JP4095278B2 - Communication device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention also relates MPEG, HD, the communication equipment that transmits video data, such as SD and SDL format.
[0002]
[Prior art]
In a network using an IEEE 1394 serial bus, SD format, SDL format, MPEG2 format, etc. are used as compression formats of moving image data transmitted over the network. Of these, the SD and SDL formats are used as compression formats for digital video. SDL has a higher compression rate than SD, so when a long time is taken with a digital video camera, recording is performed in the SDL format.
[0003]
However, since the image quality of the SDL is lower than that of the SD, the usage method of switching to the SDL after the remaining amount of the recording tape is reduced is also performed, so two formats with different compression ratios are mixed in a single recording tape. It will be.
[0004]
[Problems to be solved by the invention]
Since the switching position between the SD and SDL formats in the tape to be reproduced is not clear, it is desirable to secure a bandwidth for SD beforehand when the data is transmitted over the IEEE 1394 network. If only SDL bandwidth is secured for SDL data, there is a shortage of devices that transmit data when the data changes from SDL to SD with respect to the isochronous resource manager. Bandwidth must be reserved, and data may be missed at that time. In addition, it is not always possible to secure a bandwidth, and therefore it is desirable to secure a wide bandwidth in advance. However, in this case, since a band larger than its own transmission data is secured, there is a possibility that the transmission request of other devices may be hindered.
[0005]
Accordingly, the present invention allows the opening of the band not used, shall be the purpose of enabling efficient use of the network.
[0006]
[Means for Solving the Problems]
Communication device according to the present invention is, for example, a communication device for transmitting said first isochronous data using the second band wider than the first band necessary for transmission of the first isochronous data, the Receiving means for receiving a bandwidth release request from another device that cannot transmit the second isochronous data using the second bandwidth because the second bandwidth cannot be acquired; and the bandwidth release request receive, and the case where the second opening is possible bandwidth of the bandwidth acquisition for acquiring the first band to transmit said first isochronous data using the pre-Symbol first band have a means, the case where it can not be acquired the first zone, so as not to release the pre-Symbol second band, if it has been possible to acquire the first band, the First isoc Without changing the compression format of eggplant data, using the first band to transmit said first isochronous data, and wherein the Turkey to open the second band.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples with reference to the drawings.
[0014]
[Example 1]
FIG. 1 shows a network in which a plurality of devices are connected by an IEEE 1394 serial bus. This network is composed of a device A101, a device B102, a device C103, a device D104, and a device E105. Here, the device A101 has data in the SDL format on the channel Ch1, and the device B102 has the SD format on the channel Ch2. Sending over the network. In this network, the device E105 is an isochronous resource manager and manages the bandwidth of the network. 2 and 3 show the state of the bandwidth on the network. In FIG. 2, reference numeral 201 denotes an isochronous cycle start packet, which means the start of the cycle time when isochronous data is transmitted. 202 is an isochronous packet transmitted by the device A101 and 203 is transmitted by the device B102. Reference numeral 206 denotes a remaining bandwidth for an asynchronous transaction, and reference numeral 207 denotes an isochronous cycle time. Here, the devices A and B reserve the bandwidths on the network for isochronous data transmission with 204 and 205 as much as necessary for SD data transmission, respectively.
[0015]
In such a network, the device C103 is when there is a request to transmit data 301 in the SD format, equipment C103 because the rest is not a frequency band 30 2's SDL amount of network bandwidth is bandwidth is opened by another device Have to wait until. Therefore, the device C103 transmits a bandwidth release request to each device that is transmitting isochronous data on the network. The release request is made by the Function Control Protocol (FCP). The device C103 first writes a release request command to the offset address 0xFFFFF0000B00 of the device A101. FIG. 4 is a diagram showing the format of FCP, and the command is determined by a combination of opcode and operand of this format. In Subunit Type is 0 x 1F showing the Unit, the a command type ctype is 0x00 indicating a "control" is specified. For opcode and operand, a value not already used as a standard is defined as a bandwidth release request command and used.
[0016]
The device A101 that has received this command first checks whether or not it can respond to the bandwidth release request. Before the device A 101 starts data transmission, the user sets whether or not the device A 101 releases the band 204. When the device A101 is in a state where the band can be released, a response is returned by Interim in response to the release request from the device C103. If the bandwidth cannot be released, a response is returned as “Rejected”. When the release of the band 204 is completed, the device A101 returns Accept to the device C103 as a response. In the case of returning Interim, the device A 101 releases the band 204 according to the flow shown in FIG. 5 in order to release the band.
[0017]
When the bandwidth release request is received in step 501, it is confirmed in step 502 whether the bandwidth 204 can be released. If it is set in step 503 to step 504 that the band can be released, and an extra band is secured, the Interim is returned to the band opening request source by FCP, and is currently transmitted by itself. A band corresponding to the SDL for transmitting the data of the existing SDL format on another channel is secured. If band securing fails, a Reject is transmitted to the band release request source by FCP (step 509). If the bandwidth is successfully secured, SDL data is transmitted in the secured bandwidth (step 505). In step 506, the data transmitted in the SD band 204 is stopped, and in step 507, the SD band 204 is released. In step 508, the device 204 is notified that the band 204 has been released by returning an Accept.
[0018]
FIG. 6 visually shows a state where the band of the device A101 is released. Reference numeral 601 denotes an SDL format packet currently transmitted by the device A101. In response to the release request, the device A101 secures a band for SDL transmission as indicated by 603, and transmits the same data as the data 601 of the channel Ch1 that has already been transmitted in the band 603 on another channel Ch3. After that, by releasing the band 604 reserved for SD, it is possible to respond to requests from other devices on the network. Further, on the data receiving side, the data 601 on the channel Ch1 and the data 602 on the other channel Ch3 are received at the same time, so that data can be prevented from being missed.
[0019]
【The invention's effect】
According to the present invention, it is possible to release a band that is not being used, and it is possible to efficiently use the network.
[Brief description of the drawings]
FIG. 1 is a diagram showing an IEEE 1394 serial bus network composed of a plurality of devices. FIG. 2 is a diagram showing a bandwidth state on the IEEE 1394 serial bus. FIG. 3 is a diagram showing a bandwidth state on the IEEE 1394 serial bus. FIG. 4 is a diagram showing the format of Function Control Protocol. FIG. 5 is a flowchart showing processing at the time of releasing the band. FIG. 6 is a diagram showing visually the state of the band at the time of releasing the band.
101 Device A
102 Device B
103 Device C
104 Equipment D
105 Equipment E
201 Isochronous cycle start packet 202 Isochronous packet 203 transmitted by device A101 Isochronous packet 204 transmitted by device B102 Band (device A101)
205 band (device B102)
206 Remaining bandwidth for asynchronous transaction 207 Isochronous cycle time 301 Data in SD format of device C103 302 Remaining network bandwidth (for SDL)
601 SDL format packet 602 transmitted by the device A101 Channel Ch3 data 603 Band 604 Band Ch1 Channel Ch2 Channel Ch3 Channel (another channel)

