JPH10210102A - Data transfer device and method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To realize highly efficient data transfer. SOLUTION: At least a first and a second having different properties.
Error correction transfer unit 13 that performs error correction data transfer suitable for the first data in a data transfer device that receives the data of the first data and transfers the first and second data to an external device.
And an error-correction-free transfer unit 14 that performs error-correction-free data transfer suitable for the second data, and controls the first and second data to be selectively performed by one of the two transfer units 13 and 14. And a control unit 17 for performing the operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a data transfer device and method, and more particularly to a data transfer device and method suitable for transferring data having different properties.

[0002]

2. Description of the Related Art At present, personal computers (PCs)
SCSI (Smal
l Computer System Interfa
ce), RS-232C (registered trademark), Centronics, and the like. However, the external bus used so far is a bus specialized for each peripheral device connected thereto, and has adopted a specific transfer method.

A conventional example in which peripheral devices are connected using these external buses will be described with reference to FIGS. 6 and 7. FIG. FIG. 6 shows a host 101 such as a PC and an external bus 11.
Reference numeral 3 denotes a peripheral device 102 such as a printer connected to the host 101.

The host 101 has an address signal line 103, a data signal line 104, and a control signal line 105 as a system bus.
adOnly Memory) 106, RAM (Ran
dom Access Memory) 107, overall control unit 108, display control unit 109, storage unit 110, I / O
The control unit 111 and the host external bus control unit 112 are connected. The overall control unit 108 selects each functional block by the address signal line 103, and
4 and the control signal line 105, the operation of each block is controlled, and the overall operation of the host 101 is controlled.

The ROM 106 stores basic program codes such as a method of controlling access between the overall control unit 108 and each functional block. RAM 107 is
An operation module required from the operating system of the entire system, an operation module of an application, data required during operation, a driver of an external peripheral device, and the like stored in the ROM 106 or the storage unit 110 by the overall control unit 108. And a memory for temporarily storing parameters required by each module during operation. The display control unit 109 controls an external display device 130 such as a CRT monitor and a liquid crystal display.

[0006] The storage unit 110 includes an HDD (Hard Di).
SK Drive), a storage device such as a CD-ROM drive, and a control unit thereof, and stores an application execution file and a data file created by the application. The I / O control unit 111 includes:
An input device 140 such as a keyboard and a mouse is connected, and enables a user to input desired control information. The host external bus control unit 112 is connected to the peripheral device 102 via the external bus 113 and
2 to send and receive data.

FIG. 7 is a block diagram showing an example of the configuration of the host external bus control unit 112.

An address signal line 103, a data signal line 104, and a control signal line 105 of the system bus are connected to the control unit 37, and the control unit is controlled by a control procedure sent according to an instruction from the general control unit 108 (see FIG. 6). 37 controls the buffer 31 and the data transfer unit 33. External bus 113
Is transferred from the data signal line 104 to the buffer 31 temporarily. The data transfer unit 33 generates a signal of a procedure described later, transmits and receives data to and from the peripheral device 102 via the transceiver 36, and transmits the result to the control unit 37 or the buffer 31.
Pass to.

The peripheral device external bus control unit 117 of the peripheral device 102 shown in FIG. 6 has the same configuration as the host external bus control unit 112 described above.

The user inputs desired control information to the I / O control unit 111 using the input device 140 to cause the host 101 to perform a desired operation. External display device 1
The user selects an application or a data file stored in the storage unit 110 while viewing the screen displayed on the screen 30 and activates the application. Further, the user inputs the application and performs a series of operations.
At this time, when a request to transfer the work result to the peripheral device 102 occurs, data transfer is performed using the host external bus control unit 112 and the external bus 113.

A description will be given by taking a printer as an example of the peripheral device 102. The peripheral device 102 includes an address signal line 114, a data signal line 115, and a control signal line 1 as internal buses.
The internal bus has a peripheral device external bus control unit 1
17, a motor control unit 118, a head control unit 119, a peripheral device control unit 120, a ROM 121, a RAM 122, and an image processing unit 123 are connected. Peripheral device control unit 120
Performs selection of each functional block by an address signal line 114 and control of data transfer by a data signal line 115 and a control signal line 116, whereby the peripheral device 102
Control the operation of.

