JP2008034924A - Video decoder and mobile digital broadcasting receiver provided with the video decoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video decoder power, the consumption of which can be reduced to the utmost, while ensuring image display with natural motion for a program, such as a sports program where display of motion is important. <P>SOLUTION: A received program recognition means recognizes the type of a received program, a frame type limit means limits decode processing of frames of a setting type, only during reception of a program of a prescribed kind on the basis of power saving settings so as to reduce the power consumption of the video decoder 11; and this results in the power consumption being reduced to the utmost, while ensuring the image display of natural motions for the programs, such as sports programs where display of motion is important. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a video decoder for receiving digital television broadcasts and a portable digital broadcast receiver including the video decoder, and more particularly to a novel power saving structure thereof.

  Conventionally, digital television broadcasting such as so-called terrestrial digital broadcasting (high-definition broadcasting) and one-segment broadcasting is H.264. H.264 / MPEG-4 AVC or H.264. H.264 / AVC. The data is compressed by H.264 image compression or MPEG-2 image compression and transmitted wirelessly or by wire.

  A digital broadcast receiver that receives this type of digital television broadcast demodulates the digital RF signal received by the tuner into baseband digital reception information by a digital demodulator, and demultiplexes MPEG2 into the digital reception information. Processing is performed to separate the multiplexed video, audio, and additional information into individual streams (transport streams).

  Furthermore, the video decoder, audio decoder, and data decoder for receiving digital TV broadcasts synchronize each stream with time based on the time information of each stream, etc. Decode and play the data.

  At this time, a video stream of video (mainly video) is distributed in units of GOP (Group of pictures), each GOP includes three types of frames called I picture, B picture, and P picture. A picture frame is decoded independently, a B picture frame is decoded by predicting motion from the previous and past (past and future) frames, and a P picture is predicted by moving from the previous (past) frame. Decode it.

  Then, the digital data of the video of the received program decoded and reproduced by the video decoder is sent as it is or converted into an analog signal and sent to the display processing unit at the subsequent stage, and the video of the received program is displayed on the liquid crystal display by this display processing unit. Display on a screen display device such as a plasma display or a CRT.

  In many cases, the digital TV broadcast receiving decoder is formed by software processing of a dedicated IC or a microcomputer.

  By the way, this type of digital broadcast receiver includes not only a stationary type operating with a commercial power supply but also a portable type operating with a battery.

  In addition, it is desired that the digital broadcasting receiver of either a stationary type or a portable type be configured to save power as much as possible, and a built-in video decoder (actually the dedicated IC or microcomputer forming this decoder) It is important to save power.

  Especially in the case of portable digital broadcast receivers, the ratio of the power consumption of the video decoder to the power consumption of the entire receiver is larger than that of a stationary type relatively large screen. Therefore, the power saving of the video decoder contributes greatly.

  Therefore, in this type of portable digital broadcast receiver, when the battery power level (voltage) falls to the set threshold, the video decoder power consumption is reduced by suppressing the rate of decoding video frames (frame rate). It has been proposed to reduce the power consumption of the battery power supply (see, for example, Patent Document 1).

  Further, in this kind of portable digital broadcast receiver, when the remaining battery power is low, it is proposed to reduce the power consumption of the battery power by lowering the frequency of the operation clock of the video decoder (for example, (See Patent Document 2).

Furthermore, in a simple decoded image monitor apparatus equipped with a similar video decoder, the power consumption of the battery power supply is detected by detecting the appearance of an I frame and decoding only the I frame and not decoding the video frame except for the I frame. Has been proposed (see, for example, Patent Document 3).
JP 2005-223454 A (abstract, claim 1, paragraphs [0015]-[0022], FIG. 1, FIG. 2, etc.) JP 2003-204493 A (claim 8, paragraphs [0067]-[0071], FIG. 16, FIG. 17, etc.) JP 2004-23173 A (abstract, claim 8, paragraphs [0039]-[0040], [0063], FIG. 1, etc.)

  As described in Patent Document 1, in a power saving configuration in which frames for decoding received video are thinned out only based on a decrease in battery power level and the power consumption of the video decoder is reduced, if the battery power level decreases, Even for programs such as programs whose motion display is important, frames to be decoded are thinned out, and only intermittent and unnatural motion screen display can be performed, and there is a problem that the video display performance of the decoded output of the video decoder is remarkably deteriorated. .

