KR20070032325A - Digital data recording device and recording method - Google Patents

Abstract

In the case where digital data of variable bit rate is recorded in a continuous area for each unit period, generation of fragmentation is suppressed. When the data amount of the buffer memory is equal to or greater than the unit period, the digital data of the buffer memory is read out for each unit period, and the read digital data is recorded as a continuous area (step 106). If the amount of data in the buffer memory is less than the unit period, the data amount is predicted from the time corresponding to the data amount of the digital data less than the unit period and the length of the unit period (step 112). The digital data of the unit period is recorded in the recordable area in which the digital data of the predicted data amount can be continuously recorded (step 106).

Digital data

Description

Digital data recording device and recording method {DIGITAL DATA RECORDING DEVICE AND RECORDING METHOD}

The present invention relates to a recording apparatus and a recording method of digital data.

In a minidisc (registered trademark) used for recording and reproducing digital audio data, one cluster is formed for each predetermined amount of digital data, and the one cluster is a recording unit on the disk.

In such a system, a system is proposed in which a period of about 10 to 20 seconds is assumed to be one unit, and recording is performed such that the digital data in this unit period occupies a continuous area on the disc.

3 is for explaining a signal processing method of such a system, the video signal and the audio signal, for example, as shown in FIG. 3A, the digital data (program) of MPEG2 (Motion Picture Experts Group Phase 2) method Stream) (DM). This data DM is sequentially written to the buffer memory as shown in FIG. 3B, and intermittently read out as data DR as shown in FIG. 3C.

In this case, the data DR divides the MPEG (Motion Picture Experts Group) data DM for each unit period TUNIT, and the data for each unit period TUNIT is time-base-compressed for each period TREC and fixed. The signal read at speed. At this time, the unit period (TUNIT) is any length of 10 to 20 seconds. The length of the unit period TUNIT may be changed during one recording, but in general, the unit period TUNIT is fixed during at least one recording in order to avoid complicated systems and controls. .

The period TREC is a period in which the read data #n is recorded on the disc, and it will be apparent from the following description, but the length of the period TREC is not constant. Further, the period between one period TREC and the next period TREC becomes the seek period of the recording head or the pause period of recording. The data DM for each period TUNIT or the data DR for each period TREC are referred to as data #n (n = 1, 2, 3, ...).

Then, a write modulation process is performed on the data DR read out from the buffer memory, and the data DR subjected to this modulation process is a disk in the order of data # 1, # 2, # 3, ... Is written on.

In addition, since the MPEG data DM has a variable bit rate and the length of the unit period TUNIT is constant, the data amount (data size) of the data #n included in the unit period TUNIT is the period ( TUNIT) changes in response to the contents of video and audio. When the MPEG data DM is read out as the data DR every recording period TREC and recorded on the disc, the bit rate of the data DR is constant, so that the length of the recording period TREC is the period. It changes in correspondence with the contents of the data DR in TREC. In addition, the size of the recording area corresponding to one recording period TREC changes in correspondence with the contents of the data #n in the period TREC.

FIG. 4A shows an aspect in which the data amount (data remaining amount) DBUF of the buffer memory shown in FIG. 3 changes, and FIG. 4B shows an aspect of writing to the disc. In addition, since bad sectors are generated on the disc or recording or erasing is repeated, if an old recording section is fragmented, an area that cannot be used for recording is generated. Indicates an area that cannot be used. In addition, an area without a sign and a symbol is a recordable area.

In FIG. 4A, when the start of recording is instructed from the time point t0, the recording head seeks to the start position of the first recordable area on the disc, and the MPEG data (DM) from the time point t0 to the buffer memory (DM). ) Recording begins. Therefore, the data amount DBUF in the buffer memory gradually increases from the time point t0. In addition, this increase rate is not constant because the data DM is a variable bit rate.

When the data amount DBUF reaches the upper limit DLIM of the buffer memory from the time point t1, the data DM of the buffer memory is read out as the data # 1 of the data DR from the time point t1. Therefore, the data amount DBUF gradually decreases from the time point t1. In reality, data DM is recorded continuously even after the period t1.

When the data # 1 for one unit period TUNIT is read from the time point t2, the reading is finished once, and thus the data amount DBUF gradually increases again from the time point t2.