The peripheral device external bus control unit 112 is connected to the host 101 via the external bus 113, and sends and receives data to and from the host 101. The motor control unit 118 drives a paper feed and head driving motor in accordance with the control of the peripheral device control unit 120. Head control unit 1
Reference numeral 19 receives data to be printed and controls the recording head to perform printing. The image processing unit 123 further performs image processing on the transferred data.

A program for operating the peripheral device control unit 120 is stored in the ROM 121, and the peripheral device control unit 120 processes data sent to the peripheral device external bus control unit 117 according to the program. Control of other functional blocks to enable printing. RAM1
Reference numeral 22 is used to store data to be transmitted or parameters generated during processing.

Next, a series of operations described above will be described with reference to FIGS. Here, a case in which a user creates a document as shown in FIG. 10 by a predetermined application and prints out the document, for example, will be described. In the example of FIG. 10, a page 1001 is a print unit, and includes a text area 1002 and an image area 1003 such as a natural image.

When the user issues a print start command on the application, this is notified to the printer driver (S81). The printer driver notifies the system of printer setting information such as paper size and print quality (S82).

The system requests print data from the application (S83), and the application converts the print data into data in a predetermined format required by the system and transfers the data to the system (S84). The system temporarily stores the transferred data in the RAM 107 or the storage unit 110 (S85), and notifies the application of termination permission (S86). The application receives the permission notification, ends the printing operation, and shifts to a state of receiving the next operation (S87).

Next, the system divides the data stored in S85 into a data amount large enough to be processed by the printer driver, and transfers the data to the printer driver in band units (S89). The printer driver performs image processing for generating image data optimal for the target printer from the received data (S90). For example, color space conversion, color matching, rasterization, edge enhancement, softness, etc. In these processes, an optimal combination is selected according to the text area 1002 and the image area 1003. The image data generated in S90 is converted into a printer control command (S91) and passed to the system together with a data transfer request to the printer (S91).
92).

The system transfers the received printer control command to the host external bus control unit 112 (S9).
3). The host external bus control unit 112 transfers the received printer control command to the peripheral device external bus control unit 117 via the external bus 113 in the error correction transfer mode (S94, S95). At the end of the data transfer,
The host external bus control unit 112 notifies the system of the end of the data transfer (S97).

FIG. 11 shows an example of the transfer method at this time. In FIG. 11, Tx is the data transmission side, and here corresponds to the host external bus control unit 112. Also, Rx
Is a data receiving side, and corresponds to the peripheral device external bus control unit 117 here.

First, a token signal indicating transmission destination designation and start of data transmission is transmitted from Tx to Rx. The Rx that has received the Token signal enters a reception preparation state and waits for a data signal to be transmitted. T
x then sends a data signal (Data0 in the figure) to Rx. After confirming reception of the data signal (Data0), Rx transmits an ACK signal indicating successful reception to Tx. By receiving the ACK signal by Tx,
One data transfer ends. When transmitting and receiving an amount of data that cannot be transferred at one time, the above procedure is repeated by dividing the data into a size that can be transmitted and received.

Incidentally, it is generally used that an error correction code is added to data on the assumption that an error occurs in data transfer on a data transfer path. For example, a Hamming code, an RM (Reed Muller) code, a BCH (Bose Chaudhuri Hocq)
unenghem) code, convolutional code, CRC (Cyc)
like Redundancy Check) code, R
There is an error correction code such as an S (Reed Solomon) code.

As an example, when a CRC code is used, it is possible for the receiving side Rx to check whether an error has occurred in the data. For example, when it is determined that an error has occurred in the transmission of Data1, an Rx signal is output. Instead, a NAK signal indicating a retransmission request is transmitted to the transmitting side Tx. N
Upon receiving the AK signal, Rx determines that an error has occurred in data transfer, and transmits Data1 again. Dat
If a1 is received normally, Rx sends an ACK signal to Tx.

Even if an error occurs during data transfer, it is possible to transfer error-free data by using means such as retransmission.

Returning to FIG. 9, upon receiving the data, the peripheral device external bus control unit 117 notifies the peripheral device control unit 120 of the printer that the data has been transmitted.
The peripheral device control unit 120 controls each functional block so as to perform printout according to the received data (S9).
6). When the end of the data transfer is notified (S9)
7) The system repeats S89 to S97 until one of the pages to be printed is completed (S98). This is repeated for all pages for which printing is requested (S99).

