JPH09116593A - Data communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the number of terminals of such an equipment that inputs and outputs the real-time digital signals such as the digital audio signals, music/ musical instrument signals, etc. SOLUTION: Each of converters 6 and 7 is provided with a function that performs the mutual conversion between the signal format of a digital audio interface and that of an IEEE-1394. For instance, the digital audio interface signal outputted from a CD player 1 is sent to the converter 6 and converted into an isochronous transmission format packet of the IEEE-1394. This converted packet is sent to the converter 7 and converted again into the digital audio interface. The MD recorder 3 records the digital audio signal. Thus it is possible to carry out the bidirectional data communication among plural MIDI musical instruments by means of a converter having a function that performs the mutual conversion between the MIDI signal format and the IEEE-1394 signal format.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for bidirectionally transmitting a real-time digital signal such as a digital audio signal or a music / instrument signal, and more specifically, it relates to a terminal in a device for inputting or outputting a digital signal. The present invention relates to a technique for reducing the number and transmitting a digital audio signal and a music / musical instrument signal in a common format.

[0002]

2. Description of the Related Art In recent years, it has been common practice to connect digital audio devices or electronic musical instruments by digital signal lines to transmit digital signals.

For example, a digital audio interface (hereinafter simply referred to as a digital audio interface) specified by the document of IEC958 is used in a consumer or professional digital audio device.

FIG. 25 shows an example of transmission of a digital audio signal using a digital audio interface. In this figure, the output interface 81 is, for example, a CD
(Compact disc) Built in player,
The input interface 89 is, for example, an MD (mini disc)
Built into the recorder. Then, the digital audio signal written in the register 82 of the output interface 81 is read from here, the error correction code is added in the parity / bit addition circuit 83, and the biphase mark modulation is performed in the biphase modulation / synchronization pattern addition circuit 84. And a sync pattern addition process to obtain a digital audio signal conforming to the digital audio interface, which is output from, for example, the output terminal of the CD player. Then, it is input to the input interface 89 from the input terminal of the MD recorder via the coaxial cable 85 or the optical fiber cable 87. here,
When transmitting via the optical fiber cable 87, for example, a transmitting module 86 provided in a CD player converts a digital audio signal conforming to a digital audio interface into an optical signal, and for example, a receiving module 88 provided in an MD recorder. The optical signal is converted into a digital audio signal conforming to the digital audio interface.

In the input interface 89, the sync pattern detection / bi-phase demodulation circuit 90 receives the sync pattern detection and the bi-phase mark demodulation processing, the parity / bit check circuit 91 receives the error correction processing, and the original data is passed through the register 92. Digital audio signal of
For example, digital recording circuit of MD recorder (not shown)
Sent to

[0006] Incidentally, when digital recording is performed from an MD recorder to another MD recorder or a DAT (digital audio tape) recorder, and when the MD recorder is connected to a digital preamplifier equipped with a DA converter and a digital signal is directly transmitted. For this reason, it is necessary to provide the MD recorder with an output interface of a digital audio interface.

FIG. 26 shows the structure of a subframe of the digital audio interface. FIG. 27 shows the structure of subframes, frames, and blocks of the digital audio interface.

As shown in FIG. 26, in the digital audio interface protocol, a subframe is a channel 1 (left channel) or channel 2 (right channel) of a stereo signal, or channels 1, 2, 3 of a 4-channel stereo signal. And 4 are transmitted. And

Sync, preamble ... 4 bits for b0 to b3 AUX (auxiliary bit) ... 4 bits for b4 to b7 Audio data ... 20 bits for b8 to b27 Validity flag ... b28 1 bit of user data ... 1 bit of b29 Channel status ... 1 bit of b30 Parity bit ... 1 bit of b31 A total of 32 bits.

As shown in FIG. 27, the frame has a length of 64 bits, which is twice the length of the subframe. The CD has a sampling frequency of 44.1 kHz and records a 16-bit 2-channel stereo signal. When the CD signal is transmitted by the digital audio interface, the MSB of 16-bit CD data is put in b27 of the subframe of the digital audio interface, and the LSB is put in b12. In addition, subframes b11 to b
8, from the AUX b7 to 4 bits b4 add 0 _2. Therefore, the transmission speed of the CD signal with the digital audio interface is 44.1 kHz × 64 bits.
= 2.8224 Mbps. In the digital audio interface, the sampling frequency is 44.1.
In addition to kHz, it corresponds to 48 kHz and 32 kHz.

In the channel coding of the digital audio interface, when the bit period is T, a logical "0" is represented by 2 bits 00 ₂ or 11 ₂ having a period of T / 2, and a logical "1" is also represented by T / 2. 01 ₂ or 10 ₂
The bi-phase mark modulation represented by is performed. The maximum inversion interval of bi-phase mark modulation is T of the bit period, and the minimum inversion interval is T / 2.

The synchronization and preamble use unique symbols including 3T / 2, which is out of the rule of biphase mark modulation. There are three types of this symbol: the beginning of a block and the beginning B of channel 1, the beginning M of channel 1, the beginning W of channel 2, 3 or 4,

B: 11101000 ₂ or 00010111 ₂ M: 1110010 ₂ or 000111012 ₂ W: 11100100 ₂ or 00011011 ₂ are used.

As shown in FIG. 27, 192 frames make up one block, and a B preamble is placed at the beginning of the block. Also, various data can be transmitted with the channel status as a table of 192 bits for one block. It should be noted that this table does not specify data corresponding to device control signals or device addresses.

Since no address information is added to the digital audio interface, point-to-point
Point communication, that is, data transmission is performed only between devices connected by a cable. Therefore, in a device such as a TV (television receiver) of a video device or an amplifier or a receiver of an audio system, which is a center of signal connection, signal lines of a digital audio interface are concentrated in a tree shape from a plurality of digital audio devices. Will be connected.

FIG. 28 shows an example of a system in which a large number of audio equipments and video equipments are centrally connected to a digital amplifier. In this example, the digital audio broadcasting tuner 10 is used for the digital amplifier 102 having a DA converter.
1, speaker 103, CD player 104 and 10
5, MD recorder 106, DAT recorder 107,
And digital video cassette recorder (hereinafter DVCR)
108) are connected centrally.

The respective devices are unidirectionally or bidirectionally connected by the above-mentioned signal line (coaxial cable, optical fiber) of the digital audio interface. Since the digital audio interface is capable of transmitting in only one direction, it can be used between devices connected in both directions (MD recorder 106, DAT recorder 107, DVCR1).
08 between each device and the digital amplifier 102) are provided with two signal lines.

Further, in the system of FIG. 28, for example, when recording from the CD player 104 or 105 to the MD recorder 106, without performing acquisition,
In order to carry out automatically, it is necessary to transmit a control signal therefor between these devices. But,
As described above, the digital audio interface does not prescribe a method for transmitting such a control signal, and therefore it is necessary to additionally use a control interface. Therefore, the digital amplifier 102 and each device are connected by a control bus. There are various standards for such a control interface.