  Further, when the operation clock frequency of the video decoder is lowered as described in Patent Document 2, as a result, a frame of a moving image to be decoded is thinned out.

  For this reason, the power saving configuration described in Patent Document 2 is substantially the same as the power saving configuration described in Patent Document 1, and the level of the battery power supply is reduced even in the power saving configuration described in Patent Document 2. As a result, even for programs such as sports programs in which motion display is important, only intermittent and unnatural screen display can be performed, and there is a problem that the video display performance of the decoded output is significantly lowered.

  Further, as described in Patent Document 3, in the power saving configuration that unconditionally selects and decodes only the I frame and reduces the power consumption of the battery power source, only the I frame is obtained even when the battery power source is sufficient. In addition, there is a problem that decoding is performed by thinning out, and in addition, only intermittent and unnatural motion screen display can be performed in programs where movement display is important, such as sports programs, and the video display performance of the decoded output is significantly reduced. There is also a problem to do.

  The present invention relates to a novel video decoder for saving power as much as possible while ensuring a natural motion screen display for a program in which motion display is important, such as a sports program, and a portable digital equipped with the video decoder. An object is to provide a broadcast receiver. In the present application, the “digital broadcast receiver” includes those equipped with a video recording / reproducing apparatus such as an HDD or a DVD.

  In order to achieve the above object, a video decoder of the present invention is a video decoder that receives a video stream of received video of a digital television broadcast and decodes various picture frames of the video stream into a digital video output. A reception program recognition unit for recognizing a type of a received program, and a frame number limiting unit for thinning out the frame to be decoded only during reception of a predetermined type of program according to a power saving setting. ).

  The video decoder of the present invention recognizes the type of received program in a video decoder that receives a video stream of received video of a digital television broadcast and decodes various picture frames of the video stream into a digital video output. And a frame type restriction means for restricting the decoding processing of the set type frame only during reception of a predetermined type of program by power saving setting. At this time, it is preferable that the frame restricted by the frame type restriction means is an I picture frame.

  Furthermore, the video decoder according to the present invention is the video decoder according to any one of claims 1 to 3, wherein the battery power source is supplied with power, and the detection of a decrease in the remaining capacity of the battery power source to a predetermined amount is detected. Power saving setting means for setting the power saving is provided (claim 4).

  Next, a portable digital broadcast receiver according to the present invention comprises the video decoder according to claim 4 and is operated by the battery power supply (claim 5).

  According to the first aspect of the present invention, when the power saving is set based on the recognition of the type of program received by the received program recognition unit, the frame number limiting unit decodes a frame to be decoded only during reception of a predetermined type of program. The power consumption of the video decoder can be reduced by thinning out.

  Therefore, by setting a predetermined type of program to news or weather forecasts other than programs whose movements are important, such as sports programs, a natural movement screen display is displayed for programs whose movements are important. Thus, it is possible to provide a novel video decoder having a power saving configuration that can save power as much as possible.

  Further, regardless of whether it is a stationary type or a portable type, it can be applied to a video decoder of a digital broadcast receiver, and further power saving can be achieved without impairing the screen display performance of the receiver.

  According to the invention of claim 2, when the power saving setting is made based on the recognition of the type of program received by the received program recognition means, the set type is set only during reception of a predetermined type of program by the frame type restriction means. The power consumption of the video decoder can be reduced by limiting the frame decoding process.

  Then, by setting a predetermined type of program to news, weather forecasts, etc. other than programs whose movements are important such as sports programs, it is important to display movements of sports programs as in the case of the invention of claim 1. For new programs, we can provide a new video decoder with a power-saving configuration designed to save power as much as possible while ensuring a natural motion screen display. By applying to the video decoder of the receiver, further power saving can be achieved without impairing the screen display performance of the receiver.

  Further, according to the invention of claim 3, by making the frame restricted by the frame type restriction means of claim 2 an I picture frame, not only the I picture frame is intermittently decoded but also simultaneously Also, the frames of the previous and subsequent P pictures and B pictures are not decoded, and the frames to be effectively decoded can be thinned out, and further effective power saving can be achieved.

