JPH07162968A - Signal input switching system and signal input/output managing system - Google Patents

Abstract

PURPOSE:To simplify a produce for switching the input of an equipment to input an AV signal. CONSTITUTION:A command master gives the request that 'output to CH1' to a CAM 1 (A1). Corresponding to this request, the CAM 1 answers the command master that 'output OK and output to CH1' (A2). On receiving this answer, the command master gives the request that 'input CH1' to a VTR 1 (A3). Then, the VTR 1 answers the command master that 'CH1 input OK' (A4).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal input switching system and an input / output management system in a communication system in which a control signal and an information signal are mixed and can be transmitted in a packet and connected by a bus.

[0002]

2. Description of the Related Art Conventionally, for example, a video tape recorder (hereinafter referred to as VTR), a television receiver (hereinafter referred to as TV)
AV equipment such as) is connected by a digital communication line,
D2 is a communication system for transmitting V signals in packets.
A communication system using B (Domestic Digital Bus) is considered.

First, an example of such a communication system will be described with reference to FIG. This communication system is
The V device includes a TV, a camcorder (hereinafter referred to as CAM), VTR-A and VTR-B. And the output plug P3 of the CAM and the input plug P1 of the TV,
Between the output plug P3 of the VTR-A and the input plug P1 of the VTR-B, and between the output plug P3 of the TV and the input plug P1 of the VTR-A are AV signal lines L1, L2 and L3 capable of transmitting the AV signal only in one direction. It is connected. Also, CA
M and VTR-A, VTR-A and VTR-B, TV and VT
The RA signals are connected by control signal lines (buses) D1, D2, D3 capable of bidirectionally transmitting control signals. Since each AV device has an input / output function of a control signal and an AV signal, bidirectional transmission of the control signal can be performed between the CAM and the TV or VTR-B, and the CAM to the VTR-B can be transmitted.
AV signals can be sent to A or VTR-B.

FIG. 20 shows the main configuration of each AV device in the communication system of FIG. The AV signal input / output plugs of each AV device are exposed to the outside directly from a functional unit called a switch box (SWBox).
2, P3, and the other numbers are indicated by the AV signal line.
It is connected to the input / output plug of V equipment. In addition, other A
A control signal line is connected to the V device separately from the AV signal line by a bus, and commands such as connection control are transmitted and received. Furthermore, each AV device has its own functional unit,
For example, a VTR has a deck for recording / playback and a tuner for selecting a received signal, and a TV has a monitor and an amplifier. Further, although not shown, an AVC (AV controller) for controlling the operation of the entire AV equipment is provided. Hereinafter, these functional units will be referred to as subdevices in this specification.

In the communication system configured as described above, two types of methods for performing control connection are considered. Hereinafter, these are referred to as a connection control method 1 and a connection control method 2, and will be described in order.

According to the connection control method 1, each AV device allows the user to previously set connection configuration information indicating which plug of which partner AV device is connected to which plug, in which direction, input / output, in which direction. keeping. By this, when receiving the connection control command,
Depending on the purpose, connect the sub device that is the source of the AV signal and the output plug that seems to reach the destination, or connect the input plug of the specified number and the appropriate output plug, and pass it through the AV equipment. At the same time, the command is propagated to the AV device connected to the end of the output plug. Then, the object is achieved when the command reaches the subdevice in the specific AV device designated as the destination.

At this time, since a command cannot be propagated to the non-bus compatible AV equipment through the control signal line, the plug number of the AV equipment connected to the AV equipment is directly designated (for example, FIG. 20). If a non-bus compatible AV device is connected to the plug P2 of the VTR device B, the connection control for the non-bus compatible AV device is performed by the VT.
This is done by specifying the plug P2 of the R device B).

Next, in the connection control method 2, one central AV device (hereinafter referred to as AV center) is
For each plug of the device, all connection information indicating which port of which partner AV device is connected in which direction (In / Out) is managed. Then, when a command requesting an AV signal connection is received via the control signal line, the command is transmitted to the target AV device via the control signal line. The target AV device receives this command,
Switch the input.

