Abstract:
An audio signal processing method for repairing an anomalous state such as noise, a discontinuity, and a break of sound, comprising detecting the anomalous state of an audio signal, deleting the audio signal in the anomalous segment, deducing the correct audio signal by referring to the waveform of the audio signal before and after the deleted segment, generating a repair signal for repairing the signal in the deleted segment based on the deduced result, inserting the repair signal into the deleted segment, and connecting it to the audio signal before and after the deleted segment.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a method and apparatus for processing an audio signal and apparatuses using the same. More particularly, the present invention relates to a method an apparatus for eliminating shot noise, discontinuity, and a data loss and repairing an audio signal and apparatuses using the same.  
         [0003]     The present invention is applied to compensation for loss of sound occurring when performing high speed reproduction (special reproduction) etc. in a receiver of a broadcasted audio signal, a reproduction system of an audio signal recorded on a magnetic tape, an optical disk, an opto-magnetic disk, or the like, and a decoding system of a digitally transmitted audio signal, for example, a Hi-Fi video apparatus, a digital video apparatus (digital video signal recording and/or reproducing apparatus), and an 8 mm video apparatus.  
         [0004]     2. Description of the Related Art  
         [0005]     In a receiver of a broadcasted audio signal, a reproduction system of an audio signal recorded on a magnetic tape, optical disk, opto-magnetic disk, or the like, a decoder of a digitally transmitted audio signal, etc., there is sometimes shot noise, discontinuity of data, and data loss—frequently occurrences in a communication path, a recording apparatus, a reproducing apparatus, packet communication, etc.  
         [0006]     Such noise is generated everywhere due to, for example, noise generated in the air or in the apparatus, scratches or dust on the magnetic tape, scratches or dust on the optical disk, scratches or dust on an analog record disk, and reading error of the reproducing apparatus. Such noise causes a remarkably incongruity in sound.  
         [0007]     In the past, when such noise and discontinuity occurred, the method of reducing the noise component by a low pass filter, a high pass filter, or the like and the method of replacing segments of data loss by the signal before and after them (Japanese Unexamined Patent Publication (Kokai) No. 9-274772) have been tried. Further, particularly, when digital data is used, the noise and the discontinuity have been reduced by means of prevalue hold, mean value interpolation, attenuation interpolation, muting, or the like  
         [0008]     However, a frequency filter distorts the normal signal portion as well and further is not that effective in elimination of short time and wide frequency band signals such as shot noise and discontinuity.  
         [0009]     Further, prevalue hold and mean value interpolation are problematic in that a discontinuity newly occurs with the preceding and following data, so incongruity in sound is newly caused.  
         [0010]     As concrete audio signal processing apparatuses, related art of Hi-Fi video apparatuses, digital video signal recording and/or reproducing apparatuses, 8 mm video apparatuses, etc. and problems thereof will be explained.  
         [0011]     A Hi-Fi video apparatus using a magnetic tape has, as illustrated in  FIG. 3 , two tracks, that is, a fixed audio track and a Hi-Fi audio track, as tracks for recording an audio signal on the magnetic tape.  
         [0012]     The fixed track is oriented parallel to the tape running direction and is provided at a position independent from the video signal track. It is scanned by a fixed head  17  illustrated in  FIG. 2  and has a low dynamic range, a low frequency range, and a high noise level in structure. It is usually used for only monaural recording.  
         [0013]     The Hi-Fi track is helically scanned by a rotary head drum  16  illustrated in  FIG. 2  and records an audio signal by deep layer recording etc.* at the same position as the video track. It has a high dynamic range, a high frequency range, and a low noise level and is usually used for stereo recording.  
         [0014]     In general, the Hi-Fi track is used for high quality sound reproduction at the time of normal reproduction, while the fixed track is used for low quality sound reproduction at the time of special (high speed) reproduction.  
         [0015]     For example, Japanese Unexamined Patent Publication (Kokai) No. 5-292449 discloses a method of reproducing a video signal recorded on a video track at an (N+1)/N speed. However, the fixed track has to be used for reproduction of the audio signal. The reason for this is that, as shown in  FIG. 4 , at the time of special reproduction, the rotary head scans a plurality of Hi-Fi tracks by obliquely traversing them (helically scans them), so the video signal can be reproduced as one image by combining a plurality of fields, but, in contrast, noise due to discontinuity of the scanning of the rotary head frequently occurs in the audio signal to cause remarkable incongruity in sound, so the Hi-Fi track cannot be used. Therefore, the Hi-Fi track is not used. Instead, the fixed track is used using the fixed head  17 —which is free from the problem of discontinuous scanning of the head.  
         [0016]     In high speed reproduction for a head search or the like, in the case of high speed reproduction at 2× speed or more, a high quality of sound is not always required, so there is little problem.  
         [0017]     However, when trying to save time while fully viewing and listening to the content by reproduction at a slightly high speed, for example, a 1.2× speed, the quality of sound when reproducing the audio signal recorded on the fixed audio track, which is fixed to such high speed reproduction, is insufficient. Therefore, utilization of the Hi-Fi audio track providing a high quality audio signal has been demanded.  
