JP2004228749A - Data transfer method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a controller to receive a video image from an apparatus other than the controller and to transmit/receive a video image between two apparatuses other than the controller while warranting the frequency band in a system connected to an IEEE (the institute of electrical and electronical engineers, inc.) 1394 bus. <P>SOLUTION: In the figure, a PC 101 sets a broadcast connection to a camera 102 under a receptible condition of a VTR 103 and sets a point-to-point connection to the camera 102 in a form of overriding the broadcast connection to warrant data transfer between the camera 102 and the VTR 103. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a data transfer method for performing data transfer between a plurality of devices connected on a bus having a synchronous transfer function.
[0002]
[Prior art]
2. Description of the Related Art In recent years, with the spread of digital technology in digital cameras and digital video, attempts have been made to connect such digital devices to the same bus and control them with a personal computer (hereinafter, PC). . In such a bus, the IEEE 1394 bus is capable of transmitting signals between arbitrary devices in any connection form, being capable of hot-plugging and unplugging a cable used for connection, and real-time data such as AV signals. (Isochronous data) and non-real-time data (asynchronous data) such as device control commands can be transmitted at the same time, and it is expected to be widely used in the future as a digital bus with excellent compatibility with PCs and related devices. ing.
[0003]
Hereinafter, a conventional data transfer method will be described.
[0004]
FIG. 13 shows a system diagram of a conventional data transfer method. In FIG. 13, reference numeral 101 denotes a personal computer (hereinafter, PC); 102, a camera; and 103, a VTR. These devices are connected to an IEEE 1394 bus. The PC 101 is a PC that sends a control command to another device to perform control and receives data from the other device, and the camera 102 transmits data such as video and receives a control command from the other device to perform remote control. The VTR 103 is a VTR that can transmit and receive data to and from other devices and can perform remote control by receiving control commands from other devices.
[0005]
The operation will be described below with reference to the above system diagram.
[0006]
First, the IEEE 1394 transfer includes an asynchronous transaction and an isochronous transaction. The asynchronous transaction is used when data is transferred asynchronously, and is a transfer that guarantees that data is reliably transmitted to a destination and does not guarantee a transmission delay time. The isochronous transaction is a synchronous transfer and is suitable for transmission of a moving image, audio, and the like, and guarantees real-time transfer. In this system, the control command from the PC is performed in an asynchronous transaction, and the transfer of a video image from a camera or the like is performed in an isochronous transaction.
[0007]
In order to perform data transfer, arbitration between devices must first be performed so that data transfer can be performed. Making this state is expressed below when a connection is established. The connection includes a broadcast connection and a point-to-point connection. A broadcast connection is a connection that does not guarantee a connection between transmission and reception, and can be disconnected from any device. On the other hand, a point-to-point connection is a connection that can guarantee a connection between transmitting and receiving devices, and can be disconnected only by a device that has established a connection.
[0008]
In IEEE1394, multiplexing and transfer are performed using a channel. Channels exist from 0 to 63 channels, and data transmission and reception can be performed by combining channels on the transmission side and the reception side.
[0009]
IEEE 1394 has several transfer speeds. Specifically, there are S100 for transferring at 100 Mbps and S200 for transferring at 200 Mbps. Current PCs and the like support up to 400 Mbps S400. The transfer speed is selected depending on the capacity between the transmitting device and the receiving device, and the transfer speed can be changed for each channel.
[0010]
Here, in FIG. 13, the video from the camera 102 is received not only by the PC 101 but also by the VTR 103, and data transfer from the camera 102 to the PC 101 and the VTR 103 must be guaranteed. Conventionally, data transfer has been guaranteed by establishing point-to-point connections between the camera 102 and the PC 101 and between the camera 102 and the VTR 103. The procedure for establishing a connection is performed when the PC 101 establishes a point-to-point connection between the PC 101 and the camera 102 and establishes a point-to-point connection between the camera 102 and the VTR 103, or when the PC 101 establishes a connection to the camera 102 or the VTR 103. It is known that a connection is made by requesting that a connection be made. This method is a method described in JP-A-2001-274803.
[0011]
In order for the PC 101 to establish a point-to-point connection between the camera 102 and the VTR 103, the PC 101 secures a bandwidth on the bus, and then sets the output device to output data and the input device to input data. The connection was established after setting.