In recent years, MIDI (Musical)
Instrument Digital Interf
ace), performance information, control information, synchronization information and the like are transmitted between electronic musical instruments (hereinafter simply referred to as MIDI musical instruments) connected to each other by an interface defined by the standard.

The MIDI standard has three types of terminals: a MIDI IN terminal (hereinafter referred to as IN), a MIDI OUT terminal (hereinafter referred to as OUT), and a MIDI THRU terminal (hereinafter referred to as THRU).
And OUT are standard equipment, and many instruments are equipped with THRU. THRU is a terminal having a function of directly outputting the MIDI signal input from IN.

As shown in FIG. 29, from the OUT of the MIDI musical instrument (master) 110 to the MIDI musical instrument (slave) 1
When the MIDI dedicated cable (hereinafter referred to as the MIDI cable) is connected to IN of 11 and the keyboard of the MIDI musical instrument 110 is played, the MIDI musical instrument 111 is also played. The master is a device that generates MIDI data, such as an electronic musical instrument with a keyboard or a sequencer, and is called a MIDI controller. As a slave, a sound source module having no keyboard, only a sound source module, an effector or any other MIDI musical instrument can be connected.

As shown in FIG. 30, the MIDI musical instrument 112
From the OUT to the IN of another MIDI musical instrument 113, and further from THRU to the IN of another MIDI musical instrument 114, and further from THRU to another MIDI musical instrument 1
It can be connected to 15 INs in cascade to play multiple MIDI instruments simultaneously. However, since the MIDI signal deteriorates every time a THRU is passed, the number of cascaded connections by THRU as shown in FIG. 30 is usually limited to three to four.

Therefore, in order to connect a plurality of MIDI musical instruments, as shown in FIG. 31, the OUT of the MIDI musical instrument 116 is output.
Parabox (also called THRU box) 11
7 and enter multiple MIDs from the THRU box output.
A method of connecting to the IN of the I musical instruments 118 to 121 is used. However, when many MIDI musical instruments are connected, there is a problem that MIDI cables are concentrated in the THRU box.

Normally, in MIDI communication, whether or not the receiving (slave) side is receiving correctly is transmitted (master).
The side does not know anything and the transmission is performed in open loop. However, as in the case of transmission of sampling data described later, when the data amount is large among MIDI signals, the data is divided and packet-transmitted. At this time, the receiving side has a function of performing an error check to confirm whether or not the data is correctly sent, and requesting retransmission if the data is not correctly sent. This is called transfer by handshake. When performing a handshake, see Figure 3.
As shown in FIG. 2, the IN and MI of the MIDI master 122
It is necessary to connect the OUT of the DI slave 123 with a MIDI cable.

Although the MIDI musical instrument has terminals for IN and OUT, it does not support two-way communication since the master and slave stand by for fixed one-way communication.
Therefore, the MID once set as a slave
There is a problem that even if the keyboard of the I musical instrument is played, the master MIDI musical instrument cannot be smoothed. Also, the cascaded system of FIG. 30 and the THR of FIG.
In a system using the U-box, the device to be the master is predetermined and it is necessary to determine the order of connecting MIDI musical instruments for playing. For this reason, there is a problem in that resetting when moving an instrument is inconvenient and it is difficult to change the configuration of the instrument once set.

A message transmitted between MIDI musical instruments is called a MIDI message. MIDI Message is
It is represented by a byte string of 1 byte or more. As shown in FIG. 33, the byte string of the MIDI message is divided into a status byte and a data byte. The status byte is
It represents the type of MIDI message, and bit 7 of the MSB is "1". The status byte is usually accompanied by a fixed number of data bytes. However, some messages do not carry data bytes. Bit 7 of the MSB of the data byte is "0".

As shown in FIG. 34, MIDI messages are classified into channel messages and system messages. The channel message is performance information for controlling individual musical instruments, and the system message is control information and synchronization information for controlling the entire MIDI system. Since the MIDI message is not assigned with a control command for connecting musical instruments to each other, it is impossible to change the system setting or configuration through the MIDI standard.

System messages are classified into system exclusive messages, system common messages, and system real-time messages. Channel messages include channel voice messages (hereinafter referred to as voice messages) and channel mode messages (hereinafter referred to as mode messages).

Except for the system exclusive message, the number of data bytes of the MIDI message is 2 bytes or less, that is, the status byte is 3 bytes or less. In FIG. 34, a lower case n representing the status byte in hexadecimal is used to specify the MIDI channel.

FIG. 35 shows a method of designating a MIDI channel. 30 and 31, when a plurality of MIDI musical instruments are connected to a MIDI controller by a MIDI cable, each MIDI musical instrument can be independently played by designating a MIDI channel. MID
The I channel is 4 bits, and up to 16 channels can be designated.

FIG. 36 shows an example of how to use the MIDI channel. MIDI controller 124 has 3 MIDs
I musical instruments 125, 126, 127 are connected. MIDI instrument 125 is saxophone, MIDI instrument 126 is piano, M
The IDI musical instrument 127 sets an electric bass tone color. If the MIDI controller 124 sends performance data for each part, each musical instrument produces a sound for each part.

As described above, according to the MIDI standard, a message can be transmitted by designating a specific MIDI musical instrument from a plurality of MIDI musical instruments on the receiving side (slave) through the MIDI channel. However, since the lower 4 bits of the status byte are used to specify the MIDI channel, it is difficult to increase the number of MIDI channels to 16 or more.

As shown in FIG. 33, the MIDI standard operates at an asynchronous serial transfer of 31.25 kbps (± 1%). Transfer is start bit, bit 0, ... bit 7, stop bit (total 10 bits)
The start bit is a logical "0" and the stop bit is a logical "1". To transfer 1 byte requires 10 × (1 / 31.25 kHz) = 320 μS. In the MIDI system, the note-on message that sounds one tone requires 3 bytes, so 320 to play one tone by MIDI.
It takes μS × 3 = about 1 mS.

A MIDI musical instrument equipped with a sampling function is called a sampler. Sampling is a process in which a user converts the timbre of a live musical instrument into digital data and records it in a memory or the like. Then, at the time of reproduction, digital data is taken out from the memory at arbitrary timing and a sound is produced.
The sample data, which is one of the universal system exclusive messages, is used to transmit the sampling data extracted from the sampler. The universal system exclusive message allows data transmission and reception between MIDI musical instruments of different manufacturers. The sample dump is a common format for transmitting sampler sampling data.

FIG. 37 shows the data format of three MIDI messages including a sample dump request, a dump header, and a data packet. When the dump request of (1) is issued by the MIDI musical instrument, (2)
Is transmitted, and then the data packet of (3) is transmitted. The data packet has a fixed length of 127 bytes, and the maximum data length is 120 bytes.

Usually, the sampled waveform data has several tens of kilobytes, and it is necessary to transmit a large number of data packets. When transmitting such a large amount of data at once,
It is not possible to transmit performance information such as channel messages at the same time because it takes time to transmit and receive MIDI. For this reason, the MIDI input / output function is usually provided with a switch for turning off so as not to receive the system exclusive message.

