JP2017158163A - Data transmission device, data generation device, and data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data transmission device, data generation device, and data transmission system that in performing multiplex transmission on a plurality of pieces of synchronously generated flow data by using a switching hub in a network of the Ethernet (R), perform individual delay control on the flow data before transmission.SOLUTION: A data transmission device 1 of a first embodiment of the present invention, before performing transmission to a switching hub using a frame for enabling transmission of a predetermined data group composing flow data through a network, adds a delay to data to be transmitted in units of the flow data. A data transmission device 1 of a second embodiment of the present invention adds a delay to data to be transmitted in units of divided flow data obtained by dividing a piece of flow data. A data transmission system of the present invention comprises a plurality of data transmission devices 1 and a management device 6 for making it possible to individually set a delay amount with respect to each delay.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for multiplexing and transmitting a plurality of flow data generated synchronously using a switching hub in an Ethernet (registered trademark) network. The present invention relates to a data transmission device, a data generation device, and a data transmission system that are transmitted through the network.

  Development of 4K (resolution 3960 × 2160) and 8K (resolution 7920 × 4320) as a next-generation video signal format from the current mainstream video format 2K (resolution 1980 × 1080) is in progress. As the definition of video signals increases, the amount of information increases, and the development of a system for transmitting video signals is required. The video signal rate is about 1.5 Gbps at 2K, about 12 Gbps at 4K, and up to 144 Gbps at 8K in an uncompressed state.

  Thus, HD-SDI (High Definition Serial Digital Interface) is conventionally used for transmission of 2K video signals (see, for example, Non-Patent Document 1), but a plurality of HD-SDI signals are transmitted for 4K and 8K transmissions. It is considered that transmission is performed using a plurality of cables, or transmission at a higher rate such as 3G-SDI or 12G-SDI.

  On the other hand, paying attention to the wide band of Ethernet (registered trademark), which is a general-purpose data transmission method, studies on video transmission systems using the Ethernet (registered trademark) network instead of SDI are also underway. In other words, by using the Ethernet (registered trademark) network, there is an advantage that a plurality of camera images, and further, audio and auxiliary data other than the images can be transmitted through one communication line. In video transmission in a professional program production environment such as television video, transmission of uncompressed signals is common because it is desirable to have as low delay and high image quality as possible, but in units of one frame or one line in television video. Development of a technology that realizes compression with a low delay and a low compression rate has also been performed (see, for example, Non-Patent Document 2).

  By the way, in the program production infrastructure, it is generally performed to synchronize a plurality of photographing cameras using PTP (for example, see Non-Patent Document 3). Its synchronization accuracy is less than a few microseconds.

  Also disclosed is a real-time video information compression / transmission device that compresses and transmits video information of a plurality of channels in real time (see, for example, Patent Document 1).

  In this real-time video information compression and transmission apparatus, when video information of a plurality of channels is received, real-time encoding is performed at a predetermined cycle, and the real-time encoded frame data is sequentially divided into a plurality of packets for each frame, By providing a plurality of sets of transmission control units that control transmission timing and sequentially transmit to the network, corresponding to each of the video information of the plurality of channels, by detecting packet loss of packets transmitted to the network, In each of the plurality of sets of sending control units, adjustment control of each sending timing is performed.

Japanese Patent No. 3888505

“SMPTE ST297: 2006 Serial Digital Fiber Transmission System for SMPTE 259M, SMPTE 344M, SMPTE 292M and SMPTE 424M Signals”, SMPTE ST297: 2006, Nov. 3 2006 Tim Borer, “The VC-2 Low Delay Video Codec”, [online], White Paper WHP 238, August 2013, [searched January 8, 2016], Internet <URL: http://downloads.bbc.co .uk / rd / pubs / whp / whp-pdf-files / WHP238.pdf> “1588-2008 IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems”, IEEE std. 1588-2008, July 24 2008

  As described above, in a video transmission system using an Ethernet (registered trademark) network (hereinafter also simply referred to as “network”), it is possible to transmit a plurality of camera videos, and also include audio and auxiliary data other than videos. Assumed.

  In the program production infrastructure, it is common practice to synchronize a plurality of photographing cameras using PTP. That is, when creating a video work using a plurality of shooting cameras, in order to maintain the temporal consistency of the video signal when switching the video signal between the shooting cameras, The generation timing is synchronized.