         [0018]     In a digital video signal recording and/or reproducing apparatus using a magnetic tape, when giving as an example the format of for example a consumer digital video system, as shown in  FIG. 24 , a helical track inclined with respect to the tape running direction is divided into units of blocks. A compressed and encoded video signal is recorded at the center, while the audio signal and auxiliary signals are recorded on the two sides.  
         [0019]     At the time of high speed reproduction in the digital video signal recording and/or reproducing apparatus, as shown in  FIG. 25 , a skip in the middle of a track is avoided by an auto-tracking mechanism. However, the discontinuity of the audio signal occurring due to the tracks not being read at the time of high speed reproduction causes a remarkable incongruity in sound at the time of reproduction in the same way as the case of a Hi-Fi video apparatus.  
         [0020]     As the audio signal processing for reducing such incongruity in sound at the time of high speed reproduction in such a digital video signal recording and/or reproducing apparatus, various countermeasures have been considered heretofore. Examples thereof will be explained below.  
         [0021]     (1) The method of permitting the discontinuity and connecting the signal as it is (Japanese Patent No. 2,687.706),  
         [0022]     (2) The method of muting the discontinuous portion,  
         [0023]     (3) The method of changing the speed of the rotary head to match the tape running speed and reading all data (Japanese Patent No. 2,766,065),  
         [0024]     (4) The method of replacing the lost portions of the audio signal by the data before and after it (Japanese Unexamined Patent Publication (Kokai) No. 9-274772), and  
         [0025]     (5) The method of connecting the audio signal before and after a lost portion by a cross fading (Japanese Patent No. 2,737,182).  
         [0026]     With the methods of (1) and (2), however, discontinuity or muting periodically occurs, so the incongruity cannot be solved.  
         [0027]     With the method of (3), the apparatus becomes complex and further the data becomes too large, so time compression and sampling rate conversion are necessary. As a result, a new incongruity in sound such as a rise in sound pitch is caused.  
         [0028]     With the method of (4), although there is the effect of reduction of the incongruity without muting the frames from which data has been lost, discontinuity still occurs before and after the replaced data. Accordingly, there is a problem of how to repair the audio signal without incongruity.  
         [0029]     With the method of (5), although the discontinuity is solved by a cross fading of the data before and after the discontinuity, this is done without considering waveform periodicity etc., so there is a problem in that incongruity due to mismatch of phase is newly caused.  
         [0030]     An 8 mm video apparatus recording and reproducing an audio signal by a rotary head suffers from problems similar to those described above.  
         [0031]     A magnetic recording apparatus using not magnetic tape, but a fixed disk is excellent in random accessability, so the problem such as the skip of a track due to the physical structure described above does not occur. However, a certain time is required for reading data. Therefore, at the time of high speed reproduction, it is sometimes necessary to deliberately reduce the number of read fields. At this time, the problem of discontinuity of sound similar to the above arises.  
       SUMMARY OF THE INVENTION  
       [0032]     An object of the present invention is to provide an audio signal processing method and apparatus for eliminating shot noise and smoothly interpolating discontinuity of an audio signal without distorting a normal portion and thereby reducing the incongruity in sound and apparatuses using the same.  
         [0033]     Another object of the present invention is to provide a method an apparatus for processing a reproduced audio signal to an audio signal free from incongruity in sound at the time of high speed reproduction in a magnetic tape type audio signal reproducing apparatus reproducing an audio signal recorded by helical scanning of a rotary audio head on a magnetic tape such as a Hi-Fi video apparatus, digital video signal recording and/or reproducing apparatus, and 8 mm video apparatus and such apparatuses using the same.  
         [0034]     Still another object of the present invention is to provide a method and apparatus for processing a reproduced audio signal to an audio signal free from incongruity in sound at the time of high speed reproduction in a rotary audio signal reproducing apparatus reproducing an audio signal recorded on a substantially randomly accessable rotary recording medium such as a magnetic disk, optical disk, and opto-magnetic disk and such apparatuses using the same.  
         [0035]     According to a first aspect of the present invention, there is provided an audio signal processing method comprising the steps of deleting an audio signal in an anomalous segment, deducing a correct audio signal by referring to the waveform of the audio signal before and after the deleted segment, generating a repair signal for repairing the signal of the deleted segment based on the deduced result, inserting the repair signal into the deleted segment, and connecting the same with the audio signal before and after the deleted segment.  
         [0036]     Preferably, the method further comprises detecting an anomalous state of the audio signal and performing the above processing when detecting the anomalous state.  
         [0037]     Preferably, the method further comprises evaluating the similarity of signal waveform before and after the deleted segment in the step of deducing the audio signal, generating the repair signal by the waveform with the greatest similarity in the step of generating the repair signal, and smoothly connecting the inserted repair signal and the audio signal before and after the deleted segment in the step of connecting the audio signal.  