At this time, it is possible to specify the subdevice by category (BS tuner, Hi8 deck, etc.) by the first connection request from the command master. However, the plug can be specified at the time of the connection request only for the plug of oneself who knows the structure.

[0010]

However, in the connection control method 1, the control signal line is congested by sequentially propagating commands to the adjacent AV equipment. Also,
There may be an infinite loop depending on the setting of AV equipment interposed in the middle. Further, in order to directly specify the plug number, it is necessary for the command master to know the configuration of the AV device to be controlled, and further the connection configuration of the AV device of the entire system.

Further, in the connection control method 2, even if the connection is simple with the partner connected at the end of the plug,
It cannot be realized without requesting the AV center. Also, you can specify it in the subdevice category when making a connection request, but you can specify the plug only for your own plug that knows the structure.

Further, in either of the connection control methods, when another AV device exists between the AV device that has requested the connection and the target AV device, all the AV devices existing between the AV devices are passed. Therefore, it is necessary to set the input / output of the AV signal. Therefore, as the number of AV devices that make up the system increases, it becomes necessary to set the input / output.
The number of V devices increases and control becomes complicated. Therefore, it is necessary to take measures such as limiting the system configuration. Also, AV
Since the signal line can transmit signals only when the power of the AV device is ON, it is necessary that the power of all AV devices passing through be ON.

It is an object of the present invention to provide a signal input switching system and an input / output management system which can solve such problems.

[0014]

In order to solve the above problems, the present invention provides a predetermined device in a communication system in which a control signal and an information signal are mixed and can be transmitted by a packet. Directly or indirectly requests the output of the information signal to the desired device, the desired device responds to the output request, the position information of the output information signal to the predetermined device, The predetermined device is configured to input the information signal based on the position information.

Further, according to the present invention, in a communication system in which a control signal and an information signal are mixed and transmitted in a packet and connected by a bus, a predetermined device directly or indirectly responds to a desired device. An information signal output request is made, the desired device counts the number of devices for which the information signal output request is made by the counting means, and further, the desired device receives an input from the device receiving the information signal. Upon receiving the notification of the stop, the count value of the counting means is reduced, and the output of the information signal is stopped when the count value of the counting means becomes zero.

The predetermined device may be configured to request the output of the information signal from the desired device via the control device. For example, in the case of an AV communication system, the VTR is configured to request the output of the AV signal from another VTR via the edit controller.

Further, the control device or a predetermined device may store the address of the desired device. Further, the control device or a predetermined device may be configured to inquire the position information (channel number) of the information signal from a desired device.

[0018]

According to the present invention, the predetermined device requests the desired device to output the information signal, and the desired device responds to the request by returning the position of the output information signal, By knowing the position of the information signal from the response, the device switches the input so that the information signal at that position can be input.

By outputting the information signal only when there is a device inputting the information signal, it is possible to prevent the unused information signal from being unnecessarily passed to the bus.

Further, if the address of the desired device is held, it can be notified to the desired device by looking at this address when the device to which the information signal is input is no longer present. .

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [1] Communication system to which the present invention is applied [2] Concept of signal input switching [3] Concrete example [4] Concept of signal input / output management [5] A detailed description will be given in the order of specific examples.

[1] Communication System to which the Present Invention is Applied FIG. 1 is a system configuration diagram showing an example of the configuration of a communication system to which the present invention is applied. This communication system includes CAM 1, TV 1, VTRs 1 to 4 and an editing machine (editing controller) as AV equipment. And CAM1
And TV1, TV1 and VTR3, VTR3 and VTR1 and editor, VTR1 and VTR2, and editor and VTR4 are connected by a P1394 serial bus. P1
The 394 serial bus can transmit control signals and AV signals in a mixed manner in both directions. In addition, each device is P139
4 It has a function of relaying control signals and AV signals on the serial bus.