  Therefore, consider a video transmission system using a network as shown in FIG. In the video transmission system shown in FIG. 6, N (N is an integer of 2 or more) data generators 2-1,... 2) is synchronized by a synchronization signal from the synchronization control device 5. Each data generation device 2 is a device that generates camera video, and audio and auxiliary data other than video as video information, and can be a photographing camera, for example.

  Since the output of a general photographic camera is configured with an SDI data structure, when the output of the photographic camera is transmitted via the Ethernet (registered trademark) network, an SDI / Ethernet (registered trademark) conversion function is provided on the output side. A packet generation device is arranged. Also, when the output of the photographing camera is configured with an ASI (Asynchronous Serial Interface) data structure, a packet generation device having an ASI / Ethernet (registered trademark) conversion function is arranged in the output unit.

  Here, it is assumed that the output of each data generation device 2 such as a photographing camera is transmitted via the Ethernet (registered trademark) network, and is collectively referred to as the data generation device 2 having an SDI / Ethernet (registered trademark) conversion function. explain.

  Each data generation device 2 intermittently outputs its own video information and other data for each predetermined data group (hereinafter referred to as “flow data”) at a transmission timing based on the synchronization signal. Configured to do. That is, it is assumed that the lump data group (that is, flow data) is composed of an Ethernet (registered trademark) frame group having a predetermined frame size (size in which the payload portion is equal to or smaller than the MTU). Note that the Ethernet (registered trademark) frame is also referred to as an Ethernet (registered trademark) packet, and is referred to as an “E frame” in the present specification. The MTU is the maximum length of an Ethernet (registered trademark) frame payload that can be transmitted on the network.

  Then, the data of the synchronized plural data generation devices 2 are multiplexed onto one communication line by a switching hub 3 (also referred to as “Ethernet (registered trademark) switch”) in the middle of the route in the network, and the video switcher 4 is transmitted. The video switcher 4 is a device that can switch which data generation device 2 data (video information or the like) is output to a display device (not shown) by an external operation.

Since each data generation device 2 is synchronized by a synchronization signal from the synchronization control device 5, a group of E frames that are continuously output at the same transmission timing (time t1, t2,...) At regular intervals. Will be output. For example, in the illustrated example, each of an E frame D _C1 output from the data generation device 2-1, an E frame D _C2 output from the data generation device 2-2, and an E frame D _CN output from the data generation device 2 -N. Are output to the switching hub 3 at times t1, t2,. The synchronization accuracy is several microseconds or less, and when multiplexed by the switching hub 3, collision of flow data from each data generation device 2 frequently occurs, and data loss (a plurality of IPs in an E frame occurs due to the collision). When the packet is transmitted, the packet loss) occurs.

  In general, the general switching hub 3 includes a buffer for absorbing the collision, and the flow data is temporarily stored in the buffer and then output in order. However, the amount of data of the video information constituting the flow data is very large and cannot be absorbed by the buffer amount of the buffer mounted on the general switching hub 3 in many cases. On the other hand, mounting a buffer having a large buffer amount for video transmission on the switching hub 3 is not preferable because the cost of the switching hub 3 increases.

  Further, by applying the technique of Patent Document 1 as the switching hub 3 and detecting packet loss of packets corresponding to the flow data transmitted from the switching hub 3 and divided, the transmission timing adjustment control in each data generation device 2 is performed. The flow data of each data generation device 2 synchronized by the same synchronization signal is at the same timing at regular intervals on the input side of the switching hub 3 even if a mechanism for substantially feedback control is performed so that Therefore, the output of the packet corresponding to the divided flow data still has the same timing, and collisions at the output stage of the switching hub 3 frequently occur.

  Therefore, a technique is desired in which a plurality of flow data synchronously generated in the previous stage of the switching hub 3 are individually subjected to delay control and transmitted.

  In view of the above-described problems, an object of the present invention is to generate the synchronization at a preceding stage of the switching hub when multiple pieces of flow data generated synchronously using the switching hub in the Ethernet (registered trademark) network are multiplexed. Another object of the present invention is to provide a data transmission device, a data generation device, and a data transmission system that individually perform delay control on transmitted flow data.

  The data transmission device according to the first aspect of the present invention is a data that multiplex-transmits a plurality of flow data that are synchronously generated by each of a plurality of predetermined data generation devices using a switching hub in an Ethernet (registered trademark) network. In the transmission system, a data transmission device that individually delay-controls one flow data among the plurality of flow data generated in synchronization and transmits the flow data through the network, and the predetermined data group constituting the flow data is A delay giving means for giving a delay to data to be transmitted in units of the flow data before sending to the switching hub using a frame that can be transmitted on the network, and directing the data with the delay to the switching hub Transmitting means for transmitting.