On the other hand, the periods t1 to t2 are also the recording period TREC, and the data # 1 read out from the buffer memory in the periods t1 to t2 is a disk as a continuous area as shown in Fig. 4B. It is recorded in

When the reading of the data # 1 from the buffer memory is finished from the time point t2, the area of the area necessary for writing the data # 2 is written from the data amount of the next data # 2 in the buffer memory. The size is calculated, and in the periods t2 to t3, the recording head is seeked to the recordable area that satisfies the size of the calculated area.

When the seek of the recording head ends from the time point t3, similarly to the time point t1, the data # 2 of the buffer memory is read from the time point t3 and recorded on the disc. Therefore, the data amount DBUF gradually decreases from the time point t3.

In this way, processing similar to the processing in the periods t1 to t2 to t3 is repeated in the periods t3 to t4 to t5 so that the data # 2 is recorded on the disc, and the periods t5 to t6 to Repeated at t7), the data # 3 is recorded on the disc.

When the time t7 is reached, the reading of the data # 4 and the writing to the disc are started. However, in the case of Fig. 4, since the data amount DBUF of the data # 4 remaining in the buffer memory at time t7 is less than one unit period TUNIT, the data in the buffer memory at time t8. The amount DBUF becomes zero. For this reason, at the time point t8, the reading of the data # 4 from the buffer memory and the writing of the data # 4 to the disk are stopped once. Therefore, only the front part # 4A of data # 4 is recorded. From the time point t8, the data amount DBUF of the buffer memory increases again.

When the data amount DBUF reaches the upper limit DLIM of the buffer memory at the time point t9, the remaining portion # 4B of the data # 4 is read from the buffer memory, and the remaining portion (# 4B) is recorded on the disc so as to continue in the area of the front portion # 4A recorded in the periods t7 to t8. Therefore, as shown in FIG. 4A, the reading of the data # 4 is divided in time, but as shown in FIG. 4B, the area in which the data # 4 is recorded is continuous.

Then, when the remaining portion # 4B of the data # 4 and the writing to the disk are finished at the time point t10, the processing after the time point t2 is repeated. Therefore, the data DR, that is, the MPEG data DM, is recorded on the disc as one continuous area every one unit period TUNIT.

The above is the reading and writing of the data DR viewed from the buffer memory, and the aspect of writing to the disk. Therefore, in the above-described system, recording is performed so that MPEG data in this unit period TUNIT occupies a continuous area on the disc, in units of a period TUNIT of about 10 to 20 seconds.

Therefore, according to the system described above, during recording, the period TREC for recording to the disc becomes intermittent, and the disc drive can be stopped in the periods t0 to t1, t8 to t9, and so on. The average power consumption required for a drive can be reduced, and a recording device using a battery as a power source, for example, a video camera-integrated recorder, can lengthen the shooting and recording time.

In addition, since the length of the unit period (TUNIT) is fixed and the area on the disc corresponding to one unit period (TUNIT) is continuous, the playback head can be reliably squeezed during playback (and recording). Since the video signal and the audio signal can be obtained continuously at the connection portion of the unit period (TUNIT), video and audio can be reproduced seamlessly at the connection portion.

Moreover, as a prior art document, Unexamined-Japanese-Patent No. 5-54518 is mentioned, for example.

By the way, for example, in the case of the time point t1, since the MPEG data DM is accumulated for one unit period TUNIT or more in the buffer memory, the data amount of the data # 1 is detected as described above. It is sufficient to calculate the size of the area necessary for recording the data # 1, and then seek the recording head to a recordable area that satisfies the size of the calculated area. This also applies to the time points t4, t6, t10 and the like.

However, at the time point t6, for example, since the data # 4 in the buffer memory is less than one unit period TUNIT, the total data amount of the data # 4 is not clear. For this reason, when data # 4 is recorded, the process as shown in FIG. 5 is performed. That is, first, the maximum amount of data that can be taken in one unit period (TUNIT) is assumed, and as shown in Fig. 5A, the size (SBLK) of the recordable area necessary for recording the maximum amount of data is obtained. .

In the case of FIG. 5B, the size of the recordable area ABLK_A following the recorded area of the data # 3 is smaller than the required size of the recordable area SBLK. Then, the recording head is seeked into the recordable area ABLK_B larger than the required size SBLK, and as shown in Fig. 5C, data # 4A is recorded in the recordable area ABLK_B, and thereafter. , Data # 4B is recorded, and then data # 5 and subsequent are recorded in order.

