Abstract:
A recording medium reproduction apparatus is provided, which apparatus includes: a reproduction instruction unit which inputs instructions on a direction and a rate of a scratch reproduction of a recording medium; a data storage unit which stores data read out from the recording medium, the data being separated by a reference position at which the scratch reproduction is started into first and second halves each having a predetermined time length; and a scratch reproduction system which reads and reproduces the data stored in the data storage unit in accordance with the instructions input by the reproduction instruction unit.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention generally relates to recording medium reproduction apparatus, and more particularly to a recording medium reproduction apparatus which performs a special reproduction of a recording medium.  
           [0003]    2. Description of the Related Art  
           [0004]    Conventionally, a method of playing music called scratch, which method employs a record and a record player, has been known. According to this scratch method, for example, in the field of dance music, a player called disc jockey (DJ) controls the rotation of a record rotating on a turntable to play dance music.  
           [0005]    An operation according to the scratch method (a scratch operation) is performed as follows. First, the DJ rotates the record in a reverse direction by a few centimeters with a reproducing stylus being placed thereon. Then, the DJ rotates the record in a forward (reproduction) direction and again in the reverse direction. The DJ repeats the above-described scratch operation several times. A sound reproduced by the scratch method is a combination of a sound generated when the reproduction stylus traces a groove of the record in the reverse direction to the reproduction direction, and a short phrase reproduced when the record is rotated in the forward direction thereafter. A rhythm unique to the scratch method is generated by repeating the above-described combination of the sound and the short phrase several times. The rhythm generated by the scratch method is an essential, important element of some dance music.  
           [0006]    Conventionally, the DJ performs the scratch method employing an analog record. According to the scratch method, the scratch sound is obtained by continuously rotating the analog record in the forward and reverse directions over a given range at a high or low speed in reproducing music recorded on the analog record. It is strongly desired to generate the same scratch sound also from a recording medium such as a compact disk (CD) storing digital music data.  
           [0007]    However, according to a conventional CD reproduction apparatus, it is impossible to generate a scratch sound as in the case of the analog record by continuously rotating a CD in forward and reverse directions over a given range at a high or low speed in reproducing music recorded on the CD, thus preventing a scratch effect from being obtained.  
         SUMMARY OF THE INVENTION  
         [0008]    It is a general object of the present invention to provide a recording medium reproduction apparatus in which the above-described disadvantage is eliminated.  
           [0009]    A more specific object of the present invention is to provide a recording medium reproduction apparatus which can perform a scratch operation so that a scratch sound conventionally generated by using an analog record can be generated by using a recording medium stored with digital music data.  
           [0010]    The above objects of the present invention are achieved by a recording medium reproduction apparatus including: a reproduction instruction unit which inputs instructions on a direction and a rate of a scratch reproduction of a recording medium; a data storage unit which stores data read out from the recording medium, the data being separated by a reference position at which the scratch reproduction is started into first and second halves each having a predetermined time length; and a scratch reproduction system which reads and reproduces the data stored in the data storage unit in accordance with the instructions input by the reproduction instruction unit.  
           [0011]    By thus storing the future and past data with respect to the reference position, which data are read out from the recording medium, and by reproducing the stored data based on the input instructions on the direction and rate of the scratch reproduction, the scratch reproduction can be performed by using the recording medium stored with digital music data.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings, in which:  
         [0013]    [0013]FIG. 1 is a block diagram of an embodiment of a recording medium reproduction apparatus according to the present invention;  
         [0014]    [0014]FIG. 2 is a block diagram showing functions of a data maintenance DSP shown in FIG. 1;  
         [0015]    [0015]FIG. 3 is a block diagram showing functions of a CD sound effect DSP and a sampler effect DSP shown in FIG. 1;  
         [0016]    [0016]FIG. 4 is a plan view of controller units of a pair of the recording medium reproduction apparatus according to the present invention;  
         [0017]    [0017]FIG. 5 is a graph of an embodiment of a scratch operation;  
         [0018]    [0018]FIG. 6 is a diagram showing a state of a DRAM for storing audio data during a scratch operation;  
         [0019]    [0019]FIGS. 7 through 9 are flowcharts of a process of a scratch processing performed by the data maintenance DSP according to an embodiment of the present invention; and  
         [0020]    [0020]FIG. 10 is a flowchart of a process of a scratch correction processing performed by the data maintenance DSP according to an embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]    A description will now be given, with reference to the accompanying drawings, of embodiments of the present invention.  