  The data transmission apparatus according to the second aspect of the present invention uses a switching hub in an Ethernet (registered trademark) network to multiplex-transmit a plurality of flow data generated synchronously by each of a plurality of predetermined data generation apparatuses. In the data transmission system, a data transmission device that individually delay-controls one flow data among the plurality of flow data generated synchronously and transmits the flow data through the network, and a predetermined data group constituting the flow data A delay adding means for giving a delay to data to be transmitted in divided flow data units divided for the one flow data until the frame is transmitted to the switching hub using a frame that can be transmitted in the network; Send the assigned data to the switching hub Characterized in that it comprises a signal means.

  Also, in the data transmission device according to the first aspect of the present invention, the delay adding means relates to the delay according to a predetermined formula using at least a coefficient based on the data amount of the flow data unit, the physical bandwidth of the network, and a random number. It has a function of autonomously determining the delay amount.

  Also, in the data transmission device according to the second aspect of the present invention, the delay adding means uses the delay equation according to a predetermined formula using at least a data amount of the divided flow data unit, a physical bandwidth of the network, and a coefficient based on a random number. It has a function of autonomously determining the amount of delay related to.

  Furthermore, the data generation device according to the present invention is a data generation device that generates flow data composed of a set of predetermined data, and the data transmission device of the present invention is connected to an output unit that transmits the generated flow data to the outside. It is characterized by providing.

  Furthermore, a data transmission system according to the present invention uses a switching hub in an Ethernet (registered trademark) network to multiplex-transmit a plurality of flow data that are synchronously generated by each of a plurality of predetermined data generation devices. In addition, the data transmission device according to the present invention includes a plurality of data transmission devices, and further includes a management device capable of individually setting a delay amount related to the delay for the plurality of data transmission devices. And

  It is possible to reduce the rate of data collision when multiplexing a plurality of flow data generated synchronously using a switching hub in an Ethernet (registered trademark) network, and as a result, it is possible to reduce or suppress the risk of data loss. it can.

  Further, not only a general switching hub can be used, but also the buffer amount of the switching hub can be made smaller.

It is a block diagram which shows schematic structure of the video transmission system to which the data transmission apparatus and data transmission system of 1st Embodiment by this invention are applied. It is a block diagram which shows schematic structure of the data transmission apparatus of 1st Embodiment by this invention. It is a figure which shows the example of a transmission timing in the data transmission system of 1st Embodiment by this invention. It is a block diagram which shows schematic structure of the data transmission apparatus of 2nd Embodiment by this invention. It is a figure which shows the example of a transmission timing in the data transmission system of 2nd Embodiment by this invention. It is a block diagram which shows schematic structure of the video transmission system assumed from a prior art.

  Hereinafter, a data transmission device 1 and a data transmission system 10 according to embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
(Data transmission system)
FIG. 1 is a block diagram showing a schematic configuration of a video transmission system using an Ethernet (registered trademark) network to which the data transmission device 1 and the data transmission system 10 according to the first embodiment of the present invention are applied. The N data generation devices 2 (N is an integer of 2 or more) will be described by taking, as an example, a photographic camera that generates camera video as well as audio and auxiliary data other than video as video information. It can also be configured as an encoder or a recording device that compresses the non-compressed signal, and operates in synchronization with the synchronization signal from the synchronization control device 5.

  Note that the output of a general photographing camera is composed of an SDI or ASI data structure, and a packet generation device having an SDI (ASI) / Ethernet (registered trademark) conversion function is arranged on the output side. Here, it is assumed that the output of each data generation device 2 such as a photographing camera is transmitted via the Ethernet (registered trademark) network, and is collectively referred to as the data generation device 2 having an SDI / Ethernet (registered trademark) conversion function. explain. However, since the interface between the data generation device 2 and the data transmission device 1 may be SDI, ASI, or other formats, in this case, an interface conversion function for converting to an Ethernet (registered trademark) frame is provided. A single input stage or output stage may be provided.

  Then, the data of the synchronized N data generation devices 2 are respectively transmitted to N data transmission devices 1-1,..., 1-N (hereinafter not individually specified) via a predetermined communication line. Are collectively referred to as “data transmission device 1”).

  At this time, each data generation device 2 is configured to intermittently output data such as its own video information or the like for each “flow data” that is a predetermined lump of data group at a transmission timing based on the synchronization signal. Is done. That is, in the example described below, the lump data group (that is, flow data) is configured by an E frame group having a predetermined frame size (size in which the payload portion is equal to or smaller than the MTU).

