JP3876885B2 - Method for controlling a network for transmitting audio signals - Google Patents

Description

  The present invention relates to a network control method for transmitting a digital audio signal.

  Conventionally, there has been a technology for transmitting audio signals of a plurality of channels (ch) in real time in a CSMA / CD (Carrier Sense, Multiple Access with Collision Detection) type network. A typical example is CobraNet (trademark of Peak Audio Inc., see Non-Patent Document 1) using 100BASE Ethernet (Ethernet, registered trademark of Fuji Xerox Co., Ltd.).

  In the CSMA / CD method, an arbitration method for collision (when multiple nodes start transmission at the same time) is negotiated, but when a collision occurs, retransmission is performed after a predetermined time, so transmission band loss Is quite big. For this reason, there are many inconveniences when applied to transmission of audio signals that require real-time transmission. Therefore, in CobraNet, each node transfers a predetermined number of samples in a predetermined order every predetermined cycle. As a result, the occurrence of such a collision is prevented, and real-time transmission of audio signals of up to 128 channels using the 100BASE band fully is possible (Isochronous transfer). In CobraNet, serial communication between nodes can be performed by using a time not used for transmitting an audio signal in the cycle (Asynchronous transfer).

  CobraNet is provided with a mechanism for synchronizing a waveform processing clock (sampling clock) between nodes in order to perform real-time transmission of audio signals as described above and perform synchronized processing as a whole. Specifically, one node called a conductor is determined, a master clock is supplied from the conductor to other nodes on the network, a waveform processing clock synchronized with the master clock is generated at all nodes, and the waveform processing is performed. Waveform processing of various devices connected to the node is performed based on the clock. Which node will be a conductor is determined during network negotiation based on the priority given to the node. The priority of each node can be arbitrarily set as a parameter by the user. Each node is provided with an operation element for selecting a source from which a signal is used as a word clock. The word clock (hereinafter referred to as WC) is a reference clock signal used for generating a waveform processing clock.

For example, when it is desired to set a certain node as a conductor, an operation for selecting an appropriate WC source is performed and a high priority is set at the node. In addition, in order to set other nodes as performers (nodes other than conductors), each of the other nodes is set to use a clock signal supplied via the network as a WC, and the priority of the node is lowered. To do. When the system is operated after the above settings, the above-described one node becomes a conductor and the other node becomes a performer by the CobraNet negotiation function to start the operation. The conductor generates a waveform processing clock from the WC output from the selected WC source, performs waveform processing of various devices connected to the node based on the waveform processing clock, and transmits the WC via the network To the performer. The performer generates a waveform processing clock from the transmitted WC, and performs waveform processing of various devices connected to the node based on the waveform processing clock. Thereby, the operation | movement synchronized as a whole is implement | achieved.
"Audio Networks An Overview", explanatory material for Peak Audio Inc., http://www.peakaudio.com/PDF/CNTraining2.pdf

  By the way, in order to set a node as a conductor (parent node) or performer (child node) as described above, both WC selection and priority setting must be performed, which is an operation that is difficult for the user to understand. It was.

  An object of the present invention is to make it possible to set a node on a network to be a conductor or a performer with a simple operation in view of the above-described problems in the prior art.

  In order to achieve the above object, the present invention provides a network control method for transmitting an audio signal between a plurality of nodes, and any one of a plurality of nodes connected to a CSMA / CD network. When the source of the waveform processing clock that specifies the waveform processing operation is selected, if that source is other than the supply source via the network, the node is set as the parent node (conductor if CobraNet) and the network A setting command indicating that the node is a child node (a performer in the case of CobraNet) is issued to the other nodes above. A node that has received a setting command indicating that it is a child node sets its own node as a child node. If the network is determined to be a parent node or a child node depending on the priority, the priority is set to be higher or lower.