         [0022]    [0022]FIG. 1 is a block diagram of an embodiment of a recording medium reproduction apparatus according to the present invention. According to FIG. 1, a CD reproduction unit  10  rotationally drives a CD that is a recording medium at a reproduction rate twice as high as a normal reproduction rate (double rate). A reproduction signal reproduced at the double rate by a pickup of the CD reproduction unit  10  is supplied to a CD reproduction digital signal processor (DSP) in the CD reproduction unit  10  via a radiofrequency (RF) amplifier. In the CD reproduction DSP, a signal processing, such as a demodulation using eight to fourteen modulation (EFM) or a decoding using cross-interleave Reed-Solomon code (CIRC), is performed on the reproduction signal.  
         [0023]    A subcode is separated from the reproduction signal to be decoded. The subcode data is stored in a random access memory (RAM) in a main microcomputer  12  in accordance with a counter signal supplied from the main microcomputer  12 . Audio data subjected to the signal processing in the CD reproduction DSP is supplied to a data maintenance DSP  14 . A dynamic RAM (DRAM)  16  for storing the audio data is connected to the data maintenance DSP  14 , which serves as a memory controller. The DRAM  16  is capable of storing the audio data transmitted from the data maintenance DSP  14  for approximately ten seconds for example, and serves to realize a variety of functions, such as an anti-shock function for providing protection when a sound skip is caused by a defect in the audio data, a quick start function for instantaneously starting a desired tune, a seamless loop function for repeatedly reproducing the audio data between predetermined two points, a function for a scratch processing, a function for varying the tempo of a tune, and a brake function for gradually reducing the reproduction rate to stop the reproduction.  
         [0024]    The data maintenance DSP  14  writes the audio data read at the double rate into the DRAM  16  in accordance with the counter signal supplied from the main microcomputer  12 , and simultaneously reads the audio data at a single rate (normal rate) in accordance with the counter signal supplied from the main microcomputer  12  so as to supply the audio data to a CD sound effect DSP  18 .  
         [0025]    A work memory DRAM  20  is connected to the CD sound effect DSP  18 , which performs a variety of effect processing, such as a key (musical interval) adjustment, an output level adjustment, and a voice reduction function to reduce only the volume of the vocal sound of a tune. The audio data output from the DSP  18  is supplied to a digital-to-analog (D/A) converter  22  through a digital filter, and is also supplied to a sampler effect DSP  26 .  
         [0026]    An audio data storage DRAM  28  is connected to the sampler effect DSP  26 , which serves as a memory controller. The audio data storage DRAM  28  is capable of storing the audio data for approximately ten seconds, for example. The sampler effect DSP  26  performs a sampler processing. The sampler effect DSP  26  stores the audio data picked up during a period between sampling start and end points specified by a user into the audio data storage DRAM  28 , and reads the stored audio data at a reproduction timing specified by the user to supply the stored audio data to a D/A converter  30  and to the DSP  18 . The DSP  18  combines the output audio data thereof with the audio data supplied from the DSP  26  to supply the combined audio data to the D/A converter  22 .  
         [0027]    The main microcomputer  12  is connected to an erasable and programmable read only memory (EPROM)  32  storing programs and data for processing and to an electrically erasable and programmable read only memory (EEPROM)  34  into which a variety of set values of each tune or track, such as a tempo value and a loop point, are stored. A clock generator  36  generates a clock signal and supplies the clock signal to the CD reproduction unit  10  and to the main microcomputer  12 .  
