JP2000049830A - Device, system and method for transmitting digital signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To send available bit rate(ABR) data while using an empty band by detecting use band information from a transmission line for transmitting data while using a packet, calculating a usable band amount from the reference value of a band amount and the use band information and sending packets of less than the determined data amount. SOLUTION: At ABR transmission equipment 121, a packet monitoring part 123 monitors an isochronous packet transmitted by RT-VBR transmission equipment 101 and the use band amount of the RT-VBR transmission equipment 101 is detected. A second control part 125 of the ABR transmission equipment 121 calculates the data amount of packets to be sent out. A value obtd. by subtracting the band amount detected by the packet monitoring part 123 from the total band amount is defined as the usable band amount and data amount are made less than a value obtd. by dividing this usable band amount with a cycle time. According to the instruction of the second control part 125, an ABR data sending part 124 sends out packets through a second IEEE 1394 interface 122.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal transmitting apparatus and a transmitting method for transmitting digital signals including video and audio via a bus.

[0002]

2. Description of the Related Art In recent years, AV buses for transmitting digitized video, audio data, or other digital data such as computer data via a common bus have been actively studied. As this AV bus, for example, IEEE
E (Institute of Electric)
and Electronics Engineer
s) 1394 High Performance S
A bus specified by the serial bus (hereinafter, IEEE 1394) standard is used.

FIG. 4 shows an example of the configuration of an AV bus based on IEEE1394. In FIG. 4, reference numeral 401 denotes a first video / audio (hereinafter, AV) transmitting device, 402 denotes a first AV receiving device,
403 is a data transmission device, 404 is a second AV transmission device, 405 is a data reception device, 406 is a second AV reception device, 411 is a first control unit, 412 is a second control unit,
413 is a third control unit, 414 is a fourth control unit, 415
Represents the fifth control unit, 416 represents the sixth control unit, and 421 represents the first control unit.
422 is a first AV data receiver, 423 is a data transmitter, 424 is a second AV data transmitter, 425 is a data receiver, 426 is a second AV data receiver, 431 is A first IEEE 1394 interface, 432 is a second IEEE 1394 interface, 433 is a third IEEE 1394 interface, 434 is a fourth IEEE 1394 interface, 435 is a fifth IEEE 1394 interface, and 436 is a sixth IEEE 1394 interface.

[0004] As shown in FIG.
AV, data signals, and control signals are transmitted via a common IEEE 1394 serial bus via a 394 interface. Each data is transmitted in a packet format, and uses a bus in a time division multiplex format.

[0005] There are two types of packets, isochronous packets and asynchronous packets. The isochronous packet is mainly used for transmitting AV data, and the asynchronous packet is mainly used for transmitting control data and the like. Hereinafter, data transmission in IEEE 1394 will be described with reference to the drawings.

FIG. 5 is a diagram showing an IEEE 1394 data transmission format. In FIG. 5, 501 is a cycle start packet of cycle m, and 502 is cycle m
, 503 is an isochronous packet of device K in cycle m, 504 is an isochronous packet of device L in cycle m, 505
Are the asynchronous packets of device A in cycle m, 5
06 is the first acknowledgment packet, 507 is the asynchronous packet of device B in cycle m, 508 is the second acknowledgment packet, 511 is the cycle start packet of cycle m + 1, and 512 is the isochronous packet of device J in cycle m + 1. It is. Numeral 521 indicates the internal configuration of the isochronous packet. The transmission data is stored in the datafield part. Also data
The _length field stores information on the number of data bytes in the transmission data packet. The other fields are not directly related to the content of the present invention, and thus the description is omitted.

Hereinafter, description will be made with reference to FIG. IEEE13
There is one device serving as a cycle master node on the 94 bus. The cycle master node has a fixed time interval (12
(5 microseconds) to transmit a cycle start packet. Immediately after the detection of the cycle start packet 501, the isochronous data transmission device waits for a certain period of time (isochronous gap), and then arbitrates with another isochronous data transmission device to acquire the right to use the bus. The device that has acquired the right to use (device J in FIG. 5) sends out the packet 502.