  A connection apparatus to which the method according to the present invention is applied is, for example, a connection apparatus that transmits an audio signal by connecting to a CSMA / CD network, and includes an interface that connects to the network, and an interface that connects an audio device. Depending on whether the self-connected device is set as the only parent node on the network or a child node other than the parent node, if it is a parent node, the transmission right is secured every predetermined time. A start packet for starting a transmission cycle for transmitting a waveform packet in real time is transmitted. If it is a child node, the start packet is received and the start of the transmission cycle is recognized and given to the own node within the transmission cycle. Means for transmitting an audio signal between nodes in real time by transmitting waveform packets in a predetermined order; A means for selecting a source of a waveform processing clock that defines an operation of waveform processing performed by the own connection device and the connected audio device; and when the selected source is other than a supply source via the network, A means for issuing a setting command indicating that it is to be a child node to a connection device that is another node on the network, and a setting command indicating that it is to be a child node from the network. And a means for setting the own connection device as a child node.

  The connection device to which the method according to the present invention is applied is, for example, a connection device that transmits an audio signal by connecting to a CSMA / CD network, and connects an interface connected to the network and an audio device. Based on the interface, the priority set in the self-connecting device and the priority set in the other connecting device connected to the network, the self-connecting device is the only parent node on the network, or the parent In addition to setting a child node other than the node, if it is a parent node, a transmission right is secured every predetermined time and a start packet for starting a transmission cycle for transmitting a waveform packet in real time is transmitted. Receiving the start packet and recognizing the start of the transmission cycle, the order given to the own node within the transmission cycle Means for transmitting an audio signal between nodes in real time by transmitting a waveform packet at a means, and means for selecting a source of a waveform processing clock that defines an operation of waveform processing performed by the self-connection device and the connected acoustic device; When the selected source is other than the supply source via the network, the priority of the own connection device is set higher and the priority is set lower for the connection device which is another node on the network. It is characterized by comprising means for issuing a command and means for setting the priority of the own connection device low when a setting command for lowering the priority is received from the network.

  According to the present invention, which of the plurality of nodes of the network transmitting the audio signal is automatically determined according to the selection of the WC source, the parent node and the child node are set. Functions and operations are not required, and it is possible to set a node on the network as a parent or a child with a simple operation.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is an overall configuration diagram of a system to which a network control method according to the present invention is applied. General-purpose I / O nodes 101 and 102 and amplifier I / O nodes 103 and 104 are connected to the network 100. The network 100 is a CSMA / CD local area network (LAN). In addition, although it illustrated like a ring type topology here, the form of a network is arbitrary.

  The general-purpose I / O node 101 is connected to a microphone (including an analog / digital converter) 112 and a recorder 113 for inputting / outputting waveform data as digital data. The PC 111 is a personal computer (PC) for performing various controls of the general-purpose I / O node 101 and the network 100. Similarly, a microphone 122, a recorder 123, and a mixer 121 are connected to the general-purpose I / O node 102. A plurality of amplifiers (including a digital / analog converter) 131 are connected to the amplifier I / O node 103, and a speaker 132 that emits an output signal from the amplifier is connected to each amplifier. Similarly, a plurality of amplifiers 141 are connected to the amplifier I / O node 104, and a speaker 142 is connected to each amplifier. General-purpose I / O nodes 101 and 102 and amplifier I / O nodes 103 and 104 each have an address on the network and can communicate with each other.

  1, for example, (1) an audio signal from the microphone 112 or the recorder 113 is transmitted from the general-purpose I / O node 101 to the general-purpose I / O node 102 via the network 100, and the general-purpose I / O node 102 To the mixer 121 for mixing processing and recording on the recorder 123. (2) The audio signals output from the microphone 112, the recorder 113, the mixer 121, etc. are converted into general-purpose I / O nodes 101 and 102. To the amplifier I / O nodes 103 and 104, passed to the amplifiers 131 and 141, and emitted by the speakers 132 and 142. In this case, the network 100 needs to have a mechanism for transferring musical sound waveform data (audio signal) in real time. In this system, CobraNet described in the prior art column is used as such a mechanism.

