of the transmission of the still image, the still image is displayed on the receiving side at time [phase].

Further, at time (3), in response to the request for switching to the moving image, the station controller 40 performs switching processing.

Then, at time @, when the input image signal is switched to a moving image, the station controller 40 transmits a video transmission start signal to the encoding device 50 (time @).

When the CPU 52 of the encoding device 50 receives the video transmission start signal, the CPU 52 of the encoding device 50 calculates a predetermined time T,' required from the start of receiving the video signal to the establishment of synchronization in the encoding device 50. The encoding and transmission of the moving image are started at the time [phase] when the predetermined time TS' has elapsed.

In response, on the receiving side, display of the moving image is resumed from time ■.

FIG. 7 shows that a still image switching request is transmitted from the CPU 52 of the encoding device 50 to the station controller 40 at time 3, as in FIG. This example shows a case where input of a still image is not started.

As shown in steps 304 and 306 in FIG. 4, the CPU 52 of the encoding device 50 starts transmitting still images as shown in FIG. 6 for a predetermined period of time after sending the still image switching request. In other words, if the information indicating that the switching of the input image from a moving image to a still image is completed is not transmitted, the video switching request is timed out and the moving image is encoded again from time ■. and start transmission. In response, the receiving side also releases the frozen state and starts displaying the moving image again from time (3). In this case, no still image is displayed on the receiving side.

〔Effect of the invention〕

According to the image coding switching method and the image coding switching system of the present invention, when switching image signals, the coding device can restart the coding process at an appropriate timing, and the transmission request It is also possible to check whether or not the image signal with which the image has been detected has been input.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of the image encoding switching method of the present invention, FIG. 2 is a basic configuration diagram of the first form of the image encoding switching system of the present invention, and FIG. 3 is a basic configuration diagram of the image encoding switching method of the present invention. A basic configuration diagram of the second embodiment of the system; FIG. 4 is a diagram showing a procedure in an embodiment of the present invention; FIG. 5 is a diagram showing an outline of the hardware configuration in an embodiment of the present invention; 7 is a timing diagram of an embodiment of the present invention, FIG. 8 is a diagram showing the overall configuration of an image encoding and decoding system, and FIG. 9 is a timing diagram of a conventional image encoding switching system. It is. [Description of symbols] 1... Transmission image instruction input unit, 2... Image input switching control unit, 3... Image input state detection unit, 5... Encoding unit, 6... Encoding control 7... Timekeeping unit, 8... Encoding device, 9... Central control unit, 40... Station controller, 41... Video/still image switching control unit, 42... Video /Still image switching detection section, 43.51...
・Peripheral interface adapter, 44.52...
CPU. 45.53...Asynchronous interface adapter,
46.54...driver/receiver, 47...first
still image transmission request switch, 50... encoding device, 5
5... Encoding unit, 56... Second still image transmission request switch, 71.72... Camera, 73... Station controller, 75.77... Encoding/decoding device, 76...Equipment human power department, 74...Remote human power department. Principle configuration diagram of the procedure of the image coding switching system according to the present invention

Claims (1)

[Claims] 1. In an image encoding system that selects one of a plurality of image signals, encodes it, and transmits it, an image switching request (S
1), the encoding of the image signal being transmitted is stopped (S3
), confirm that switching of image signal input is completed (S5)
An image encoding switching method characterized in that, after waiting for a predetermined time (S6), the switched image signal is encoded and transmitted (S7). 2. In an image encoding system comprising an encoding device (8) including an encoding unit (5) that encodes and transmits one of the plurality of image signals, one of the plurality of image signals a transmission image instruction input unit (1) that inputs an instruction to select, encode, and transmit; and an image input switching control unit (1) that switches the input image signal from the image signal being transmitted to the image signal according to the instruction input; 2
), and an image input state detection unit (3) that detects the input state of the image signal, and the encoding device (8) receives information on the input state and switches to the image signal according to the instruction input. a timer unit (7) that measures a predetermined time after confirming that the predetermined time has passed; an encoding control unit (6) that controls the encoding unit (5) to start encoding;
An image encoding switching system comprising: 3. The encoding device (8) includes the encoding control unit (6)
and a central control unit (9) including a clock unit (7), and after the central control unit (9) encodes and transmits a still image according to the instruction input, the central control unit (9) controls the image input switching control unit (
2). The image encoding switching system according to claim 2, wherein the image encoding switching system according to claim 2, controls switching to input the image signal being transmitted again by controlling 2), and controlling the image signal being transmitted to be encoded and transmitted. . 4. The encoding device (8) includes the encoding control unit (6)
and a central control unit (9) including a clock unit (7), and the central control unit (9) includes the image input state detection unit (3).
), when it is recognized that there is no input of the instructed image signal for a predetermined period of time after the instruction is inputted, the encoding of the image signal being transmitted is started again. The image encoding switching system according to item 2.