  According to the fourth aspect of the present invention, when the remaining capacity of the battery power supply to be fed is reduced to a predetermined amount, the power saving setting means automatically sets the power saving, and the decoding process is performed only during reception of a predetermined type of program. The video of the received program can be decoded and reproduced by thinning out the frames to be received (or limiting the types of frames to be decoded).

  Further, according to the invention of claim 5, when the remaining capacity of the battery power source as the operation power source is reduced to a predetermined amount, the video decoder is automatically set to the power saving by the power saving setting means, and the reception of the predetermined type of program is performed. It is possible to decode and reproduce the video of the received program by thinning out the frames to be decoded only (or limiting the types of frames to be decoded).

  Then, by setting a predetermined type of program to news or weather forecasts other than programs whose movement is important, such as sports programs, a natural movement screen display is displayed for programs whose movement is important such as sports programs. Thus, it is possible to provide a novel portable digital broadcast receiver having a power saving configuration that can save power as much as possible.

  Next, in order to describe the present invention in more detail, one embodiment thereof will be described in detail with reference to FIGS.

  1 is a block diagram of a portable digital broadcast receiver to which the present invention is applied, FIG. 2 is a detailed block diagram of the video decoder of FIG. 1, FIG. 3 is a flowchart for explaining the operation of the video decoder of FIG. Is a detailed flowchart of the normal decoding of FIG. 3, and FIG. 5 is a detailed flowchart of the I-frame decoding of FIG.

  The portable digital broadcast receiver shown in FIG. 1 includes a battery power source 1 composed of a primary battery or a secondary battery. The battery power source 1 is constantly supplied with power to a main control unit 2 of a microcomputer (CPU) and a power switch 3 is connected. To the power line of the circuit unit 4.

  While the power switch 3 is off, the main control unit 2 executes a standby control program held in the storage device 5 and waits for a power-on operation and timer activation.

  When a power-on operation or timer activation occurs during this standby and the power switch 3 is turned on, the battery power source 1 is fed to each part of the circuit unit 4 and the portable digital broadcast receiver enters an operating state.

  The main control unit 2 executes the main control program of the storage device 5 and enters a state where various operations such as channel selection, screen display, and volume adjustment of the operation unit 6 or a remote controller (not shown) are accepted.

  Then, the main control unit 2 executes reception control according to the selection of the reception channel or the timer setting, and based on the reception control, the reception channel of the digital television broadcast such as high-definition broadcast or digital terrestrial television broadcast captured by the antenna 7 is determined. Radio waves (or radio waves of a reception channel transmitted by cable) are received and selected by the digital tuner 8, and a reception signal (digital RF signal) of the digital tuner 8 is demodulated into baseband digital reception information by the digital demodulator 9.

  Further, the digital reception information of the reception channel of the digital demodulator 9 is sent to the demultiplexer 10, and the video, audio, and additional information multiplexed with the digital reception information are separated by the well-known MPEG2 separation process of the demultiplexer 10. Separated into individual streams (transport stream; TS), that is, a video stream, an audio stream, and a data stream.

  The video stream is transferred to the video decoder 11, the audio stream is transferred to the audio decoder 12, and the data stream is transferred to the data decoder 13.

  Each of the decoders 11 to 13 is formed by software processing of an ASIC (dedicated integrated circuit) or a microcomputer, like the digital tuner 8, the digital demodulator 9, the demultiplexer 10, and the like. Decode and send to main controller 2.

  At this time, the main control unit 2 detects the audio information of the audio stream, the time information of the reproduction timing of the video information of the data stream, the information of the reproduction order, etc. from the additional information, and based on these information, the video decoder 11, the audio decoder 12 decoding processes are controlled.

  The video decoder 11 is configured, for example, as shown in FIG. 2, and the internal operation is controlled by the video control unit 11 a controlled by the main control unit 2, and the video of the input video stream is converted into the audio of the audio decoder 12. The decoding process is performed in synchronization with the decoding of the audio from the stream.

  By the way, the video stream of video is distributed in units of GOP as described above, and each GOP includes three types of frames called I picture, B picture, and P picture, and the video de-control unit 11a is contained in the frame of each picture. The type (I picture, P picture, B picture) of each frame of the video stream is determined from the picture header.