Therefore, as shown in Fig. 5C, even when the size of the area required for actually recording the data # 4 is smaller than the recordable area ABLK_A, the recordable area ABLK_A is used to record the data # 4. It will not be used for.

As a result, if the state where the data amount DBUF of the buffer memory is less than one unit period TUNIT is repeated as in the time point t6, an area which cannot be used for writing increases, and the actual usable space on the disk is increased. Area decreases. In addition, since MPEG data DR is divided and recorded more than necessary, the number of seeks at the time of recording increases, and as a result, the number of seeks at the time of reproduction also increases.

In addition, even when the recordable area ABLK_A is configured to be used for other recordings, unnecessary seeks are generated during the recording, power consumption increases, and seeks that are not necessary even during reproduction are generated. In addition, the power consumption during reproduction also increases.

Thus, in the case of Fig. 4A, even when the time point t7 is reached, the remaining portion # 4B of the data # 4 to the buffer memory is not started to be read and written to the data # 4 (front part # 4A). If the data amount DBUF of the buffer memory reaches the upper limit DLIM as in the time point t1, the data read # 4 from the buffer memory and the disk are read out as in the time point t1. It is considered to start recording. In this case, since the required area can be obtained from the data amount of data #n actually recorded, the recordable area can be effectively used.

However, in this method, for example, the data amount DBUF of the buffer memory at the time point t6 may be almost equal to the maximum value of the data amount in one unit period TUNIT in some cases. When the data rate of MPEG data is high, the data amount DBUF changes in a range from a value close to the maximum value of the data amount in one unit period TUNIT to an upper limit DLIM. The capacity of the memory becomes small.

The present invention is intended to solve the above problems.

In the present invention,

A buffer memory in which digital data of variable bit rate is recorded, and the recorded digital data is intermittently read;

A recording head for recording the digital data read out from the buffer memory onto a disc;

And a control circuit for controlling the recording position when recording the digital data read out from the buffer memory onto the disc,

This control circuit,

When the data amount of digital data in the buffer memory is longer than a unit period,

While reading the digital data in the buffer memory by the unit period,

Seeking the recording head to a recordable area capable of recording the read digital data as a continuous area,

The read digital data is recorded in the recordable area of the signature as a continuous area for each unit period,

When the data amount of the digital data in the buffer memory is less than the unit period,

Predicting the data amount of the digital data in the unit period including the digital data less than the unit period from the time corresponding to the data amount of the digital data less than the unit period, and the length of the unit period; together,

Seeking the recording head to a recordable area capable of continuously recording digital data of the predicted data amount,

The digital data of the data amount less than the unit period is recorded in the recordable area of the signature,

Subsequent to this recording portion, the digital data recording apparatus is configured to record the remaining digital data of the unit period including the digital data less than the unit period.

Also,

While recording the digital data of variable bit rate in the buffer memory, the recorded digital data is intermittently read out,

In the case of supplying the digital data read out from the buffer memory to the recording head and recording on the disk,

When the data amount of digital data in the buffer memory is longer than a unit period,

While reading the digital data in the buffer memory by the unit period,

Seeking the recording head to a recordable area capable of recording the read digital data as a continuous area,

The read digital data is recorded in the recordable area of the signature as a continuous area for each unit period,

When the data amount of the digital data in the buffer memory is less than the unit period,

DPRE = DBUF + (TUNIT-TBUF) × BMAX

     DPRE: Estimated amount of data

     DBUF: Data amount of data remaining in the buffer memory

     TUNIT: the length of the unit period

     TBUF: reproduction time of data remaining in the buffer memory

     BMAX: maximum bit rate of the digital data

By predicting the data amount DPRE of the digital data in the unit period including the digital data less than the unit period,

Seeking the recording head to a recordable area capable of continuously recording the digital data of the predicted data amount DPRE,

The digital data of the data amount less than the unit period is recorded in the recordable area of the signature,

Subsequent to this recording portion, the digital data recording method is such that the remaining digital data of the unit period including the digital data less than the unit period is recorded.