Data is output to the printer connected to the outside of the host according to the procedure as described above. The communication procedure between the host and other peripheral devices is generally performed in the same manner.

[0026]

However, for example, using a printer as a peripheral device, a page 10 as shown in FIG.
When 01 is printed out, the spatial redundancy in the image area 1003 is very large, so that an error occurring at an error occurrence rate assumed on the external bus is invisible. In addition, since the image area 1003 has a very large amount of data and takes a long time to transfer, it is desirable to reduce the time used for data transfer as much as possible.

Further, a music reproducing device, a video reproducing device,
In the case of peripheral devices that use data that requires real-time properties such as telephone equipment, rather than the occurrence of some errors,
It becomes important to transfer data in time.

However, having only one of the above-mentioned conventional transfer procedures as shown in FIG. 11 cannot meet these requests for data transfer and takes a certain transfer time regardless of the nature of the data to be transferred. There was a problem that.

Accordingly, the present invention has been made in view of the above points, and has as its object to provide a data transfer apparatus and method which solve the above-mentioned problems.

[0030]

In order to achieve the above object, an apparatus according to the present invention according to claim 1 receives at least first and second data having different properties and receives the first and second data. A first data transfer unit for performing data transfer suitable for the first data, and a second data transfer for performing data transfer suitable for the second data. Means, and control means for controlling the first and second data to be selectively performed by one of the first and second data transfer means.

Here, the second data has a higher degree of redundancy than the first data, and the first data transfer means corrects the error of the first data, and the second data transfer means May not perform error correction of the second data.

Here, the control means selectively transmits either the data from the first data transfer means or the data from the second data transfer means to the external device via an external bus. It may also include a selection transmission unit.

Here, the external device may be an image output device.

Here, the image output device may be a printer.

Further, the image output device may be a video playback device.

Further, the external device may be an audio reproducing device, and the second data transfer means may transfer the second data in synchronization with a predetermined reference time.

In order to achieve the above object, a method of the present invention according to claim 8, wherein at least first and second data having different properties are input, and the first and second data are transmitted to an external device. In the data transfer method for transferring, a first data transfer suitable for the first data and a second data transfer suitable for the second data are selectively performed.

Here, the second data has a higher degree of redundancy than the first data, and performs error correction of the first data by the first data transfer, and performs the error correction of the first data by the second data transfer. Error correction of the second data may not be performed.

Here, either the first or second data transfer data can be selectively transmitted to the external device via an external bus.

[0040]

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

FIG. 1 is a system block diagram of one embodiment of the present invention. As shown in FIG. 1, the overall configuration of the system is the same as that of the conventional example, and the description of the same functional blocks as those of the conventional example described with reference to FIG. 6 will be omitted. FIG. 2 is a block diagram of a host external bus control unit 112a as a main part according to an embodiment of the present invention.

In FIG. 2, a control signal line 105, a data signal line 104, and an address signal line 103 of the system bus are connected to the control unit 17, and an overall control unit 108 (FIG. 1).
The control unit 17 controls the buffer 11 and the two switches (SW) 12,
15 and the error-correction transfer unit 13 and the error-correction-free transfer unit 14. The error correction transfer unit 13 performs error correction transfer using, for example, a CRC code.

Data transferred to the peripheral device 102 via the external bus 113 is temporarily stored in the buffer 11 from the data signal line 104. The transfer data is reconfigured into the transfer data by one of the error correction transfer units 13 and the transfer unit 14 without error correction. This selection is made by the switches 12 and 15. Each of the transfer units generates a signal of a procedure described later, transmits and receives data to and from the peripheral device 102 via the switch 15 and the transceiver 36, and transmits the result directly to the control unit 37 or to the buffer 31. Pass through. This processing will be described later in detail.

The peripheral device external bus control unit 117a of the peripheral device 102 has the same configuration as that of the host external bus control unit 112a.

Next, the characteristic operation flow of the present invention will be described with reference to FIGS. 3, 4, and 5, and FIGS. 8, 10, and 11, which are also used in the description of the prior art.

Here, a case where a user creates a document as shown in FIG. 10 by a predetermined application and prints out the document, for example, will be described. In the example of FIG. 10, a page 1001 is a print unit, and includes a text area 1002 and an image area 1003 such as a natural image.

Referring to FIG. 8, when the user issues a print start command on the application, this is notified to the printer driver (S81). The printer driver is
The system is notified of printer setting information such as paper size and print quality (S82).