  When each data transmission device 1 receives each E frame group from each synchronized data generation device 2 in units of flow data, each data transmission device 1 individually delays and transmits it to the switching hub 3 in the middle of the route via the network.

  When the switching hub 3 receives the E frame from each data transmission device 1, the switching hub 3 multiplexes it on one communication line and transmits it to the video switcher 4. The video switcher 4 is a device that can switch which data generation device 2 data (video information or the like) is output to a display device (not shown) by an external operation. The configuration of the switching hub 3 and the video switcher 4 is the same as that of the conventional technique.

  Here, since each data generation device 2 is synchronized by the synchronization signal from the synchronization control device 5, the flow data including a group of consecutive E frames is associated with each corresponding transmission timing at the same transmission timing. The data is output to the data transmission apparatus 1.

  Therefore, the data transmission device 1 does not immediately transmit to the switching hub 3 after preparing for transmission as a transmission timing to the switching hub 3, but transmits after giving a delay. The N data transmission apparatuses 1 are configured to disperse signal input timings to the switching hub 3 by inserting delays individually for data transmission, as will be described in detail later.

  In addition, as shown in FIG. 1, although not essential, a management device 6 that manages and sets or controls the transmission timings of the N data transmission devices 1 can also be provided. A data transmission device 1 and a management device 6 are provided.

  Hereinafter, the data transmission apparatus 1 and the data transmission system 10 of the present embodiment will be described more specifically with reference to FIG.

(Data transmission equipment)
FIG. 2 is a block diagram showing a schematic configuration of the data transmission device 1 according to the first embodiment of the present invention. The data transmission device 1 includes a reception unit 11, a variable delay buffer 12, a transmission unit 13, and a transmission timing control unit 14. The transmission timing control unit 14 includes a reception data amount monitoring unit 141, a delay amount calculation unit 142, and a delay amount setting unit 143.

  The receiving unit 11 receives the flow data (E frame group) from the data generation device 2 and outputs it to the variable delay buffer 12. In addition, the reception unit 11 outputs the received data amount of the flow data (E frame group) received at regular intervals to the transmission timing control unit 14.

  The variable delay buffer 12 temporarily accumulates the data of the E frame group of the received flow data, and outputs the E frame to the transmission unit 13 on a first-in first-out basis based on the transmission instruction whose delay is controlled by the transmission timing control unit 14.

  The transmission unit 13 transmits the E frame output from the variable delay buffer 12 to the switching hub 3 in units of flow data based on the transmission instruction from the transmission timing control unit 14. As a result, the data transmission apparatus 1 delays and outputs the entire data of the E frame group of the received flow data by a delay amount described later.

  Here, in the transmission timing control unit 14, the reception data amount monitoring unit 141 monitors the reception data amount of the flow data (E frame group) received at regular intervals obtained from the reception unit 11.

  Then, the delay amount calculation unit 142 obtains information on the reception data amount (reception data amount in units of flow data) for each predetermined period from the reception data amount monitoring unit 141, and calculates the delay amount for output delay.

  Subsequently, the delay amount setting unit 143 performs delay control on the output of the E frame group in units of flow data temporarily stored in the variable delay buffer 12 based on the delay amount calculated by the delay amount calculation unit 142. A transmission instruction is output to the variable delay buffer 12.

  The header information of the E frame in the flow data unit output from the data transmission device 1 uses the header information of the E frame obtained from the data generation device 2 as it is, or transmits header information instructed from the management device 6. A configuration may be adopted in which the unit 13 newly gives and outputs.

  Regarding the setting of the delay amount, there are two methods: a method of autonomously controlling delay by the data transmission device 1 and a method of controlling delay based on an external instruction from the management device 6.

(Autonomous delay control)
First, when delay control is autonomously performed by the data transmission device 1, the management device 6 is not necessarily installed. In the case of this delay control, the data transmission device 1 determines the delay amount D by an integral multiple of a value obtained by dividing the received data amount by an integral multiple of the physical bandwidth of Ethernet (registered trademark) based on the equation (1). . The delay amount D is the time from the data reception time to the transmission time by the data transmission apparatus 1, and is the amount of time to delay the output.