  FIG. 2 shows a schematic configuration of the general-purpose I / O nodes 101 and 102 and the amplifier I / O nodes 103 and 104. The node 200 includes a central processing unit (CPU) 201, a flash memory 202, a random access memory (RAM) 203, a panel operator 204, a display 205, a PC input / output interface (I / O) 206, and a waveform processing clock generator 207. , A word clock (WC) selection unit 208, a digital waveform I / O 209, a digital signal processor (DSP) 210, and a LAN I / O 211. These parts are interconnected by a bus line.

  The CPU 201 is a processing device that controls the overall operation of the node 200. The flash memory 202 is a non-volatile memory that stores a control program executed by the CPU 201 and various data. A RAM 203 is a volatile memory used as a load area or a work area for programs executed by the CPU 201. The panel operator 204 is an operator such as various switches provided on the external panel of the node 200, and includes a WC selection switch 506 described later with reference to FIG. The display 205 is a display for various statuses provided on the external panel, and includes LEDs 501 to 504 and 505-0 to 505-9, which will be described later with reference to FIG. The PC I / O 206 is an interface for connecting to an external PC.

  The waveform processing clock generator 207 generates a waveform processing clock synchronized with the WC supplied from the WC selection unit 208 by an internal phase lock loop (PLL), and the waveform processing clock is converted into a digital waveform I / O 209, a DSP 210, And the LAN I / O 211. LOCK indicates a lock signal, and “1” is output when the waveform processing clock generated in synchronization with the WC is stable (locked state), and “0” is output when the waveform processing clock is not stable (unlocked state). The The digital waveform I / O 209 is an interface for exchanging digital waveform data (audio signals) with connected audio equipment (amplifier, mixer, A / D converter, D / A converter, etc.). The digital waveform I / O 209 is provided with two input / output terminals so that a plurality of audio devices can be connected, and stereo digital waveform data for four systems can be input / output for each input / output terminal. Yes. The DSP 210 performs signal processing of an audio signal (for example, when an audio signal received by the LAN I / O 211 is output to the digital waveform I / O 209 side, or an audio signal input from the digital waveform I / O 209 is transmitted from the LAN I / O 211. For example, a format conversion process. The LAN I / O 211 is an interface for connecting to the network 100. Since the digital waveform I / O 209, the DSP 210, and the LAN I / O 211 are portions related to waveform processing, synchronized processing is performed based on the waveform processing clock supplied from the waveform processing clock generator 207.

  The WC selection unit 208 performs processing for selecting a WC to be used in the node 200. The first WC that can be selected is an external WC (arrow 221). The external WC is a signal from an external clock generator connected to the external WC terminal of the node 200. Second, the clock signal from the digital waveform I / O 209 can be WC (arrow 222). Various acoustic devices connected to the digital waveform I / O 209 perform processing of waveform data. In this case, the sampling clock for waveform data input from the device is WC. As described above, the digital waveform I / O 209 receives a plurality of systems of digital waveform data from a plurality of acoustic devices, and selects one system of digital waveform data as WC. Third, it is possible to select a WC based on the timing of a beat packet (described later) received from the network 100 via the LAN I / O 211 (arrow 223). Since the beat packet includes a time stamp, the time stamp is passed to the waveform processing clock generator 207 to generate a waveform processing clock synchronized with the timing of the network. The operation for selecting the WC as described above will be described later.