         [0028]    The main microcomputer  12  reads the subcode from the RAM housed therein in accordance with the counter signal to supply the subcode to a microcomputer  42  of a controller unit  40 . The microcomputer  42  converts the subcode into a time code and displays the time code on a display unit  44 . The controller unit  40 , which includes an operation unit  46  including a variety of operation keys operated by the user, is connected to the microcomputer  42 .  
         [0029]    [0029]FIG. 2 is a block diagram showing functions of the DSP  14 , and FIG. 3 is a block diagram showing functions of the DSPs  18  and  26 . As shown in FIG. 2, a comparison/connection function  50  of the DSP  14 , in accordance with the counter signal supplied from the main microcomputer  12 , compares audio data read at the double rate with the last data stored in the DRAM  16 , and connects the audio data to the last data stored in the DRAM  16 . A memory write function  51  writes the connected audio data into the DRAM  16 . A memory read function  52  reads audio data out of the DRAM  16 . A tempo function  54  varies a read rate of the memory read function  52  for a tempo adjustment. A fade-in/fade-out function  55  adjusts the level of audio data at a time of fade-in or fade-out.  
         [0030]    In FIG. 3, a de-emphasis function  60  of the DSP  18  performs a de-emphasis processing to return an emphasis level at a time of CD recording to its original level. A key adjustment function  61  fixes the tempo and variably adjusts the key. A beats per minute (BPM) function  62  counts the number of beats per minute of a tune. A voice reduction function  63  reduces the volume of the vocal sound of a tune. An output level adjustment function  64  adjusts an output level. The output level adjustment function  64  outputs the audio data through a combination function  65 , and supplies the audio data to a sampler function  67  of the DSP  26  when a switch  66  is “ON”.  
         [0031]    The sampler function  67  writes audio data into the DRAM  28 , and, when a switch  70  is “ON”, reads the audio data out of the DRAM  28 . A tempo adjustment function  68  adjusts the tempo of the audio data supplied from the sampler function  67 . A key adjustment function  69  fixes the tempo and variably adjusts the key. Thereafter, the key adjustment function  69  outputs the audio data through the switch  70 , and supplies the audio data to the combination function  65  through a switch  71  of the DSP  18 , which switch is switched “ON” together with the switch  70 . The combination function  65  combines the audio data supplied from the key adjustment function  69  with the audio data supplied from the output level adjustment function  64  to output the combined audio data.  
         [0032]    The recording medium reproduction apparatus shown in FIG. 1 is used in pairs, and the main microcomputers of the two recording medium reproduction apparatus exchange control information between each other to be interlocked with each other in operation. FIG. 4 is a plan view of the controller units  40  of a pair of the recording medium reproduction apparatus. Since the respective controller units  40  have the same structure, only one of the respective units  40  is referred to by numerals in a description thereof given below.  
         [0033]    According to FIG. 4, a display  80  of the display unit  44  displays a variety of information such as a track number and a time code, while a display  81  of the display unit  44  displays a BPM value. The operation unit  46  includes a preset key  82 , a jog dial  83 , a skip key  84 , a search key  85 , a play/pause key  86 , a bank key  87 , a memory key  88 , a recall key  89 , an enter key  90 , a TAP key  91 , a BPM key  92 , a tempo SYNC key  93 , a beat SYNC key  94 , a loop key  95 , an A key  96 , a B key  97 , a sample key  98 , an IN key  99 , an OUT key  100 , a tempo key  101 , a tempo volume  102 , a scratch key  103 , a brake key  104 , a ten key  105 , a jog speed setting key  106 , and a queue key  107 .  
         [0034]    According to the present invention, to perform a scratch operation, the scratch key  103  is first pressed to set the controller unit  40  ready for a scratch, and the jog dial  83  is rotated to perform a scratch reproduction. The jog dial  83  employs a rotary encoder or the like and transmits rotation detection pulses to the microcomputer  42  so that the speed, direction, and cessation of the rotation of the jog dial  83  can be recognized. The jog dial  83  is rotated clockwise to perform a forward reproduction, and is rotated counterclockwise to perform a reverse reproduction. The scratch reproduction can be performed even when a normal reproduction is paused or performed.  