         [0038]     Further preferably, the method further comprises measuring and successively adding a time discrepancy between a segment with the waveform connected by using the repair signal and a segment with the anomalous signal deleted therefrom and performing the processing of the deducing step, repair signal generation step, and signal connection step again when a sum of the time discrepancy exceeds a constant time discrepancy so as to adjust the time discrepancy.  
         [0039]     Preferably, the method further comprises calculating a correlation function for the audio signal before and after the deleted segment in the step of deducing the audio signal and evaluating the similarity by referring to the calculated correlation function.  
         [0040]     Alternatively, the method further comprises calculating a correlation function for the audio signal before and after the deleted segment in the step of generating the repair signal and cross fading the audio signal or cross fading the audio signal before and after the deleted segment to smoothly connect it in the step of connecting the audio signal.  
         [0041]     The method may detect the anomalous state by detecting skip scanning of a reading means when reading an audio signal from a recording medium.  
         [0042]     Alternatively, it may detect the anomalous state by statistically processing the audio signal and detecting a sudden fluctuation in the audio signal.  
         [0043]     According to a second aspect of the present invention, there is provided an audio signal processing method comprising the steps of deleting an audio signal of a noise segment of noise and discontinuity due to shot noise superposed on the audio signal or a signal skip, evaluating a similarity of signal waveform before and after the noise segment, and smoothly connecting waveforms to give a maximum similarity.  
         [0044]     According to a third aspect of the present invention, there is provided an audio signal processing apparatus utilizing the above audio signal processing methods.  
         [0045]     The audio signal processing apparatus comprises a signal deleting means for deleting an audio signal of an anomalous segment, a deducing means for deducing a correct audio signal by referring to waveform of the audio signal before and after the deleted segment, a repair signal generating means for generating a repair signal for repairing the signal of the deleted segment based on the deduced result, and a signal connecting means for inserting the repair signal into the deleted segment and connecting the same with the audio signal before and after the deleted segment.  
         [0046]     The audio signal processing apparatus may further comprise an anomaly detecting means for detecting an anomalous state of the audio signal and performing the processing when detecting the anomalous state. The anomalous state is generated at for example a track skip at the time of high speed reproduction or switching of the rotary head in a Hi-Fi video apparatus.  
         [0047]     When detecting the anomalous state, the apparatus deletes the audio signal of the anomalous state portion. Then, considering the continuity of the audio signal, it deduces the audio signal of the deleted portion by referring to the audio signal before and after the deleted portion. Next, it generates a repair signal corresponding to the correct audio signal. Finally, it inserts the repair signal into the deleted segment and connects it to the audio signal before and after the deletion.  
         [0048]     The present invention may be applied to a Hi-Fi video apparatus, digital video apparatus (digital video signal recording and/or reproducing apparatus), 8 mm video apparatus, magnetic disk apparatus, etc.  
         [0049]     As a result, even in the case of high speed reproduction in for example a Hi-Fi video apparatus and 8 mm video apparatus, a high quality Hi-Fi audio signal can be reproduced. Further, pulse noise generated at the time of high speed reproduction of a digital video apparatus is reduced, the incongruity in sound is reduced, and high quality reproduction becomes possible.  
         [0050]     For example, in a Hi-Fi video apparatus, even when trying to save time while fully viewing and listening to the content by reproduction at 1.2× speed, a high quality audio signal can be reproduced. In a magnetic disk apparatus, it becomes possible to obtain a greater margin in the access time and therefore perform time division processing with other tasks without exceeding the limit of the access time. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0051]     These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawings, in which:  
         [0052]      FIG. 1  is a schematic view of the configuration of a first example of a Hi-Fi video apparatus according to an embodiment of the present invention;  
         [0053]      FIG. 2  is a schematic view of tape running and a rotary head of the Hi-Fi video apparatus illustrated in  FIG. 1 ;  
         [0054]      FIG. 3  is a view of a track structure of a tape recording surface of a magnetic tape in the Hi-Fi video apparatus illustrated in  FIG. 1 ;  
         [0055]      FIG. 4  is a view of a trace of a head when reproducing a video Hi-Fi audio track of the magnetic tape illustrated in  FIG. 3  at the time of high speed reproduction;  
         [0056]      FIG. 5  is a view of details of the track structure of the magnetic tape of the Hi-Fi video apparatus illustrated in  FIG. 1  and a head trace at the time of high speed reproduction;  
         [0057]      FIG. 6  is a flow chart of an operation of a track skip detector illustrated in  FIG. 1 ;  
         [0058]      FIGS. 7A  to  7 C are views of a rotary head switch operation in a Hi-Fi video apparatus, in which  FIG. 7A  is a view of a recording track, a used head, and an azimuth thereof,  FIG. 7B  is a view of a rotary head pulse and a track skip pulse at the time of high speed reproduction, and  FIG. 7C  is a view of a reproduction track, a used head, and the azimuth thereof by a head switch operation;  