[0008] The device that failed to acquire the right to use arbitrates again at intervals of the isochronous gap after the transmission of the packet 502 from the device J, and the device (device K in FIG. 5) that has acquired the right to use the packet 503
Is sent. This operation is repeated, and each isochronous transmission device transmits data.

After each isochronous transmission device on the bus transmits a packet, each device transmits an asynchronous packet. A device that transmits an asynchronous packet detects a gap (subaction gap) that is longer than the isochronous gap, recognizes that the transmission cycle of the isochronous packet has ended, and performs arbitration for transmitting the asynchronous packet. The device that has acquired the right to use (device A in FIG. 5) transmits the asynchronous packet 505, and completes the transmission by receiving the reception confirmation 506 from the receiving device. A device that has obtained the right to use by performing the next arbitration through the subaction gap after the transmission is completed (device B in FIG. 5)
Sends out the asynchronous packet 507.

The acquisition of the bus use right and the packet transmission are performed for each cycle. That is, in the case of FIG. 5, if 125 microseconds of the cycle m is completed at the time when the asynchronous transmission of the device B is completed, the cycle master node transmits the cycle start packet 511 and starts the next cycle (cycle m + 1).

Each isochronous transmission device is guaranteed to transmit an isochronous packet once per cycle. With this configuration, the amount of bandwidth used for isochronous communication is guaranteed on the IEEE 1394 bus.

There is always one device including an isochronous resource manager on a bus for performing isochronous communication. Isochronous resource manager is BAN
DWIDTH_AVAILABLE register (hereinafter B_
A register) manages the amount of bandwidth used by each isochronous transmission device. That is, the device that starts the isochronous transmission refers to the B_A register, subtracts the used bandwidth amount from the register value, and performs rewriting. When transmission is completed, addition and rewriting are performed. If the required bandwidth cannot be secured, the device cannot perform transmission.

Next, consider a case in which data whose usage bandwidth changes with time (hereinafter referred to as variable rate data) is transmitted isochronously.

In variable-rate data transmission, required data arrives at a designated time at a receiving side, that is, data (Real Time-Variable) for which isochronism needs to be guaranteed.
leBit Rate (hereinafter, RT-VBR) transmission and data that does not require isochronous guarantee (Available Bi)
t Rate: Hereinafter, there is ABR) transmission. RT-VBR
DVD (Digital Versatil)
e Disc) -Video data, examples of ABR include computer download data.

When isochronous transmission of RT-VBR data is performed, in order to guarantee isochronousness, the band used must be R
It is necessary to ensure the maximum bandwidth that occurs in T-VBR transmission. For example, in the case of DVD-Video, a band of 10.08 Mbps or more, which is the maximum band amount, is secured.

In the case of isochronous transmission of ABR data, it is not necessary to secure the maximum bandwidth unlike the case of RT-VBR. That is, even if data cannot be transmitted at a certain timing, no problem occurs if the data is transmitted at the next timing. However, if the allocated bandwidth is small, the time required for data transmission increases.

Consider a case where an RT-VBR transmission device and an ABR transmission device are connected on an IEEE 1394 bus. FIG.
FIG. 2 is a diagram illustrating a transmission system in which an RT-VBR transmission device and an ABR transmission device are connected. However, the receiving device is omitted. 6, reference numeral 601 denotes an RT-VBR transmission device, 602 denotes a first IEEE 1394 interface, 603 denotes a first control unit, 604 denotes an RT-VBR data transmission unit, 604 denotes an ABR transmission device, and 622 denotes a second I.
An IEEE 1394 interface, 623 a second control unit, 624 an ABR data transmission unit, 641 a device including an isochronous resource manager, 642 a third I
The IEEE 1394 interface 643 is a third control unit.

Prior to the start of data transmission, the RT-VBR transmission device 601 and the ABR transmission device 621 start transmitting data after subtracting the used bandwidth from the B_A register value of the isochronous resource manager.

Consider a case where the total bandwidth is 20 Mbps and the RT-VBR transmitter transmits 1 Mbps to 10 Mbps, and the ABR transmitter transmits 2 Mbps to 10 Mbps.