[0012]
In addition, when either the camera 102 or the VTR 103 establishes a point-to-point connection, a command for requesting that the PC 101 establish a connection to either the camera 102 or the VTR 103 is newly provided on the bus.
[0013]
[Patent Document 1]
JP 2001-274803 A
[Problems to be solved by the invention]
When a point-to-point connection is established by the method described above, the point-to-point connection between the camera 102 and the PC 101 in FIG. 13 is connected by the maximum output speed of the camera 102 and the channel that the PC can receive. In some cases. For example, if the camera 102 can output in S200, the speed of the point-to-point connection is set in S200. Channels span any unused channels. In this example, the channel is set to 0 channel. Next, when a point-to-point connection is established between the camera 102 and the VTR 103, the condition of the output side of the already established point-to-point connection cannot be changed, so that the connection is made at channel 0 and at the speed of S200. In this data transfer method, two point-to-point connections can be set up to guarantee data transfer between the respective devices, but the output condition of the output device is the condition of the point-to-point connection set up first. Here, if the receivable condition of the VTR 103 is a device with a fixed channel of 63 or corresponds only to the speed up to S100, data cannot be received correctly, and an error occurs on the receiving device side. Was.
[0015]
Further, since a controller such as a current PC does not support establishing a point-to-point connection between two devices other than itself, it cannot support a device already used by a user. Also, in the method of providing a new command, there arises a problem that the command is not a command within the standard, and the standard cannot be changed or a device already used by the user cannot be used. Therefore, there is a demand that data transfer can be performed even using current general-purpose devices.
[0016]
Further, the current PC can not only operate as a controller but also capture an image and display it on a monitor in real time. Furthermore, it is also possible to record on an internal hard disk. When a plurality of images are captured and displayed, the processing capacity of the controller may be exceeded and the processing of the controller may become unstable. There is a demand for controlling the number of videos to be displayed without affecting the video being recorded on the hard disk in consideration of the processing capability of the controller.
[0017]
It is an object of the present invention to enable a controller to receive video from devices other than the controller device and to transmit and receive video between two devices other than the controller in the current IEEE 1394 bus standard.
[0018]
[Means for Solving the Problems]
In order to solve this problem, the invention described in claim 1 of the present invention
Specify at least two device pairs,
A point-to-point connection in which only the connected device can disconnect the connection,
Without specifying the device pair,
Using a broadcast connection that can be disconnected from any of the devices having a connection control function,
In a bus that reserves a band and performs synchronous transfer,
A first device for controlling other devices;
A second device for transmitting data,
A data transfer method in which a third device that receives data from the second device is connected,
The first device,
Requesting the second device to establish a broadcast connection to the third device for the second device,
The second device is
A broadcast connection to the third device,
Set up under the receivable condition of the third device,
The first device,
A point-to-point connection between the first and second devices,
A method of overwriting the broadcast connection established between the second device and the third device is used.
[0019]
This method has an effect that transfer can be guaranteed without establishing a point-to-point connection between two devices other than the own device.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
The invention described in claim 1 of the present invention
Specify at least two device pairs,
A point-to-point connection in which only the connected device can disconnect the connection,
Without specifying the device pair,
Using a broadcast connection that can be disconnected from any of the devices having a connection control function,
In a bus that reserves a band and performs synchronous transfer,
A first device for controlling other devices;
A second device for transmitting data,
A data transfer method in which a third device that receives data from the second device is connected,
The first device,
Requesting the second device to establish a broadcast connection to the third device for the second device,
The second device is
A broadcast connection to the third device,
Set up under the receivable condition of the third device,
The first device,
A point-to-point connection between the first and second devices,
It is characterized in that it is overwritten on a broadcast connection established between the second device and the third device,
This is a data transfer method having an effect that transfer can be guaranteed without establishing a point-to-point connection between the second device and the third device.
[0021]
The invention described in claim 2 is
The bus is
Multiplexing at least two logical channels,
The second device is
Establish a broadcast connection by specifying a channel to the third device,
The first device,
A point-to-point connection between the first and second devices,
Stretched between the second device and the third device,
It is characterized by overwriting the broadcast connection on the same channel,
2. The data transfer method according to claim 1, wherein the data transfer method has an effect that the data transfer method can be used even on a bus that performs multiplex transfer on a logical channel.