         [0059]      FIG. 8  is a flow chart of the rotary head switch operation in a head switch illustrated in  FIG. 1 ;  
         [0060]      FIG. 9  is a view of the configuration of a waveform connector illustrated in  FIG. 1 ;  
         [0061]      FIG. 10  is a view of the configuration of a signal buffer illustrated in  FIG. 9 ;  
         [0062]      FIG. 11  is a flow chart of the operation of a signal processor in the waveform connector illustrated in  FIG. 9 ;  
         [0063]      FIG. 12  is a waveform diagram of an input signal subjected to the signal processing in the waveform connector of  FIG. 9 ;  
         [0064]      FIG. 13  is a waveform diagram of a signal with an anomalous portion deleted therefrom in the waveform connector of  FIG. 9 ;  
         [0065]      FIG. 14  is a signal waveform diagram for explaining a method of detecting similar waveforms in the waveform connector of  FIG. 9 ;  
         [0066]      FIG. 15  is a signal waveform diagram for explaining a method of connecting the waveform in the waveform connector of  FIG. 9 ;  
         [0067]      FIG. 16  is a signal waveform diagram for explaining a second method of detecting similar waveforms in the waveform connector of  FIG. 9 ;  
         [0068]      FIG. 17  is a signal waveform diagram for explaining a method of shifting waveform signals for connecting the waveform in the waveform connector of  FIG. 9 ;  
         [0069]      FIG. 18  is a signal waveform diagram for explaining a method of preparing a similar waveform for connecting the waveform in the waveform connector of  FIG. 9  and inserting the same;  
         [0070]      FIG. 19  is a schematic view of the configuration of a second example of a Hi-Fi video apparatus according to an embodiment of the present invention;  
         [0071]      FIG. 20  is a view of the configuration of the waveform connector in  FIG. 19 ;  
         [0072]      FIG. 21  is a view of the configuration of an anomaly detector in  FIG. 20 ;  
         [0073]      FIG. 22  is a flow chart of the operation of a signal processor in the waveform connector illustrated in  FIG. 19 ;  
         [0074]      FIG. 23  is a view of the configuration of a digital video signal recording and/or reproducing apparatus according to a second embodiment of the present invention;  
         [0075]      FIG. 24  is a view of a track structure of a recording surface of a consumer use digital video tape in  FIG. 23 ;  
         [0076]      FIG. 25  is a view of a head scanning trace at the time of high speed reproduction of the digital video signal recording and/or reproducing apparatus of  FIG. 23 ;  
         [0077]      FIG. 26  is a view of the configuration of the waveform connector illustrated in  FIG. 23 ;  
         [0078]      FIG. 27  is a view of the track structure of an 8 mm video tape according to a third embodiment of the present invention;  
         [0079]      FIG. 28  is a view of the configuration of a magnetic disk apparatus according to a fourth embodiment of the present invention; and  
         [0080]      FIG. 29  is a graph of the operation timing of the magnetic disk apparatus of  FIG. 28 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0081]     First, preferred embodiments of the audio signal processing method and apparatus of the present invention will be explained.  
         [0082]     Note that the gist of the present invention resides in the processing for repairing anomaly of an audio signal—not the recording of the audio signal. Similarly, processing of a video signals is not its gist. Accordingly, so far as they do not particularly relate to the present invention, the recording of an audio signal and the processing of a video signal will not be referred to.  
         [0083]     However, the present invention is not limited to only an audio signal reproducing apparatus. The present invention can also be applied to a digital video signal recording and/or reproducing apparatus using the audio signal processing method and apparatus of the present invention and an audio signal and/or video signal recording and/or reproducing apparatus using the audio signal processing method and apparatus of the present invention.  
         [0084]     First Example of Hi-Fi Video Apparatus  
         [0085]     As a first embodiment of use of the audio signal processing apparatus of the present invention, a first example of a Hi-Fi video apparatus will be explained by referring to  FIG. 1  to  FIG. 8 .  
         [0086]      FIG. 1  is a view of the configuration of a Hi-Fi video apparatus according to the first embodiment of the present invention, while  FIG. 2  is a schematic view of tape running and a rotary head of the Hi-Fi video apparatus illustrated in  FIG. 1 .  
         [0087]     The Hi-Fi video apparatus  1  has a rotary head controller  11 , a head switch  12 , a track skip detector  13 , an FM demodulator  14 , a waveform connector  15 , a rotary head drum  16  with rotary heads A 1  and A 2  and B 1  and B 2  mounted thereon, a fixed head  17 , a not illustrated rotation drive controller of the rotary head drum  16 , a not illustrated running drive controller of a magnetic tape  18 , a not illustrated audio signal reproducing apparatus, and a not illustrated video signal reproducing apparatus.  
         [0088]     The rotation drive controller of the rotary head drum  16 , the running drive controller of the magnetic tape  18 , the audio signal reproducing apparatus, and the video signal reproducing apparatus are not directly related to the present invention, so the illustration was omitted, but they are similar to those in the well known apparatuses.  
         [0089]     The Hi-Fi video apparatus  1  records an audio signal and a video signal on the magnetic tape  18  and reproduces the audio signal and the video signal recorded on the magnetic tape  18  by helical scanning using the rotary head drum  16  with the rotary heads A 1 , A 2 , B 1 , and B 2 .  