         [0035]    [0035]FIG. 5 is a graph of an embodiment of a scratch operation.  
         [0036]    The scratch operation can be performed by pressing the scratch key  103  and then rotating the jog dial  83  clockwise and counterclockwise. The reproduction rate varies depending on the rotation speed of the jog dial  83 . The reproduction rate varies over a range of ± 50% of the normal reproduction rate. When the scratch operation is performed from a PLAY (normal reproduction) state in which the reproduction is performed at a constant rate (normal reproduction rate), the reproduction is set in the PLAY state after the scratch operation is over. Time required to set the reproduction in the PLAY state after the scratch operation is over can be changed by the preset key  82 . If the required time is set in the EEPROM  34  shown in FIG. 1 to have four values of 0.2 second, which is a default value (standard), 0.1 second, 0.5 second, and 1.0 second, by selecting a selection mode by the preset key  82 , the set values can be changed by the jog dial  83  to be determined by the enter key  90 .  
         [0037]    Compared with the set value of 0.1 second, a normal reproduced sound takes time in being output after the scratch operation with the set value of 0.5 second, thus preventing the succession of the scratch operation and the normal reproduction operation. When the scratch operation is performed from a READY (pause) state in which the jog dial  83  remains stationary, the reproduction is set in the READY state after the scratch operation is over.  
         [0038]    For example, if the scratch operation is performed to take paths indicated by arrows shown in FIG. 5, the jog dial  83  is rotated clockwise at a speed of two rotations per second from the stationary state thereof to set the forward reproduction rate at a rate of +50%. Thereafter, the jog dial  83  is set at rest and then is rotated counterclockwise at a speed of 0.7 rotation per second (three-quarters rotation per second) to set the reverse reproduction rate at a rate of −25%. Thus, any scratch operation can be realized by the combination of the clockwise and counterclockwise rotation and the rotational speed of the jog dial  83 . In FIG. 5, “+” shows a rate higher than the constant rate, and “−” shows a rate lower than the constant rate. Further, in FIG. 5, the solid lines show the forward reproduction and the broken lines show the reverse reproduction.  
         [0039]    The above-described values of the rotational speed with respect to the reproduction rates are examples. The rotational speed with respect to the reproduction rate can be changed by the preset key  82 . If the rotational speed of the jog dial  83  with respect to the reproduction rate of +50% is set in the EEPROM  34  shown in FIG. 1 to have three values of two rotations per second, which is a default value, three rotations per second, and 1.5 rotations per second, by selecting the selection mode by the preset key  82 , the set values can be changed by the jog dial  83  to be determined by the enter key  90 . The values of the rotational speed of the jog dial  83  with respect to the minus reproduction rates are simultaneously changed at the same rate.  
         [0040]    If the operation speed of the jog dial  83  remains the same, compared with the value of three rotations per second at the reproduction rate of +50%, the scratch operation can reproduce a higher-keyed sound over a longer reproduction length with the value of 1.5 rotations per second at the reproduction rate of +50%.  
         [0041]    Further, the rotational speed of the jog dial  83  with respect to the reproduction rate can be changed by means of the jog speed setting switch  106 . A dial  106 A of the jog speed setting switch  106  is turned counterclockwise to be set at a position of “2” so that the rotational speed with respect to the reproduction rate can be set to have double the value set by the preset key  82 . If the dial  106 A is set at a center position of “1”, the rotational speed can be set to have the value set by the preset key  82 . If the dial  106 A is turned clockwise to be set at a position of “½”, the rotational speed can be set to have half the value set by the preset key  82 . The values of the rotational speed with respect to the reproduction rate can be changed gradually or continuously within a range from the above-described position “½ to the position “2” of the dial  106 A. The jog speed setting switch  106  allows the DJ to easily set a desired value of the rotational speed with respect to the reproduction rate, and to achieve a scratch performance with a desired key over a desired reproduction length.  