According to the present invention, for example, when the data amount of digital data in the buffer memory is less than the unit period, for example, data # 4, the data in the unit period is taken into consideration in consideration of the time corresponding to the data amount. Since the amount is estimated and the recording head is seeked from the prediction result to the required recordable area, the disk can be used effectively.

In addition, since the recordable area is effectively used from the beginning, the number of seeks at the time of recording is reduced, and as a result, the number of seeks at the time of reproduction is also reduced, so that the recording time and the reproduction time can be lengthened in a device using a battery. have. In addition, the entire capacity of the buffer memory can be effectively used.

1 is a system diagram showing one embodiment of the present invention.

2 is a flow chart showing one embodiment of the present invention.

3 is a view for explaining the present invention.

4 is a view for explaining the present invention.

5 is a view for explaining the present invention.

1 shows an example of a recording apparatus according to the present invention. The digital video signal and the digital audio signal are supplied to the video encoder 12V and the audio encoder 12A through the input terminals 11V and 11A and encoded in digital data (elementary stream), for example, in the MPEG2 system. do. The encoded output is supplied to the multiplexer 13 and multiplexed into one MPEG2 digital data (program stream) DM, and the multiplexer 13 is, for example, as shown in Fig. 3A. MPEG data DM are continuously taken out.

As shown in Fig. 4A, for example, the MPEG data DM is recorded in the buffer memory 14 and sequentially read as the data DR, and the read data DR is modulated. It is supplied to the circuit 15 to perform a modulation for recording to become a recording signal. This recording signal is supplied to the recording head 16, and is recorded on the disk 19, for example, as shown in FIG. 4B.

In addition, in order to realize the above process, the drive control unit 17 is provided, and a system controller 18 constituted by a microcomputer is provided. The recording position of the recording head 16 with respect to the disc 19 is controlled by the system controller 18 via the drive control unit 17. In this example, the system controller 18 also has the function of a memory controller, and the system controller 18 controls the writing of the data DM and the reading of the data DR in the buffer memory 14. .

In addition, the multiplexer 13 and the modulation circuit 15 are also controlled by the system controller 18 corresponding to the data DM, DR. The recordable area of the disk 19 and the area which cannot be used for recording are grasped and managed by the system controller 18, and are recorded on the disk 19 when the management information changes.

In this manner, the digital video signal and the digital audio signal are recorded on the disc 19.

The system controller 18 is provided with, for example, a recording routine 100 shown in FIG. 2 as part of a program executed by the microcomputer constituting this. This writing routine 100 is executed for each recording of data #n, and can be appropriately written even when the data amount DBUF of the buffer memory 14 is less than one unit period TUNIT as in the time point t6. Seeking to the area is realized.

That is, when it is the end point of the previous recording period TREC such as the time points t2, t4, t6, t10, and the like, the processing of the microcomputer constituting the system controller 18 is executed in step 101 of the routine 100. From then on, in step 102, it is determined whether or not the data amount DBUF of the buffer memory 14 is equal to or greater than one unit period TUNIT minutes.

When the data amount DBUF of the buffer memory 14 is equal to or greater than one unit period TUNIT minutes, such as the time points t2 and t4, the process proceeds from step 102 to step 103, and in this step 103, The data amount of the data #n for the first one unit period TUNIT of the data DM of the buffer memory 14 is calculated.

Subsequently, in step 104, on the basis of the management information of the disk 19 managed by the system controller 18, it is possible to continuously record data (#n) of the data amount calculated in step 103. The area is searched, and then in step 105, the recording head 16 is seeked to the recordable area searched by step 104.

Then, in step 106, the data (#n) whose data amount is calculated in step 103 is recorded as the continuous area in the recordable area seeked in step 105, and then the routine 100 in step 107. To exit. The end points are the time points t2 and t4 and the like.

In this way, for example, data # 1, # 2, # 3 are recorded on the disk 19 so that each is one continuous area.

On the other hand, in step 102, when the data amount DBUF of the buffer memory 14 is less than one unit period TUNIT, as in the time point t6, the process proceeds from step 102 to step 111, and this step At 111, the data amount DBUF of the data DM remaining in the buffer memory 14 is calculated.

Next, in step 112, in the case of Fig. 4, the data amount of data # 4 is predicted by the equation (1). That is, the data amount DPRE of the unit period TUNIT to which the data #n remaining in the buffer memory 14 belongs is predicted according to the expression (1).