         [0090]      FIG. 3  is a view of a track structure of the tape recording surface in the Hi-Fi video apparatus.  
         [0091]     A pair of rotary heads A 1  and A 2  and a pair of rotary heads B 1  and B 2  shown in  FIG. 1  are arranged, as shown in  FIG. 2 , at positions rotationally symmetric with respect to a center O of the rotary head drum  16 , that is, facing positions 180 degrees apart, at the rotary head drum  16 . The rotary heads A 1  and A 2  are arranged at adjacent positions and have azimuth angles reverse to each other. Also, the rotary heads B 1  and B 2  are similarly arranged at adjacent positions and have azimuth angles reverse to each other. The rotary heads A 1  and B 2  and the rotary heads A 2  and B 1  are given the same azimuth angles. This arrangement is called a double azimuth type. As will be explained later, such a configuration is employed at the time of high speed reproduction so that the reproduction head scans the recorded track at a different azimuth angle from that at the time of recording.  
         [0092]     The rotary head controller  11 , head switch  12 , track skip detector  13 , FM demodulator  14 , and the waveform connector  15  will be briefly explained next.  
         [0093]     The rotary head controller  11  controls a not illustrated drive system so as to rotate the rotary head drum  16  at a designated speed. At the same time, it generates a rotary head pulse S 11  whenever the rotary heads A 1  and B 1  pass an origin C illustrated in  FIG. 2  and outputs it to the head switch  12 .  
         [0094]     The track skip detector  13  compares the signal levels of the signals obtained from the rotary heads A 1 , A 2 , B 1 , and B 2  to monitor if the rotary head having the maximum signal level changes from the rotary head A 1  to A 2 , from the rotary head A 2  to A 1 , from the rotary head B 1  to B 2 , or from the rotary head B 2  to B 1 . Where it detects a change of the rotary heads, it concludes there was a track skip, generates a track skip pulse S 13  at that time, and outputs the track skip pulse to the head switch  12  and the waveform connector  15 .  
         [0095]     The head switch  12  receives as its inputs the detection signals of the rotary heads A 1 , A 2 , B 1 , and B 2  and selects one of the detection signals of the rotary heads A 1 , A 2 , B 1 , and B 2  in accordance with the rotary head pulse S 11  from the rotary head controller  11  and the track skip pulse S 13  from the track skip detector  13 .  
         [0096]     The rotary head pulse S 11  output from the rotary head controller  11  is the signal detecting the passage of the rotary head drum  16  through the position C, so indicates one revolution of the rotary head drum  16 . It is also the signal for discriminating the positions of the pair of rotary heads A 1  and A 2  and the pair of rotary heads B 1  and B 2 . On the other hand, the track skip pulse S 13  detected at the track skip detector  13  is a signal indicating that the rotary heads A 1  and A 2  or the rotary heads B 1  and B 2  skipped a track in the magnetic tape  18 . Accordingly, the head switch  12  switches between the rotary heads An and B by the rotary head pulse S 11  from the rotary head controller  11  and switches between the rotary heads  1  and  2  by the track skip pulse S 13  from the track skip detector  13 . Note that, the rotary head A indicates the rotary heads A 1  and A 2 , and similarly the rotary head B indicates the rotary heads B 1  and B 2 . Further, the rotary head  1  indicates the rotary heads A 1  and B 1 , and the rotary head  2  indicates the rotary heads A 2  and B 2 .  
         [0097]     The FM demodulator  14  demodulates the audio signal selected at the head switch  12  and inputs the same to the waveform connector  15 .  
         [0098]     The waveform connector  15  smoothly connects the signal FM demodulated at the FM demodulator  14  while maintaining the continuity and outputs the same as the repaired audio signal to deal with the anomalous state such as the discontinuity of the signal or skip or noise from the timing based on the track skip pulse S 13  detected at the track skip detector  13 .  
         [0099]     Details of the high speed reproduction operation of the Hi-Fi video apparatus  1  will be explained next.  
         [0100]     Track Skip Detector  
         [0101]      FIG. 3  is a view of the track structure of the tape recording surface of the magnetic tape  18  of a Hi-Fi video apparatus.  
         [0102]      FIG. 4  is a view of the trace of the head at the time of high speed reproduction of the video Hi-Fi audio track of the magnetic tape  18  illustrated in  FIG. 3 .  
         [0103]      FIG. 5  is a view of the track structure of the magnetic tape  18  and the head trace at the time of high speed reproduction. Symbols R 1  to R 7  shown in  FIG. 5  are track numbers attached for convenience for the explanation of the present embodiment, while symbols Q 1  to Q 7  are scanning numbers attached for convenience for the explanation of the present embodiment  
         [0104]     The track skip detector detects the time of occurrence of a track skip indicated by a mark O at the time of high speed reproduction as shown in  FIG. 4  and  FIG. 5 , generates a track skip pulse S 13  at that time, and outputs the track skip pulse S 13  to the head switch  12  and the waveform connector  15 .  