[0022]
The invention according to claim 3 is:
The bus is
Transmit at different transmission speeds for each channel,
The second device is
Establish a broadcast connection by specifying the transmission speed to the third device,
The first device,
A point-to-point connection between the first and second devices,
Stretched between the second device and the third device,
It is characterized by overwriting the broadcast connection at the same transmission rate,
3. The data transfer method according to claim 2, wherein the data transfer method has an effect of being able to be used even on a bus capable of transferring at a plurality of speeds.
[0023]
The invention described in claim 4 is
The first device,
Prior to establishing a broadcast connection between the second device and the third device,
In the second device,
By specifying the condition of the broadcast connection between the second device and the third device,
The data transfer method according to claim 2 or claim 3, having an effect that a condition of a broadcast connection can be designated from a controller.
[0024]
The invention according to claim 5 is
The bus is
A data transfer device that multiplexes asynchronous transfer in which packet delay is not guaranteed but arrival is guaranteed in addition to synchronous transfer,
The control from the first device is performed using asynchronous transfer or synchronous transfer,
5. The data transfer method according to claim 1, wherein the command is transmitted by asynchronous transfer and the command can be transmitted reliably.
[0025]
The invention according to claim 6 is
The bus is
It is an IEEE 1394 bus,
6. The data transfer method according to claim 1, wherein the data transfer method has an effect of being realized by an IEEE 1394 bus.
[0026]
The invention according to claim 7 is
The control from the first device includes:
Using AV / C commands of the IEEE 1394 bus standard,
7. The data transfer method according to claim 6, wherein the data transfer method has an operation capable of being transferred by an AV / C command of the IEEE 1394 bus standard.
[0027]
The invention according to claim 8 is
The control device is
According to the output channel and output speed of the oPCR setting of the second device,
Characterized by establishing a point-to-point connection between the second device and the third device,
8. The operation according to claim 7, wherein a transfer between the second device and the third device can be guaranteed only by establishing a point-to-point connection between the first device and the second device. This is the data transfer method.
[0028]
The invention according to claim 9 is
At least two devices
Connected to a bus that reserves bandwidth and performs synchronous transfer,
A first device that switches the decoding size of the video and displays the screen,
A data transfer method in which at least one second device that outputs an image to the first device is connected,
The first device,
Processing capacity of the first device,
Compare the video currently being displayed with the decoding processing amount of the video to be displayed,
If the processing capacity of the first device is insufficient,
The feature is to increase the number of video display screens by reducing the decode size of the video displayed in advance,
This is a data transfer method having the effect of increasing the number of images that can be displayed.
[0029]
The invention according to claim 10 is
The first device,
The feature is not to switch the decode size while recording the input video,
10. The data transfer method according to claim 9, wherein the data transfer method has an effect of not affecting a video being recorded on the HDD.
[0030]
The invention according to claim 11 is
The first device,
Characterized by being a computer,
11. The data transfer method according to claim 9, wherein the data transfer method has an operation easily controlled by a computer.
[0031]
The invention according to claim 12 is
The first device,
The feature is that video is recorded on the hard disk in the computer,
The data transfer method according to claim 11, which has an operation of recording an image in a computer.
[0032]
The invention according to claim 13 is:
The bus is
It is an IEEE 1394 bus,
13. The data transfer method according to claim 9, which has an effect of being able to be used by an IEEE 1394 bus.
[0033]
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0034]
(Embodiment 1)
FIG. 1 is a diagram for explaining a data transfer method according to the present invention. In FIG. 1, reference numeral 101 denotes a PC, 102 denotes a camera, 103 denotes a VTR, and these devices are connected to an IEEE 1394 bus. The PC 101 sends a control command to the camera 102 and the VTR 103 to perform remote control such as pan / tilt control of the camera 102 and reproduction / recording of the VTR 103, and also receives video data from the camera 102 and the VTR 103 and performs monitor display. In the PC, the camera 102 is a camera that transmits data such as images and receives control commands from other devices, and the VTR 103 is a VTR that receives data from other devices and receives control commands from other devices. The video data of the camera 102 is received by the PC 101 and also received by the VTR 103. As a specific usage, the PC 101 controls the VTR 103 by remote operation from the PC 101 while outputting the image of the camera to the monitor of the PC 101, and performs recording from the camera 102 to the VTR 103.