FIG. 7 shows an example of the change over time of the amount of bandwidth used by both transmitters. In the example of FIG. 7, the RT-VBR usage band is 10 Mbps in the time intervals cycle 1 to cycle 4,
3 Mbps, 8 Mbps, 1 Mbps, ABR bandwidth used is 2 Mbps, 9 Mbps, 5 Mbps, 10 Mbps
And change.

When securing the maximum bandwidth for both the RT-VBR and the ABR, the secured bandwidth amount is a total of 20 Mbps. On the other hand, the actually used bandwidth amounts are 12 Mbps, 12 Mbps, 13 Mbps, 11 Mbps as shown in FIG.
bps.

In this case, the transmission of RT-VBR and ABR is guaranteed, but 20 Mbps is always ensured even though the actually used bandwidth is around 12 Mbps, and other isochronous transmission is performed during this time. It is not possible.

Since ABR data does not require isochronism, it is not always necessary to transmit data according to the amount of data that occurs. FIG. 8 shows a case where the assigned bandwidth is 2 Mbps for ABR transmission. In this case, the total bandwidth to be reserved is 1
2 Mbps, and the remaining 8 Mbps can be used for other isochronous transmissions. In this case, since the transmission band of the ABR is limited, the time required for the ABR data transmission increases.

[0024]

In the above configuration, AB
When a large band is allocated to the R data, the band allocated to other isochronous data transmission is reduced, and when a small band is allocated, the time required for ABR data transmission increases.

[0025]

In order to solve the above-mentioned problems, a digital signal transmitting apparatus according to the present invention comprises: a digital interface connected to a transmission line for transmitting data using packets; A packet monitoring unit for detecting a bandwidth amount, a control unit for holding a reference value of a bandwidth amount, calculating an available bandwidth amount from the reference value and the used bandwidth information, and determining a data amount of a packet to be transmitted; and the control unit. Based on the instruction, the packet transmission means for transmitting a packet having the data amount or less is monitored to monitor the amount of bandwidth used by the RT-VBR transmission device, and the RT-VBR transmission device ABR data is transmitted using a band that is not used.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a digital signal transmission system according to the present embodiment. 101 is an RT-VBR transmission device, 102 is a first IEEE 1394 interface, 103 is a first control unit, and 104 is an RT-VBR data transmission unit. , 121 is an ABR transmission device, and 122 is a second I
An IEEE 1394 interface, 123 is a packet monitoring unit, 124 is an ABR data transmission unit, 125 is a second control unit, 141 is a device including an isochronous resource manager, 142 is a third IEEE 1394 interface, and 143 is a third control unit. .

Prior to the start of data transmission, the ABR transmitting device 121 negotiates with the RT-VBR transmitting device 101 and
The BR device determines the used bandwidth amount requested from the isochronous resource manager. The negotiation is performed, for example, by using an asynchronous packet with the RT-VBR transmission apparatus 101 and the A-
The communication is performed by the BR transmission device 121.

In this embodiment, as an example, the RT-VBR
The bandwidth used by the transmitting device is 1 Mbps to 10 Mbps
s, the band used by the ABR transmission device is 2 Mbps to 1
The case of 0 Mbps is shown. In this case, the RT-VBR transmission device writes 10 Mbps and the ABR transmission device uses 2 Mbps as the used bandwidth amount, and writes the B_A register. At this time AB
The second control unit 125 of the R transmitting apparatus 121 stores 12 Mbps as the total bandwidth that can be used by both apparatuses.

After writing, both transmitting devices start transmitting data. At this time, the RT-VBR transmission device transmits data in the same manner as in the related art.

In the ABR transmission apparatus 121, the packet monitoring unit 123 monitors the isochronous packet transmitted by the RT-VBR transmission apparatus 101, and outputs the RT-VBR.
Detect the used bandwidth of the transmitting device.

As a method of obtaining the bandwidth, for example, data_len written in the isochronous packet is used.
Reference the gth field. data_length
Information about the number of data bytes in the packet is written in the field. The number of data bytes obtained by reference is divided by 125 microseconds, which is the cycle time, to obtain the bandwidth used by the RT-VBR transmission device in the cycle. You can get the quantity.

