JPH08129522A - Transfer method for multimedia data - Google Patents

Abstract

PURPOSE: To prevent a decrease in transfer efficiency and an omission of data by providing a method which adaptively determines the kind of data to be transferred with top priority corresponding to the input buffering states of respective data kinds and transfers the data, in a multimedia system. CONSTITUTION: The data write rates of FIFO memories 13 and 23 in which image data and speech data are buffered, are encoded by state encoders 15 and 25 by using state tables 16 and 26, and data of which FIFO memory should be transferred with top priority, is determined by an arbiter 17 according to the respective encoding states by using an arbitration table 18 and reported to a DMAC 10 with a DREG signal. The arbitration table 18 has such table constitution that transfer from an FIFO memory side which is relatively large in write rate is given priority, and respective data are transferred to a buffer memory 6 with good balance according to the input states.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transferring multimedia data, and more particularly, it is applied to a multimedia recording / reproducing apparatus which handles data such as still images, moving images, characters and voices in a unified manner and is of a different type. The present invention relates to a method of transferring a plurality of data by using a common bus in a system.

[0002]

2. Description of the Related Art With the advent of the full-fledged multimedia era, attention has been paid to the development of multimedia systems. In such systems, coding systems and transfer rates such as moving image data, audio data and control data have been attracting attention. It is necessary to integrally process multiple types of data that differ in terms such as the above. Therefore,
An important issue is how to efficiently transfer each data in the system while handling each data in an integrated manner.

As a conventional technique for dealing with the problem of data transfer in a multimedia system, Japanese Patent Laid-Open No. 4-3459.
There is a "multimedia recorder" disclosed in No.85. The invention according to the above-mentioned publication aims at integrally recording / reproducing various data without significantly increasing the access rate to a recording medium such as a hard disk, and the system circuit thereof has a configuration as shown in FIG. It has become.

In the figure, 1 is a CPU, 2 is a ROM / RAM for storing a control program for the entire system and an R / W area of an HDD, which will be described later, 3 is an operating section, 3a is an operating I / F,
4 is a display unit, 4a is a display I / F, 5 is a bus control unit, 56 is a buffer memory for temporarily storing audio data / image data / sequencer (MIDI) data, 57 is a hard disk device (HDD), and 57a is Hard disk controller (HD
C), 58, 59, and 60 are image I / O and MIDI- that have built-in A / D converters, D / A converters, and data buffers, and fulfill the input / output interface function of image data / MIDI data / audio data. I / O, audio I / O, 61 is DMAC (Dir
ect Memory Access Controller), and each unit and the like are connected to an address / data bus and a control bus controlled by the bus control unit 5 as shown in the figure. And the operation unit
Based on the instruction input from 3, the CPU 1 generates an interrupt and sets the instruction mode by giving priority to the current mode, but in the recording / playback mode, the DMAC 61 causes each I / O 58,5
9,60-buffer memory 56-HDC 57a executes a DMA transfer of data through a bus path, records input audio data / image data / MIDI data on a disk by the HDD 57, and records each data read from the disk on the HDD 57. Output from each I / O 58, 59, 60.

In this case, each I / O 58, 59, 60 and HDC 57a individually send data transfer requests REQ1 to REQ4 to the DMAC 61, and the DMAC 61 sends a bus surrender request (BU) to the bus control unit 5.
SREQ) is output, and when the CPU1 permits, the bus control unit 5
Returns BUSACK to DMAC61, surrenders the bus, and BUSA
The DMAC 61 that received the CK has one of the I
Outputs ACK1 to 4 to / O58,59,60 or HDC57a. That is, although the data transfer requests REQ1 to REQ4 to the DMAC61 may be made at the same time, the DMAC61 always requests REQ1 (voice I / O60)> REQ2 (MIDI-I / O59)> REQ3 (image I / O).
O58)> REQ4 (HDC57a) is returned in the priority order of ACK1-4. Then, the DMAC 61 outputs the voice I / O in the case of ACK1.
O60, MIDI-I / O59 in the case of ACK2, image I / O58 in the case of ACK3, HDC57a in the case of ACK4, and the transfer right in the recording mode. Data is transferred through the bus path of I / O → buffer memory 56 → HDC 57a.
→ buffer memory 56 → data is transferred through the I / O bus path to which the transfer right is given.