Claims (5)

A communication device for transmitting the first isochronous data using a second band wider than the first band required for transmitting the first isochronous data,
Receiving means for receiving a bandwidth release request from another device that cannot transmit the second isochronous data using the second band because the second band cannot be acquired;
Receiving the bandwidth release request, and the case where the second opening is possible bandwidth of the first band to transmit said first isochronous data using the pre-Symbol first band possess a bandwidth acquiring means for acquiring,
Wherein if it can not be acquired the first zone, so as not to release the pre-Symbol second band,
The case has been successfully obtained a first band, without changing the compression format of said first isochronous data, and transmitting the first isochronous data using the first band, said first communication device comprising a Turkey to open the band 2. Wherein when opening the second band, the communication apparatus according to claim 1 that opening the second band, characterized by the Turkey be notified to the other equipment. Receiving the bandwidth release request, and the case where the second is not possible opening of the band, communication according to claim 1 or 2, characterized in that to avoid getting the previous SL first band apparatus. The compression format of the first and second isochronous data communication apparatus according to any one of claims 1 to 3, characterized in that the compression format of the video data. In addition to transmitting the first isochronous data using the first band, after acquiring the first band and before releasing the second band, the second band communication apparatus according to any one of 4 from claim 1, wherein the benzalkonium to send the first isochronous data using.

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