Based on the bandwidth, the second control unit 125
Calculates the data amount of the packet to be transmitted. As an example, a value obtained by subtracting the bandwidth amount detected by the packet monitoring unit 123 from the total bandwidth amount is defined as an available bandwidth amount, and a data amount equal to or less than a value obtained by dividing the available bandwidth amount by a cycle time of 125 microseconds. I do.

In accordance with an instruction from the second control unit 125, ABR
The data transmitting unit 124 transmits the packet via the second IEEE 1394 interface 122. On this occasion,
The packet of the ABR transmitter 121 is transmitted during the cycle by RT
-Sent after the packet of the VBR transmitting apparatus 101.

FIG. 2 shows an example of packet transmission in the present embodiment. In FIG. 2, 201, 211, 221,
231 is a cycle start packet of each cycle, 202, 212, 222, and 232 are isochronous packets used by the RT-VBR transmitter in each cycle, and 203, 213, 223, and 233 are ABR transmitters in each cycle. This is an isochronous packet to be used. The number below each isochronous packet is obtained by converting the number of data bytes of the packet into the used bandwidth amount in each cycle. As an example, one cycle is 125 microseconds and the number of data bytes of the packet is 1.
If it is 6 bytes, the used bandwidth is 16 × 8 / 0.000
125 = 1.024 Mbps. In the example of FIG. 2, each value is an integer for simplicity. Asynchronous transmission packets are omitted because they do not directly relate to the contents of the present invention.

In cycle 1, the RT-VBR transmission device 10
1 uses 10 Mbps. The isochronous packet monitoring unit 123 monitors this packet and notifies the second control unit 125 of the used bandwidth information of the RT-VBR transmission device 101. The second control unit 125 compares this information with the total bandwidth amount of 12 Mbps, and calculates that the available bandwidth amount in this cycle is 2 Mbps. The ABR data transmitting section 124 receives this and transmits 2 Mbps data as an isochronous packet 203.

In cycle 2, the RT-VBR transmission device 10
1 uses 3 Mbps. The isochronous packet monitoring unit 123 monitors this packet and notifies the second control unit 125 of the used bandwidth information of the RT-VBR transmission device 101. The second control unit 125 compares this information with the total bandwidth amount of 12 Mbps, and calculates that the available bandwidth amount in this cycle is 9 Mbps. In response to this, the ABR data transmission unit 124 transmits data of 9 Mbps as an isochronous packet 213.

In cycle 3, the RT-VBR transmission device 10
1 uses 8 Mbps. The isochronous packet monitoring unit 123 monitors this packet and notifies the second control unit 125 of the used bandwidth information of the RT-VBR transmission device 101. The second control unit 125 compares this information with the total bandwidth amount of 12 Mbps, and calculates that the available bandwidth amount in this cycle is 4 Mbps. The ABR data transmission unit 124 receives this and transmits data of 4 Mbps as an isochronous packet 223.

In cycle 4, the RT-VBR transmission device 10
1 uses 1 Mbps. The isochronous packet monitoring unit 123 monitors this packet and notifies the second control unit 125 of the used bandwidth information of the RT-VBR transmission device 101. The second control unit 125 compares this information with the total bandwidth of 12 Mbps, and calculates that the bandwidth available in this cycle is 11 Mbps. However, since the maximum amount that the ABR transmission device can transmit is 10 Mbps,
In this case, the BR data transmitting unit 124 transmits data of 10 Mbps as the isochronous packet 233.

When the data to be transmitted is not ready, the ABR transmitting device 121 transmits as a packet an amount smaller than the amount of bandwidth that can be used in a cycle.

FIG. 3 shows the change over time in the amount of bandwidth used by both transmitting apparatuses in this embodiment. According to this embodiment, it is shown that ABR data transmission can be performed while effectively using the allocated band.

As described above, according to the present embodiment,
When the bandwidth required by the RT-VBR transmission device is small, the amount of bandwidth used by the ABR transmission device can be increased, and the bandwidth can be used effectively.

The present invention is not limited to the above embodiment, but can be applied to other devices or systems. Also, the numerical values used in the above embodiment are examples, and the present invention is not limited to these.

In this embodiment, the RT-VBR
Although the case where the number of the transmission device and the ABR transmission device is one has been described, the same can be realized when there are two or more devices.