         [0042]    [0042]FIG. 6 is a diagram showing a state of the DRAM  16  during a scratch operation.  
         [0043]    According to FIG. 6, the audio data is stored in positions clockwise from SA to VWA in an order reproduced in the CD reproduction unit  10 . A normal scratch reproduction by the scratch operation always reproduces the audio data from the CD at the double rate, and stores the reproduced audio data in the DRAM  16 . A maximum of 11-second-long audio data is stored over the positions SA to VWA in the DRAM  16 . The position SA is set as a readout reference position during a normal anti-shock reproduction.  
         [0044]    In the case of a reproduction in a scratch mode, with a position RA, which is a counterclockwise mid-position between the positions VWA and SA, being set as a reference position, the 5.5-second-long first half of the audio data (future data) is stored in the DRAM  16  over a region from the reference position RA to the position VWA, and the 5.5-second-long second half of the audio data (past data) is stored in the DRAM  16  over a region from the position SA to the reference position RA. The first and second halves of the audio data are necessary for the forward and reverse reproductions, respectively. With the reproduction being in the READY state in the scratch mode, if both of the 5.5-second-long future and past audio data are not stored in the respective above-described regions, one or both of the 5.5-second-long first and second halves of the audio data is/are reproduced so as to supplement deficient data. After the deficient data is stored, by operating the jog dial  83 , the data stored in the DRAM  16  is read out in accordance with the rotational direction and speed of the jog dial  83  so that the scratch reproduction is performed. As shown in FIG. 6, the above-described regions are stored with the respective 5.5-second-long future and past data. However, only five-second-long data from the reference position RA is actually reproduced from each of the 5.5-second-long future and past data by the scratch operation.  
         [0045]    In the case of rotating the jog dial  83  counterclockwise to perform the reverse reproduction, the audio data is reproduced by the scratch operation for five seconds from the reference position RA toward the position SA, and the reproduction of the audio data is ceased at a position 0.5 second short of the position SA. When the rotation of the jog dial  83  is stopped during the above-described operation, the normal reproduction is performed in the scratch mode in the case of the scratch reproduction in the PLAY state, and the reproduction enters the READY state in the case of the scratch reproduction in the READY state.  
         [0046]    On the other hand, in the case of rotating the jog dial  83  clockwise to perform the forward reproduction, the audio data is reproduced by the scratch operation for five seconds from the reference position RA toward the position VWA. Thereafter, when the audio data is read out from the DRAM  16  up to a position 0.5 second short of the position VWA, the next audio data is prefetched from the CD to be stored in the DRAM  16  over a region following the position VWA. When the rotation of the jog dial  83  is stopped during the above-described operation, the normal reproduction is performed in the scratch mode in the case of the scratch reproduction in the PLAY state, and the reproduction enters the READY state in the case of the scratch reproduction in the READY state. Further, when a reproduction position falls between two tunes (tracks) during the scratch operation, the scratch reproduction is ceased because there is a section without any signal between the two tunes (tracks).  