FIG. 2 is a block diagram showing the basic structure of a VTR which is an example of AV equipment in the communication system of FIG. The VTR is a deck subdevice 1 and a tuner subdevice 2, which are basic blocks as a VTR, an operation unit 3 and a display unit 4, which are user interfaces, and V.
In addition to the microcomputer 5 that controls the operation of the entire TR, P13
Digital interface (hereinafter referred to as digital I / F) for 94 serial bus, deck sub device 1-tuner sub device 2-digital I / F
A switch box subdevice 4 for switching signals between 6 is provided. If the AV device is a TV, a monitor subdevice and an amplifier subdevice are provided instead of the deck subdevice 1, and if it is CAM, a camera subdevice is provided instead of the tuner subdevice 1.

The display unit 6 of each AV device is constructed so that the names of all the devices on the communication system are displayed by fluorescent tubes, as shown in FIG. 3, for example, and the key 4a of the operation unit 4 can be operated. With, it is possible to select a partner who transmits or receives an AV signal. Note that all devices on the communication system may be displayed simultaneously or sequentially. Also, only devices other than oneself may be displayed. Further, these operations can be configured to be performed using an infrared remote controller or a mouse. When the device is a TV, it can be displayed on the monitor subdevice. A pictogram (icon) can be displayed instead of the device name.

In the communication system of FIG. 1, as shown in FIG. 4, communication is performed in a predetermined communication cycle (for example, 125 μs). Then, it is possible to perform both synchronous communication in which communication is continuously performed at a constant data rate such as a digital video signal, and asynchronous communication in which connection control commands and the like are transmitted irregularly as needed.

There is a cycle start packet CSP at the beginning of the communication cycle, and a period for transmitting a packet for synchronous communication is set subsequently to the cycle start packet CSP. Channel number 1, 2, 3, ... for each packet that performs synchronous communication
By adding N, it is possible to perform a plurality of synchronous communications. For example, if channel 1 is assigned to communication from CAM1 to VTR1, CAM
1 transmits a synchronous communication packet with channel number 1 immediately after the cycle start packet CSP, and VTR1
Communicates by monitoring the bus and fetching a synchronous communication packet with channel number 1. Furthermore, VT
If channel 2 is assigned to communication from R3 to VTR4, communication from CAM1 to VTR1 and VTR
The communication from 3 to the VTR 4 can be performed in parallel.

After the transmission of the synchronous communication packets of all channels is completed, the period until the next cycle start packet CSP is used for asynchronous communication. Asynchronous communication packets (packets A and B in FIG. 4) have physical and logical addresses of the transmitting device and the receiving device, and each node takes in the packet with its own address.

[2] Concept of Signal Input Switching FIG. 5 shows an example of a main configuration of an asynchronous communication packet used in a communication system to which the present invention is applied. In this figure,
The master address is the logical address of the source of the packet,
The slave address is the logical address of the destination, the frame type is the packet type (command, response, inquiry, etc.),
SSSA / DADA is a source or destination subdevice address, and OPC (opcode) and OPR (operand) are command contents.

The CAM will be described below with reference to FIG. 6 showing the input switching procedure and FIG. 7 showing the packets used in each procedure.
An example of recording a reproduced image of No. 1 with the VTR 1 will be described. First, the command master asks CAM1 "CH?
Output to. "(A1). On the other hand, C
AM1 responds to the command master (output OK. Output to CH1.) (A2).
The command master inputs "CH1" to VTR1.
(A3). Then, the VTR1 replies to the command master with "CH1 input OK." (A4). This completes the input switching process.

Here, the command master is an AV device which first outputs a command, and whether or not it has a function of becoming a command master in advance.
The AV device serving as the command master changes depending on whether the V device is used to select a communication partner (see a specific example described later). Also, SW BOX (switch box) in SSDA / DSDA of a packet means that the purpose of the command is input / output switching. Also, P1394
The input switching command in (1) is tentatively called P1394 input switching. Further, Deck (deck) in the destination of the AV signal means a deck sub device of CAM1.