[0037]

As described above, the conventional digital audio interface standard has the problems described in (1) and (2) below.

(1) Two transmission lines are required to carry out bidirectional transmission, and two terminals for input and output are required on the device side.

(2) The number of transmission lines increases in the device that is the center of the system, and a plurality of input and output terminals are concentrated.
If another interface is provided for control, the number of terminals that input / output to / from the device further increases.

Further, the conventional message transmission according to the MIDI standard has the problems described in the following (3) to (7).

(3) Despite the fact that the MIDI musical instrument is equipped with IN and OUT terminals, it defines only one-way communication and is not applicable to two-way communication.

(4) MIDI that becomes the master of the system
The musical instrument is fixed, and a flexible MIDI system cannot be built.

(5) When connecting multiple musical instruments, T
The cables are concentrated in the HRU box. (6) Since the transmission speed is slow, it is difficult to transmit a large amount of data. (7) System connection information and control commands for connection are not prepared.

Furthermore, a digital audio device using the above-mentioned digital audio interface, for example, C
The digital audio signal reproduced by the D player is combined with the musical performance information of the electronic musical instrument, or the sound (vocal) recorded / reproduced by the MD recorder is combined with the musical performance information of the electronic musical instrument and is digitally recorded (recorded). However, since the MIDI standard and the digital audio interface have different data formats and data transmission rates, it has been difficult to digitally connect the electronic musical instrument and the digital audio device.

The present invention has been made in view of the above circumstances, and reduces the number of input / output terminals as compared with a conventional system using a one-way interface.
In particular, it is an object of the present invention to provide a data communication method in which the number of cables and terminals required for signal and control of equipment which is the center of the system is reduced.

Another object of the present invention is to provide a data communication method capable of enhancing the function of an electronic musical instrument.

[0047]

In order to solve the above problems, a data communication method according to the present invention uses an interface format for transmitting digital data in one direction and transmitting digital data in two directions. It is characterized in that the interface is converted into an isochronous transmission format or an asynchronous transmission format.

In the present invention, the digital signal is, for example, a digital audio signal or a music / instrument signal.

In the present invention, when the interface format for transmitting music / musical instrument signals in one direction is converted into digital data transmission in bidirectional manner and transmitted, the music / musical instrument signal dedicated format is transmitted. It can be transmitted in a format or in a transmission format for audio / video equipment.

In the present invention, a control signal transmitted by an interface for transmitting digital data in one direction or another interface connected to a device having the interface is used as an asynchronous interface of the interface for transmitting digital data in two directions. It may be converted into a transmission format and transmitted together with digital data in the isochronous transmission format.

Furthermore, it is preferable that the header of the isochronous transmission format packet is common to a plurality of types of digital data (linear digital audio, non-linear digital audio, music / instrument signal, etc.). Then, the header may be provided with an identification code for identifying a mode in which a plurality of types of digital data are transmitted in synchronization with an isochronous transmission cycle and a mode in which they are transmitted asynchronously. Further, an identification code for identifying the type of digital data can be added to the data in the isochronous transmission format.

Further, it is possible to bit-compress the synchronization signal of the interface which transmits digital data in one direction and take it in the isochronous transmission header of the interface which transmits digital data in both directions.

Furthermore, it is preferable that the size of the data block in the isochronous transmission format of the interface that transmits digital data bidirectionally be the same regardless of the sampling frequency of the interface that transmits digital data unidirectionally. is there.

In the present invention, all of the electronic musical instruments that connect to the bidirectional digital interface can be senders.

[0055]

Embodiments of the present invention will be described below in detail with reference to the drawings. The following two embodiments describe the present invention as IEEE-1394 High P.
performance Serial Bus (hereinafter I
It is applied to the EEE-1394 serial bus).

(First Embodiment) A bidirectional data transmission system to which the present invention is applied includes, for example, a CD player 1 as a digital audio device as shown in FIG.
, DAT recorder 2, MD recorder 3, CD
A player 4 is provided. These digital audio devices have a digital audio interface. The CD player 1 and the DAT recorder 2 are connected to an IEC958 / IEEE-1394 converter (hereinafter simply referred to as a converter) 6 by a signal line of a digital audio interface and a control bus. The MD recorder 3 and the CD player 4 are connected to the converter 7 by a signal line of a digital audio interface and a control bus. Further, the converter 6 and the converter 7
And the DVCR (digital video cassette recorder) 5 are connected by an IEEE-1394 serial bus cable. DVCR5 is IEEE-1394
It has a digital interface to a serial bus and can send and receive digital audio / video signals without going through a converter.

The system using the IEEE-1394 serial bus can adopt a tree type topology in addition to the cascade type bus type topology as shown in FIG.

The converter 6 and the converter 7 are the digital audio interface protocol and IEEE-1394.
It has a function to convert the protocol of each other. In this case, a digital audio signal conforming to the digital audio interface is transmitted in the IEEE-1394 isochronous mode. The isochronous mode is a mode in which data transmission is performed in synchronization with an 8 kHz (125 μs) isochronous cycle generated by a device that becomes a cycle master in the data transmission system.
It is used to transmit real-time signal data such as moving image signals, digital audio signals, and music / instrument signals.

The converters 6 and 7 also have a function of mutually converting the control bus protocol and the IEEE-1394 protocol. In this case, the control command of the control bus is transmitted in the asynchronous mode of IEEE-1394. The asynchronous mode is used for recording or reading data in a storage device such as a hard disk device in a non-real time mode, or for transmitting a control signal of a device.

FIG. 2 shows the basic structure of the converter. Converter 2
0 is a physical layer block (PHY) 21 for the IEEE-1394 serial bus and a link layer block (LIN).
C) 22, CPU 23, digital audio I / O
24.

The physical layer block 21 is IEEE-139.
4 Physical layer control such as arbitration of serial bus, encoding / decoding of communication data, supply of bias voltage, etc. The link layer block 22 includes an asynchronous data processing unit 25 and an isochronous data processing unit 2.
6 for performing link layer control such as packet generation / detection, header CRC and data CRC generation / detection.
Then, the CPU 23 controls the application layer. Further, the digital audio I / O 24 communicates the digital audio signal with the isochronous data processing unit 26 of the link layer block and sends the control signal to the CPU 23.
Communicate with. In addition, digital audio I / O
24 buffers these signals.

In the system of FIG. 1 described above, for example, a CD
The digital audio signal reproduced by the player 1 is formed into a signal conforming to the digital audio interface and transmitted to the converter 6. In the converter 6, the digital audio signal input from the digital audio I / O 24 is sent to the isochronous data processing unit 26 of the link layer block 22, where an IEEE-1394 isochronous data block packet (hereinafter referred to as an isopacket) is sent. Create and physical layer block 21 to I
It is sent to the EEE-1394 serial bus. In the converter 7, the isopacket input from the physical layer block 21 is sent to the digital audio I / O 24 via the isochronous data processing unit 26, where it is returned to a signal conforming to the digital audio interface and sent to the MD recorder 3. Now record the digital audio signal.