[0006]

By the way, in the above-mentioned multimedia recorder, the reason why the priority order of DMA transfer control is determined as described above is "based on the urgency of execution of DMA transfer". Specifically, "reproduced audio becomes extremely unnatural if data transfer of audio signals is not performed correctly at each sampling.
Regarding the data transfer of the IDI signal, the timing of data transfer is not as severe as that of the audio signal, and the priority is lower. Similarly, regarding image signals, it is considered that the switching of screens is not managed so severely as compared with the change timing of voice or automatic performance, and the priority is lower than these. Since the buffer memory 56 has a time margin, the HDC 57a and the buffer memory 56
Another DMA transfer is requested during data transfer between
Even if it is interrupted and executed first, no particular problem occurs. Is explained.

However, when multimedia data is transferred in a time division manner through a common bus in the system, the data amount per unit time of each data type often changes greatly in time, and as described above, data transfer is performed. If a fixed priority order is set, the high priority data will be recorded / reproduced with certainty, but the low priority data cannot be guaranteed. For example, in the above multimedia recorder, when the data amount of the audio data to be transferred in a certain time period tends to be constant or decreasing, but the data amount of the image data greatly increases, the DMAC 61 always operates. Since the transfer of the audio data is given the highest priority, the transfer efficiency of the image data becomes very poor. Specifically, in the recording mode, when the recording efficiency of the HDD 57 decreases and the input rate of the image data exceeds the allowable value of the built-in data buffer of the image I / O 58, the image data is lost and reproduced. In the mode, the reproduction image is deteriorated due to the loss of the image data at the transfer stage, and the output failure due to the delay of the transfer occurs. That is,
In the multimedia decoder described above, the priority of data transfer is fixedly set according to the degree of influence on recording / playback based on the characteristics of each data type, but conversely, it is the time of the data amount of each data type. It becomes a factor that cannot respond to dynamic changes, and it can be said that it remains an important issue for realizing reliable recording and reproduction.

Therefore, according to the present invention, in a multimedia system, the priority of data transfer is adaptively changed according to the input buffering state (input data amount) of image data, audio data, etc. to balance each data type. It was created for the purpose of providing a data transfer method capable of transferring efficiently and efficiently.

[0009]

According to the present invention, each buffer means for temporarily storing a plurality of different types of input data in a data type and the occupied state of write data in each buffer means are detected in real time. Each detecting means and arbitration means for determining the buffer means for which the data transfer should be given the highest priority based on the occupied state detected by each of the detecting means are provided, and the data transfer means is the buffer means determined by the arbitrating means. And a method for transferring multimedia data, which is characterized in that the write data of the above is transferred to a transfer destination.

Further, in the invention, each detecting means obtains an occupancy rate of the write data in the corresponding buffer means, and determines which range divided by a plurality of thresholds the obtained occupancy rate belongs to. , Which can be configured as a means for outputting the encoded data corresponding to each divided range based on the determination result, and the arbitration means gives the highest priority to the data transfer based on the output state of the encoded data of each of the detecting means. It can be configured as a means for determining the buffer means to be used.

[0011]

Each buffer means buffers the input data according to the data type, and the amount of data input to each buffer means is real time as the occupied state of the write data detected by each detection means for each data type. You can check. The arbitration means, based on its respective occupation state,
A decision is made to preferentially grant the data transfer right to the buffer means having a relatively large amount of data. Then, the result of the determination is notified to the data transfer means, and the data transfer means transfers the write data of the determined buffer means to the transfer destination.

Therefore, in the present invention, the priority of data transfer is not fixedly set according to the data type, but the priority is set according to the input state (input data amount) of each data to each buffer means. Since it is determined adaptively, each data can be transferred in a well-balanced manner. That is,
When one data type has a much larger data volume than other data types in a certain time zone, the transfer time for that data type is increased, and the transfer for a specific data type is performed. It is possible to prevent delay and data loss.

Each of the detecting means of the present invention may detect the occupancy rate as a percentage and finely, but a method of dividing the state of the buffer means by a plurality of thresholds can also be adopted. According to that method, the divided state can be represented by encoded data having a small number of bits, and the arbitration means can easily determine the buffer means that gives the data transfer right based on the output state of the encoded data of each detection means. can do.