         [0105]     The principle of generation the track skip pulse S 13  in the track skip detector  13  will be explained next.  
         [0106]     In the helical scanning of the Hi-Fi video tape shown in  FIG. 3 , as partially indicated by hatching in the track, the recording azimuth angles of the adjoining tracks are different. In the case of for example a VHS Hi-Fi video, an angle of +30 degrees is given for every track. When head scanning over a plurality of tracks as shown in  FIG. 4  and  FIG. 5 , the azimuth angle of the recording surface becomes reverse at the time when the track skip indicated by the mark O occurs, the angle of the head in use loses compatibility, and the other head forming the pair becomes compatible. Due to this, the magnitudes of the output levels of the paired (A 1  and A 2  and B 1  and B 2 ) heads are switched with each other.  
         [0107]      FIG. 6  is a flow chart of the processing of the track skip detector  13 .  
         [0108]     The track skip detector  13  follows the above principle of detection and refers to the rotary head pulse S 11  from the rotary head controller  11  to judge whether the rotary heads A 1  and A 2  are located at the tape surface of the magnetic tape  18  or the rotary heads B 1  and B 2  are located at the tape surface of the magnetic tape  18  (S 1 ). When the rotary heads A 1  and A 2  are located at the tape surface of the magnetic tape  18 , it compares the signal levels of the rotary heads A 1  and A 2 . When detecting that they are replaced with heads outputting signals having a larger level (S 2 , S 4 : S 2 , S 4 ), it generates the track skip pulse S 13  (S 5 ). Similarly, when the rotary heads B 1  and B 2  are located on the tape surface of the magnetic tape  18 , it compares the signal levels of the rotary heads B 1  and B 2 . When detecting that they are replaced with heads outputting signals having a larger level (S 6  to S 8 ), it generates the track skip pulse S 13  (S 5 )  FIGS. 7A  to  7 C are graphs showing the rotary head switch operation.  
         [0109]     The track skip pulse S 13  may be a single pulse in the head switch  12  as illustrated in  FIG. 7B . However, the waveform connector  15  explained later requires the time when the track skip was generated. Therefore, the track skip pulse S 13  to be given to the head switch  12  is made a one-pulse signal as illustrated in  FIG. 7B . On the other hand, as the track skip pulse S 13  to be given to the waveform connector  15 , other than the one-pulse signal, the track skip generation time is informed. Alternatively, only a one-pulse signal is given to the waveform connector  15  and the time when receiving the track skip pulse S 13  is stored in the waveform connector  15 . In the present embodiment, as will be explained later by referring to  FIG. 9  and  FIG. 10 , the case is illustrated where, when one pulse of the track skip pulse S 13  is supplied from the track skip detector  13  to the waveform connector  15 , a buffer controller  1551  in the waveform connector  15  sets the position anomaly flag indicating that time in a signal buffer  152 .  
         [0110]     Rotary Head Switch  
         [0111]     The rotary head switch  12  receives as its input the rotary head pulse S 11  output from the rotary head controller  11  and the track skip pulse S 13  output from the track skip detector  13  and switches the detection signals of the reproduction heads A 1 , A 2 , B 1 , and B 2 .  
         [0112]     At the time of recording, as illustrated in  FIG. 7A , the data is recorded by azimuth angles alternating for every track by using the rotary heads A 1  and B 1  having reverse azimuths located at facing positions. Namely, as illustrated in  FIG. 5 , the audio signal is recorded on a track R 1  by the rotary head A 1  with a positive azimuth (for example +30 degrees), and audio signal is recorded on a track R 2  by the rotary head B 1  with a negative azimuth (for example −30 degrees). The audio signal is then alternately recorded in a similar way to that described above. Note that an explanation of the recording of the video signal is omitted.  
         [0113]     At the time of normal reproduction of the recorded audio signal, in the same way as the time of recording explained above by referring to  FIG. 7A , the data is reproduced by azimuth angles alternating for every track by using the rotary heads A 1  and B 1  having the reverse azimuths located at facing positions.  
         [0114]     At the time of recording in the Hi-Fi video apparatus  1  of the present embodiment, the operation at the time of normal reproduction is similar to the operation of the usual well known Hi-Fi video apparatus.  
         [0115]     At the time of high speed reproduction, as illustrated in  FIG. 7B , the rotary head controller  11  generates the rotary head pulse S 11  at the time when the reproduction head trace returns to the lowermost end and the track skip detector  13  generates the track skip pulse S 13  at the position of the track skip given the mark  0  in  FIG. 5 .  
         [0116]      FIG. 7C  is a graph of the head switch operation in the head switch  12 .  
         [0117]      FIG. 8  is a flow chart of the rotary head switch operation in the head switch  12 .  
         [0118]     The rotary heads “A 11 ” and “B” in the head switch  12  are switched at the timing of generation of the rotary head pulse S 11  output from the rotary head controller  11 , while the rotary heads “1” and “2” in the head switch  12  are switched matching with the timing of the generation of the track skip pulse S 13  in the track skip detector  13 .  