The system requests print data from the application (S83), and the application converts the print data into data in a predetermined format required by the system and transfers the data to the system (S84). The system temporarily stores the transferred data in the RAM 107 or the storage unit 110 (S85), and notifies the application of termination permission (S86). The application receives the permission notification, ends the printing operation, and shifts to a state of receiving the next operation (S87).

Referring now to FIG. 3, the system includes a step S8.
The data stored in step 5 is divided into data amounts large enough to be processed by the printer driver, and the data is transferred to the printer driver in band units (S301). The printer driver performs image processing for generating image data optimal for the target printer (peripheral device 102) from the received data (S302). For example, color space conversion, color matching, rasterization, edge enhancement, softness, etc. These processes are performed in the text area 1002,
An optimal combination is selected according to the image area 1003.

The image data generated in S302 is converted into a printer control command (S303), and it is determined whether the image data is a printer control command for the text area 1002 (S304). At this time, if it is a printer control command for the text area 1002, a data transfer request for error correction is issued (S305). If the printer control command for the image area 1003 is not the printer control command for the text area 1002, the error correction is performed. A request for data transfer with no data is issued (S306).

The text area 1002 generally has a small spatial redundancy, and if the error is left as it is, it is easy to visually recognize it and it becomes remarkably visible. I do. On the other hand, since the image area 1003 generally has a large spatial redundancy and is hardly visible and hardly visible even if an error is left as it is, the error-free transfer without error correction processing is performed. Is selected to shorten the transfer time.
Most of the printer control commands in the image area 1003 are bitmap data of an image, and the amount of information is very large. Therefore, it is desirable to reduce the data transfer time.

The system transfers the received printer control command to the host external bus control unit 112a (S3).
07). At this time, one of the error correction transfer and the transfer without error correction is selected according to a request from the printer driver. The system determines whether the selected mode is the error correction transfer mode (308), and in accordance with the determination result, sends the control data to the control unit 17 of the host external bus control unit 112a so as to operate in the selected transfer mode. Notify (S3
09 or S401).

If the printer control command to be transferred is the text area 1002, the system requests and specifies the error correction transfer mode to the control unit 17 of the host external bus control unit 112a (S309). The control unit 17 includes the switches 12 and 1
5 so that the data is reconstructed by the error correction transfer unit 13 into transfer data. At this time, the error correction transfer unit 13 performs transmission / reception with another block, and the transfer unit 14 without error correction performs switching control so as not to transmit / receive data with the other block. At the same time, the peripheral device external bus control unit 117a is also set and notified to operate in the same error correction transfer mode (S310).

After setting the peripheral device external bus control unit 117a to operate in the error correction transfer mode (S311),
The host external bus control unit 1 notifies that the setting operation has been completed.
12a is notified (S312).

Data transfer is performed when the operation modes of both external bus control units are aligned. That is, the host external bus control unit 112a transmits the received printer control command to the peripheral device external bus control unit 1 via the external bus 113.
17a in the error correction transfer mode (S31).
3, S314). When the data transfer to the peripheral device external bus control unit 117a is completed, the host external bus control unit 112a notifies the system of the end of the error-free data transfer in the error correction transfer mode (S316).

As a transfer method at this time, a transfer procedure in the same error correction transfer mode as that described in the conventional example with reference to FIG. 11 is employed.

In FIG. 11, Tx is the data transmission side, and here corresponds to the host external bus control unit 112a. Rx is a data receiving side, and corresponds to the peripheral device external bus control unit 117a.

First, a token signal indicating transmission destination designation and start of data transmission is transmitted from Tx to Rx. The Rx that has received the Token signal enters a reception preparation state and waits for a data signal to be transmitted. T
x then sends a data signal (Data0 in the figure) to Rx. After confirming reception of the data signal (Data0), Rx transmits an ACK signal indicating successful reception to Tx. By receiving the ACK signal by Tx,
One data transfer ends. When transmitting and receiving an amount of data that cannot be transferred at one time, the above procedure is repeated by dividing the data into a size that can be transmitted and received.

When a CRC code is used as an example of the above-described various error correction codes, it is possible for the receiving side Rx to check whether an error has occurred in the data. If it is determined that the transmission has been performed, a NAK signal indicating a retransmission request is transmitted to the transmitting side Tx instead of the ACK signal. Upon receiving the NAK signal, Rx determines that an error has occurred in data transfer,
Data1 is transmitted again. If Data1 is received normally, Rx sends an ACK signal to Tx.