In particular, when the occupancy rate of each buffer means is treated as a percentage, the priority of data transfer frequently changes and the transfer switching time becomes long when the rate changes with a close value. However, according to the method described above, such an inconvenience does not occur because it is regarded as the same occupied state within the divided range by the threshold value, and there is also an advantage that each detecting means and arbitrating means can have a programmable table configuration. is there.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the "multimedia data transfer method" of the present invention will be described in detail below with reference to FIGS. However, in the present embodiment, a case will be described in which the input audio signal and image signal are encoded, and each compressed data thereof is transferred and recorded. First, FIG. 1 is a system circuit diagram showing a recording system of a multimedia system.
U1, ROM / RAM2, operation unit 3, operation I / F3a, display unit
The circuit configurations of 4, the display I / F 4a, and the bus control unit 5 are the same as those of the system circuit of FIG. In the circuit of this embodiment, the buffer memory 6 for temporarily storing the compressed audio data and image data is stored in the main bus (address / data bus and control bus) controlled by the bus control unit 5.
, The HDC 7a, the image compression unit 8, the audio compression unit 9, and the DMAC 10 are bus-connected as shown in the figure, and the DMAC 10 and the bus control unit 5 are the BUSREQ signal line and the BUSACK signal line, and the DMAC 10 and the image. The arbiter 17 (described later) on the compression unit 8 side is connected to the DREQ signal line, and the DMAC 10 and the transfer control units 14 and 24 (described later) of the units 8 and 9 are connected to each other by the ACK signal line.

The image compression unit 8 receives an input I / F 11 to which an image signal is input and image data received by the input I / F 11 from an MPEG (Moving Picture Image Coding Exp).
ertsGroup) image encoding unit 12 to be encoded by the method, the image compression FIFO memory 13 for temporarily buffering the encoded compressed image data in the FIFO (First-In First-Out) method,
A transfer control unit 14 that executes transfer control of compressed image data to and from the main bus, a state encoder 15 that detects write and read addresses to the image FIFO memory 13 and encodes the write state, and a state encoder 15 Based on the state table 16 used for encoding by the encoder, the encoded data by the state encoder 15 and the encoded data by the state encoder 25 (described later) on the audio compression unit 9 side [no DREQ] / [DREQ1] / [DREQ2]
Arbiter 17 that outputs the signal (data transfer request signal) of
The arbiter 17 includes an arbitration table 18 used when selectively outputting the DREQ signal, and the DREQ signal line of the arbiter 17 is also connected to the transfer control unit 14.

On the other hand, the audio compression unit 9 includes an input I / F 21 to which an audio signal is input, an audio encoding unit 22 for encoding the audio data received by the input I / F 21 by the MPEG system,
A transfer control unit 24 that executes transfer control of compressed audio data between the audio FIFO memory 23 that temporarily buffers encoded compressed audio data using the FIFO method and the main bus.
And a state encoder 25 that detects a write address and a read address to the voice FIFO memory 23 and encodes the write state, and a state table 26 used by the state encoder 25 for encoding. Is input to the arbiter 17 on the image compression unit 8 side, and the DREQ signal line of the arbiter 17 is also connected to the transfer control unit 24.

Further, the state tables 16 and 26 of the image compression unit 8 and the audio compression unit 9 have the structure shown in FIG. 2, and the total storage capacity of the FIFO memories 13 and 23 of the units 8 and 9 is the same. Write ratio to 0 (%) / 1 to 10 (%) / 1
It is divided into 1 to 80 (%) / 81 to 100 (%), and 2-bit state encoded data of "00" / "01" / "10" / "11" is associated with each write rate. Also,
The arbitration table 18 of the image compression unit 8 has a configuration as shown in FIG. 3, and includes an image FIFO memory 13 and an audio FIFO.
The code data of [no DREQ], [DREQ1], and [DREQ2] are associated with the binary relationship by the combination of each encoded data of the memory 23. Here, [no DREQ] indicates that there is no data transfer request, [DREQ1] indicates a data transfer request on the image compression unit 8 side, and [DREQ2] indicates a data transfer request on the audio compression unit 9 side. The DREQ signal must indicate the three types of status, but there is no DREQ / DREQ1
/ [DREQ2] is 2 for "11" / "10" / "01"
It can correspond to bit-encoded data.