  The three types of frames are digital information of compressed video that constitutes about 30 video signal frames per second (about 15 frames per second for one-segment broadcasting). An I picture frame is included at a rate of one frame every 0.5 seconds (1 second if 1Seg). Unlike the other two types of frames (P picture and B picture frames), the I picture frame is alone. It can be decoded. In addition, it is necessary to predict and compensate for the motion of the image of both the B picture frame before and after (past and future) during decoding, and the P picture frame from the previous (past) frame during decoding. It is necessary to predict and compensate for the movement.

  Then, based on the determination of the type of the frame, usually, based on the control of the normal decoding process of the video control unit 11a, the variable length decoding of the variable length decoding unit 11b of FIG. Inverse scanning, inverse quantization of the inverse quantization unit 11d, and inverse discrete cosine transform of the inverse DTC unit 11e are performed.

  At this time, with respect to the frame of the I picture, the inverse discrete cosine transform of the inverse DTC unit 11e can be performed to decode the frame alone to decode digital video data, and the decoded video data is added to the adder. The video signal is output from 11f to a video D / A converter 14 (hereinafter referred to as DAC) 14 and is stored and held in the frame memory 11g so as to be rewritten.

  For the P picture and B picture frames, the inverse DTC unit 11e performs the inverse discrete cosine transform, and then reads the frame from the frame memory 11g before, after or after the previous frame or the data of the previous frame. The compensation data is added by the adder 11f, motion compensation is performed to decode the digital video data, and the decoded video data is output from the adder 11f to the video DAC 14 and is stored and held in the frame memory 11g in a rewritable manner.

  Then, the digital video data of the reception channel decoded by the video decoder 11 is converted into an analog video signal by the video DAC 14, and the liquid crystal display 15 as a screen display device is driven by this video signal and received by the liquid crystal display 15. Display the channel's digital broadcast on the screen.

  The audio decoder 12 decodes digital audio data from the input audio stream, sends the decoded audio data to the audio DAC 16 at the subsequent stage, and the audio DAC 16 converts the audio data into an analog audio signal. The speaker device 17 is driven by the signal to output the digital broadcast of the reception channel as audio.

  While the remaining capacity of the battery power source 1 is sufficient, the video decoder 11 decodes all the frames of the I picture, B picture, and P picture, so that a program such as a sports program whose motion display is important can be improved. indicate.

  However, when the remaining capacity of the battery power source 1 is reduced, the video display is continued for as long as possible while securing a natural motion screen display for a program in which a motion display such as a sports program is important. As will be described, the frames to be decoded by the video decoder 11 are limited depending on the type of program, the power consumption of the video decoder 11 is suppressed, and the illumination consumption of the battery power supply 1 is reduced.

  That is, the video control unit 11a of the video decoder 11 executes a preset video decoding control program shown in FIGS. 3 to 5 so that the received program recognition means for recognizing the type of the received program and the battery power source 1 Power saving setting means for setting the power saving upon detection of a decrease in the remaining capacity to a predetermined amount, and a decoding stop control means, and a normal decoding mode and an I frame decoding mode according to the remaining capacity of the battery power supply 1 Then, the decoding stop control is selectively performed.

  The received program recognition means then receives the genre (type) of the current program being received from the EIT information (program genre information indicated in the content descriptor of the table) included in the data stream header input via the main control unit 2. )

  Further, in this embodiment, the frame type limiting means sets the I picture frame to a frame whose decoding process is restricted, and performs the decoding process of the I picture frame only during reception of a predetermined type of program according to the power saving setting. The number of images is limited to one of three or one of three, or the I picture frame decoding process is limited to one every two seconds or one every three seconds.

  Further, the power saving setting means sets the remaining capacity (power amount) Wx of the battery power source 1 which is detected by monitoring the current of the battery power source 1 by the battery remaining amount checker 18 provided in the circuit unit 4 and the setting. The normal decoding limit threshold value Wsa is compared, and when the remaining capacity Wx falls below the threshold value Wsa, the power saving is automatically set.

  Further, the decoding stop control means compares the remaining capacity (power amount) Wx with an operation stop threshold value Wsb smaller than the threshold value Wsa, and when the remaining capacity (power amount) Wx decreases to the threshold value Wsb. The video decoder 11 is controlled to be stopped.