         [0119]     For example, as exemplified in  FIG. 7C , the head switch first uses the rotary heads (A 1 , B 1 ) (step  11  in  FIG. 8 ). In a scanning period Q 1 , it scans the R 1  track (positive azimuth) by the rotary head A 1  (positive azimuth).  
         [0120]     When the rotary head A 1  finishes scanning the R 1  track and shifts to the R 2  track, the head switch  12  switches the rotary head A 1  to the rotary head B 1  (step  13 ) matching with the reception of the rotary head pulse S 11  from the rotary head controller  11  ( FIG. 8 , step  12 ).  
         [0121]     In a scanning period Q 2 , the scanning of the R 2  track (negative azimuth) is started by the rotary head B 1  (negative azimuth), but a skip to an R 3  track (positive azimuth) occurs in the middle. The head switch  12  switches the use of the rotary heads (A 1 , B 1 ) to the use of the rotary heads (A 2 , B 2 ) (step  15 ) at the time of generation of the track skip pulse S 13  from the track skip detector  13  (step  15 ) and scans the remainder of the R 3  track (positive azimuth) by the rotary head B 2  (positive azimuth).  
         [0122]     In a scanning period Q 3 , an R 4  track (negative azimuth) is scanned by the rotary head A 2  (negative azimuth). In a scanning period Q 4 , an R 5  track (positive azimuth) is scanned by the rotary head B 2  (positive azimuth).  
         [0123]     In a scanning period Q 5 , an R 6  track (negative azimuth) is scanned by the rotary head A 2  (negative azimuth), a switch is made to the use of the rotary heads (A 1 , B 1 ) matching with the generation of the track skip pulse S 13 , and an R 7  track (positive azimuth) is scanned by the rotary head A 1  (positive azimuth).  
         [0124]     The head switch  12  repeats the above operations. Note that, along with the switching of the rotary heads in the head switch  12 , a pulse-like noise is sometimes generated. This noise is one of the anomalous signals of the present invention.  
         [0125]     Due to the above operation, the head switch  12  transmits the detection signals of the rotary heads A 1 , A 2 , B 1 , and B 2  compatible with the operation (scanning) of the rotary heads A 1 , A 2 , B 1 , and B 2  at the time of high speed reproduction to the FM demodulator  14 .  
         [0126]     The FM demodulator  14  demodulates the audio signals transmitted from the head switch  12  by a well known method.  
         [0127]     Waveform Connector (First Embodiment)  
         [0128]     The waveform connector  15  of the first embodiment of the audio signal processing method of the present invention will be explained by referring to  FIG. 9  to  FIG. 11  and  FIG. 12  to  FIG. 18 .  
         [0129]      FIG. 9  is a view of the configuration of the waveform connector  15 .  
         [0130]      FIG. 10  is a view of the processing of the signal buffer  152 .  
         [0131]      FIG. 11  is a flow chart of the processing of a signal processor  155 .  
         [0132]      FIG. 12  to  FIG. 18  are views of the waveforms of the signals processed at the waveform connector.  
         [0133]     The waveform connector  15  is a waveform connector utilizing the track skip pulse S 13  generated in the track skip detector  13 . The track skip time becomes clear from the track skip pulse S 13 , so the waveform connector  15  connects the waveform by utilizing this.  
         [0134]     The waveform connector  15  illustrated in  FIG. 9  has an A/D converter  151 , a signal buffer  152 , a D/A converter  154 , and a signal processor  155 .  
         [0135]     When the audio signal is input in a digital format, the A/D converter  151  and the D/A converter  154  are unnecessary.  
         [0136]     The A/D converter  151  converts an analog audio signal S 14  demodulated at the FM demodulator  14  shown in  FIG. 12  to a digital audio signal.  
         [0137]     Signal Buffer  
         [0138]     As illustrated in  FIG. 10 , the signal buffer  152  comprises a for example 16-bit signal buffer and a 1-bit anomaly flag located at a position corresponding to the position of the audio signal to be stored. The content of the signal buffer  152  is shifted rightward every sampling time. New data is added to the input position and the data at the output position is output. The audio signal stored in the signal buffer  152  is stored in time series, so the storage position of the audio signal corresponds to the time. The output position and the processing center position do not vary, but the input position varies in accordance with the time discrepancy due the processing of the signal processor.  
         [0139]     The D/A converter  154  converts the digital audio signal output from the signal buffer  152  to an analog audio signal.  
         [0140]     Signal Processor  
         [0141]     The signal processor  155  illustrated in  FIG. 9  has a buffer controller  1551 , an anomaly deleter  1552 , a waveform connector  1553 , a pseudo waveform generator  1554 , a time discrepancy storage  1555 , and a pseudo waveform detector  1556 .  
         [0142]     The signal processor  155  monitors the existence of generation of the track skip pulse S 13  and performs a series of processing of anomalous segment deletion, waveform connection, and pseudo waveform insertion when an anomalous state arises in the waveform due to the generation of the track skip pulse S 13 .  