[3] Specific Example (1) When Playback Image of CAM1 is Recorded by VTR1 and VTR2 As described above, the display portions of VTR1 and VTR2 are configured so that AV equipment on the communication system is displayed by the fluorescent tube. The user can see the C
AM1 can be selected as a communication partner (input partner). In this way, the user can
When the operation mode is set using 2, VTR1 and VTR2 become command masters. The operation will be described below with reference to FIG. 8 showing the input switching procedure and FIG. 9 showing an example of the packet structure of the command used in each of them.

First, the VTR1 asks the CAM1 "CH?
Output to. "(B1). Then, in response to this, the CAM1 replies to the VTR1 with "output OK. Output to CH1" (B2). VTR1 inputs CH1 and starts recording.

Next, similar to the processing of VTR1, VTR2
Requests CAM1 to "output to CH?" (B3). Then, in response to this, CAM1 replies to VTR2 with "output OK. Output to CH1." (B
4). VTR2 also inputs CH1 and starts recording.

Here, first, VTR1 is CAM1.
It is described that the VTR2 sends the command to the CAM1 and then the VTR2 sends the command to the CAM1, but in reality, these operations are performed independently.

(2) When the playback image of the VTR 3 is recorded by the VTR 4 using the editing machine In this case, the VTR 3 is output using the display section of the editing machine AV
Select as device and VTR4 as input AV device. In this case, the editor becomes the command master. The input switching procedure will be described below with reference to FIGS. 10 and 11.

First, the editing machine which is the command master
The VTR 3 is requested to “output to CH?” (C1). Then, in response to this, VTR3 outputs CH2 because CH1 has already been used, and replies to the editing machine, "Output OK. Output to CH2." (C2). Next, the editing machine requests the VTR 4 to "input CH2" (C3). On the other hand, VTR4 sends "CH
2 inputs OK. "(C4). The VTR 4 inputs CH2 and starts recording.

[4] Concept of signal input / output management Hereinafter, with reference to FIG. 12 showing an input / output management procedure and FIG. 12 showing a packet used in each procedure, a reproduced image of the CAM1 is recorded by the VTR1, and then the VTR1 is recorded. An example in the case of interrupting recording will be described.

First, the command master requests CAM1 to "output to CH?", And further holds the address of CAM1 (D1). Here, as the address, the product category address (device logical address) is used instead of the node ID (device physical address) peculiar to the P1394 serial bus. The reason for this is that, for example, when dubbing between predetermined AV devices and another AV device unrelated to the AV device is removed from the system, the bus is reset. At this time,
The node ID after resetting also changes because the system configuration changes, but this is because the recording status can be protected because the product category address is held in the register of the AV device.

Then, in response to this, CAM1 replies to the command master (output OK. Output to CH1.) And adds 1 to the count value of the input device (D2). Here, the number of input devices is counted. However, it is not necessary to hold the address of the command master that requested output. Conversely, since there may be multiple input AV devices, it is difficult to hold all the addresses of the device that requested output. Here, the command master holds information that CAM1 is outputting to CH1.

In response to this, the command master requests the VTR1 to "input CH1" (D
3). Again, it is not necessary to hold the address, but since it is necessary to manage responsibly the number of partner devices that have requested input, the count value of the device that requested input is incremented by one. However, when input is requested, it is considered to be a quasi-output machine, and when output is requested, it is considered to be an output machine. The input device is counted both when input is requested and when output is requested, but both can be made with a common structure.

Next, the VTR 1 sends "C" to the command master.
H1 input OK. And holds the address of the command master (D4). Up to this point, the input / output setting is completed and the VTR 1 starts recording the output of the CAM 1.

