Video transmission system and input switching device

Abstract

To provide a technique for enabling implementation of a plurality of outputs in a video transmission system using an HDMI.SOLUTION: A video transmission system comprises a plurality of source apparatuses for transmitting video signals, a plurality of sink apparatuses for receiving the video signals, and an input switching device. The input switching device comprises: a plurality of input ports connected to the plurality of source apparatuses; a plurality of output ports connected to the plurality of sink apparatuses; a distributor capable of outputting a video signal received by each input port from one or more output ports selected from the plurality of output ports; and a control unit that in response to a CEC command, for selecting one source apparatus, received at the output port, controls the distributor so as to output a video signal received at an input port connected to the source apparatus indicated by the CEC command from an output port at which the CEC command is received.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a video transmission system and an input switching device. [Background technology]

[0002] HDMI (High-definition Multimedia Interface), a registered trademark, is known as one of the video transmission standards. Video transmission systems using HDMI are used in a variety of situations. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Quantum Data White Pater: Designing CEC into your next HDMI Product, Quantum Data Inc. Summary of the Invention [Problem to be solved by the invention]

[0004] One use case for HDMI-based video transmission systems is the connection of multiple output devices (e.g., display devices) to an HDMI network. However, the current HDMI standard does not support this. As a result, when multiple output devices are connected to an HDMI network, the device control function, CEC (Consumer Electronics Control), does not function properly. Furthermore, sending the same video to multiple output devices requires distributing (mirroring) the video and outputting it to multiple ports, but this function is not currently provided in HDMI.

[0005] The problem to be solved by the present invention is to provide a technology that enables a video transmission system using HDMI to support multiple outputs. [Means for solving the problem]

[0006] According to one embodiment, the video transmission system includes a plurality of source devices that transmit video signals, a plurality of sink devices that receive the video signals, and an input switching device interposed between the plurality of source devices and the sink devices. The input switching device includes a plurality of input ports, a plurality of output ports, a distributor, and a control unit. The plurality of input ports are connected to the plurality of source devices. The plurality of output ports are connected to the plurality of sink devices. The distributor is capable of outputting video signals received at each input port from one or more output ports selected from the plurality of output ports. In response to a first Consumer Electronics Control (CEC) command received at an output port and used to select one source device from the plurality of source devices, the control unit controls the distributor to output the video signal received at the input port connected to the one source device identified by the first CEC command from the output port that received the first CEC command. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a functional block diagram showing a video transmission system according to an embodiment. [Figure 2] FIG. 2 is a diagram for explaining path control in the input switching device according to the embodiment. [Figure 3] FIG. 2 is a block diagram showing a CEC network configuration in the input switching device according to the embodiment. [Figure 4] FIG. 1 is a block diagram showing a hardware configuration of a video transmission system according to an embodiment. [Figure 5] FIG. 4 is a sequence diagram showing an input switching method according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described with reference to the drawings. Throughout the drawings, components having similar functions or configurations are designated by the same reference numerals, and duplicate descriptions will be omitted where appropriate. In addition, to distinguish between components having similar functions or configurations, a subscript may be added to the reference numeral. The subscript is written after the reference numeral, separated by a hyphen "-".

[0009] The current HDMI-CEC standard defines that output devices must be assigned a logical address of 0 and a physical address of 0.0.0.0. Therefore, multiple output devices cannot exist on a CEC network. Furthermore, video signals sent from input devices are specified as output destinations with the physical address "0.0.0.0." For this reason, even if multiple output devices exist on a CEC network, it is not possible to control the route for transmitting video signals to the desired output device.

[0010] An input switching device according to an embodiment described below enables each output device to select a desired input device from among the multiple input devices using a CEC command (also called a CEC message) in a video transmission system in which multiple input devices and multiple output devices exist on a CEC network. The input switching device also enables the assignment of a logical address "0" and a physical address "0.0.0.0" to the multiple output devices present on the CEC network.

[0011] Fig. 1 schematically illustrates an exemplary configuration of a video transmission system 10 according to an embodiment. As illustrated in Fig. 1, the video transmission system 10 includes an input switching device 20, a source device 30, a sink device 40, and an HDMI cable 50. The input switching device 20, the source device 30, and the sink device 40 support the HDMI-CEC standard. In the example of Fig. 1, four source devices 30-1 to 30-4 are illustrated as the source devices 30, and three sink devices 40-1 to 40-3 are illustrated as the sink devices 40.