Similarly, the digital audio signal reproduced by the CD player 4 can be digitally recorded in the DAT recorder 2. Further, digital recording can be performed in the digital audio data recording area of the DVCR 5.

When transmitting the control command in the system of FIG. 1, for example, the control command output from the CD player 1 is transmitted to the converter 6 via the control bus. In the converter 6, the control command input from the digital audio I / O 24 is sent from the CPU 23 to the asynchronous data processing unit 25 of the link layer block 22, and here, the IEEE-1394 asynchronous data block packet (hereinafter referred to as an asynchronous packet). Is generated and sent from the physical layer block 21 to the IEEE-1394 serial bus. In the converter 7, the asynchronous packet input from the physical layer block 21 is sent to the digital audio I / O 24 via the asynchronous data processing unit 25 and the CPU 23. Then, here, the command on the control bus is returned and sent to the MD recorder 3 to control its operation.

FIG. 3 shows the timing when the digital audio signal and the control command are transmitted from the CD player 1 to the MD recorder 3 and the digital audio signal and the control command from the DAT recorder 2 to the DVCR 5 in the system of FIG. An example is shown.

The signal stream A is a digital audio signal transmitted from the CD player 1 to the MD recorder 3, and the signal stream B is a digital audio signal transmitted from the DAT recorder 2 to the DVCR 5. These signal streams A and B are input to the converter 6 via a digital audio interface.

Further, the command A 11A and 11B are C
It is an example of a control command that the D player 1 and the MD recorder 3 exchange with each other. And 12A of command B
And 12B are examples of control commands that the DAT recorder 2 and the DVCR 5 exchange with each other. These are all input to the converter 6 by the digital audio interface.

The signal streams A and B are converted into isopackets in the converter 6 and then transmitted on the IEEE-1394 serial bus in an isochronous cycle of 125 μs. The data transmission rate in this case is 100 Mb
It is set to either ps, 200 Mbps or 400 Mbps. In FIG. 3, the signal stream A is converted into the isopackets 13A to 13F, and the signal stream B is converted into the isopackets 14A to 14F.

The commands 11A and 11B are converted into asynchronous packets 15A and 15B, and the commands 12A and 12B are converted into asynchronous packets 16A and 16B.

The isopacket and the asynchronous packet are time-division multiplexed and transmitted on the IEEE-1394 serial bus. At this time, the isopackets 13A to 13F and 14A to 14F are transmitted using different channels. The device on the IEEE-1394 serial bus takes in the required isopacket by looking at the channel number written in the isopacket header (details will be described later). In addition, the asynchronous packet 15
The A and 15B and the asynchronous packets 16A and 16B have a source device address and a destination device address. For details of such data transmission control on the IEEE-1394 serial bus, see IEEE-13.
Since it is disclosed by the 94 specifications, it will not be described here.

The isopacket and the asynchronous packet transmitted on the IEEE-1394 serial bus are input to the converter 7. The isopackets 13A to 13F are returned to the original signal stream A and sent to the MD recorder 3 via the digital audio interface. The asynchronous packets 15A and 15B are also returned to the original commands 11A and 11B and sent to the MD recorder 3 via the control bus.

On the other hand, the isopackets 14A to 14F are directly transmitted to the DVC via the IEEE-1394 serial bus.
It is sent to R5 and taken in. Similarly, the asynchronous packets 16A and 16B are also directly used in IEEE-1394.
It is sent to the DVCR 5 via the serial bus and taken in.

Next, a digital audio signal conforming to the digital audio interface is transferred to IEEE-139.
The method for placing the packet in the No. 4 iso packet will be described in detail.

FIG. 4 shows an IEEE-1394 isopacket. The data block packet of IEEE-1394 is represented by a unit of 32 bits (hereinafter referred to as a quadlet). The channel in the first quadlet indicates the isochronous channel number. An isochannel can be identified by a 6-bit 64 channel. When 2 bits of the tag (tag) field are 01 ₂ , a 2-quadlet common isochronous packet header (hereinafter referred to as a CIP header) is inserted at the beginning of the data field. The value of tag is 01 ₂ for the purpose of handling real-time data of a digital audio / video signal of a digital video device or a digital audio device. This embodiment relates to the case of tag = 01 _2. Incidentally, when the tag = 00 _2, insertion of the CIP header is not required.

[0075] C when 5 takes a value tag = 01 ₂
The IP header is shown. The quadlet at the beginning of the CIP header has the same bit assignment depending on the format. The source node ID (hereinafter referred to as SID) is the IEEE- of the device that sends the isopacket.
Indicates the node ID on the 1394 serial bus. The data block size (hereinafter referred to as DBS) is a number that represents the length of the data block by a quadlet. The number of fractions (hereinafter referred to as FN) is the number of data blocks into which the source packet is divided. The quadlet padding count (hereinafter referred to as QPC) is FN 00 ₂
Used when taking a value other than. The source packet header (hereinafter referred to as SPH) is set to 1 ₂ when the source packet has its own source header. A data block counter (hereinafter referred to as DBC) is an 8-bit continuous counter and is used to detect transmission loss of a source packet. Format ID field in the second quadlet of the CIP header (hereinafter referred to as FMT)
Is used to identify the format transmitted on the IEEE-1394 serial bus. The format-dependent field (hereinafter referred to as FDF) has its specifications determined by the FMT.

FIG. 6 shows an example of FMT allocation. As shown in this figure, DVCR, 0 with FMT = 000000 ₂
0000 ₁₂ specifies the MPEG signal transmission format. The digital audio uncompressed FMT = 000010 ₂ (hereinafter referred to as linear audio), 0
00011 digital audio is bit compressed ₂ (hereinafter referred to as non-linear audio) 000100 ₂
Specify the music / instrument transmission format with. FMT =
In the case of 111110 ₂ , the manufacturer's original specification is accepted within the range of the regulation of the CIP header. Also, FMT = 11
When the _{1111 2, DBS, FN, QPC} , SPH,
The definition of each field of DBC is canceled.

FIG. 7 shows a CIP header common to linear audio, non-linear audio and music / instrument. The format of this header is the data format field (hereinafter referred to as DATAF) in the FDF of FIG.
And synchronization time Sync Time (hereinafter referred to as SYT)
It is divided into By making the digital audio data assigned by FMT and the data transmission format of music / instrument common, shared transmission on the IEEE-1394 serial bus becomes easy.

FIG. 8 shows the structure of SYT. When the value of the time stamp is given, 16 bits of SYT are 4 bits of cycle count (Cycle count),
1 of cycle offset
Divide into 2 bits. This cycle count is based on IEEE
The value of the lower 4 bits of 13 bits of the cycle count of the cycle time register provided in the cycle master on the -1394 serial bus is used. As the 12-bit cycle offset, the 12-bit value of the cycle offset of the cycle time register is used as it is.