         [0047]    [0047]FIGS. 7 through 9 show a flowchart of a process of a scratch processing performed by the DSP  14  according to an embodiment of the present invention. First, in step S 100  of FIG. 7, the scratch key  103  is pressed to set the scratch mode. Then, in step S 101 , it is determined whether the reproduction is in the PLAY state. If it is determined in step S 101  that the reproduction is in the PLAY state, the process goes to step S 102 . In step S 102 , audio data read in advance into the DRAM  16  is set to be 5.5 seconds long, and, while keeping 5.5-second-long audio data already read out from the DRAM  16  and stored therein over the region from a present reproduction position (a data readout position on the DRAM  16 ), which is set to be the reference position RA, to the position SA, the 5.5-second-long audio data reproduced from the CD is kept in the DRAM  16  over the region from the reference position RA to the position VWA. Thereafter, in step S 103 , the rotation of the jog dial  83  is waited for, and when the jog dial  83  is rotated, the process goes to step S 104 . In step S 104 , if the reproduction is in the READY state, readout from the DRAM  16  of the DSP  14  is permitted, and if the reproduction is the scratch reproduction in the PLAY state, writing into the DRAM  16  of the DSP  14  is inhibited. Next, in step S 105 , a rotational speed of the jog dial  83  is detected, and, in step S 106 , a reproduction rate corresponding to the rotational speed (TEMPO) is determined. Thus, in steps S 101  through S 106 , it is determined whether the reproduction is in the PLAY state or in the READY state in the scratch mode, and, in compliance with the respective states, data is written and stored into the DRAM  16 , and the reproduction rate is set. Steps following step S 106  are shown in FIG. 8.  
         [0048]    If it is determined in step S 101  that the reproduction is not in the PLAY state, in step S 117 , it is determined whether the reproduction is in the READY state. If it is determined in step S 117  that the reproduction is in the READY state, the process goes to step S 118  and steps shown in FIG. 9 are performed. On the other hand, if it is determined that the reproduction is not in the READY state, this scratch processing ends.  
         [0049]    In FIG. 8, first in step S 107 , it is determined, based on the detection result of the rotation of the jog dial  83  in step S 103 , whether the jog dial  83  is rotated in a forward direction. If it is determined that the jog dial  83  is not rotated in the forward direction, that is, that the jog dial  83  is rotated in a reverse direction, the process goes to step S 108 . In step S 108 , the readout from the DRAM  16  of the DSP  14  is performed in a reverse direction toward the position SA from the present reproduction position. In performing step S 108  for the first time, the readout from the DRAM  16  is started from the reference position RA. Thereafter, in step S 109 , the scratch reproduction is performed. During this scratch reproduction, in step S 110 , it is determined whether the readout position proceeds in the reverse direction to a position 0.5 second short of an enabled SA position. If it is determined in step S 110  that the readout position proceeds to the position 0.5 second short of the enabled SA position, in step S 111 , the readout from the DRAM  16  is inhibited and the reproduction is ceased.  
         [0050]    Thereafter, the process returns to step S 101  shown in FIG. 7 and the steps thereafter are performed so that an operation such as the writing of data into the DRAM  16  during the reproduction in the PLAY state is performed. If it is determined in step S 110  that the readout position does not proceed to the position 0.5 second short of the position SA, in step S 116 , it is determined whether the rotation of the jog dial  83  is stopped. If it is determined that the rotation of the jog dial  83  is stopped, step S 107  and the steps thereafter shown in FIG. 7 are performed. If it is determined that the rotation is not stopped, step S 104  and the steps thereafter shown in FIG. 7 are performed.  
         [0051]    If it is determined in step S 107  that the jog dial  83  is rotated in the forward direction, the process goes to step S 112 . In step S 112 , the readout from the DRAM  16  of the DSP  14  is performed in a forward direction toward the position VWA from the present reproduction position. In performing step S 112  for the first time, the readout from the DRAM  16  is started from the reference position RA. Thereafter, in step S 113 , the scratch reproduction is performed. During this scratch reproduction, in step S 114 , it is determined whether the readout position proceeds in the forward direction to the position 0.5 second short of an enabled VWA position. If it is determined in step S 114  that the readout position proceeds to the position 0.5 second short of the enabled VWA position, in step S 115 , the readout from the DRAM  16  is continued to continue the scratch reproduction, and the next audio data is prefetched from the CD to be stored in the region following the position VWA on the DRAM  16 .  
         [0052]    Next, in step S 116 , it is determined whether the rotation of the jog dial  83  is stopped. If it is determined that the rotation is stopped, the process returns to step S 101  shown in FIG. 7 and the steps thereafter are performed. If it is determined that the rotation is not stopped, the process returns to step S 104  shown in FIG. 7 and the steps thereafter are performed. Thus, the scratch reproduction can be performed in the PLAY state in the scratch mode through steps S 102  through S 116 .  