In the above multimedia system configuration, when the recording mode is set from the operation unit 3 and the image signal and the audio signal are input to the image compression unit 8 and the audio compression unit 9, respectively, the following procedure is performed. Perform arbitration and data transfer operations. First, the image signal input to the image compression unit 8 is input to the image encoding unit 1 via the input I / F 11.
2 is input to the image coding unit 12, is subjected to compression processing by the MPEG method in the image coding unit 12, and is written in the image FIFO memory 13. The image signal input to the audio compression unit 9 is input I /
It is input to the voice encoding unit 22 via F21, and the voice encoding unit 22
A voice FIFO that has been compressed by the MPEG method at 22
Written to memory 23.

The state encoders 15 and 25 of each unit 8 and 9, the state tables 16 and 26, the arbiter 17 and the arbitration table 18 on the image compression unit 8 side execute the arbitration operation shown in the flowchart of FIG. Each state encoder 15,25 is always FIFO memory 1 of each unit 8,9
The write and read addresses of 3, 23 are detected, and the write rate of each FIFO memory 13, 23 is obtained based on the real-time write and read addresses (S1).
Further, each state encoder 15, 25 refers to each state table 16, 26, converts each write rate obtained above into state encode data and outputs it to the arbiter 17 (S
2). Therefore, for example, when the writing rate of the image FIFO memory 13 is in the range of 11 to 80% and the writing rate of the audio FIFO memory 23 is in the range of 1 to 10%, the state encoder 15 indicates “10”. State encoder 25 is "01"
Will be output.

On the other hand, the arbiter 17 receives each of the above state encode data, and immediately refers to the arbitration table 18 to output the data transfer request signal corresponding to the combination of each encode data to the DREQ signal line (S3). For example, in the above state, "10" is input from the state encoder 15 side.
Since "01" is received from the state encoder 25 side, the signal [DREQ1] ("10") is output. Since this arbitration operation (S1 to S3) is executed in real time, the DREQ signal of the arbiter 17 changes according to the write rate to the FIFO memories 13 and 23, and as shown in the table configuration of FIG. In the relative relationship between the input image data and the audio data, [DREQ1] is set when the image data is large, and [DREQ2] ("01" when the audio data is large). ) But both are 0
In the case of%, [No DREQ] ("11") is output. Incidentally, in the present embodiment, considering that the data amount of the image data is large in the normal signal input state, as is apparent from the table configuration of FIG. 3, the writing rates of the FIFO memories 13 and 23 are the same. If it belongs to the category, [DR
EQ1] is preferentially output.

Next, the data transfer operation in this multimedia system will be described with reference to the flowchart of FIG. As mentioned above, the arbiter 17 is an image FIFO.
[DREQ1], [DREQ2], or [No DREQ] based on the write rate of encoded data in the memory 13 and the voice FIFO memory 23
Is output (S10). Now from arbiter 17 to DREQ signal line
If [DREQ1] is output, DMAC10 will output [DRE1].
Based on the reception of [Q1], [BUSREQ] is output to the BUSREQ signal line, and the bus control unit 5 receives it (S11). Then, the bus control section 5 receives the permission of the CPU 1 and surrenders the main bus in the control state of the CPU 1 to the DMAC 10, and upon completion of the bus surrender operation, the DMAC is sent through the BUSACK signal line.
Return [BUSACK] to 10 (S12).

Upon receiving [BUSACK], the DMAC 10 completes the data transfer ready set.
A confirmation ACK signal is output to the K signal line (S14). However, in this case, since the data transfer ready is based on the [DREQ1] output of the arbiter 17, the data transfer ready relates to the transfer from the transfer control unit 14 on the image compression unit 8 side to the buffer memory 6, and the ACK.
The signal is [ACK1]. The type of the ACK signal output by the DMAC 10 is [ACK1] described above or [ACK2] based on [DREQ2] described below. However, including the state of [no ACK], [no ACK] / [ACK1] / [ACK2] is "11" / "10" /
It is indicated by 2-bit encoded data of "01".