[0035]
First, the PC 101 establishes a broadcast connection with the camera 102 under conditions that the VTR 103 can receive. FIG. 2 is a conceptual diagram illustrating a broadcast connection. The configuration is the same as that shown in FIG. The broadcast connection is shown by an arrow (dotted line) in FIG. FIG. 3 is a diagram showing a plurality of channels for isochronous transfer on a bus, and representing connections on the channels. Specifically, a method in which the camera 102 establishes a broadcast connection will be described. When the PC 101 requests the camera 102 to output a video, the camera 102 attempts to output a stream under the conditions set in the camera. A broadcast connection is established to output a stream to the IEEE 1394 bus. This is a process that is always performed by the device. By using this, a broadcast connection can be established. A request to output a stream from the PC 101 can be realized by using a DIGITAL OUTPUT command of the AV protocol.
[0036]
The conditions to be set in the camera will be described. If the receivable speed of the VTR 103 is S100, the setting of the camera 102 is set to be output in S100. Attempts to establish a connection, and outputs a video if a broadcast connection is established. Similarly, when the VTR 103 is a VTR that can be received on 63 channels, it can be handled by setting the camera 102 to output on 63 channels. This is illustrated in more detail in FIG. A plurality of isochronous channels exist in the IEEE 1394 bus. FIG. 3 illustrates the case where 63 channels are used, and 63 channels are mainly illustrated. In this state, the connection between the camera 102 and the VTR 103 is a broadcast connection, and is not in a state where transfer is guaranteed, and may be disconnected from another device.
[0037]
Next, the PC 101 establishes a point-to-point connection with the camera 102. Since the camera 102 has already established a broadcast connection to the VTR 103, the camera 102 establishes a point-to-point connection by overriding the broadcast connection without newly securing resources. FIG. 4 is a conceptual diagram in which a point-to-point connection is established. The configuration is the same as that shown in FIG. An arrow (double line) from the camera 102 to the PC 101 in FIG. 4 indicates a point-to-point connection. The configuration in FIG. 5 is the same as the configuration in FIG. 3, and is a diagram expressing connections on the bus in more detail. A point-to-point connection (double arrow) is established while overwriting the broadcast connection. Under the same conditions as the broadcast connection, a point-to-point connection is established with (isochronous channel: 63 channels, output speed: S100).
[0038]
As described above, the broadcast connection between the camera 102 and the VTR 103 is a connection that does not guarantee the connection. However, by overriding the point-to-point connection between the camera 102 and the PC 101, the broadcast connection is protected by the point-to-point connection. Data transfer between the VTR 102 and the VTR 103 can be guaranteed. Further, this method can be dealt with by using only the functions of the conventional device and the functions included in the conventional standard.
[0039]
(Embodiment 2)
Since the description will be made with the same configuration as in the first embodiment, the description of the configuration will be omitted, and only different points from the first embodiment will be described.
[0040]
First, the format of the oPCR of the camera 102 is shown in FIG. oPCR indicates the state of the connection of the output device. Only the fields in the format that need to be described in the present embodiment will be described. "online" indicates whether the output device is online. bcc indicates the number of broadcast connections being established. pcc indicates the number of point-to-point connections established. channel indicates a channel to output. dr indicates the data transfer rate.
[0041]
Here, when the oPCR of the camera 102 is online, the bcc and pcc are not set, and the channel and the dr are devices set to receive the VTR 103, the PC 101 is connected to the PC 101 and the camera 102. By establishing a point-to-point connection between the camera 102 and the channel and dr of the camera 102, the PC 101 can establish a point-to-point connection under conditions that the VTR 103 can receive data without establishing a broadcast connection. After that, when the VTR 103 receives data, a connection between the camera 102 and the VTR 103 can be protected even if a broadcast connection is established, as in the first embodiment.
[0042]
(Embodiment 3)
FIG. 7 shows a connection diagram of the devices. In FIG. 7, reference numeral 701 denotes a PC, and 704 a hard disk for recording video data. Reference numeral 702 denotes a camera # 1, reference numeral 703 denotes a camera #n, a PC 701 receives a video from a device connected to the bus and displays the video on a monitor on the PC 701, a hard disk 704 records video data, # 1 (702) and camera #n (703) output video on the bus.
[0043]
FIG. 8 is an example of a PC screen, in which a plurality of video data from the bus are displayed on the screen.