In the present embodiment, prior to the start of data transmission, the ABR transmitting apparatus and the RT-VBR transmitting apparatus negotiate using an asynchronous packet. However, another method, for example, using an isochronous packet or using another signal. It may be performed by a line or set in advance.

Further, in the present embodiment, 2 Mbps, which is the minimum used band, is requested to the isochronous resource manager as the used band of the ABR transmission. However, the same applies if an arbitrary value is requested.

In this embodiment, the ABR transmitting apparatus has transmitted all data that can be transmitted, but it is not always necessary to transmit all data. For example, a mode in which the control unit holds the target average data rate and adjusts the transmission data amount so that the data rate approaches the target average data rate can be realized.

Further, in the present embodiment, each calculation is converted into the amount of bandwidth. However, the same applies when the calculation is performed by converting the amount of data into one cycle.

In this embodiment, the amount of packet data is obtained by referring to the data_length field. However, the amount of packet data may be measured by a counter, and can be realized by any method capable of detecting the amount of data.

Also, in this embodiment, the ABR transmitting apparatus has negotiated with the RT-VBR transmitting apparatus and determined the amount of bandwidth to be used. However, other apparatuses can perform the negotiation and notify the ABR transmitting apparatus of the total bandwidth. The same applies if another device writes to the B_A register.

In this embodiment, the data amount of the packet used by the RT-VBR transmission device is extracted to determine the packet data amount of the ABR transmission device.
-The VBR transmission device transmits the amount of packet data or the amount of bandwidth used in the same cycle, for example, using isochronous packets, and the packet monitoring unit determines the amount of ABR packet data in the cycle based on the detected amount of data or the amount of bandwidth used. The same can be realized by using a shape.

In this embodiment, the amount of packet data used by the RT-VBR transmission apparatus is extracted to determine the amount of packet data of the ABR transmission apparatus.
-The VBR transmission device transmits the amount of packet data or the amount of bandwidth used in the next cycle, and the packet monitoring unit uses the detected amount of data or the amount of bandwidth to use in the AB in the next cycle.
The same can be realized by using a form that determines the amount of R packet data. At this time, either the asynchronous packet or the isochronous packet may be used for transmitting the packet data amount or the used bandwidth amount.

In the present embodiment, the RT-VBR transmitting apparatus transmits a packet in each cycle. If there is no data to be transmitted, an empty packet or a dummy packet is transmitted. , RT-VB
The ABR transmitting apparatus can transmit a packet even in a cycle in which the R transmitting apparatus does not transmit data.

[0053]

As described above, the digital signal transmitting apparatus according to the present invention comprises a digital interface connected to a transmission line for transmitting data using a packet, and a packet monitoring means for detecting used band information from the transmission line. A control unit that holds a reference value of a bandwidth amount, calculates an available bandwidth amount from the reference value and the used bandwidth information, and determines a data amount of a packet to be transmitted. A packet transmitting means for transmitting a packet having a data amount of less than or equal to
The amount of bandwidth used by the T-VBR transmitting apparatus is monitored, and the
By transmitting ABR data using a band not used by the VBR transmitting apparatus in the frame, the RT-VB
An empty band generated when transmitting R data can be used for ABR data transmission, and the band can be used effectively.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a digital signal transmission / reception system according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of packet transmission according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a change over time in a used bandwidth amount according to the first embodiment of the present invention;

FIG. 4 is a diagram showing a configuration example of an AV bus based on IEEE1394.

FIG. 5 is a diagram showing an IEEE 1394 data transmission format;

FIG. 6 is a diagram showing a transmission system in which an RT-VBR transmission device and an ABR transmission device are connected.

FIG. 7 is a diagram showing a time change of the used bandwidth when the bandwidth allocated to the ABR is set to 10 Mbps;

FIG. 8 is a diagram showing a time change of the used bandwidth when the bandwidth allocated to the ABR is 2 Mbps.