  FIG. 3 shows a time chart of a transmission cycle in the network 100, that is, CobraNet. The beat packet 301 is a beat packet (that is, a start packet that starts a transmission cycle for transmitting a waveform packet in real time) that the conductor forcibly secures a transmission right every predetermined transmission cycle 300 and transmits it. Show. The beat packet 301 includes a time stamp and an ordered list of nodes that are allowed to send waveform packets in isochronous transfer after the beat packet. The beat packet 301 is received by all the nodes on the network, whereby each node recognizes the order in which the node transmits the waveform packet for isochronous transfer. After the beat packet 301, each node transmits waveform packets 302-1, 302-2, 302-3,. It should be noted that the method of passing the transmission right to each node according to the order is arbitrary. For example, a scheme in which a token indicating a transmission right is passed to each node may be used. As described above, a time interval for transmitting waveform data to be transmitted by each node is secured, and real-time transmission is possible. When the transmission of the waveform packet is completed, a communication packet 303 for performing asynchronous asynchronous transfer communication is transmitted.

  When it is desired to transmit waveform data at a certain node, first, a reservation request for notifying that there is data to be transmitted from the node is transmitted to the conductor by Asynchronous transfer. The conductor incorporates the node into the order list based on the reservation request, and transmits the beat packet 301 including the order list. As a result, the node that has issued the reservation request can transmit a waveform packet when its turn is reached by isochronous transfer.

  One waveform packet (for example, 302-1) can include waveform data for eight channels. The waveform data for one channel consists of 64 samples (sampling rate fixed at 48kHz). The number of packets that can be transmitted by one node is not limited to one packet, and a maximum of four packets can be transmitted. The 1.33 msec that is one cycle time of the transmission cycle 300 of the isochronous transfer is determined based on the sampling rate of 48 kHz. This is because the time for 64 samples at this rate is 1.33 msec. Therefore, this one transmission cycle is a time that allows transmission of 64 samples in each of all nodes. The time stamp given to the beat packet that is sequentially received indicates the timing of the first sample among the 64 samples of the packet, and the WC based on the timing of the beat packet described above has a timing of approximately 64 etc. for each about 1.33 msec. Generated by dividing.

  FIG. 4 shows a procedure of transmission processing in the LAN I / O 211. FIG. 4A shows processing executed by the LAN I / O 211 of the conductor node every transmission cycle 300 (every 64 sample times) in FIG. In step 401, a transmission right on the network is secured, and in step 402, a beat packet 301 is generated and transmitted.

  FIG. 4B shows a process executed when each node (which may be either a conductor or a performer) has a transmission right (that is, when an order comes). In step 411, a waveform packet to be transmitted from the node is generated and transmitted.

  FIG. 5 is an external view of the hardware panel constituting each node. Reference numerals 501 to 504 denote indicators (LEDs) indicating the states of the network and the node. The WC LOCK 501 is an LED indicating a LOCK state in the waveform processing clock generator 207 (FIG. 2) of the node. The WC LOCK 501 is lit when locked to the selected WC source and blinks when unlocked. The CONDUCT 502 is lit when the node is a CobraNet conductor. The LINK 503 lights up when the node is correctly connected to the CobraNet network (communication is possible). The ERROR 504 lights up when the connection of the node to the network is not established, and blinks when an error occurs in the network interface.

  Reference numerals 505-0 to 505-9 denote indicators (LEDs) for displaying the currently selected WC source. NETWORK 505-0 is lit when the node selects WC from the CobraNet network (arrow 223 in FIG. 2). The WC IN 505-1 lights up when the WC input from the WC input terminal provided on the rear panel of the node is selected (arrow 221 in FIG. 2). 505-2 to 505-5 and 505-6 to 505-9 are respectively input (IN) from various digital devices (such as a microphone, a recorder, and a mixer) connected to the first input / output terminal and the second input / output terminal. A) and which line of WC is selected from the four lines of stereo waveform data input as input (IN B) (arrow 222 in FIG. 2). Any one of these indicators 505-0 to 505-9 is lit. The WC selection switch 506 is an operator that selects a WC source. In the initial state of the node, NETWORK 505-0 is lit and WC from the network is selected. When the WC selection switch 506 is pressed from here, the indicator 505-0 is turned off and the WC IN 505-1 is turned on. Hereinafter, every time the WC selection switch 506 is operated, the lighting state shifts in the order of the number of * of 505- *, and the selection state of the WC source is switched accordingly.