D = D ₁ × n ₁ (1)
here,
D ₁ = F / (α · B),
n ₁ = rand (0, floor (α · B / R))

  Note that F is the received data amount [bit] in units of flow data (E frame group) received at regular intervals, B is the physical bandwidth [bps] of the output line, R is the average transmission rate [bps] of the output signal, α Is a predetermined integer parameter greater than or equal to 1, Rand (x, y) is a random number that outputs an integer greater than or equal to x and less than y, and floor (x) is a maximum integer less than or equal to x.

  In the illustrated example, since the data transmission device 1 is externally attached to the data generation device 2, the data transmission device 1 receives flow data (E frame group) from the data generation device 2 and performs delay control. However, the data transmission device 1 may be built in the data generation device 2. In this case, raw data such as video information generated by the data generation device 2 is sequentially assigned to E frames of a predetermined frame size as flow data, and the delay amount D is determined from the data generation time of the E frames by the data transmission device 1. This is the amount of time to delay the output until the transmission time.

  By causing each of the N data transmission apparatuses 1 to perform autonomous delay control in this way, the rate of data collision at the time of multiplex transmission of a plurality of flow data in the switching hub 3 on the network can be reduced. As a result, the risk of data loss can be reduced or suppressed. FIG. 3 shows an example of the transmission timing of the two data transmission apparatuses 1 in the data transmission system 10 of the first embodiment according to the present invention, and the shaded portion indicates the data amount in units of flow data output from the data generation apparatus 2. On the other hand, the data amount of the flow data unit which the data transmission apparatus 1 delay-outputs is illustrated.

Referring to FIG. 3, for example, when data transmission apparatuses 1-1 and 1-2 receive flow data of a group of E frames from synchronized data generation apparatuses 2-1 and 2-2, respectively, at the same signal input timing. The delay amount D is autonomously determined by a value obtained by dividing the received data amount F of the flow data unit by an integer multiple α of the physical band B and a random number n ₁ (integer). Then, each of the data transmission apparatuses 1-1 and 1-2 receives the received data amount F (the hatched portion in the figure) in flow data units received at time α · D ₁ from the data reception time on the physical band B. The transmission is delayed toward the switching hub 3 with a delay amount D determined autonomously by the random number n ₁ .

  As a result, each of the data transmission apparatuses 1-1 and 1-2 individually outputs a lump of flow data (in this example, an E frame group) received at the same signal input timing, and outputs them in the switching hub 3. The rate of data collision at the time of multiplex transmission of a plurality of flow data can be reduced, and as a result, the risk of data loss can be reduced or suppressed. And the buffer amount required for buffer control by the switching hub 3 can also be made smaller.

(Delay control based on external instructions)
As shown in FIGS. 1 and 2, the management device 6 may be configured to instruct and set the respective delay amounts in the N data transmission devices 1. In this case, as illustrated in FIG. 2, the management device 6 sets the delay amount to each delay amount setting unit 143 with an arbitrary value within a range that does not match the N data transmission devices 1. In the case of delay control based on this external instruction, if the operator of the management device 6 arbitrarily determines and sets the delay amount, the data transmission device 1 does not necessarily set the received data amount monitoring unit 141 and the delay amount calculation unit 142. It is not necessary to have.

  However, the management device 6 acquires the delay amount calculated by the delay amount calculation unit 142 in each of the N data transmission devices 1, and an arbitrary value in a range where the delay amount does not match the N data transmission devices 1. It is preferable to set to each delay amount setting unit 143. At this time, the operator of the management device 6 can determine and set the delay amount. However, the management device 6 uses the delay amount calculated by the delay amount calculation unit 142 in each of the N data transmission devices 1. And the N data transmission apparatuses 1 are preferably configured to be set by automatic control with an arbitrary value within a range where the delay amount does not match.

[Second Embodiment]
(Data transmission system)
The data transmission system 10 according to the second embodiment of the present invention can be configured in the same manner as that shown in FIG. However, as will be described later, the configuration of the data transmission device 1 of the second embodiment is partially different from that of the first embodiment.

  As shown in FIG. 1, N data generation apparatuses 2 (N is an integer of 2 or more) are camera images in this example, and further, an example is a shooting camera that generates audio and auxiliary data other than video as video information. As described above, it can be configured as an encoder or a recording device that compresses an uncompressed signal from the photographing camera, and operates in synchronization with the synchronization signal from the synchronization control device 5.

  Also in this example, it is assumed that the output of each data generation device 2 such as a photographing camera is transmitted via the Ethernet (registered trademark) network, and is summarized as the data generation device 2 having an SDI / Ethernet (registered trademark) conversion function. To explain.