Even if an error occurs during data transfer, it is possible to transfer error-free data by using such means as retransmission.

Returning to FIG. 3 and FIG.
Is notified of the end of the data transfer, the system proceeds to S301 to S316 until one of the pages to be printed ends.
Is repeated (S409). This process is repeated for all pages for which printing is requested (S410).

When the print control command is the image area 1
The case where it is determined in S308 that the data is 003 will be described.

If the printer control command to be transferred is for the image area 1003, the system requests and specifies the error-correction-free transfer mode to the control unit 17 of the host external bus control unit 112a (S401). The control unit 17 controls the switches 12 and 15 so that the data is reconstructed into the transfer data by the transfer unit 14 without error correction. At this time, the error-correction transfer unit 14 performs transmission and reception with other blocks, and the error-correction transfer unit 13 performs switching control so as not to transmit and receive data with the other blocks. At the same time, the peripheral device external bus control unit 117a is also set and notified to operate in the same error correction transfer mode (S
402).

After setting the peripheral device external bus control section 117a to operate in the transfer mode without error correction (S40).
3) Notify the host external bus control unit 112a that the setting operation has been completed (S404).

Data transfer is performed when the operation modes of both external bus control units are aligned. That is, the host external bus control unit 112a transmits the received printer control command to the peripheral device external bus control unit 1 via the external bus 113.
17a in the error-free transfer mode (S4).
05, S406). The peripheral device external bus control unit 117a that has received the data notifies the peripheral device control unit 120 of the printer that the data has been transmitted. Peripheral device control unit 1
20 controls each functional block so as to perform printout according to the received data (S407). When the data transfer is completed, the host external bus control unit 11
2a notifies the system of the end of the data transfer in the error-correction-free transfer mode (S408).

FIG. 5 shows an example of the transfer method at this time.
Tx is the transmission side, here the host external bus control unit 112a
It is. Also, Rx corresponds to the receiving side, here the peripheral device external bus control unit 117a.

First, a token signal indicating transmission destination designation and start of data transmission is transmitted from Tx to Rx. The Rx that has received the Token signal enters a reception preparation state and waits for a data signal to be transmitted. T
x continues to output the data signal (Data0 in FIG. 5) to Rx
Send to

Here, unlike in the error correction transfer mode shown in FIG. 11, Rx does not transmit a signal (ACK signal) for confirming data reception. Therefore,
NAK even if it detects that there is an error in the transferred data
It is possible to reduce the transfer time by transmitting a signal without requesting retransmission.

When transmitting an amount of data that cannot be transferred at one time, the above procedure is repeated by dividing the data into a size that can be transmitted and received.

The peripheral device external bus control unit 117a receiving the data notifies the peripheral device control unit 120 of the printer that the data has been transmitted. The peripheral device control unit 120 controls each functional block so as to perform printout according to the received data (S407).

When the end of the data transfer in the no error correction mode is notified (S408), the system repeats the processing of S401 to S408 until one of the pages to be printed ends (S409). This is repeated for all pages for which printing is requested (S4).
10).

As described above, the generated image data is converted into a printer control command,
It is determined which of the printer control commands 002 and 1003 is the printer control command, and the data transfer is performed by selecting either the error-correction transfer mode or the error-correction transfer mode according to the determination result. As described above, the two types of transfer modes having different error correction capabilities and transfer speeds are combined, and if an error occurs, data which may cause trouble, for example, a control command, the text area 1002 described in the embodiment.
For data transfer such as the above, reliable data transfer is performed by using error correction transfer. On the other hand, for data transfer in which the occurrence of errors in the image area 1003 or the like does not cause much problem, data transfer with priority on transfer time is performed by using transfer without error correction.

As described above, according to the present embodiment, the transfer method suitable for the nature of the data to be transferred is selectively adopted as needed, so that the transfer time and the quality of the transferred data can be efficiently transferred without waste. Can be realized.

In the present embodiment, a printer has been described as an example of a peripheral device.
A video playback device may be used. Such peripheral device data is divided into control commands for the device, music / audio information, and video information. Therefore, if error correction transfer is performed for data such as control commands, and music / audio information, video information, and the like are transferred without error correction, efficient data transfer without waste can be performed.