  FIG. 6A shows processing when the WC selection switch 506 is operated in each node. In step 601, the register WSEL is incremented. In the register WSEL, a value indicating the WC source currently selected in the node (same as the value * of the indicator 505- * indicating the selection state of the WC source in FIG. 5) is set. The initial value when the power is turned on is WSEL = 0. If WSEL = 10 is not satisfied in step 602, a command for setting priority L (low priority) is transmitted to another node in step 603. Next, at step 604, the WC from the source indicated by WSEL is supplied to the waveform processing clock generator 207. At this time, since the waveform processing clock generator 207 is in an unlocked state, the lock LED (WC LOCK 501 in FIG. 5) is finally blinked in step 605 to indicate that it is in an unlocked state, and the processing is terminated. To do. When WSEL = 10 in step 602, WSEL is reset to 0 in step 606, the priority of the node is set low in step 607, and WC based on the beat packet from the network is set to waveform processing clock generator 207 in step 608. To step 605.

  FIG. 6B shows processing when the waveform processing clock generator 207 can stably generate a waveform processing clock synchronized with WC and the output LOCK changes to 1. In step 611, the lock LED 501 is set to a lighting state. In step 612, it is determined whether WSEL = 0. Otherwise, the priority of the node is set high (H) in step 613, and the process ends. If WSEL = 0 in step 612, the processing is terminated as it is.

  According to the above embodiment, the priority for determining whether to become a conductor or performer is automatically set according to the selection of the WC source. When the user wants to use a node as a conductor, the user only needs to operate the WC selection switch 506 of the node to select a source other than the network source. By this selection, the priority of the node is set high and the priority of other nodes is set low as described with reference to FIG. Thereafter, the CobraNet function sets a node with a higher priority as a conductor and a node with a lower priority as a performer. As a result, the function and operation for setting the priority of each node, which has been necessary in the past, are unnecessary. Note that the priority setting function itself of each node may be eliminated, but may be left. In that case, the one set later is more effective between the priority setting by the processing of FIG. 6 according to the selection of the WC source and the priority setting by the user's direct priority setting operation. . In addition, since the timing for increasing the priority is not the timing when the WC from the external device is selected as the WC source, but the time when the lock for the selected WC is established, the device switches to the parent node in the network. As soon as possible, the operation based on the stable waveform processing clock can be started (there is no or short period during which the clock becomes unstable after switching). In addition, when a WC that cannot be locked is selected, it is possible to prevent the occurrence of noise without switching to the parent node.

  In the above-described embodiment, CobraNet has been described as an example. However, the present invention is not limited to CobraNet, and beat packets (start of starting transmission cycle 300) from various networks (conductors (parent nodes)) capable of transmitting audio signals. Packet), and thereafter, each node transmits a waveform packet in a predetermined order within a predetermined time). In the above embodiment, the setting of the priority of each node is set to indirectly become a conductor or performer. However, the setting of becoming a conductor or performer directly to each node is set. If there is a function to be performed, the node may be set as a conductor instead of setting the priority high, and the node may be set as a performer instead of setting the priority low.

  In addition, stereo digital signals are input / output to / from the external device, but the digital signals input / output from the external device may be in monaural signal units, such as 4 channels or 8 channels. Multiple channel signal units may be used.

  In this embodiment, when a WC from a connected audio device is selected as a WC source, first, a priority L setting command is sent to another node (step 603). Instead of performing the processing when the WC is selected, the processing may be performed before or after step 613 when LOCK changes to “1”. This change has no effect on the current parent node settings in the network until the clock generator 207 locks to the WC supplied in step 604. Therefore, when it is no longer necessary to change the current setting after operating the WC selection switch 506, the WC selection switch 506 is appropriately operated during the period in which the lock LED is blinking to set the state to select the WC from the network. You can achieve that goal.