  Each data generation device 2 is configured similarly to the first embodiment. That is, each data generation device 2 is configured to intermittently output data such as its own video information for each “flow data” that is a predetermined group of data at a transmission timing based on the synchronization signal. The Also in this example, the lump data group (that is, flow data) is composed of E frame groups of a predetermined frame size (size in which the payload portion is equal to or smaller than the MTU).

  Then, the data of the synchronized N data generation apparatuses 2 are output to the corresponding N data transmission apparatuses 1 via a predetermined communication line.

  When each data transmission device 1 receives each E frame group from each synchronized data generation device 2 in units of flow data, each data transmission device 1 is individually delayed and transmitted to the switching hub 3 via the Ethernet (registered trademark) network. In addition, one flow data is divided and a delay is given to the E frame in units of divided flow data. Each data transmission apparatus 1 transmits an E frame to which a delay is given in units of divided flow data toward the switching hub 3. As a result, the input data flow can be divided and smoothed, and a delay can be inserted to disperse the signal input timing to the switching hub 3.

  Further, as in the first embodiment, although not essential, a management device 6 that manages and sets or controls the transmission timing of the N data transmission devices 1 may be provided. The division ratio into the divided flow data is preferably set and changeable by the management device 6.

  Hereinafter, the data transmission device 1 and the data transmission system 10 of the present embodiment will be described more specifically with reference to FIG.

(Data transmission equipment)
FIG. 4 is a block diagram showing a schematic configuration of the data transmission apparatus 1 according to the second embodiment of the present invention. The data transmission apparatus 1 includes a reception unit 11, a variable delay buffer 12, a transmission unit 13, a transmission timing control unit 14, and a data division unit 15. The transmission timing control unit 14 includes a reception data amount monitoring unit 141, a delay amount calculation unit 142, and a delay amount setting unit 143. In addition, about the structure of the data transmission apparatus 1 of 2nd Embodiment, the same reference number is attached | subjected to the component similar to 1st Embodiment.

  The receiving unit 11 receives the flow data (E frame group) from the data generation device 2 and outputs it to the data dividing unit 15. In addition, the reception unit 11 outputs the received data amount of the flow data (E frame group) received at regular intervals to the transmission timing control unit 14.

  The data dividing unit 15 divides the data of the E frame group constituting the flow data received via the receiving unit 11, and outputs the divided data to the variable delay buffer 12 as the data of the E frame group in the divided flow data unit. Further, the data dividing unit 15 outputs information on the division ratio to the transmission timing control unit 14. There are two types of data division methods. The first data division method is a method of reconfiguration by dividing only the data of the payload part included in the E frame group and dividing it into a plurality of E frame groups (that is, a plurality of divided flow data). On the other hand, the second data division method is a method of dividing into a plurality of E frame groups (that is, a plurality of divided flow data) while simply maintaining the structure of the E frame. In this case, since the data division unit is every E frame, the data division processing becomes simple. At this time, the size to be divided into flow data corresponds to, for example, the length obtained by removing the header length from the E frame constituting the flow data. In this example, the management device 6 can change the setting of the division ratio into the divided flow data for the data division unit 15 for each of the N data transmission devices 1. Accordingly, the information on the division ratio to the division flow data is necessary information when the configuration can be changed by the management device 6, but information on such a division ratio is used when a predetermined fixed division ratio is used. Is not required to be notified again from the data dividing unit 15 to the transmission timing control unit 14 as known.

  The variable delay buffer 12 temporarily stores the data of the E frame group in the divided flow data unit, and based on the transmission instruction controlled in delay by the transmission timing control unit 14, the E frame group of the divided flow data unit in the first-in first-out manner. Output to the transmitter 13.

  The transmission unit 13 transmits the E frame output from the variable delay buffer 12 to the switching hub 3 in units of divided flow data based on the transmission instruction from the transmission timing control unit 14. As a result, the data transmission apparatus 1 divides the entire data of the E frame group of the received flow data, and outputs the divided data (E frame group of divided flow data units) with a delay amount to be described later.

  Here, in the transmission timing control unit 14, the reception data amount monitoring unit 141 monitors the reception data amount in the flow data (E frame group) received by the reception unit 11 at regular intervals. The received data amount monitoring unit 141 also acquires information on the division ratio regarding the division flow data obtained from the data division unit 15.

  Then, the delay amount calculation unit 142 obtains the received data amount (reception data amount in units of flow data) and the division ratio information for each fixed period from the received data amount monitoring unit 141, and calculates the delay amount for output delay. The data amount of the divided flow data is obtained from the received data amount of the flow data and the division ratio.