FIG. 9 is an example of bit allocation of DATAF of linear audio. In this figure, the asynchronous mode is a transmission mode in which the time stamp of SYT is used without being synchronized with the cycle of 125 μs in the isochronous mode. It is used to convert a digital audio interface signal of a device, which is generally not synchronized with an external clock, such as a CD player for a consumer, into the IEEE-1394 format.

The synchronous mode is a mode of transmission synchronized with an isochronous cycle of 125 μs, and is used for equipment capable of synchronizing with an external clock of a commercial CD player or recorder.

The Raw audio specification is that a device that does not have an input / output terminal of a digital audio interface defines a digital audio signal that does not depend on the format as I.
Used when transmitting on the EE0-1394 serial bus.

In this embodiment, the signal stream of the digital audio interface is divided into blocks to form a source packet, which is transmitted with a header. 4 for digital audio interface
Three types of sampling frequencies (hereinafter referred to as Fs) of 8 kHz, 44.1 kHz, and 32 kHz are defined.
One block of digital audio interface is 19
Since it is 2 frames, the length of 1 block is

Fs: 48 kHz ... 192/48 kHz = 4 ms Fs: 44.1 kHz ... 192 / 44.1 kHz = 4.335374 ms Fs: 32 kHz ... 192/32 kHz = 6 ms.

Therefore, the maximum number of isopackets in each Fs in one block is: Fs: 48 kHz ... 4 ms / 125 μs = 32 Fs: 44.1 kHz ... 4.35374 ms / 125 μs≈35 Fs: 32 kHz ..6 ms / 125 .mu.s = 48.

In the present embodiment, regardless of the value of Fs,
The number of isopackets containing data is set to 24 in one block. Then, the other isopacket transmits a packet having only a header without a source packet (hereinafter referred to as a dummy packet).

Since the number of bits of data in one block is 64 bits × 192 = 12288 bits, the number of bits of valid packet data is 12288 bits ÷ 24 =
It is 512 bits. If this is converted to a quadlet, 16
It becomes a quadlet and DBC = 16 = 00010000
₂ The 16 quadlets correspond to 16 subframes of the digital audio interface, that is, 8 frames.

FIG. 10 shows an example in which these 8 frames are transmitted as an isopacket as one unit. Calculating the time required for each frame to store 8 frames of data in the buffer in the converter,

Fs: 48 kHz ... 8 ÷ 48 kHz = 166.7 μs Fs: 44.1 kHz ... 8 ÷ 44.1 kHz = 181.4 μs Fs: 32 kHz ... 8 ÷ 32 kHz = 250 μs.

As shown in FIG. 10, Fs = 44.1 kH
For z, approximately 35-24 = during transmission of one block.
There are 11 dummy packets, and 2 valid packets
After transmitting one, one dummy packet will be transmitted.

When Fs is 48 kHz, FIG.
32-24 = during transmission of one block, as shown in
There are 8 dummy packets, and one dummy packet will be transmitted after transmitting about 3 valid packets.

Similarly, when Fs is 32 kHz, as shown in FIG.
As shown in Fig. 2, 48-24 are transmitted during transmission of one block.
= 24 dummy packets are transmitted, and almost valid packets and dummy packets are transmitted alternately.

FIG. 13 shows an example of an isopacket format. As shown in this figure, the contents of the 32-bit sub-frame of the digital audio interface are directly transferred to the isopacket. However, 4 bits of sync / preamble

B: LSB 11 ** MSB M: LSB 01 ** MSB W: LSB 00 ** MSB Here, normally, 00 ₂ is inserted as **.
A combination of 20-bit audio data, 4-bit auxiliary data, and ** can be used as 26-bit audio data.

As shown in this figure and FIG. 10, in this embodiment, when transmitting a signal of a digital audio interface, one isopacket has 8 data parts.
It is transmitted in units of one frame. As shown in FIG. 27, the first quadlet of the data part is B or M, and does not start with W. Then, B is located in the first quadlet of the data section, and is never in the middle of the data section. Here, the audio data is transmitted first from the LSB, but it may be determined to be transmitted first from the MSB.

(Second Embodiment) FIG. 14 shows a second embodiment of a bidirectional data transmission system to which the present invention is applied. This data transmission system includes MIDI musical instruments 31 to 31.
34, CD player 35, MD recorder 36
A MIDI / IEEE-1394 converter (hereinafter simply referred to as a converter) 37 to 40, a personal computer (hereinafter referred to as a personal computer) 41, and a hard disk device 4
2 are provided.

Then, the OUT of the MIDI musical instruments 31 to 34
Are converters 37 to 40 via MIDI cables, respectively.
Connected to the IN of the MIDI instruments 31-34,
O of converter 37-40 by MIDI cable respectively
Connected to UT.

Further, the converters 37 to 40, the CD player 35, the MD recorder 36, the personal computer 41, and the hard disk device 42 are commonly connected by an IEEE-1394 serial bus. That is, these devices
It has a node ID on the EEE-1394 serial bus.

The converters 37 to 40 receive the MIDI signal and IEEE.
Performs mutual conversion with the E-1394 serial bus protocol. For example, the MIDI signal input from the OUT of the MIDI musical instrument 31 to the IN of the converter 37 is
Is converted into an IEEE-1394 isopacket or an asynchronous packet, and is sent to the IEEE-1394 serial bus. On the contrary, the packet sent from another MIDI musical instrument to the IEEE-1394 serial bus through another converter and received by the converter 37 is converted into a MIDI signal here, and OUT to MIDI musical instrument 31
Sent to IN.

CD player 35 and MD recorder 3
6 includes a digital audio interface and the IEC958 / IEEE-1394 converter shown in FIG. 2, and can internally perform mutual conversion between protocols. Therefore, the iso packet and the asynchronous packet can be directly transmitted / received to / from the IEEE-1394 serial bus. Note that, as in FIG. 1, IEC958 / IEEE-
The 1394 converter may be provided outside the CD player 35 and the MD recorder 36.

Personal computer 41 and hard disk device 42
Has a digital interface (physical layer block and link layer block in FIG. 2) for the IEEE-1394 serial bus, and can directly send and receive isopackets and asynchronous packets to and from the IEEE-1394 serial bus.

According to the bidirectional communication system configured as described above, the MIDI output from the MIDI musical instrument 31
The performance information of the musical instruments 32 to 34 is transmitted by the converter 37 to the IEEE.
Converted to E-1394 serial bus protocol,
It is sent to the EEE-1394 serial bus. And
The converters 38-40 are converted back into the performance information of the MIDI musical instruments 32-34, and the MIDI musical instruments 32-3 are respectively converted.
Input to IN of 4. As a result, the MIDI musical instrument 31
You can play ~ 34 at the same time.

The performance information and control information of the MIDI musical instrument can be recorded and reproduced on the hard disk device 42. Further, on-screen display can be displayed on the display of the personal computer 41.