[Explanation of symbols]

 101,601 RT-VBR transmission device 121,621 ABR transmission device 123 Packet monitoring unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K028 AA11 KK32 LL15 LL22 LL42 RR03 5K030 GA03 HA08 HB01 HB02 HB28 JA01 JA07 KX18 LC01 MB09 MC07 5K032 AA01 CC05 CD01 DB24

Claims (29)

[Claims] 1. A digital interface connected to a transmission path for transmitting data using a packet, a packet monitoring means for detecting used bandwidth information from the transmission path, and a reference value for a bandwidth amount, A control unit that calculates an available bandwidth amount from the used bandwidth information and determines a data amount of a packet to be transmitted, and a packet transmission unit that transmits a packet having the data amount or less based on an instruction of the control unit. Digital signal transmission device characterized by the above-mentioned. 2. The used bandwidth information is the amount of transmission packet data of one or more other devices. The control means calculates the currently used bandwidth of the other device from the transmission packet data amount, and calculates the used bandwidth from a reference value. 2. The digital signal transmitting apparatus according to claim 1, wherein the reduced bandwidth is used as a usable bandwidth. 3. A transmission path for transmitting a cycle start packet in a predetermined cycle, wherein the packet transmission means transmits the packet in a cycle in which the used bandwidth information is detected.
The digital signal transmitting device according to any one of the above. 4. The used bandwidth information is the amount of transmission packet data continuously transmitted by the other device, and the control means calculates the used bandwidth amount continuously used by the other device from the transmission packet data amount, and calculates the used bandwidth from the reference value. 2. The bandwidth amount obtained by reducing the bandwidth amount is used as the usable bandwidth amount.
A digital signal transmitting device according to claim 1. 5. A transmission line for transmitting a cycle start packet in a predetermined cycle, wherein the packet transmitting means transmits the packet in the next cycle after detecting the used bandwidth information. 5. The digital signal transmitting device according to any one of 4. 6. A transmission path for transmitting data using a packet, comprising at least one first digital signal transmission device and at least one second digital signal transmission device, wherein the first digital signal transmission device transmits data using packets. A first digital interface connected to the first digital interface, and first packet transmitting means for transmitting used bandwidth information including the amount of bandwidth used by the device as a packet different from the transmission packet, and transmitting the second digital signal. A second digital interface connected to the transmission line; a packet monitoring means for detecting the used band information from the transmission line; a reference value for a bandwidth amount, and a use amount based on the reference value and the used band information. Control means for calculating an available bandwidth amount and determining an amount of packet data to be transmitted next; and a second means for transmitting packets equal to or less than the packet data amount. Digital signal transmission system characterized in that it comprises a socket sending means. 7. The control means calculates a used bandwidth of the first digital signal transmitting apparatus from the used bandwidth information, and sets a bandwidth obtained by subtracting the used bandwidth from a reference value as an available bandwidth. Digital signal transmission system. 8. A transmission path in which a cycle start packet is transmitted in a predetermined cycle. The first digital signal transmitting apparatus uses the amount of data of the transmission packet in the cycle as bandwidth information to be used and transmits the transmission packet in the cycle. The transmission according to any one of claims 6 and 7, wherein the transmission is performed within a previous cycle, and the second digital signal transmission apparatus transmits the packet within a cycle following the detection of the used bandwidth information. Digital signal transmission system. 9. A transmission path in which a cycle start packet is transmitted in a predetermined cycle, wherein the first digital signal transmitting apparatus uses the amount of transmission packet data in the cycle as bandwidth information to be used and transmits the transmission packet. 8. The digital signal transmission system according to claim 6, wherein the transmission is performed in the same cycle, and the second digital signal transmission apparatus transmits the packet in a cycle in which the used band information is detected. 10. A digital interface connected to a transmission path for transmitting data using a packet, and packet transmitting means for transmitting used bandwidth information including the amount of bandwidth used by the apparatus in a packet different from the transmission packet. A digital signal transmitting device comprising: 11. A transmission path for transmitting a cycle start packet in a predetermined cycle, a transmission packet data amount in the cycle being used bandwidth information, and transmission within a cycle immediately before transmission of the transmission packet. The digital signal transmitting device according to claim 10, wherein: 12. A cycle start packet is connected to a transmission path in which transmission is performed in a predetermined cycle, and the amount of transmission packet data in the cycle is used as bandwidth information, and is transmitted in the same cycle as the transmission packet transmission cycle. The digital signal transmitting device according to claim 10, wherein: 13. The control means negotiates with one or more other devices including one or more first digital signal transmitting devices before starting transmission to determine a minimum used bandwidth, and determines a total used bandwidth of the other devices. 