         [0053]    Step S 117  shown in FIG. 7, in which step it is determined whether the reproduction is in the READY state, is followed by step S 118  shown in FIG. 9 and steps thereafter. In step S 118 , it is determined whether 5.5-second-long future and past audio data are already stored in the DRAM  16  over corresponding regions extending in the respective forward and reverse directions from a reproduction position at the time of the READY state. If it is determined that both of the 5.5-second-long future and past audio data are not stored in the respective regions, in step S 120 , it is determined whether it is the future audio data stored in the forward direction that is insufficient. If it is determined that the future data is insufficient, in step S 124 , data reproduced from the CD is written into the DRAM  16  over a region extending from the last VWA position so that the data is read into the DRAM  16  in advance.  
         [0054]    On the other hand, if it is determined in step S 120  that the future audio data stored in the forward direction is sufficient, but that the past audio data stored in the reverse direction is insufficient, in step S 121 , the DSP  14  is initialized. Then, in step S 122 , a position 5.5 seconds away in the reverse direction from the reproduction position at the time of the READY state is searched on the DRAM  16 . In step S 123 , data reproduced from the CD is written into the DRAM  16  over a region extending from the searched position so that 11-second-long data is read into the DRAM  16  in advance. Thereafter, the process returns to step S 118  and the steps thereafter are performed.  
         [0055]    If it is determined in step S 118  that both of the 5.5-second-long future and past audio data are stored in the respective regions, in step S 119 , the replay of the CR is paused at the last enabled VWA position, and the writing into the DRAM  16  is inhibited. Thereafter, the process returns to step S 103  and the steps thereafter are performed.  
         [0056]    By thus storing, in compliance with the PLAY and READY states in the scratch mode, the 5.5-second-long future and past data in the DRAM  16  over the respective regions extending in the forward and reverse directions from the scratch reproduction position and by performing the scratch operation using the stored data, the same scratch reproduction as that by an analog record player can be performed.  
         [0057]    According to the above-described embodiment, the rotational speed of the jog dial  83  is detected in step S 105 . However, the rotational speed of the jog dial  83  rotated by the DJ varies slightly. Therefore, there is always an error between the actual rotational speed and time in the forward direction and those in the reverse direction. Thus, when the jog dial  83  is rotated, for example, clockwise from its initial position to start readout from the position RA on the DRAM  16 , and then, is rotated counterclockwise to be returned to the initial position, the present reproduction position often deviates from the reference position RA. Therefore, when the jog dial  83  is further rotated clockwise from the initial position after being returned thereto so as to repeat the scratch operation, a readout start position on the DRAM  16  deviates from the above-described position RA so that an initial reproduced sound deviates from a desired sound.  
         [0058]    [0058]FIG. 10 is a flowchart of a process of a scratch correction processing performed by the DSP  14  according to an embodiment of the present invention, in which embodiment the above-described disadvantage is eliminated. This processing is initiated when the scratch operation is started by the rotational operation of the jog dial  83 , and is performed in parallel with the processing shown in FIGS. 7 through 9.  
         [0059]    In FIG. 10, in step S 201 , the rotational direction of the jog dial  83  is detected, and in step S 202 , a first counter CA is reset. Then, in step S 203 , the first counter CA counts rotation detection pulses generated by the jog dial  83 . In step S 204 , it is determined whether the rotation of the jog dial  83  is stopped or reversed, or not. If it is determined that the rotation is not stopped or reversed, the process returns to step S 203  to continue counting the rotation detection pulses. If it is determined that the rotation is stopped, this processing ends. The stoppage of the rotation is determined when the rotation is stopped for longer than the time set by the preset key  82 , which time is required to set the reproduction in the PLAY state after the scratch operation is over.  