Further, the performance information output from the MIDI musical instrument and the reproduced digital audio signal of the CD player can be combined and recorded (recorded) in the MD recorder 36 or the hard disk device 42.

In FIG. 14, the converters 37 to 40 are IEs.
It has an ID on the EE-1394 serial bus and a source ID of an asynchronous packet (see FIGS. 16 and 17 described later).
(See M) by using its ID number
It is possible to determine whether the IDI musical instrument is transmitting a MIDI message. That is, which MID in the configuration of FIG.
The I musical instrument can also be the master, and there is no need to fix the connection as in FIG. 30 or FIG. 31, and other MIDI musical instruments can be played from any keyboard.

FIG. 15 shows the MIDI standard and IEEE-139.
An example of a 4 serial bus format converter is shown. This converter is roughly composed of a MIDI message transmitting / receiving unit, a digital interface for an IEEE-1394 serial bus, and a CPU 54.

The MIDI message transmitter / receiver uses the MID
The MIDI message buffer 51 output to the I OUT terminal and the MID input from the MIDI IN terminal
I message buffer 52 and UART (Univ
ersal Asynchronous Receive
er-Transmitter) 53.

The digital interface for the IEEE-1394 serial bus is composed of a link layer block 55 and a physical layer block 56. These are shown in FIG.
Of the corresponding blocks.

The MIDI message output from the CPU 54 is converted into asynchronous serial data by the UART 53, passes through the buffer 51, and MIDI OUT to MID.
It is output on the I cable. Also, a MIDI message input from MIDI IN passes through the buffer 52, is converted into parallel data by the UART 53, and is converted into CPU data.
54 is input.

When transmitting a MIDI message in an asynchronous packet, the MIDI message output from the CPU 54 is sent to the asynchronous data processing section 57, and from there the IE is passed via the physical layer block 56.
It is sent to the EE-1394 serial bus. And MI
When transmitting a DI message in an isopacket, the MIDI message output from the CPU 54 is sent to the isochronous data processing unit 58, from which it is sent to the IEEE-1394 serial bus via the physical layer block 56.

Next, a method of placing a music / instrument signal conforming to the MIDI standard on an asynchronous packet of the IEEE-1394 serial bus will be described.

Here, music / instrument signals are transmitted using the function control protocol of IEEE-1394 (hereinafter referred to as FCP). FCP is IEEE-1
394 is a protocol for controlling devices connected to the 394 serial bus, and transmits control commands and responses by asynchronous packets.

FIG. 16 shows a Writer request f in the asynchronous data transmission mode of IEEE-1394.
or data block packet, Wri in FIG.
te request for data quadl
Indicates an et packet. The payloads of these two packets are called FCP frames. When the length of the FCP frame is 4 bytes (= 1 quadlet), “Write
request for data quadlet ”
Is used. Source ID and destination ID
Are the source and destination addresses of asynchronous packets.

FIG. 18 shows the structure of the FCP frame in the asynchronous data transmission mode of the IEEE-1394 serial bus. The first 4 bits of the FCP frame is a command transaction set (hereinafter referred to as CTS), and CTS = 0000 ₂ is allocated for controlling audio / video equipment (hereinafter referred to as AV equipment). After CTS, the command type / response code (hereinafter CT / R
C) is 4 bits, header address (hereinafter referred to as HA) is 8 bits, OPC is 8 bits, OPR1 is 8 bits, OPR2 is 8 bits, and so on.

FIG. 19 shows F when CTS = 0000 _2.
It is an example of a data structure for transmitting a MIDI message in a CP frame. The 4 bits of CT / RC represent the type of command and response, and if the 4-bit MSB is '0', the frame is a command frame and '1'.
Then it is a response frame. The CT / RC specifications are based on the AV equipment control specifications.

As the 8 bits of HA, for example, a sub device type code and a sub device number defined by IEC Publication 1030 (hereinafter referred to as IEC-1030) can be used. The MSB 5 bits are the sub device type, and the LSB 3 bits are the sub device number. In the sub device type, a video monitor, an audio amplifier, etc. are assigned for AV equipment. As the music / instrument, for example, the sub device type of the audio effects unit (10100 ₂ ) can be used. The sub device number is used to distinguish two decks when one device has a plurality of the same sub devices such as a double cassette deck.

The status byte of the MIDI message is in 8 bits of OPC, and the first MID is in the bit of OPR1.
2 in the data byte of the I message, 8 bits of OPR2
Enter the th data byte. In IEC-1030, the MSB of OPC is "1" and the MSB of OPR is "0".
Therefore, the association between the status byte and the data byte of the MIDI message can be maintained.

In this embodiment, all the MIDI messages other than the system exclusive message are transmitted in the asynchronous data transmission mode.

FIG. 20 shows another example of the FCP frame.
In this example, the CTS has a code dedicated to music and musical instruments (for example, 00
01 ₂ ) is allocated. The CT / RC specification is CTS =
The case of 0000 ₂ may be applied. Since the message of music / instrument is specified in CTS, it is not necessary to specify the sub device in HA as shown in FIG. 19. Therefore, the status byte is put in the position of HA, and the data byte is maximum after that. 2 bytes follow. "Write request for" is stored because it fits within 4 bytes except for system exclusive messages.
data quadlet ”packet. The system exclusive message may be transmitted in the isochronous data transmission mode as in the previous example, or Wr.
ite request for data block
It is also possible to transmit in the asynchronous data transmission mode by k packets.

The destination IDs shown in FIGS. 16 and 17 are used when the number of musical instruments in the communication system is small.
You can specify the ID of the converter that connects to a particular instrument. On the other hand, the number of devices that can be directly connected to the IEEE-1394 serial bus is 63, and when sending MIDI messages with the same content to many MIDI musical instruments, broadcast to the destination ID (Bloodcast).
Specify the ID.

The converter which has received the asynchronous packet including FIGS. 19 and 20 converts it into a MIDI message and sends it to the MIDI musical instrument. The MIDI musical instrument confirms the designated channel from the lower 4 bits of the status byte shown in FIG. 35, and if the channel is designated, produces a sound.

The current MIDI signal is low speed,
Since it is packet transmission, asynchronous transmission of the IEEE-1394 serial bus is suitable for MIDI message transmission. However, IEEE-1394
Isochronous data transmission is more suitable for coexistence with speeding up of the MIDI standard and digital audio signal transmission on a serial bus, and for system exclusive messages among the current MIDI messages. Therefore,
Next, the music / instrument signal conforming to the MIDI standard is transmitted to the IEEE.
A method of loading an isochronous packet on the E-1394 serial bus will be described.

The format of the isochronous packet has been described with reference to FIGS. MID
By converting the MIDI channel of the I message into a channel for isochronous transmission, 16 different channels can be configured on isochronous transmission.
In addition, if the MIDI standard is expanded in the future, or in a higher-speed music / instrument data transmission format,
4 isochronous packets can be transmitted.
FIG. 21 is an example of bit allocation of DATAF in a format related to music / instrument with FMT = 000100 _{2 in} the CIP header.