This is because music / audio information, video information, and the like have a very large data amount and a large temporal / spatial redundancy, so that the data transfer time can be shortened without performing error correction, Is given priority over error-free transfer. Further, since music / audio information and video information need to be transferred in synchronization with a predetermined reference time for their continuity, an error-correction-free transfer method that performs time synchronization with a data transfer mode is employed. Is more desirable.

The present invention does not limit the transfer method to only the method described in the above-described embodiment. IEEE-1394, which is being recommended, and USB which is under specification, are being developed.
(Universal Serial BUS) or another external bus in which a plurality of transfer methods are defined may be employed. Features such as IEEE-1394 and USB support multiple transfer modes,
The purpose is to connect multiple peripheral devices with one external bus.

The method of the present invention may be applied to a system composed of a plurality of devices or an apparatus composed of one device. Needless to say, the method of the present invention can also be applied to a case where the method is achieved by supplying a program to a system or an apparatus. In this case, by reading out a storage medium storing a program represented by software for achieving the method of the present invention into a system or an apparatus, the system or apparatus can receive the effects of the method of the present invention. Become.

[0078]

As described above, according to the apparatus of the present invention, at least the first and second data having different properties are inputted, and the first and second data are transferred to an external device. By controlling the first and second data to be selectively performed by any of the first or second data transfer means suitable for each,
There is an effect that efficient data transfer can be realized.

According to the method of the present invention, at least the first and second data having different properties are input, and the first and second data are transferred to an external device. By selectively performing the first data transfer suitable for the second data transfer and the second data transfer suitable for the second data, there is an effect that efficient data transfer can be realized.

[Brief description of the drawings]

FIG. 1 is a system block diagram of an overall configuration of a data transfer device according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a data transfer device according to an embodiment of the present invention.

FIG. 3 is a flowchart of data transfer according to an embodiment of the present invention;

FIG. 4 is a flowchart of data transfer according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram of a transfer mode without error correction according to an embodiment of the present invention.

FIG. 6 is a system block diagram of the overall configuration of a conventional data transfer device.

FIG. 7 is a schematic block diagram of a conventional data transfer device.

FIG. 8 is a flowchart of a conventional data transfer.

FIG. 9 is a flowchart of a conventional data transfer.

FIG. 10 is a diagram illustrating an example of a print output output according to the present invention.

FIG. 11 is an explanatory diagram of a conventional error correction transfer mode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Buffer 12, 15 Switch 13 Error correction transfer part 14 Error correction transfer part 16 Transceiver 17 Control part 103 Address signal line 104 Data signal line 105 Control signal line 112, 112a Host external bus control part 113 External bus 117, 117a Peripheral equipment External bus control unit

Claims (10)

[Claims] At least a first and a second having different properties
A first data transfer unit for performing data transfer suitable for the first data, wherein the first data transfer unit transfers the first and second data to an external device; A second data transfer unit that performs data transfer suitable for: and a control unit that controls the first and second data to be selectively performed by one of the first and second data transfer units. A data transfer device comprising: 2. The second data has a higher redundancy than the first data, the first data transfer means corrects an error in the first data, and the second data transfer means 2. The data transfer device according to claim 1, wherein error correction of the second data is not performed. 3. The method according to claim 1, wherein the control unit selectively transmits either the data from the first data transfer unit or the data from the second data transfer unit to the external device via an external bus. 3. The data transfer device according to claim 1, further comprising a transmission unit. 4. The data transfer device according to claim 1, wherein the external device is an image output device. 5. The data transfer device according to claim 4, wherein the image output device is a printer. 6. The data transfer device according to claim 4, wherein the image output device is a video playback device. 7. The apparatus according to claim 1, wherein the external device is an audio reproducing device, and wherein the second data transfer unit transfers the second data in synchronization with a predetermined reference time. 3. The data transfer device according to any one of 3. 8. At least a first and a second of different properties
A first data transfer suitable for the first data and a second data transfer method, wherein the first and second data are transferred to an external device.
A second data transfer suitable for said data is selectively performed. 9. The second data has a higher redundancy than the first data. The first data transfer corrects the error of the first data, and the second data transfer corrects an error of the first data. 9. The data transfer method according to claim 8, wherein error correction of the second data is not performed. 10. The data according to claim 8, wherein one of the first and second data transfer data is selectively transmitted to the external device via an external bus. Transfer method.