  On the other hand, predetermined types of programs are programs of sufficient genre even for still images such as news and weather forecasts other than programs of genres where movement display is important, such as sports programs, etc. To the video control unit 11a in advance.

  Then, the video control unit 11a starts executing the video decode control program when the power is turned on. When a video stream is input to the video decoder 11, the process proceeds from step A1 to step A2 in FIG. 3, and the video control unit 11a receives the video stream. The genre of the program being received is recognized by the program recognition means.

  Further, the process proceeds from step A2 in FIG. 3 to step A3, the power saving setting means and the decoding stop control means are operated, and the battery remaining amount checker 18 input to the video control unit 11a via the main control unit 2 detects it. The current remaining capacity Wx is compared with the set threshold values Wsa and Wsb.

  If Wx ≧ Wsa, the remaining capacity Wx is sufficiently large. Therefore, the process proceeds from step A3 to step A4 in FIG. 3, and the video decoder 11 is controlled to the normal decoding mode.

  In this normal decoding mode control, the decoding process in steps B1 to B4 in FIG. 4 is performed regardless of the type (genre) of the program, and all the frames of the I picture, P picture, and B picture are decoded as described above. . As a result, all types of programs including programs whose movement is important, such as sports programs, are displayed well.

  When the decoding process in steps B1 to B4 in FIG. 4 is completed, the process returns from step A4 in FIG. 3 to step A1 through step A5 until the power is turned off, and the next video stream is decoded.

  Next, when the remaining capacity Wx of the battery power source 1 falls below the threshold value Wsa and Wsa> Wx ≧ Wsb, the video control unit 11a is set to power saving control, and the process proceeds from step A3 to step A6 in FIG. It is determined whether the program being received is a predetermined type of program of a sufficient genre even in the above-described still image such as news or weather forecast.

  And if it is a program other than the predetermined type of program such as a program of a genre in which movement display such as a sports program is important, the program proceeds from step A6 to step A4 in FIG. The screen display performance of the system should not be degraded.

  On the other hand, if the predetermined type of program is a sufficient genre even in the case of a still image, the process proceeds from step A6 in FIG. 3 to step A7 to switch to I frame decoding mode control, and the processing in steps C1 to C4 in FIG. Execute.

  That is, the frame type restricting means operates, selects an I picture frame in step C1 of FIG. 5, and further performs decoding processing of the I picture frame in step C2. Only one sheet out of three sheets, or one sheet corresponding to one sheet every two seconds or one sheet every three seconds is extracted.

  Then, the extracted (restricted) I picture frame is decoded in step C3 in FIG. 5, and the digital image data obtained by decoding the I picture in the frame memory 11g can be rewritten in the frame memory 11g in step C4. In step C5, the image data is output to the video DAC 14.

  When the decoding process in steps C1 to C5 in FIG. 5 is completed, the process returns from step A4 in FIG. 3 to step A1 through step A5 until the power is turned off, and the next video stream is decoded.

  Therefore, while the remaining capacity Wx of the battery power supply 1 is Wsa> Wx ≧ Wsb, the decoding process of the limited I-picture frame is restricted, so that the power consumption of the video decoder 11 is reduced, and the battery power supply 1 Less power consumption.

  If the decoding of the I picture frame is restricted, the motion compensation of the previous and subsequent P picture frames and the B picture frame cannot be performed. The power consumption of the video decoder 11 is further reduced, the efficiency of power saving is improved, and the power consumption of the battery power source 1 is further reduced.

  As a result, it is possible to extend the display time for a program such as a sports program in which movement display is important while saving natural power on the screen and saving power as much as possible.

  During the power saving setting, it is preferable to further reduce the power consumption of the battery power source 1 by reducing the light amount of the backlight of the liquid crystal display 15 or reducing the volume of the speaker device 17. Of course.

  By the way, when the remaining capacity Wx of the battery power source 1 is reduced to Wsb ≧ Wx, the process proceeds from step A3 to step A8 in FIG. 3, and the video decoder 11 is controlled to be stopped by the decoding stop control means. Consumption is extremely reduced to prevent overdischarge of the battery power supply 1 and the like.