Next, the sampling data transmission of the MIDI musical instrument which becomes the slave and the digital signal data OU are transmitted.
Isochronous data transmission in the present invention will be described using an example of feedback from the T terminal.

FIG. 22 is a block diagram of a MIDI musical instrument for performing isochronous data transmission. The MIDI IN terminal and MIDI OUT terminal of this MIDI musical instrument are shown in FIG.
It shall be connected to the input / output terminal of the converter of. As shown in FIG. 22, this MIDI musical instrument has a tone color synthesis section 6
0, a switch 61, a keyboard 62, a D / A converter 63, an amplifier 64, and a speaker 65.

The key data and the touch data from the keyboard 62 are sent to the tone color synthesis section 60 through the switch 61. The tone color synthesis unit 60 synthesizes a digital tone color waveform signal based on the key data and the touch data. Also, MIDI
The message is converted from the IN terminal through the switch 61 into key data and touch data, which are input to the tone color synthesis unit 60. Therefore, without playing the keyboard 62,
It can be played by a MIDI message from IN.

The tone color synthesis method includes the FM method and the PCM method. In the PCM system, the actual sound is digitally stored and read out from the memory by a command from the keyboard or a MIDI message during reproduction.

The digital signal output from the tone color synthesis section 60 is converted into an analog signal by the D / A converter 63, and passes through the amplifier 64 to generate a music sound from the speaker 65. In addition, the digital signal output from the timbre synthesizer 60 is passed through the switch 61 to output the MIDI signal O
It is also possible to input the data from the UT to the converter, convert it into the isochronous data transmission format of the IEEE-1394 serial bus, and feed it back to the device on the bus.
When feeding back a digital signal, IEEE-1
The format of 394 serial bus transmission is, for example, I
It is also possible to conform to the format of the digital audio interface defined by EC-958.

Further, this MIDI musical instrument has a sampling function. Sampling is the recording of digital data by the user. Here, it is stored in the memory in the tone color synthesis unit 60.

The sampling data output from the timbre synthesizer 60 is input to the converter from the MIDI signal output OUT through the switch 61 as in the digital signal output, and I
It can be converted to an isochronous data transmission format of the EEE-1394 serial bus and transmitted to a device on the bus.

FIG. 23 shows a method of transmitting a system exclusive message in the isochronous transmission mode of the IEEE-1394 serial bus. The data packet has a fixed data amount of 127 bytes, and when transmitted as a MIDI signal, the shortest is 320 μS × 127 = 4.06.
It takes 4 ms. The number of isochronous packets during this period is 4.064 mS / 125 μS = 325.12. I
Since data is transmitted in units of quadlet = 4 bytes on the EEE-1394 serial bus, a dummy packet of 1 byte is added to a data packet of 127 bytes to make 128 bytes (= 32 quadlets). Therefore, one isochronous packet is 1, 2, 4, 8, 16, 3
There are six possible ways to send the two quadlets.

In the method of transmitting 32 quadlets, 324 packets out of about 325 isochronous packets become dummy packets which do not transmit data. When the clock frequency is 100 MHz, the effective packet length is (32 + 5) × 32 ÷ 100 MHz = about 12 μS.

Even in the method of transmitting one quadlet by one isochronous packet, about 9 out of 10 packets become dummy packets. 1 in 1 isochronous packet
The length of an effective packet when transmitting quadlet data is (1 + 5) × 32 ÷ 100 MHz = about 2 μS. The six methods are summarized below.

Quadlet Number Valid Packet Dummy Packet Length of Valid Packet 32 1 325 11.84 μS 16 2 324 6.72 μS 8 4 322 4.16 μS 4 8 318 2.88 μS 2 16 310 2.24 μS 1 32 294 1.92 μS

Transmission of 32 quadlets in one isochronous packet occupies a band of 12 μS out of 125 μS, but since there is little possibility of dumping data from a plurality of digital samplers, MIDI messages of approximately 4 mS are transmitted in isochronous packets. Data packets can be transmitted. The number of quadlets in one isochronous packet may be selected from any of the above six types.

FIG. 24 is a block diagram showing still another example of the bidirectional data transmission system to which the present invention is applied. In this system, the electronic musical instruments 75, 76 and 80 are shown in FIG.
Since the converter shown in is built in, mutual conversion of protocols can be performed internally. Therefore, these electronic musical instruments have a node ID on the IEEE-1394 serial bus and can communicate with the protocol of the IEEE-1394 serial bus. Also, the CD player 73 and the MD recorder 74 are the same as those in FIG. 14, and the IEC958 / IEEE-1
Since it is equipped with a 394 converter, communication can be performed by the protocol of the IEEE-1394 serial bus. And DV
CR70, digital TV 71, DVD player 72,
Since the set top box 77, the personal computer 78, and the hard disk device 79 have a digital interface to the IEEE-1394 serial bus,
Communication is possible using the EEE-1394 serial bus protocol.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

For example, in FIG. 24, a digital audio device such as a CD player is not provided with a digital audio interface, but only a digital interface for an IEEE-1394 serial bus is provided.
The digital audio signal may be processed according to the -1394 protocol.

Similarly, MIDI may not be provided in the electronic musical instrument of FIG. 24, but only a digital interface for the IEEE-1394 serial bus may be provided to process music / instrument signals according to the IEEE-1394 protocol.

In the future, the IEEE-1394 serial bus will become widespread, and digital audio interfaces and MIDI will be used.
If no longer needed, these methods are effective. However,
The protocol used for the digital interface to the IEEE-1394 serial bus is the protocol corresponding to the digital audio interface, in other words, the protocol on the IEEE-1394 serial bus of FIG. Stop at. The same applies to MIDI. The "converting the format of the interface that transmits digital data in one direction to the isochronous transmission format of the interface that transmits digital data in both directions" according to the present invention includes such a form.

The present invention can be applied to, for example, synchronous transmission of linear digital audio signals, synchronous and asynchronous transmission of non-linear digital audio signals, and the like.
Further, the present invention can be applied to bidirectional transmission of control commands together with those signals.

The present invention can also be applied to digital audio data transmission formats other than high-speed interfaces for music and musical instruments and digital audio interfaces, for example.

[0142]

As described in detail above, according to the present invention, the interface format for unidirectional point-to-point or tree-like signal transmission is defined as follows.
By converting to an isochronous transmission format or an asynchronous transmission format of an interface that bidirectionally transmits digital data, the number of input / output terminals of the device can be reduced.

Therefore, in the past, the signal cables were connected in a tree shape to devices such as TV and audio amplifiers and receivers that are central to the system, including analog devices, but by applying the present invention, Bidirectional transmission of digital audio signals becomes possible by connecting only one cable. Moreover, in the past, in the case of the MIDI musical instrument, a MIDI box is connected to a parabox for connecting a plurality of musical instruments.
Although the cables are centrally wired, by applying the present invention, bidirectional transmission of performance information and control information of music / instrument signals can be performed only by connecting one cable.