  As a WC source, a WC from a network and a WC from an external device have been choices, but the waveform processing clock generator 207 of the node can be independently generated without supplying a WC, The unique waveform processing clock may be selected as the WC.

Overall configuration diagram of a system to which a network control method according to the present invention is applied Diagram showing the schematic configuration of the node Diagram showing transmission cycle time chart in CobraNet The flowchart figure which shows the procedure of the transmission process in LAN I / O External view of the hardware panels that make up each node The flowchart figure which shows a process when the LOCK which the WC selection switch is operated, and LOCK which a waveform processing clock generator outputs changes to 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Local area network (LAN) of CSMA / CD system, 101, 102 ... General-purpose I / O node, 103, 104 ... Amplifier I / O node, 112, 122 ... Microphone, 113, 123 ... Recorder, 121 ... Mixer, 131, 141 ... Amplifier, 132, 142 ... Speaker, 200 ... Node, 201 ... Central processing unit (CPU), 202 ... Flash memory, 203 ... Random access memory (RAM), 204 ... Panel operator, 205 ... Display, 206 ... PC input / output interface (I / O), 207 ... Waveform processing clock generator, 208 ... Word clock (WC) selection unit, 209 ... Digital waveform I / O, 210 ... Digital signal processor (DSP), 211 ... LAN I / O.

Claims (3)

A network control method for transmitting an audio signal between a plurality of nodes by an isochronous transfer method,
One of a plurality of nodes on the network is a parent node, the other is a child node, and each node has a waveform in a predetermined order within a predetermined time after a start packet transmitted from the parent node every predetermined time. By sending packets, it has a mechanism to transmit audio signals between nodes in real time,
As a synchronization source of a waveform processing clock indicating the processing timing of an audio signal in any one of the plurality of nodes, a clock generated based on a packet received from the parent node or an external device connected to the node Selecting the input clock; and
When the selected source is other than the clock recovered based on the received packet, it issues a setting command to instruct other nodes on the network to become child nodes, and the node Configuring it to be a node,
In the node that has received the setting instruction indicating that it becomes the child node, a step of setting the own node as a child node;
Inputting the clock selected by the selecting step and generating a waveform processing clock synchronized with the clock; and
A method for controlling an audio signal transmission comprising: transmitting an audio signal between the node and another node based on a generated waveform processing clock. A network control method for transmitting an audio signal between a plurality of nodes by an isochronous transfer method,
One of a plurality of nodes on the network is a parent node, the other is a child node, and each node has a waveform in a predetermined order within a predetermined time after a start packet transmitted from the parent node every predetermined time. A mechanism for transmitting an audio signal between nodes in real time by transmitting a packet, and a mechanism for determining one node to be the parent node based on the priority set for each node;
As a synchronization source of a waveform processing clock indicating the processing timing of an audio signal in any one of the plurality of nodes, a clock generated based on a packet received from the parent node or an external device connected to the node Selecting the input clock; and
A setting command for setting the priority of the node higher and lowering the priority of the other nodes on the network when the selected source is other than the clock recovered based on the received packet A step of issuing
In the node that has received the setting command to lower the priority, the step of setting the priority of the own node low;
Inputting the clock selected by the selecting step and generating a waveform processing clock synchronized with the clock; and
A method for controlling an audio signal transmission comprising: transmitting an audio signal between the node and another node based on a generated waveform processing clock. In the control method of the network which transmits the audio signal according to claim 1 or 2,
The step of setting the node to be a parent node or the step of setting the priority of the node to be high is that a waveform processing clock generated by the waveform processing step is selected after a new clock is selected by the selecting step. A control method for a network for transmitting an audio signal, which is executed after waiting for a stable synchronization with the selected clock.

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