[0012] The input switching device 20 has a plurality of input ports 21 and a plurality of output ports 22. In the example of Fig. 1, the input switching device 20 has three input ports 21 and three output ports 22. One source device 30 is connected to each input port 21, and one sink device 40 is connected to each output port 22. The input switching device 20 performs path control and distribution (mirror) of video signals, and can output a video signal received at a specified input port 21 from any output port 22.

[0013] Source device 30 corresponds to an input device that transmits a video signal. Examples of source device 30 include a digital video recorder, an optical disc player, a set-top box, a video camera, a streaming media stick, a personal computer, a multimedia device, etc. In an example in which the video transmission system 10 is applied to an automobile, for example, source device 30-1 is a mobile device such as a smartphone, source device 30-2 is a tuner, source device 30-3 is a BD / DVD player, and source device 30-4 is a media player.

[0014] The source device 30 is connected to the input switching device 20 or the sink device 40 via an HDMI cable 50. In the example of Fig. 1, the source device 30-1 is connected to the sink device 40-1 via the HDMI cable 50, and the source devices 30-2 to 30-4 are connected to the input switching device 20 via the HDMI cable 50. The source device 30 has an output port 31. The output port 31 of the source device 30 is connected to, for example, the input port 21 of the input switching device 20 via the HDMI cable 50.

[0015] The sink device 40 corresponds to an output device that receives and outputs (specifically, displays) a video signal. The sink device 40 may be a device equipped with a display (monitor). In an example in which the video transmission system 10 is applied to an automobile, for example, the sink device 40-1 is a center console equipped with a display, and the sink devices 40-2 and 40-3 are displays provided for the rear seats.

[0016] The sink device 40 is connected to the input switching device 20 or the source device 30 via an HDMI cable 50. In the example of Fig. 1, the sink device 40-1 is connected to the input switching device 20 and the source device 30-1 via the HDMI cable 50, and the sink devices 40-2 and 40-3 are connected to the input switching device 20 via the HDMI cable 50. The sink device 40 has one or more input ports 41. The input port 41 of the sink device 40 is connected to, for example, the output port 22 of the input switching device 20 via the HDMI cable 50.

[0017] In the example of FIG. 1, three source devices 30-2 to 30-4 and three sink devices 40-1 to 40-3 are connected to the input switching device 20. In other words, the input switching device 20 is interposed between the source devices 30-2 to 30-4 and the sink devices 40-1 to 40-3. As shown in FIG. 2, the input switching device 20 is capable of outputting a video signal received at each input port 21 from one or more output ports 22. The input switching device 20 includes a distributor 28 that is capable of outputting the video signal received at each input port 21 from one or more output ports 22 selected from the output ports 22. The distributor 28 is provided corresponding to each input port 21. The distributor 28 can copy the video signal as many times as the number of output ports 22 in order to distribute (mirror) the video signal received at the corresponding input port 21. Each output port 22 outputs the video signal received at any one of the input ports 21. A method for switching the video signals output from each output port 22 among the video signals received at the three input ports 21 will be described later. The input switching device 20 is also called an input switching distributor.

[0018] The sink device 40 first assigns an address when the power of the sink device 40 is turned on, for example. Generally, if a sink device 40 using CEC cannot be assigned the logical address "0" and physical address "0.0.0.0" prepared for sink devices, it may consider that CEC control is not possible and stop control by CEC. In order to enable the operation of multiple sink devices 40 on a CEC network such as that shown in FIG. 1, it is necessary to assign the logical address "0" and the physical address "0.0.0.0" to all of the sink devices 40.

[0019] To assign an address, sink device 40 performs output device discovery to check whether other sink devices exist on the CEC network. For output device discovery, a polling command is broadcast with logical address "0" specified in the polling command, and a response to the polling command is waited for to determine whether a sink device exists. If sink device 40 receives a response to the polling command, it recognizes that other sink devices exist on the CEC network, and if it does not receive a response to the polling command, it recognizes that other sink devices do not exist on the CEC network. A polling command specifying logical address "0" is a CEC command used to check whether other sink devices exist on the CEC network.

[0020] In order to assign logical address "0" to multiple sink devices 40, it is necessary to make it appear as if the sink device 40 assigned logical address "0" does not exist on the CEC network. In this embodiment, the input switching device 20 blocks the polling command for output device discovery (the polling command specifying logical address "0") issued by each sink device 40. In other words, the input switching device 20 intercepts the polling command for output device discovery issued by each sink device 40 and prevents it from being sent onto the CEC network. As a result, no response is returned to each sink device 40 in response to the polling command for output device discovery, and the sink device 40 can determine that no other sink devices exist on the CEC network and assign itself logical address "0."