Further, according to the present invention, the transmission format of the control command is converted into the asynchronous transmission format of the interface for bidirectionally transmitting digital data, and the isochronous transmission packet is time-division multiplexed and transmitted. This makes it possible to omit the interface cables and terminals for transmitting control commands from the system equipment.

By applying the present invention, the linear digital audio signal transmission using the digital audio interface and the non-linear digital audio and the music / musical instrument signal are converted in a format common to the bidirectional digital interface. TV
Mutual transmission and control of information signals are facilitated in a system in which a video device such as a computer or a DVCR, a personal computer, and various digital audio devices and an electronic musical instrument are connected to the same bidirectional digital interface.

Furthermore, the unidirectional music / instrument signal transmission format is converted into an asynchronous transmission mode of an interface for transmitting bidirectional digital data, and A
By matching the transmission format of the control command for the V device, it becomes easy for the music / instrument and the AV device to mutually communicate the signal and the control command.

In addition, a unidirectional music / instrument signal transmission format and its accelerated format are converted into an isochronous transmission format of an interface for transmitting bidirectional digital data, so that a large amount of data can be transmitted in a short time. Can be transmitted.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first mode of a bidirectional data transmission system to which the present invention has been applied.

FIG. 2 is a diagram showing a basic configuration of a converter shown in FIG.

3 is a diagram showing an example of a data transmission mode of isochronous and asynchronous in the system of FIG.

FIG. 4 is a diagram showing a format of an IEEE-1394 isochronous packet.

FIG. 5 is a diagram showing general specifications of a CIP header in an IEEE-1394 isochronous data transmission mode.

FIG. 6 is a diagram showing an example of format designation of digital audio, music / instrument, and the like.

FIG. 7 is a diagram showing an example of a CIP header according to the present invention.

FIG. 8 is a diagram showing an example of SYT in the present invention.

FIG. 9 is a diagram showing an example of designation of a data format in the present invention.

FIG. 10 is a diagram showing an example of conversion when the sampling frequency of the digital audio interface is 44.1 kHz in the present invention.

FIG. 11 is a diagram showing an example of conversion in the present invention when the sampling frequency of the digital audio interface is 48 kHz.

FIG. 12 is a diagram showing an example of conversion when the sampling frequency of the digital audio interface is 32 kHz in the present invention.

FIG. 13 is a diagram showing an example of an isopacket according to the present invention.

FIG. 14 is a diagram showing a second mode of a bidirectional data transmission system to which the present invention has been applied.

15 is a diagram showing the basic configuration of the converter in FIG.

FIG. 16 is a write request for d in the asynchronous data transmission mode of IEEE-1394.
It is a figure which shows an ata block packet.

FIG. 17: Write request for d in the asynchronous data transmission mode of IEEE-1394
It is a figure which shows an ata quadlet packet.

FIG. 18 is a diagram showing a structure of an FCP frame in an asynchronous data transmission mode of an IEEE-1394 serial bus.

FIG. 19 is a diagram showing an example of a data structure for transmitting a MIDI message in an FCP frame when CTS = 0000 ₂ .

FIG. 20 is a diagram showing another example of an FCP frame.

FIG. 21 is an example of bit allocation of DATAF in a format relating to music / instrument with FMT = 000100 _{2 in} the CIP header.

FIG. 22: MI for isochronous data transmission
It is a block diagram of a DI musical instrument.

[Fig. 23] IE of system exclusive message
It is a figure which shows the method of transmitting by the isochronous transmission mode of EE-1394 serial bus.

FIG. 24 is a block diagram showing still another example of a bidirectional data transmission system to which the present invention has been applied.

FIG. 25 is a diagram showing an example of transmission of a digital audio signal using a digital audio interface.

FIG. 26 is a diagram showing a structure of a subframe of a digital audio interface.

FIG. 27 is a diagram showing the structure of subframes, frames, and blocks of a digital audio interface.

FIG. 28 is a diagram showing an example of a system in which a large number of audio devices and video devices are centrally connected to a digital amplifier.

FIG. 29 is a diagram showing an example of connection of electronic musical instruments according to the MIDI standard.

FIG. 30 is a diagram showing an example in which MIDI musical instruments are connected in a cascade manner.

FIG. 31 is a diagram showing an example in which MIDI musical instruments are connected in a tree shape via a THRU box.

FIG. 32 is a diagram showing transmission of a shake hand in a MIDI musical instrument.

FIG. 33 is a diagram showing a format of a MIDI message.

FIG. 34 is a diagram showing types of MIDI messages.

FIG. 35 is a diagram showing a method of designating a MIDI channel.

FIG. 36 is a diagram showing an example of how to use a MIDI channel.

FIG. 37 is a diagram showing a data format of three MIDI messages of a sample dump request, a dump header, and a data packet.

[Explanation of symbols]

1, 4, 35, 73 ... CD player, 2 ... DAT recorder, 3, 36, 74 ... MD recorder, 5, 70 ...
DVCR, 6, 7, 20 ... IEC958 / IEEE-1
394 converter, 31-34 ... MIDI musical instrument, 38-4
0,50 ... MIDI / IEEE-1394 converter, 4
1, 78 ... Personal computer, 42, 79 ... Hard disk device, 71 ... Desidel TV, 72 ... DVD player, 7
7 ... Set top box, 75, 76, 80 ... Electronic musical instrument

Claims (10)

[Claims] 1. A data communication method, characterized in that a format of an interface for transmitting digital data in one direction is converted into an isochronous transmission format or an asynchronous transmission format of an interface for transmitting digital data in both directions. 2. The data communication method according to claim 1, wherein the digital data is a music / instrument signal. 3. The data communication method according to claim 2, wherein the music / instrument signal is transmitted in an asynchronous transmission format for audio / video equipment. 4. An asynchronous transmission format of an interface for bidirectionally transmitting digital data of a control signal transmitted by an interface for unidirectionally transmitting digital data or another interface connected to a device including the interface. The data communication method according to claim 1, wherein the data communication method is performed by converting the data into digital data in an isochronous transmission format and transmitting the digital data in an isochronous transmission format. 5. The data communication method according to claim 4, wherein the digital data is a digital audio signal. 6. The data communication method according to claim 1, wherein a header of an isochronous transmission format packet is common to a plurality of types of digital data. 7. The header is provided with an identification code for identifying a mode for transmitting a plurality of types of digital data in synchronization with an isochronous transmission cycle and a mode for transmitting asynchronously. The data communication method described in. 8. The data communication method according to claim 1, wherein an identification code for identifying the type of digital data is added to the data in the isochronous transmission format. 9. The synchronous signal of an interface for transmitting digital data in one direction is bit-compressed and taken into a header for isochronous transmission of an interface for transmitting digital data in two directions. Described data communication method. 10. The size of a data block in an isochronous transmission format of an interface for bidirectionally transmitting digital data is set to be the same regardless of the sampling frequency of the interface for unidirectionally transmitting digital data. The data communication method according to claim 1.