Next, a case where the VTR 1 interrupts recording after a while will be described. First, VTR1 informs the command master that "CH1 input has been interrupted." Then, the input is interrupted and the held command master address is cleared (D5). The Dummy (dummy) of the packet is the source C here.
It means interruption of H1.

Then, in response to this, the command master returns "CH1 input interruption OK" to the VTR1 and decrements the counter number of the input device by 1 (D6). Therefore, the total of the counters becomes 0, and it can be determined that there is no input device.

Next, from the address information stored in D1 and D2, it is understood that CAM1 is being output to CH1. Therefore, "CH1 input is interrupted."
Tell. Also, since all the input devices that I am counting no longer exist, the address is cleared (D
7).

In response to this, the CAM 1 responds to the command master with "CH1 input interrupt OK" and decrements the count value of the input device by 1. Here, the count value is 1
Therefore, the current count value becomes 0, it is determined that there is no input device, and the loading of the AV signal on the bus is interrupted (D8).

If the device which is outputting the AV signal itself, rather than the input device, interrupts the signal output for some reason, the packet is read from the input side (channel). ) Does not include the AV signal, the input of the signal is voluntarily interrupted at that time.

FIG. 14 shows the correspondence relationship between the command master and the slave devices (AV devices other than the command master) regarding whether or not address holding is required at the time of signal input / output switching.

As described above, according to the present invention, the input / output management is performed so that the unused information signal is prevented from being unnecessarily passed to the bus and more AV signal processing can be performed within the limited number of channels. It is a thing.

[5] Specific Example (1) When the reproduced image of CAM1 is recorded by VTR1 and VTR2 and input is interrupted in the order of VTR1 and VTR2

In this case, as in the above [3] (1), V
Both TR1 and VTR2 serve as command masters. The operation will be described below with reference to FIG. 15 showing the input / output management procedure and FIG. 16 showing an example of the packet structure of the command used in each of them.

First, the VTR1 sends "CH?
Output to. Request. " At the same time, the address of CAM1 is held (E1). Next, in contrast, CAM1 is V
Answer "output OK. Output to CH1" to TR1 and increase the count value of the number of input devices by 1 (E2). Therefore, VTR1 inputs CH1 and starts recording. Here, the VTR1 also holds information that the CAM1 is outputting to CH1.

Next, as in the processing of VTR1, VTR2
Requests CAM1 to "output to CH?" And holds the address of CAM1 (E3). Then, in response to this, the CAM1 replies to the VTR2, "output is OK. It is outputting to CH1", and further increments the count value of the number of input devices by 1 (E4). As a result, the total number of input devices is 2
Becomes Here, the VTR2 also holds information that the CAM1 is outputting to CH1.

After a while, VTR1 informs CAM1, which holds the address at E1, that "CH1 input has been interrupted." And the CAM that was held
The address of 1 and CH1 are cleared (E5). next,
In response to this, the CAM1 replies to the VTR1 "CH1 input interruption OK" and decrements the count value of the input device by 1 (E6). Although the total number of input devices is reduced to 1, CAM1 is changed to CH1 because there is still one input device.
Continue to output V signal.

Next, VTR2 also informs CAM1, which remembered the address at E4, that "CH1 input was interrupted." Here, the address of CAM1 and CH1 are cleared (E7). Next, CAM1 responds to VT
Answer "CH1 input interrupt OK" to R2, and further decrement the count value of the input device by one. As a result, since the counter number of the input device becomes 0, it is determined that all the input devices are exhausted, and the CAM 1 suspends the AV signal to be sent to the bus (E8).

It should be noted that the CAM 1 is AV for some reason.
If the signal output is interrupted, VTR1 and VTR2
It is judged that the AV signal is not output to H1, and the input is interrupted by the time-out process.