DPRE = DBUF + (TUNIT-TBUF) × BMAX. … … (One)

     DPRE: Estimated amount of data

     DBUF: Data amount of data remaining in buffer memory 14

     TUNIT: Length of one unit period (any one of 10 to 20 seconds)

     TBUF: reproduction time of data remaining in the buffer memory 14

     BMAX: Maximum Bit Rate of Digital Data (DM)

In this case, the data amount DBUF can be obtained, for example, from the difference between the write address and the read address for the buffer memory 14. The reproduction time TBUF can be obtained from a stream of data stored in the buffer memory 14, and for example, the number of frames may be counted by detecting a header of an image in the stream. In addition, the length TUNIT and the maximum bit rate BMAX of one unit period are values previously given to the system controller 18.

The process proceeds to Step 104 after Step 112, in which a recordable area capable of continuously recording data of the data amount DPRE predicted by Step 112 is searched, and then Step Step At 105, the recording head 16 is seeked to the recordable area searched by step 104.

Subsequently, in step 106, the data remaining in the buffer memory 14, in this case, the front part # 4A of the data # 4 is recorded in the recordable area seeked by step 105, and then, The remaining part # 4B is recorded so as to continue as one area, and the routine 100 ends by step 107.

Therefore, for example, data # 4 is recorded on the disk 19 so as to be one continuous area.

Since the routine 100 is executed for each data #n, the data DR, that is, the MPEG data DM, is recorded on the disk 19 as shown in FIG. 4, for example. . In addition, during this recording, the management information of the area recorded on the disk 19 is updated by the system controller 18 in response to the processing of the routine 100.

In this way, according to the above-described recording apparatus, MPEG data DM can be recorded on the disk 19. In addition, reproduction can be realized by a process complementary to the above-described recording. That is, in accordance with the management information recorded on the disk 19, the recording signal is intermittently reproduced from the disk 19 in the order of data #n, and the data DR is demodulated from the reproduced recording signal. The data may be sequentially recorded in the buffer memory, and the recorded data DR may be continuously read as the MPEG data DM.

As described above, according to the above-described recording apparatus, MPEG data DM can be recorded on the disc 19. In that case, in particular, according to the above-described recording apparatus, for example, like the data # 4, When one unit period TUNIT is not accumulated in the buffer memory 14 at the start time t6 of recording, the disk 19 is effective because the data amount DPRE is predicted according to equation (1). Can be used.

That is, in the case of the method shown in Fig. 5, for example, as the data # 4, the maximum data amount in one unit period TUNIT is predicted. Since the maximum data amount is predicted only in the unknown data portion # 4B in 4), the prediction data amount DPRE for the data # 4 is predicted in the case of the method shown in FIG. It becomes smaller than the data amount.

Therefore, since the predicted size (size) of the area necessary for recording the data # 4 is also less than the predicted value in the case of the method shown in FIG. 5, the data # 4 can be recorded, for example, in FIG. 5B. The probability of writing in the area ABLK_A increases. That is, in the method shown in Fig. 5, the probability of writing data DR for one unit period TUNIT in the unusable recordable area becomes high. As a result, since the recording is effectively performed even in the short recordable area, the disk 19 can be used effectively.

In addition, since the recordable area ABLK_A is effectively used from the beginning, the number of seeks at the time of recording is reduced, and as a result, the number of seeks at the time of reproduction is also reduced. I can lengthen it.

In addition, since the data amount DBUF of the buffer memory 14 varies from the minimum value 0 to the upper limit value DLIM, the entire capacity of the buffer memory 14 can be effectively used. In addition, the data DM for one unit period TUNIT cannot enter the buffer memory 14 completely due to the high bit rate of the data DR and the small capacity of the buffer memory 14. Even in this case, the full capacity of the buffer memory 14 can be effectively used.

In the above description, the disk 19 may be an optical disk such as a DVD-R (DVD Recordable) or a Blu-ray disk, or may be a magneto-optical disk such as a magneto-optical disk (MO). In the case where data of variable bit rate is recorded on the disc by unit time, the present invention can be applied regardless of the contents of the data to be recorded, the format of the signal, the type of the disc, the method of managing the data on the disc, and the like.