  Subsequently, the delay amount setting unit 143 performs delay control on the output of the E frame group of the divided flow data unit temporarily stored in the variable delay buffer 12 based on the delay amount calculated by the delay amount calculation unit 142. The transmission instruction is output to the variable delay buffer 12.

  Therefore, the transmission unit 13 gives a delay set by the delay amount setting unit 143 to the E frame group of the divided flow data unit output from the variable delay buffer 12 based on the transmission instruction from the transmission timing control unit 14. Then, the data is transmitted to the switching hub 3 on the way through the network.

  Note that the header information of the E frame of the divided flow data unit output from the data transmission device 1 uses the header information of the E frame obtained from the data generation device 2 as it is, or the header information instructed from the management device 6. It can be set as the structure which gives again by the transmission part 13 and outputs it.

  In setting the delay amount according to the second embodiment, there are two methods, ie, a method of autonomously controlling the delay by the data transmission device 1 and a method of controlling the delay based on an external instruction from the management device 6.

(Autonomous delay control)
First, when delay control is autonomously performed by the data transmission device 1, the management device 6 is not necessarily installed. In the case of this delay control, the data transmission apparatus 1 determines the delay amount D by an integral multiple of a value obtained by dividing the received data amount by an integral multiple of the physical bandwidth of Ethernet (registered trademark) based on the equation (2). . The delay amount D is the time from the data reception time to the transmission time by the data transmission apparatus 1, and is the amount of time to delay the output.

D = D ₂ × n ₂ (2)
here,
D ₂ = P / B,
n ₂ = rand (0, floor (B / R))

  Note that P is the received data amount [bit] of the divided flow data unit derived from the received data amount and the division ratio in the flow data (E frame group) received at regular intervals, and B is the physical bandwidth [bps] of the output line, R is an average transmission rate [bps] of the output signal, rand (x, y) is a random number that outputs an integer that is greater than or equal to x and less than y, and floor (x) is a maximum integer that is less than or equal to x.

  In the illustrated example, since the data transmission device 1 is externally attached to the data generation device 2, the data transmission device 1 receives flow data (E frame group) from the data generation device 2 and performs delay control. However, the data transmission device 1 may be built in the data generation device 2. In this case, raw data such as video information generated by the data generation device 2 is sequentially assigned to E frames of a predetermined frame size as flow data, and the delay amount D is determined from the data generation time of the E frames by the data transmission device 1. This is the amount of time to delay the output until the transmission time.

  By causing each of the N data transmission apparatuses 1 to perform autonomous delay control in this way, the rate of data collision at the time of multiplex transmission of a plurality of flow data in the switching hub 3 on the network can be reduced. As a result, the risk of data loss can be reduced or suppressed. FIG. 5 shows an example of transmission timings of the two data transmission apparatuses 1 in the data transmission system 10 of the second embodiment according to the present invention. The hatched portion indicates data in units of flow data output from the data generation apparatus 2. The data amount of the divided flow data unit which the data transmission apparatus 1 divides | segments and delay-outputs with respect to quantity is illustrated.

Referring to FIG. 5, for example, when data transmission apparatuses 1-1 and 1-2 receive flow data of a group of E frames from synchronized data generation apparatuses 2-1 and 2-2, respectively, at the same signal input timing. Each of the flow data is divided into a plurality of divided flow data, and a value obtained by dividing the received data amount P of the divided flow data unit by the physical band B and a random number n ₂ (integer), each of which is autonomously delayed The quantity D is determined. Then, each of the data transmission apparatuses 1-1 and 1-2 autonomously receives the received data amount P of the divided flow data unit received at time D ₂ on the physical band B as a random number n ₂ from the data reception time. The transmission is delayed toward the switching hub 3 with the determined delay amount D. The parameter α that can be set in the first embodiment is not necessary because the division ratio can be set in the second embodiment (see FIG. 4).

  As a result, each of the data transmission apparatuses 1-1 and 1-2 divides a batch of flow data (in this example, E frame group) received at the same signal input timing, and outputs them after delaying them individually. The rate of data collision at the time of multiplex transmission of a plurality of flow data in the hub 3 can be further reduced as compared with the first embodiment, and the buffer amount required in the event of a collision can be reduced, resulting in data loss. Risk can be reduced or suppressed. And the buffer amount required for buffer control by the switching hub 3 can also be made smaller.