(2) Using the editor, monitor the playback image of VTR3 on TV1 and record it on VTR4, then
When the input is interrupted in the order of VTR4 and TV1 In this case, the editor becomes the command master as in [3] (2). Therefore, VTR3 and VTR4, TV
Since it is known that data is exchanged between No. 1 and No. 1, it is not necessary to select an input target device in a fluorescent tube display of a VTR or TV. The procedure will be described below with reference to FIGS. 17 and 18.

First, the editing machine which is the command master
The VTR3 is requested to "output to CH?"
The address of VTR3 is held (F1). Then, in response to this, VTR3 has already used CH1,
Output to CH2, and answer "output OK. Output to CH2." To the editing machine and increase the count value of the input device by 1.
The editing machine also holds information that the VTR3 is outputting to CH2 (F2).

Next, the editing machine requests the TV 1 to "input CH2", and increments the count value of the device requested to be input by 1 (F3). On the other hand, TV1 sends to the editor "CH2
Input OK. And hold the address of the editor (F
4). Next, the editing machine requests the VTR 4 to "input CH2", and further increments the count value of the device requested to be input (F5). Therefore, the total number of input devices managed by the editor is 2. On the other hand, the VTR 4 replies "CH2 input OK." To the editing machine and holds the address of the editing machine (F6).

After that, the VTR 4 informs the editor, who remembered the address in F6, "The input of CH2 was interrupted." And clears the address of the editor (F7). In response to this, the editing machine tells the VTR4 "CH2 input interrupt O
K. , And decrement the count value of the device requested to be input. Therefore, the total number of input-requested devices managed by the editing machine is one. Since there is still one input device, the address of VTR3 is retained (F
8).

Next, the TV 1 informs the editor that "CH2 input has been interrupted." (F9). The editing machine decrements the count value of the device requested to be input, and the total becomes 0. Therefore, it is determined that all the input devices managed by the editing machine no longer exist, and the TV 1 replies "CH2 input interruption OK" (F10). ) To the VTR3 holding the address "C
H2 input was interrupted. , Address and CH2
Is cleared (F11). In response to this, the VTR3 replies "CH2 input interruption OK." To the editing machine, and decrements the count value of the input device counted by the VTR3 by one. As a result, the total count value becomes 0, and it can be determined that all input devices have disappeared.
The AV signal output to 2 is interrupted (F12).

For some reason, VTR3 is C
When the output to H2 is suspended, VTR4 can determine that the AV signal is not output on CH2.
Input is interrupted by timeout processing.

Also, for example, when the VTR 3 itself starts outputting and requests the TV 1 to "input CH2" and the VTR 4 requests to the VTR 3 "output", in either case. Since the meaning of the count is the same, the total count value of the input devices managed by VTR3 is 2, and when both TV1 and VTR4 are notified that "CH2 input has been interrupted." , VTR3 suspends the AV signal output to CH2.

Although the P1394 serial bus is used here, another bus can be used as long as it is a digital bus that can be mixed with control lines and signal lines. Further, in selecting the input target device, not only the fluorescent tube display but also OSD display of a TV or the like can be considered. Furthermore, the present invention is applicable not only to a system in which AV equipment is connected but also to a system in which a computer is connected to perform data communication.

[0064]

As described in detail above, according to the present invention, the following effects (1) to (6) are exhibited. (1) The output device outputs the packet carrying the information signal to an arbitrary position (channel), and the input device inquires of which position the packet is output.
Regardless of the route information between the devices existing in the communication system and the number of devices, it is only necessary to switch the input so that the device that wants to input the information signal can read the position of the packet transmitting the information signal.

(2) Since the input / output management of the information signal is performed so that the information signal is output as a packet only when there is a device inputting the information signal, the unused information signal is wastefully sent to the bus. I don't need it. Therefore, it is possible to effectively use the bus within the limited number of channels.

(3) The conventional D2B requires as many information signal lines as there are connection paths, but the present invention can be realized by one bus in which control signals and information signals are mixed. (4) Two types of information signals can be easily recorded simultaneously by several devices.