[0021] In the case of a sink device, once a logical address is assigned, the physical address is uniquely determined. In response to the assignment of the logical address "0" to itself, the sink device 40 assigns itself a physical address "0.0.0.0".

[0022] The sink device 40 to which the logical address and physical address have been properly assigned is determined to be capable of device cooperation and control by CEC, and can proceed to the subsequent input device discovery and device information acquisition processing.

[0023] To discover an input device, a polling command specifying a logical address for the source device is used. For example, numbers 1 to 14 are provided as logical addresses for source devices. The sink device sequentially transmits polling commands specifying logical addresses "1" to "14." The polling command specifying a logical address for the source device is a CEC command used to discover source devices present on the CEC network. When the sink device 40 receives a response to the polling command specifying logical address "N," it determines that a source device 30 assigned logical address "N" is present on the CEC network. Here, N is an integer from 1 to 14.

[0024] In the device information acquisition process, the sink device 40 uses the discovered logical address for the source device to acquire device information about the source device 30. The device information about the source device 30 includes, for example, a physical address, a vendor ID (identifier), an OSD (on screen display) description, and the like.

[0025] To select an input device and control its routing,<Set stream path> CEC command [physical address of source device] or<Routing Chang> The CEC command, [physical address of current source device][physical address of destination source device], is used as the input switching command. The input switching command is a CEC command used to select one of multiple source devices 30. The input switching device 20 stores the port number of the output port 22 that received the input switching command, determines the input path from the physical address of the specified source device, and connects the corresponding input port to the output port with the stored port number, thereby enabling input selection in a multiple sink device environment. The port number is identification information assigned to the output port 22.

[0026] Fig. 3 shows a schematic diagram of an example of a CEC network configuration within the input switching device 20. As shown in Fig. 3, the input switching device 20 includes an input port 21 and an output port 22, as well as an internal CEC line 23, a monitoring unit 24, and a CEC control unit 25.

[0027] The internal CEC line 23 connects the input port 21 and the output port 22 and transmits CEC commands between the input port 21 and the output port 22 .

[0028] The monitoring unit 24 is provided in each output port 22 and is connected to the internal CEC line 23 and the CEC line of the sink device 40. The monitoring unit 24 monitors CEC commands transmitted from the sink device 40 and relays the CEC commands to the internal CEC line 23 as necessary. For example, the monitoring unit 24 blocks polling commands issued by the sink device 40 for output device discovery. Specifically, when the monitoring unit 24 receives a polling command specifying logical address "0" from the sink device 40, it discards the received polling command. When the monitoring unit 24 receives a polling command issued by the sink device 40 for input device discovery, it passes the received polling command to the internal CEC line 23.

[0029] Furthermore, the monitoring unit 24 transmits a CEC command generated on the internal CEC network to the sink device 40 as necessary. For example, if the CEC command is broadcast or if the CEC command is addressed to the sink device 40 connected to the output port 22 on which the monitoring unit 24 is provided, the monitoring unit 24 transmits the CEC command to the sink device 40.

[0030] The CEC control unit 25 controls input switching, CEC command routing, and the like. For example, when a sink device 40 issues a CEC command to one of the source devices 30 and the input port 21 of the input switching unit 20 receives a response to the CEC command from the source device 30, the CEC control unit 25 directs the response to the output port 22 connected to the sink device 40 that issued the CEC command. In addition, in response to the input switching command received at the output port 22, the CEC control unit 25 controls the distributor 28 so that the video signal received at the input port 21 connected to the source device 30 indicated by the input switching command is output from the output port 22 that received the input switching command. For example, the CEC control unit 25 holds management information that associates the port number of each input port 21 with an address (e.g., a physical address) assigned to the source device 30 connected to that input port 21. The CEC control unit 25 receives an input switching command specifying the physical address of the source device 30 to be connected from the sink device 40, and identifies the input port 21 to which the source device 30 to be connected is connected by referring to the management information at the physical address indicated by the input switching command. The CEC control unit 25 connects the identified input port 21 to the output port 22 that received the input switching command.

[0031] 4 shows an example of the hardware configuration of the input switching device 20. As shown in FIG. 4, the input switching device 20 includes a processing circuit 201, a memory 202, an input interface 203, and an output interface 204.

[0032] The processing circuit 201 includes a general-purpose processor such as a CPU (Central Processing Unit) and the distributor 28 shown in FIG. 2. The memory 202 may include a non-volatile memory such as a volatile RAM (Random Access Memory) or a flash memory. The memory 202 stores a control program. When executed by the general-purpose processor of the processing circuit 201, the control program causes the processing circuit 201 to perform the processes described with respect to the monitoring unit 24 and the CEC control unit 25. In other words, the processing circuit 201 functions as the monitoring unit 24 and the CEC control unit 25 in accordance with the control program. Note that the processing circuit 201 may include a dedicated processor such as an FPGA (Field Programmable Gate Array) instead of or in addition to the general-purpose processor.