[0044]
FIG. 9 is a flowchart showing an algorithm to be displayed on the screen of the PC 701 and to be within the processing capability of the PC. 901 is a step indicating the start of processing, 902 is a step of determining whether to switch the display of an image, and 903 is a step of determining whether to add an image on the PC screen or delete an already displayed image. 904 is a step of calculating the total load amount from the display image management table and the load amount table. 905 is a step of determining whether to additionally display an image based on the load amount calculated in 904, and 906. Is a step of selecting a video whose decoding size is to be reduced from the display video management table and the recording video management table, 907 is a step of determining whether display is possible, 908 is a step of determining whether there is a recording video switching request, and 909 is A step of updating the video management table during recording; 910, a step of updating the display video management table; A step of updating the display image management table to display the image on the monitor.
[0045]
FIG. 10 shows an example of the display video management table. The display number indicates the video being displayed, and the decode size indicates the size of the video. FIG. 11 shows an example of the load amount table, in which the relationship between the decode size and the load amount is corresponded. FIG. 12 is a recording video management table, which manages the video numbers being recorded on the hard disk.
[0046]
When the process is started in step 901, it is determined in step 902 whether there is a video display switching request from the user of the PC 701. If there is a request, the process proceeds to step 903, and if not, the process proceeds to step 908. If there is no request, it is determined in step 908 whether there is a request to switch the recording of the video to the hard disk 704. If there is no request, the process proceeds to step 902. If there is a request to switch the video to the hard disk, the process proceeds to step 909. In step 909, the video management table during recording shown in FIG. 12 is updated. To end the recording, the video number is deleted. To start a new recording, the video number is added. After updating the table in step 909, the process moves to step 902.
[0047]
In step 903, it is determined whether to add or delete the video display on the monitor of the PC. If it is to be deleted, the process proceeds to step 910. If it is to be added, the process proceeds to step 904. In step 910, the video number to be deleted is deleted from the display video management table.
[0048]
In step 904, the load amount when a new video display is added is calculated based on the display video management table shown in FIG. 10, and the process proceeds to step 905.
[0049]
In step 905, based on the result calculated in step 904, it is determined whether or not an image can be displayed on the monitor of the PC 701 based on the load amount. If possible, the process proceeds to step 911; otherwise, the process proceeds to step 906.
[0050]
In step 911, an image is displayed on the monitor of the PC 701, the display image management table shown in FIG. 10 is updated, and the process proceeds to step 902.
[0051]
Step 906 is to select one of the images displayed on the monitor of the PC 701 from the images that can reduce the decode size based on the display image management table shown in FIG. 10 and the recording image management table shown in FIG. Moves to step 907 with.
[0052]
In step 907, if the selection can be made in step 906, the process proceeds to step 904, and the process for displaying again is performed.
[0053]
As described above, it is possible to protect the stability of the PC 701 by reducing the decoding size of the display on the PC 701 to reduce the load, and to perform processing so as not to hinder the recording of the PC 701 on the hard disk 704. .
[0054]
In the embodiments of the present invention, the description has been made centering on the device connection method of the present invention. However, as a storage medium of the present invention, a program executed by a computer to execute all or a part of the functions of each means described above by a computer is used. A storage medium for storing may be used. Although the control device has been described using a PC, any device having a control function, such as a camera or a VTR, can achieve the same effect. In the first embodiment, an example in which three devices are connected has been described. However, a system in which four or more devices are connected can also be used. In the third embodiment, an example in which recording is performed on a hard disk has been described. However, similar effects can be obtained with a recording device connectable to a PC, such as a disk device such as a DVD or a semiconductor memory. Although the description has been made using the IEEE 1394 bus, similar effects can be obtained with other communication devices capable of synchronous transfer, such as an ATM (Asynchronous Transfer Mode) and a USB (Universal Serial Bus).
[0055]
【The invention's effect】
As described above, the present invention has an effect that transfer can be guaranteed without establishing a point-to-point connection between two devices other than itself, even when a conventional standard and a conventional device are used. In addition, an effect is obtained in which the amount of video load can be kept within a certain value and a stable PC operation can be maintained.