(5) Compress the data amount of the information signal,
It is possible to effectively use the limited channels by managing channels such as opening channels that are no longer needed and determining the priority order of channel acquisition.

(6) Since the AV signal can be transmitted on the P1394 bus as long as the bus is alive, other AV equipment existing between the output equipment and the input equipment may be in a power-off state.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing an example of a configuration of a communication system to which the present invention is applied.

FIG. 2 is a block diagram showing a basic configuration of a VTR which is an example of AV equipment in the communication system of FIG.

3 is a diagram showing an example of a display unit of an AV device in the communication system of FIG.

FIG. 4 is a diagram showing an example of a communication cycle in a P1394 serial bus.

FIG. 5 is a diagram showing an example of a main configuration of an asynchronous communication packet used in a communication system to which the present invention is applied.

FIG. 6 is a diagram showing an input switching procedure when a reproduced image of CAM1 is recorded on a VTR1.

7 is a diagram showing the structure of a packet used in the procedure of FIG.

FIG. 8 is a diagram showing an input switching procedure when the output of CAM1 is recorded by VTR1 and VTR2.

9 is a diagram showing the structure of a packet used in the procedure of FIG.

FIG. 10: Output of VTR3 to VTR4 using an editor
It is a figure which shows the input switching procedure at the time of recording by.

11 is a diagram showing the structure of a packet used in the procedure of FIG.

FIG. 12 is a diagram showing an input / output management procedure when a reproduced image of CAM1 is recorded on a VTR1.

13 is a diagram showing an example of a packet structure used in the procedure of FIG.

FIG. 14 is a diagram showing a correspondence relationship between command master and slave devices and the presence / absence of address holding at the time of signal input / output.

FIG. 15 is a diagram showing an input / output management procedure when a reproduced image of CAM1 is recorded by VTR1 and VTR2, and then VTR1 and VTR2 interrupt input.

16 is a diagram showing an example of a packet structure used in the procedure of FIG.

FIG. 17: VTR playback image of VTR3 using an editing machine
FIG. 4 is a diagram showing an input / output management procedure in the case where video recording is performed in No. 4 and then the VTR 4 interrupts input.

FIG. 18 is a diagram showing an example of a packet structure used in the procedure of FIG. 11.

FIG. 19 is a diagram showing an example of a configuration of a communication system in which conventional AV equipment is connected by a digital communication line and an AV signal is transmitted in packets.

20 is a diagram showing a main configuration of each AV device in the communication system of FIG.

[Explanation of symbols]

VTR1 to 4 ... Video tape recorder, TV1 ... Television receiver, CAM ... Camcorder, 1 ... Deck subdevice, 2 ... Tuner subdevice, 3 ... Operation unit, 4
... Display section, 5 ... Microcomputer, 6 ... Digital I / F, 7 ...
Switch box subdevice

Claims (5)

[Claims] 1. In a communication system in which a control signal and an information signal are mixed and transmitted by a packet and connected by a bus, a predetermined device directly or indirectly outputs an information signal to a desired device. In response to the output request, the desired device responds to the predetermined device with position information of the output information signal, and the predetermined device inputs the information signal based on the position information. A signal input switching method characterized by: 2. A communication system in which a control signal and an information signal are mixed and can be transmitted in a packet and connected by a bus, and a predetermined device directly or indirectly outputs an information signal to a desired device. A request is made, the desired device counts the number of devices requesting the output of the information signal by the counting means, and further, the device to which the desired device is inputting the information signal has stopped the input. A signal input / output management system characterized by decreasing the count value of the counting means in response to the notification and stopping the output of the information signal when the count value of the counting means becomes zero. 3. The signal input / output management system according to claim 2, wherein the predetermined device requests the desired device to output an information signal via a control device. 4. The signal input / output management system according to claim 2, wherein the control device or the predetermined device stores an address of the desired device by a storage means. 5. The signal input / output management method according to claim 2, wherein the control device or the predetermined device inquires the position information of the information signal to the desired device.