[0033] The input interface 203 is an interface for connecting the source device 30 shown in Fig. 1. The input interface 203 includes the input port 21 shown in Fig. 1. The output interface 204 is an interface for connecting the sink device 40 shown in Fig. 1. The output interface 204 includes the output port 22 shown in Fig. 1.

[0034] Fig. 5 schematically shows an example of a sink device input switching sequence according to the embodiment. The series of processes shown in Fig. 5 can be performed by the video transmission system 10 shown in Fig. 1. Fig. 5 shows a monitoring unit 24 provided in one of the output ports 22 of the input switching device 20, one of the plurality of source devices 30, and one of the plurality of sink devices 40 as representatives. The monitoring unit 24 is provided in the output port 22 connected to the sink device 40 shown in Fig. 5.

[0035] First, sink device 40 performs input device discovery. Specifically, sink device 40 transmits a polling command specifying logical address "0" to check whether or not other sink devices exist on the network (step S501).

[0036] The monitoring unit 24 blocks the polling command from the sink device 40 (step S502). Specifically, the monitoring unit 24 receives the polling command from the sink device 40 and discards the received polling command. As a result, the sink device 40 does not receive an Ack response to the polling command and recognizes that no other sink devices exist on the CEC network.

[0037] When sink device 40 confirms that no other sink devices exist on the CEC network, it assigns logical address "0" and physical address "0.0.0.0" to itself (step S503).

[0038] Next, the sink device 40 performs output device discovery and device information acquisition processing. A series of processing steps from step S504 to step S512 is executed for each of the source device logical addresses "1" to "14".

[0039] Sink device 40 transmits a polling command specifying logical address "N" to check whether a source device exists on the CEC network (step S504), where N is an integer from 1 to 14.

[0040] When the monitoring unit 24 receives the polling command from the sink device 40, it transmits the received polling command to each source device 30 connected to the input switching device 20 (step S505). The CEC control unit 25 stores the port number of the output port 22 that received the polling command.

[0041] When source device 30 receives the polling command, it checks whether logical address "N" included in the received polling command matches its own logical address. If logical address "N" does not match its own logical address, source device 30 ignores the polling command. If logical address "N" matches its own logical address, source device 30 transmits an Ack response to the polling command (step S506).

[0042] When the monitoring unit 24 receives the Ack response from the source device 30, it transmits the received Ack response to the sink device 40 (step S507). Specifically, when the input port 21 of the input switching device 20 receives the Ack response from the source device 30, the CEC control unit 25 routes the Ack response so that the Ack response is transmitted from the output port 22 that received the polling command.

[0043] When sink device 40 receives an Ack response to the polling command specifying logical address "N", sink device 40 recognizes that source device 30, to which logical address "N" is assigned, exists on the CEC network.

[0044] In order to acquire device information related to source device 30 to which logical address "N" is assigned, sink device 40 transmits a device information inquiry command specifying logical address "N" to inquire about device information (step S508). The device information inquiry command is one of the CEC commands.

[0045] When the monitoring unit 24 receives the device information query command from the sink device 40, it transmits the received device information query command to each source device 30 connected to the input switching device 20 (step S509). When the source device 30 receives the device information query command, it checks whether the logical address "N" included in the device information query command matches its own logical address. If the logical address "N" does not match its own logical address, the sink device 40 ignores the device information query command. If the logical address "N" matches its own logical address, the sink device 40 transmits a device information response including device information related to the sink device 40 (step S510).

[0046] When the monitoring unit 24 receives the device information response from the source device 30, it transmits the received device information response to the sink device 40 (step S511). Specifically, when the input port 21 of the input switching device 20 receives the device information response from the source device 30, the CEC control unit 25 routes the device information response so that the device information response is transmitted from the output port 22 that received the device information query command.

[0047] Upon receiving the device information response, sink device 40 extracts the device information from the received device information response and stores the device information in memory (step S512).

[0048] After the series of processes shown in step S504 to step S512 has been executed for each of the logical addresses "1" to "14", the sink device 40 will hold the device information of all the source devices 30 present on the CEC network. When the sink device 40 acquires the device information of the plurality of source devices 30, the user can select one source device 30 from the plurality of source devices 30.

[0049] Any one of the source devices 30 is selected by a user action on the sink device 40 (step S513).