By the way, the above [DREQ1] output from the arbiter 17 is also input to the transfer control units 14 and 24 of the image compression unit 8 and the audio compression unit 9, and [DREQ1]
In this case, the transfer control unit 14 prepares to read the compressed image data buffered in the image FIFO memory 13, and completes the preparation before receiving [ACK1]. Therefore, the transfer control unit 14 can immediately transfer the compressed image data in cooperation with the DMAC 10 when [ACK1] is received from the DMAC 10 via the ACK signal line.
MAC10 is a FI for image based on [DREQ1] received previously.
The compressed image data read from the FO memory 13 is sequentially transferred to the buffer memory 6 (S16).

If the arbiter 17 continuously outputs [DREQ1], the compressed image data will be accumulated in the image data area of the buffer memory 6 (S15 to S17 → S15),
The DMAC 10 monitors the write state to the data area based on the data transfer amount, and when the data area becomes the FULL state, the recording transfer mode is once set and stored in the image data area of the buffer memory 6. Transfer the compressed image data of a specified number of data blocks to the HDC 7a, and
The data is recorded on the disc by 7 (S16 → S30, S31). Also,
When the transfer of the compressed image data in the recording transfer mode is completed and the DREQ signal remains unchanged, the transfer control unit 14
To the data transfer state from the buffer memory to the buffer memory 6 (S31 → S
17 → S15).

On the other hand, the DREQ output of the arbiter 17 changes and DR
When [DREQ2] is output to the EQ signal line, the bus control unit 5 executes DMA in the same procedure as the above-mentioned transfer of compressed image data.
The bus is released to C10 and the DMAC10 performs the data transfer ready set. In this case, the DMAC10 outputs [ACK2] to the ACK signal line (S10 → S21 to S24). Also, arbiter
Upon receiving [DREQ2] from 17, the transfer control unit 24 on the audio compression unit 9 side completes the preparation for reading and transferring the compressed audio data buffered in the audio FIFO memory 23.

After the output of [ACK2] by the DMAC10, the DMAC is output in the same manner as in the case of the transfer of the compressed image data.
10 and the transfer control unit 24 work together to transfer the compressed audio data of the audio FIFO memory 23 to the audio data area of the buffer memory 6 (S25). Furthermore, the audio data area of the buffer memory 6
In the case of FULL status, the procedure (S26 → S30, S31 → S27 → S25) related to [Recording transfer mode setting], [Recording by transferring the specified number of data blocks] and [Returning to the original status] is also This is similar to the above-described transfer of the compressed image data, and the description thereof will be omitted here.

In addition, the DREQ signal of the arbiter 17 is [no DREQ].
However, as is clear from the configuration of the state table of FIG. 2 and the arbitration table of FIG. 3, the [no DREQ] is stored in the FIFO memories 13 and 23 of the image compression unit 8 and the audio compression unit 9 respectively. Corresponding to the state of not accumulating, DM
The AC 10 does not output the BUSREQ signal in the reception state of [no DREQ], and the bus is placed in the management state of the CPU 1 to execute another mode.

As described above, in the multimedia system according to the present embodiment, the state encoders 15 and 25 use the state tables 16 and 26 to divide the real-time data amount of the compressed image data and the compressed audio data into ranges. After checking, the arbiter 17 preferentially transfers to the buffer memory 6 a data type having a large data amount based on the configuration of the arbitration table 18. Therefore, the adaptive data transfer control can always realize a well-balanced data transfer, and the data transfer efficiency is not deteriorated even in the input state where the data amount of one data is extremely larger than the other data. Further, it is possible to prevent a situation in which the data amount of specific input data in a certain time exceeds the allowance of each of the FIFO memories 13 and 23 to cause data loss.

In this embodiment, the transfer of image data and audio data is explained, but the input MID
Even in the case where a unit for buffering I data and transferring it to the buffer memory 6 is also provided,
The above data transfer method can be extended and applied. However,
In that case, a circuit for inputting state encoded data from the MIDI unit is added to the arbiter 17, and the arbitration table 18 has a ternary structure in which the encoded data is also taken into consideration. The transfer request [DREQ3] is also output. In this embodiment, the arbiter 1 is added to the image compression unit 8.
Although 7 and the arbitration table 18 are built in, these functions are not related to the data compression operation, and a method of incorporating them in another unit such as the voice compression unit 9 or a method of configuring them as an independent unit can be adopted.