[Brief description of the drawings]
FIG. 1 is a system diagram of a data transfer method according to a first embodiment of the present invention; FIG. 2 is a system diagram showing a broadcast connection of a data transfer method according to a first embodiment of the present invention; FIG. FIG. 4 is a conceptual diagram of a channel having a broadcast connection in the data transfer method according to the first embodiment. FIG. 4 is a system diagram in which a point-to-point connection in the data transfer method according to the first embodiment of the present invention is overridden. FIG. 6 is a conceptual diagram of a channel overriding a point-to-point connection in the data transfer method according to the first embodiment. FIG. 6 is a diagram showing an oPCR of the data transfer method according to the second embodiment of the present invention. FIG. 7 is a third embodiment of the present invention. FIG. 8 is a diagram illustrating a data transfer method according to a third embodiment of the present invention. FIG. 9 is a diagram illustrating a screen display. FIG. 9 is a flowchart illustrating processing of a data transfer method according to the third embodiment of the present invention. FIG. 10 is a diagram illustrating a display video management table of the data transfer method according to the third embodiment of the present invention. FIG. 11 is a diagram showing a load amount table of a data transfer method according to the third embodiment of the present invention; FIG. 12 is a diagram showing a recording video management table of the data transfer method according to the third embodiment of the present invention; Diagram of data transfer method
101 PC
102 Camera 103 VTR
701 PC
702 Camera # 1
703 Camera #n
704 Hard disk 901 Step 902 indicating start of processing Step 902 Determine whether image can be switched to display 903 Step 904 to add video on PC screen or delete video already displayed 904 Display video management table Step 905 of calculating the total load amount from the load amount table and step 906 of judging whether the image can be additionally displayed. Step 907 of selecting the image whose decode size is to be reduced. 907 Step 908 of judging whether the image can be displayed. Step 909 of judging whether or not the recording video management table is updated Step 910 Step of updating the display video management table Step 911 Step of displaying the video and updating the display video management table

Claims (13)

Specify at least two device pairs,
A point-to-point connection in which only the connected device can disconnect the connection,
Without specifying the device pair,
Using a broadcast connection that can be disconnected from any of the devices having a connection control function,
In a bus that reserves a band and performs synchronous transfer,
A first device for controlling other devices;
A second device for transmitting data,
A data transfer method in which a third device that receives data from the second device is connected,
The first device,
Requesting the second device to establish a broadcast connection to the third device for the second device,
The second device is
A broadcast connection to the third device,
Set up under the receivable condition of the third device,
The first device,
A point-to-point connection between the first and second devices,
A data transfer method characterized by overwriting a broadcast connection established between the second device and the third device. The bus is
Multiplexing at least two logical channels,
The second device is
Establish a broadcast connection by specifying a channel to the third device,
The first device,
A point-to-point connection between the first and second devices,
Stretched between the second device and the third device,
2. The data transfer method according to claim 1, wherein the broadcast connection is overwritten on the same channel. The bus is
Transmit at different transmission speeds for each channel,
The second device is
Establish a broadcast connection by specifying the transmission speed to the third device,
The first device,
A point-to-point connection between the first and second devices,
Stretched between the second device and the third device,
3. The data transfer method according to claim 2, wherein the broadcast connection is overwritten at the same transmission rate. The first device,
Prior to establishing a broadcast connection between the second device and the third device,
In the second device,
4. The data transfer method according to claim 2, wherein a condition of a broadcast connection between said second device and said third device is specified. The bus is
A data transfer device that multiplexes asynchronous transfer in which packet delay is not guaranteed but arrival is guaranteed in addition to synchronous transfer,
5. The data transfer method according to claim 1, wherein control from the first device is performed using asynchronous transfer or synchronous transfer. The bus is
6. The data transfer method according to claim 1, wherein the data transfer method is an IEEE 1394 bus. The control from the first device includes:
7. The data transfer method according to claim 6, wherein an AV / C command conforming to the IEEE 1394 bus standard is used. The first device includes:
According to the output channel and output speed of the oPCR setting of the second device,
8. The data transfer method according to claim 7, wherein a point-to-point connection is established between said second device and said third device. At least two devices
Connected to a bus that reserves bandwidth and performs synchronous transfer,
A first device that switches the decoding size of the video and displays the screen,
A data transfer method in which at least one second device that outputs an image to the first device is connected,
The first device,
Processing capacity of the first device,
Compare the video currently being displayed with the decoding processing amount of the video to be displayed,
If the processing capacity of the first device is insufficient,
A data transfer method characterized by increasing the number of video display screens by reducing the decode size of a video that is displayed in advance. The first device,
10. The data transfer method according to claim 9, wherein the decoding size is not switched during recording of the input video. The first device,
The data transfer method according to claim 9 or 10, wherein the data transfer method is a computer. The first device,
The data transfer method according to claim 11, wherein the video is recorded on a hard disk in the computer. The bus is
13. The data transfer method according to claim 9, wherein the data transfer method is an IEEE1394 bus.

Images