10. The digital signal transmission according to claim 6, wherein the sum of the minimum used bandwidth is set as a reference value and the use of the minimum used bandwidth is reserved for a transmission path. system. 14. The control means negotiates with one or more other devices before starting transmission to determine a minimum used bandwidth, and uses a total value of the used bandwidth of the other devices and the minimum used bandwidth as a reference value. The digital signal transmitting apparatus according to any one of claims 1, 2, 3, 4, and 5, wherein the use of the minimum used bandwidth amount is reserved for a transmission path. 15. The method according to claim 6, wherein the data output from the one or more first digital signal transmission devices is isochronous variable rate data. Digital signal transmission system. 16. The digital signal transmitting apparatus according to claim 10, wherein the output data is isochronous variable rate data. 17. The digital interface according to the IEEE 1 standard.
394, and 394.
5. The digital signal transmission system according to any one of 5. 18. The digital interface according to IEEE 1
394,3,5,11,1.
The digital signal transmission device according to any one of 2, 14, and 16. 19. A digital interface according to the IEEE 1 standard.
394, wherein the used band information is transmitted using isochronous communication.
The digital signal transmission system according to any one of 13, 15, and 17, 20. The digital interface according to IEEE 1
394, wherein the used band information is transmitted using isochronous communication.
The digital signal transmitting device according to any one of 5, 10, 11, 12, 14, 16, and 18. 21. A packet monitoring step for detecting used bandwidth information from a transmission line, holding a reference value of a bandwidth amount, calculating an available bandwidth amount from the reference value and the used bandwidth information, and transmitting data of a packet to be transmitted. A digital signal transmission method, comprising: a control step of determining an amount; and a packet transmitting step of transmitting a packet having the data amount or less. 22. The used bandwidth information is the amount of transmission packet data of one or more other devices. In the control step, the currently used bandwidth of another device is calculated from the amount of transmission packet data, and the used bandwidth is calculated from a reference value. 3. The bandwidth amount obtained by reducing the amount is used as an available bandwidth amount.
2. The digital signal transmission method according to 1. 23. The method according to claim 21, wherein in the packet transmitting step, the used bandwidth information is detected within a cycle of a predetermined time interval, and the packet is transmitted within the same cycle.
2. The digital signal transmission method according to any one of 2. 24. The used bandwidth information is the amount of transmission packet data that is continuously transmitted by one or more other devices. In the control step, the amount of used bandwidth that is continuously used by another device is calculated from the amount of transmission packet data, and is calculated from a reference value. 22. The digital signal transmission method according to claim 21, wherein a band amount obtained by subtracting the used band amount is used as a usable band amount. 25. The method according to claim 21, wherein in the packet transmitting step, the used bandwidth information is detected within a cycle of a predetermined time interval, and the packet is transmitted within the next cycle.
4. The digital signal transmission method according to any one of 4). 26. A digital communication system comprising: a data packet transmitting step of transmitting a data packet; and a used band information transmitting step of transmitting used band information including a band amount used by an apparatus before the transmission packet. Signal transmission method. 27. A method of transmitting used bandwidth information in a cycle immediately before transmitting a transmission packet in a used bandwidth information transmitting step, wherein a transmission packet data amount in a cycle at a constant time interval is used as bandwidth information. 28. The digital signal transmission method according to claim 26, wherein: 28. A method according to claim 28, wherein the amount of transmission packet data in a cycle at a fixed time interval is used as bandwidth information, and the bandwidth information is transmitted in the same cycle in which the transmission packet is transmitted in the bandwidth information transmitting step. Item 29. The digital signal transmission method according to Item 26. 29. In a control step, before starting transmission, negotiation with one or more other devices is performed to determine a minimum used bandwidth, and a sum of the used bandwidth of the other devices and the minimum value of the minimum used bandwidth is used as a reference value. Wherein said minimum bandwidth is reserved for a transmission path.
5. The digital signal transmission method according to any one of 5.