Further, in the present embodiment, the data transfer method of the present invention has been described for the recording system of the multimedia system, but the same idea can be applied to the reproducing system. In that case, regarding the image data area and the audio data area of the buffer memory 6 in which the image data and the audio data transferred from the HDD 7 side are written, respectively,
The write rate is detected with the same configuration as [State encoders 15 and 25 and state tables 16 and 26], and the DREQ signal corresponding to the buffering state is created with [Arbiter 17 and Arbitration table 18], and DMAC 6 sets the buffer memory. Data transfer from 6 to the image reproduction unit or the audio reproduction unit will be selectively executed.

[0032]

The "multimedia data transfer method" of the present invention has the following effects due to the above configuration. According to the first aspect of the invention, the priority order of data transfer is not fixedly determined according to the data type, but the data to be transferred is adaptively given the highest priority in accordance with the input state of each data. It enables to transfer each data in a well-balanced and efficient manner. Therefore, in the time period when the input data amount of a specific data type becomes much larger than other data types, a situation in which only the data transfer of the specific data type is greatly delayed, It is possible to prevent such a situation that the input rate of the data exceeds the allowance of the buffer means and the data is lost. Further, in the conventional technology, each I / O to D
Output a data transfer request to the MAC (data transfer means) and D
Although the MAC has a configuration having an arbitration function as well, in the present invention, the arbitration means gives the determination information (data transfer request) of the buffer means to execute the data transfer with the highest priority to the data transfer means by the signal circuit of one system. Since the notification is given, the load on the data transfer means can be reduced. According to the invention of claim 2, the occupancy rate of the write data of each buffer means is divided by a plurality of threshold values, the same state is considered within the division range, and each state can be detected by the code data. In addition to simplifying the arbitration procedure, the transfer data is frequently switched and the data transfer efficiency is lowered when the write data occupancy in each buffer means changes in a similar value. It is possible to prevent such problems. Further, since the division according to the threshold value can be changed in a programmable manner, there is also an advantage that adjustment for realizing optimum data transfer control becomes easy.

[Brief description of drawings]

FIG. 1 is a system circuit diagram showing a recording system of a multimedia system that implements a “multimedia data transfer method” of the present invention.

FIG. 2 is a diagram showing a configuration of a state table.

FIG. 3 is a diagram showing a configuration of an arbitration table.

FIG. 4 is a flowchart showing an arbitration operation procedure.

FIG. 5 is a flowchart showing a data transfer operation.

FIG. 6 is a system circuit diagram of a conventional multimedia recorder.

[Explanation of symbols]

1 ... CPU, 2 ... ROM / RAM, 3 ... operation section, 3a ... operation I / F, 4 ... display section, 4a ... display I / F, 5 ... bus control section, 6
... audio / image buffer memory, 7,57 ... HDD (hard disk device), 7a, 57a ... HDC (hard disk controller), 8 ... image compression unit, 9 ... audio compression unit, 1
0,61 ... DMAC (DMA controller) [61: Data transfer means], 11, 21 ... Input I / F, 12 ... Image encoding unit, 13 ... Image FIFO memory [buffer means], 14, 24 ... Transfer control Part [Data transfer means], 15,25 ... State encoder [Detection means],
16, 26 ... State table [detection means], 17 ... Arbiter [arbitration means], 18 ... Arbitration table [arbitration means], 22 ... Voice coding unit, 23 ... Voice FIFO memory [buffer means], 56 ... Voice / Image / MIDI buffer memory, 58 ... Image I / O (input / output I / F), 59 ... MIDI-I / O (input / output I / F), 60 ... Audio I / O (input / output I / F).

Claims (2)

[Claims] 1. Buffer means for temporarily storing a plurality of input data of different types in data types, detection means for detecting the occupied state of write data in each buffer means in real time, and An arbitration unit that determines a buffer unit for which data transfer should be given the highest priority based on the occupation state detected by the detection unit is provided, and the data transfer unit transfers the write data of the buffer unit determined by the arbitration unit to the transfer destination. A method of transferring multimedia data characterized by transferring. 2. Each detecting means obtains an occupancy rate of write data in a corresponding buffer means, determines which range divided by a plurality of threshold values the obtained occupancy rate belongs to, and the determination result is obtained. Based on the output state of the encoded data of each of the detection means, the arbitration means determines the buffer means to which the data transfer is given the highest priority. The method of transferring multimedia data according to claim 1, which is a means.