  At this time, the received program can be viewed by the audio output of the speaker device 17.

  Therefore, in the case of the above embodiment, when the remaining capacity of the battery power supply 1 is reduced, the type of frames to be decoded is limited to suppress unnecessary video decoding processing, and display of motion such as sports programs It is possible to provide a new video decoder 11 for receiving a digital broadcast having a power saving configuration that can save power as much as possible while ensuring a natural motion screen display for an important program. A new power-saving configuration including a decoder 11 and capable of extending the remaining time that can be consumed by the battery power supply 1 as much as possible while securing a natural motion screen display for programs such as sports programs in which motion display is important. A portable digital broadcast receiver can be provided.

  Further, if the remaining capacity of the battery power source 1 is not further reduced, the video decoder 11 is substantially stopped, so that the video cannot be viewed, but the program contents can be grasped for a long time by the audio output with low power consumption. It also has the advantage of being possible.

  Further, when the mode is switched to the I frame decoding mode or the decoding stop, the user (user) can recognize the state of the battery power source 1 through the switching of the mode of the video decoder 11 from the screen display state of the liquid crystal display 15. There is also an advantage that the user can recognize the state of the battery power supply 1 without providing a special configuration for notifying the state of the battery power supply 1 by an on-screen display (OSD) or the like.

  By the way, in the video decoder 11, the frame for limiting the decoding process is not limited to the frame of the I picture, but may be the frame of the P picture and the B picture, and the frame of the frame of the I picture, the P picture, and the B picture. A plurality of types of frames may be used.

  In addition, in the portable digital broadcast receiver of FIG. 3, the same effect can be obtained when a CRT or a plasma display is provided instead of the liquid crystal display 15.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, the video decoder 11 can perform decoding processing. The frame for restricting can be set in the same manner for a frame of a standard different from MPEG2.

  Further, the video decoder 11 may be provided with a frame number limiting unit instead of the frame type limiting unit, and the frame to be decoded only during reception of a predetermined type of program may be thinned out regardless of the frame type by the power saving setting. The same effects as those of the embodiment can be obtained, and in this case, there is an advantage that recognition of the type of frame is unnecessary.

  Furthermore, it goes without saying that the present invention can be applied in the same way to digital television broadcasting in which an image frame conforms to a standard different from MPEG2.

  Next, the video decoder 11 can also be applied to a stationary digital broadcast receiver that operates on a commercial power source. In this case, the power saving setting is, for example, a detection of a voltage drop when the commercial power source is powered down. You can do this.

  The present invention can be applied to various digital television broadcast video decoders and portable and stationary digital broadcast receivers. In this case, the processing procedure and the like may be different from those of the above embodiments. Of course.

It is a block diagram of the portable digital broadcast receiver of one Embodiment of this invention. FIG. 2 is a detailed block diagram of a video decoder of the portable digital broadcast receiver. It is a flowchart for operation | movement description of the video decoder of a portable digital broadcast receiver same as the above. It is a detailed flowchart of normal decoding of the video decoder of a portable digital broadcast receiver same as the above. It is a detailed flowchart of the I frame decoding of the video decoder of the portable digital broadcast receiver.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery power supply 2 Main control part 11 Video decoder 11a Video control part 18 Battery remaining amount checker

Claims (5)

Received program recognition means for recognizing the type of received program in a video decoder that receives a video stream of a received video of a digital television broadcast and decodes various picture frames of the video stream into a digital video output; A video decoder comprising: a frame number limiting means for thinning out the frames to be decoded only during reception of a predetermined type of program by setting. Received program recognition means for recognizing the type of received program in a video decoder that receives a video stream of a received video of a digital television broadcast and decodes various picture frames of the video stream into a digital video output; A video decoder, comprising: a frame type restricting unit that restricts decoding of a set type frame only during reception of a predetermined type of program.   3. The video decoder according to claim 2, wherein the frame restricted by the frame type restriction means is an I picture frame.   4. The power saving setting means according to claim 1, wherein the battery power is supplied, and the power saving is set by detecting a decrease in the remaining capacity of the battery power to a predetermined amount. A video decoder comprising:   5. A portable digital broadcast receiver comprising the video decoder according to claim 4 and operated by the battery power source.

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