(Delay control based on external instructions)
As shown in FIGS. 1 and 4, the management device 6 can also be configured to instruct and set the respective delay amounts in the N data transmission devices 1. In this case, as illustrated in FIG. 4, the management device 6 sets the delay amount to each delay amount setting unit 143 with an arbitrary value within a range that does not match the N data transmission devices 1. In the case of delay control based on this external instruction, if the operator of the management device 6 arbitrarily determines and sets the delay amount, the data transmission device 1 does not necessarily set the received data amount monitoring unit 141 and the delay amount calculation unit 142. It is not necessary to have.

  However, as in the first embodiment, the management apparatus 6 acquires the delay amount calculated by the delay amount calculation unit 142 in each of the N data transmission apparatuses 1 and delays the N data transmission apparatuses 1 with respect to the delay. It is preferable to set to each delay amount setting unit 143 with an arbitrary value in a range where the amounts do not match. At this time, the operator of the management device 6 can determine and set the delay amount. However, the management device 6 uses the delay amount calculated by the delay amount calculation unit 142 in each of the N data transmission devices 1. And the N data transmission apparatuses 1 are preferably configured to be set by automatic control with an arbitrary value within a range where the delay amount does not match.

  The present invention has been described above with reference to specific embodiments. However, the present invention is not limited to the above-described examples, and various modifications can be made without departing from the technical concept thereof. For example, in each of the embodiments described above, the configuration in which the data transmission device 1 is externally attached to the data generation device 2 has been mainly described as an example, but the configuration in which the data transmission device 1 is built in the data generation device 2 You can also Further, a data transmission system 10 in which the data transmission apparatuses 1 of the first and second embodiments are mixed can be used.

  According to the present invention, it is possible to reduce the rate of data collision when multiplexing a plurality of flow data generated synchronously using a switching hub in an Ethernet (registered trademark) network, and as a result, the risk of data loss is reduced. Therefore, the present invention is useful for video transmission system applications that multiplex-transmit a plurality of synchronously generated flow data.

DESCRIPTION OF SYMBOLS 1,1-1,1-2,1-N Data transmission apparatus 2,2-1,2-2,2-N Data generation apparatus 3 Switching hub 4 Video switcher 5 Synchronization control apparatus 6 Management apparatus 10 Data transmission system 11 Receiving unit 12 Variable delay buffer 13 Transmitting unit 14 Transmission timing control unit 141 Received data amount monitoring unit 142 Delay amount calculating unit 143 Delay amount setting unit

Claims (6)

In a data transmission system that multiplex-transmits a plurality of flow data that are synchronously generated by each of a plurality of predetermined data generation devices using a switching hub in an Ethernet (registered trademark) network, the synchronously generated plural A data transmission device that individually delay-controls one flow data among the flow data and transmits the flow data through the network,
A delay adding means for giving a delay to the data to be transmitted in units of the flow data until the predetermined data group constituting the flow data is transmitted to the switching hub using a frame that can be transmitted on the network;
Transmission means for transmitting the data with the delay to the switching hub;
A data transmission device comprising: In a data transmission system that multiplex-transmits a plurality of flow data that are synchronously generated by each of a plurality of predetermined data generation devices using a switching hub in an Ethernet (registered trademark) network, the synchronously generated plural A data transmission device that individually delay-controls one flow data among the flow data and transmits the flow data through the network,
A delay is given to the data to be transmitted in the divided flow data unit divided for the one flow data until the predetermined data group constituting the flow data is transmitted to the switching hub using a frame that can be transmitted on the network. A delay granting means,
Transmission means for transmitting the data with the delay to the switching hub;
A data transmission device comprising:   The delay adding means has a function of autonomously determining a delay amount related to the delay by a predetermined formula using at least a coefficient based on the data amount of the flow data unit, the physical bandwidth of the network, and a random number. The data transmission device according to claim 1.   The delay adding means has a function of autonomously determining a delay amount related to the delay by a predetermined formula using at least a coefficient based on a data amount of the divided flow data unit, a physical bandwidth of the network, and a random number. The data transmission device according to claim 2, wherein the data transmission device is characterized in that: A data generation device that generates flow data including a group of predetermined data,
5. A data generation apparatus comprising the data transmission apparatus according to claim 1 in an output unit that transmits the generated flow data to the outside. A data transmission system that multiplex-transmits a plurality of flow data generated synchronously by each of a plurality of predetermined data generation devices using a switching hub in an Ethernet (registered trademark) network,
3. A data transmission system comprising a plurality of data transmission devices according to claim 1 and 2, and further comprising a management device capable of individually setting a delay amount related to the delay for the plurality of data transmission devices.