         [0060]    On the other hand, if it is determined in step S 204  that the rotation is reversed, in step S 205 , a second counter CB is reset. Then, in step S 206 , the second counter CB counts the rotation detection pulses generated by the jog dial  83 . In step S 207 , it is determined whether the rotation of the jog dial  83  is stopped or reversed, or not. If it is determined that the rotation is not stopped or reversed, the process returns to step S 206  to continue counting the rotation detection pulses.  
         [0061]    If it is determined in step S 207  that the rotation is stopped or reversed, the process goes to step S 208 , in which the reference position RA is corrected. In step S 208 , a value obtained by the second counter CB is subtracted from a value obtained by the first counter CA to obtain an error pulse number. The error pulse number is multiplied by a memory shift amount per pulse to obtain an address correction amount, and the reference position RA on the DRAM  16  is shifted by the address correction amount. The memory shift amount per pulse is a value corresponding to a set value of the rotational speed of the jog dial  83  with respect to the reproduction rate. If the address correction amount is positive, the reference position RA is shifted in the rotational direction detected in step S 201  (for example, clockwise). If the address correction amount is negative, the reference position RA is shifted in a rotational direction reverse to the rotational direction detected in step S 201  (for example, counterclockwise).  
         [0062]    Next, in step S 209 , it is determined whether the rotation of the jog dial  83  is stopped. If it is determined that the rotation is stopped, this processing ends. If it is determined that the rotation is not stopped, that is, that the rotation is reversed, the process returns to step S 201  and the steps thereafter are performed.  
         [0063]    Thus, when the jog dial  83  is rotated first, for example, clockwise from the initial position and then is rotated counterclockwise to be returned to the initial position, the reference position RA is corrected so as to correspond to a rotational angle position of the jog dial  83 . Further, when the jog dial  83  is again rotated clockwise from the initial position to which the jog dial  83  is returned, the readout start position on the DRAM  16  is corrected, thus preventing an initial reproduced sound from deviating from a desired sound. According to this embodiment, in step S 209 , the error pulse number is obtained by subtracting the value obtained by the second counter CB from the value obtained by the first counter CA so that the address correction amount is obtained. However, the address correction amount may be obtained based on a ratio of the value obtained by the first counter CA to the value obtained by the second counter CB.  
         [0064]    As a variation of the scratch reproduction, when the jog dial  83  is rotated clockwise and counterclockwise in the scratch mode to perform the scratch operation, only one of sounds reproduced in the forward and reverse directions may be output while muting the other. The recording medium reproduction apparatus according to the present invention includes a function to perform such a variation of the scratch operation.  
         [0065]    First, the selection mode is selected by the preset key  82  of the operation unit  46 , and “SCRT” is selected by the jog dial  83 . Then, “NOR”, “FWD”, or “REV” is selected by the jog dial  83 . In the case of selecting “NOR”, the normal scratch reproduction is performed so that both of the sounds reproduced in the forward and reverse directions are output in the scratch mode. In the case of selecting “FWD”, the variation of the scratch reproduction is performed so that only the sound reproduced in the forward direction is output in the scratch mode. In the case of selecting “REV”, the variation of the scratch reproduction is performed so that only the sound reproduced in the reverse direction is output in the scratch mode.  
         [0066]    As a method of muting a reproduced sound in the above-described variation of the scratch reproduction, a method which stops data from being read out from the DRAM  16  during a mute period, or a method employing muting which stops an output of an audio signal during a mute period can be employed.  
         [0067]    Although a CD is used as a recording medium in the above-described embodiments, it is of course possible to use a DVD (Digital Versatile Disk), a MD (Mini Disk), a memory stick, or a flash memory as a recording medium.  
         [0068]    The present invention is not limited to the specifically disclosed embodiments, but variations and modifications may be made without departing from the scope of the present invention.  
         [0069]    The present application is based on Japanese priority applications No. 2000-050079 filed on Feb. 25, 2000, and No. 2000-367736 filed on Dec. 1, 2000, the entire contents of which are hereby incorporated by reference.