Claims (4)

A buffer memory in which digital data of variable bit rate is recorded, and the recorded digital data is intermittently read; A recording head for recording the digital data read out from the buffer memory onto a disc; And a control circuit for controlling the recording position when recording the digital data read out from the buffer memory onto the disc, This control circuit, When the data amount of digital data in the buffer memory is longer than a unit period, While reading the digital data in the buffer memory by the unit period, Seeking the recording head to a recordable area capable of recording the read digital data as a continuous area, The read digital data is recorded in the recordable area of the signature as a continuous area for each unit period, When the data amount of the digital data in the buffer memory is less than the unit period, From the time corresponding to the data amount of the digital data less than the unit period and the length of the unit period, the data amount of the digital data in the unit period including the digital data less than the unit period is predicted. with, Seeking the recording head to a recordable area capable of continuously recording digital data of the predicted data amount, The digital data of the data amount less than the unit period is recorded in the recordable area of the signature, And recording the remaining digital data of the unit period including the digital data less than the unit period following the recording portion. A buffer memory in which digital data of variable bit rate is recorded, and the recorded digital data is intermittently read; A recording head for recording the digital data read out from the buffer memory onto a disc; And a control circuit for controlling the recording position when recording the digital data read out from the buffer memory onto the disc, This control circuit, When the data amount of digital data in the buffer memory is longer than a unit period, With reading the digital data in the buffer memory by the unit period, Seeking the recording head to a recordable area capable of recording the read digital data as a continuous area, The read digital data is recorded in the recordable area of the signature as a continuous area for each unit period, When the data amount of the digital data in the buffer memory is less than the unit period, DPRE = DBUF + (TUNIT-TBUF) × BMAX      DPRE: Estimated amount of data      DBUF: Data amount of data remaining in the buffer memory      TUNIT: the length of the unit period      TBUF: reproduction time of data remaining in the buffer memory      BMAX: maximum bit rate of the digital data By predicting the data amount DPRE of the digital data in the unit period including the digital data less than the unit period, Seeking the recording head to a recordable area capable of continuously recording the digital data of the predicted data amount DPRE, The digital data of the data amount less than the unit period is recorded in the recordable area of the signature, And the remaining digital data of the unit period including the digital data less than the unit period is recorded in the recording portion. While recording the digital data of variable bit rate in the buffer memory, the recorded digital data is intermittently read out, In the case of supplying the digital data read out from the buffer memory to the recording head and recording on the disk, When the data amount of digital data in the buffer memory is longer than a unit period, While reading the digital data in the buffer memory by the unit period, Seeking the recording head to a recordable area capable of recording the read digital data as a continuous area, The read digital data is recorded in the recordable area of the signature as a continuous area for each unit period, When the data amount of the digital data in the buffer memory is less than the unit period, Predicting the data amount of the digital data in the unit period including the digital data less than the unit period from the time corresponding to the data amount of the digital data less than the unit period, and the length of the unit period; together, Seeking the recording head to a recordable area capable of continuously recording digital data of the predicted data amount, The digital data of the data amount less than the unit period is recorded in the recordable area of the signature, And the remaining digital data of the unit period including the digital data less than the unit period is recorded in the recording portion. While recording the digital data of variable bit rate in the buffer memory, the recorded digital data is read at a constant speed and intermittently, In the case of supplying the digital data read out from the buffer memory to the recording head and recording on the disk, When the data amount of digital data in the buffer memory is longer than a unit period, While reading the digital data in the buffer memory by the unit period, Seeking the recording head to a recordable area capable of recording the read digital data as a continuous area, The read digital data is recorded in the recordable area of the signature as a continuous area for each unit period, When the data amount of the digital data in the buffer memory is less than the unit period, DPRE = DBUF + (TUNIT-TBUF) × BMAX      DPRE: Estimated amount of data      DBUF: Data amount of data remaining in the buffer memory      TUNIT: the length of the unit period      TBUF: reproduction time of data remaining in the buffer memory      BMAX: maximum bit rate of the digital data By predicting the data amount DPRE of the digital data in the unit period including the digital data less than the unit period, Seeking the recording head to a recordable area capable of continuously recording the digital data of the predicted data amount DPRE, The digital data of the data amount less than the unit period is recorded in the recordable area of the signature, And the remaining digital data of the unit period including the digital data less than the unit period is recorded in the recording portion.

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