[0050] The sink device 40 broadcasts an input switching command by specifying the physical address of the source device 30 selected by the user (step S514).<set stream path> or<Routing Change> can be used.

[0051] When the monitoring unit 24 receives the input switching command from the sink device 40, the monitoring unit 24 passes the received input switching command and the port number of the output port 22 where the monitoring unit 24 is provided to the CEC control unit 25 (step S515).

[0052] When the CEC control unit 25 receives the input switching command and the port number from the monitoring unit 24, it identifies the port number associated with the physical address included in the input switching command and connects the input port 21 of the identified port number to the output port 22 that received the input switching command (step S516). As a result, the input switching device 20 transmits the video signal received from the source device 30 selected by the user to the sink device 40.

[0053] As described above, the video transmission system 10 includes an input switching device 20, a plurality of source devices 30, and a plurality of sink devices. The input switching device 20 includes a plurality of input ports 21 connected to the plurality of source devices 30, respectively, and a plurality of output ports 22 connected to the plurality of sink devices 40, respectively. The input switching device 20 includes a distributor 28 that can output a video signal received at each input port 21 from one or more output ports 22 selected from the plurality of output ports 22, and controls the distributor 28 in response to an input switching command received at the output port 22 so that the video signal received at the input port 21 connected to one source device 30 indicated by the input switching command is output from the output port 22 that received the input switching command.

[0054] According to the above configuration, in the video transmission system 10, each sink device 40 can use a CEC command to select any one source device 30 from among the multiple source devices 30. For example, path control is possible to assign the same source device 30 to multiple sink devices 40. Therefore, it is possible to operate multiple sink devices 40 in the video transmission system 10.

[0055] The input switching device 20 further includes a monitoring unit 24 that monitors CEC commands received at each output port 22 from each sink device 40, and the monitoring unit 24 blocks CEC commands for output device discovery received at the output port 22.

[0056] In the above configuration, the sink device 40 will no longer receive a response to a CEC command for output device discovery. This allows each sink device 40 to be assigned the logical address "0" and physical address "0.0.0.0" prepared for the sink device. As a result, it becomes possible to operate multiple sink devices 40 using the current CEC.

[0057] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0058] 10...video transmission system, 20...input switching device, 21...input port, 22...output port, 23...internal CEC line, 24...monitoring unit, 25...CEC control unit, 28...distributor, 30...source device, 31...output port, 40...sink device, 41...input port, 50...HDMI cable, 201...processing circuit, 202...memory, 203...input interface, 204...output interface.

Claims

1. A video transmission system comprising: a plurality of source devices that transmit video signals; a plurality of sink devices that receive the video signals; and an input switching device that is interposed between the plurality of source devices and the sink devices, The input switching device a plurality of input ports connected to the plurality of source devices; a plurality of output ports connected to the plurality of sink devices; a distributor capable of outputting a video signal received at each input port from one or more output ports selected from the plurality of output ports; a control unit that controls the distributor in response to a first Consumer Electronics Control (CEC) command received at an output port, the first CEC command being used to select one source device among the plurality of source devices, so as to output, from the output port that has received the first CEC command, a video signal received at an input port connected to the one source device indicated by the first CEC command; Equipped with Video transmission system.

2. a monitoring unit that monitors CEC commands received from each sink device at each output port; the monitoring unit blocks a second CEC command received at the output port, the second CEC command being a CEC command used to check whether another sink device exists on the CEC network; The video transmission system according to claim 1 .

3. 3. The video transmission system according to claim 2, wherein the second CEC command is a polling command specifying a logical address "0".

4. the monitoring unit transmits a third CEC command to the plurality of source devices, the third CEC command being a CEC command used to discover source devices present on the CEC network, the third CEC command being received by each output port; the control unit transmits a response to the third CEC command, which is transmitted by any one of the plurality of source devices, from an output port through which the third CEC command was received.

3. The video transmission system according to claim 2.

5. 2. The video transmission system according to claim 1, wherein the distributor is capable of copying the video signal received at each input port by the number of the plurality of output ports.

6. a plurality of input ports connected to a plurality of source devices transmitting video signals; a plurality of output ports connected to a plurality of sink devices that receive video signals; a distributor capable of outputting a video signal received at each input port from one or more output ports selected from the plurality of output ports; a control unit that controls the distributor in response to a CEC (Consumer Electronics Control) command received at an output port for selecting one source device from the plurality of source devices, so as to output a video signal received at an input port connected to the one source device indicated by the CEC command from the output port that received the CEC command; An input switching device comprising:

Images