         [0143]     Buffer Controller  
         [0144]     The buffer controller  1551  concludes that there is an anomaly in the waveform of the audio signal when there is a reception of the track skip pulse S 13  and sets the anomaly flag portion in the signal buffer  152  corresponding to that time at “1”.  
         [0145]      FIG. 12  is a waveform diagram of an audio signal S 141  output from the A/D converter  151  to the signal processor  155 . Assume that an anomalous portion exists in a period T. The period T indicates the center time of the processing of the signal buffer  152 .  
         [0146]     The buffer controller  1551  further exchanges the audio signal processed in the waveform connector  1553 , pseudo waveform generator  1554 , time discrepancy storage  1555 , and pseudo waveform detector  1556  with the signal buffer  152  to shift and replace the data in the signal buffer  152  along with the series of processing.  
         [0147]     Anomaly Deleter  
         [0148]     The anomaly deleter  1552  deletes the signal of the anomalous portion.  
         [0149]      FIG. 13  is a signal waveform diagram of the case where the anomalous portion is deleted from the signal waveform illustrated in  FIG. 12  by the anomaly deleter  1552 .  
         [0150]     W represents a deletion time width (deleted segment length), TS represents a deletion start time, and Te represents a deletion end time.  
         [0151]     Details of the deletion time width (deleted segment length) W, deletion start time TS, and deletion end time Te will be explained later. The deleted segment length W may be set longer than the maximum time length of the shot noise. It is set at for example 20 ms in the case of shot noise, and while is set at for example 5 ms in the case of discontinuity or signal skip.  
         [0152]     Waveform Connector  
         [0153]     The waveform connector  1553  overlaps and connects the waveform before and after the deleted segment illustrated in  FIG. 13  to give a maximum similarity. The similarity is evaluated according to a mutual correlation coefficient.  
         [0154]     The waveform of the input audio signal is defined as f(t) and the waveform in the forward direction of the deleted segment is represented by the following equation 1.  
                 f   a     ⁡     (   t   )       =     {               f   ⁡     (   t   )               0         ⁢           (     t   ≦     T   s       )               (     t   &gt;     T   s       )             ,               (   1   )             
 
         [0155]     The waveform in back of the deleted segment is represented by the following equation 2.  
                 f   b     ⁡     (   t   )       =     {           0         (     t   &lt;     T   e       )               f   ⁡     (   t   )             (     t   ≧     T   e       )           ,               (   2   )             
 
         [0156]     As illustrated in  FIG. 14 , when superposed on each other by exactly a length p, the mutual correlation coefficient of the superposed portions becomes as shown in the following equation 3.  
               R   ⁡     (   p   )       =         ∫   0   p     ⁢         f   a     ⁡     (     t   +     T   s     -   p     )       ⁢       f   b     ⁡     (     t   +     T   e       )       ⁢           ⁢     ⅆ   t             ∫   0   p     ⁢         f   a   2     ⁡     (     t   +     T   s     -   p     )       ⁢           ⁢     ⅆ   t     ⁢       ∫   0   p     ⁢         f   b   2     ⁡     (     t   +     T   e     -   p     )       ⁢           ⁢     ⅆ   t                       (   3   )             
 
         [0157]     This processing corresponds to calculation of the correlation by shifting the waveform in back of the deleted segment forward by exactly a length (p+W). That is calculated within a range of p min ≦p≦p max . The time difference p giving the maximum correlation coefficient is determined as an overlap segment length P.
 
 P={p|R ( p )-&gt;maximum,  p   min   ≦p≦p   max }  (4)
 
         [0158]     Here, the search range of P is made about the same degree as one pitch period of the speech or music (audio signal). For example, P min =4 ms and P max =20 ms are set.  
         [0159]     After the overlap segment length is determined, as shown in  FIG. 15 , the front and back waveform are superposed over the segment P and cross faded.  
               g   ⁡     (   t   )       =     {             f   a     ⁡     (   t   )             (     t   ≦     T   q       )                 {         (       T   s     -   t     )     ⁢       f   a     ⁡     (   t   )         +       (     t   -     T   q       )     ⁢       f   b     ⁡     (     t   +   W     )           }     /   P           (       T   q     &lt;   t   &lt;     T   s       )                 f   b     ⁡     (     t   +   W     )             (     t   ≧     T   s       )                     (   5   )             
 
         [0160]     Note that, Tq=Ts−P.  
         [0161]     Due to this method, the followings are realized:  
         [0162]     1. Sound having periodicity in the waveform like speech (vowels) or music usually has the maximum correlation in that period or a whole multiple of the same, so can be connected while maintaining the periodicity.  
         [0163]     2. Even if not a periodic waveform, it can be connected by the portion having the highest correlation, that is, similar in waveform.  
         [0164]     3. Due to the cross fading, it can be smoothly connected without discontinuity in the waveform.  
         [0165]     Time Discrepancy Storage and Pseudo Waveform Generator  
         [0166]     According to the above processing, the waveform is shortened by (W+P) time for each anomaly. Therefore, if left as it is, the discrepancy between the original sound and the processed sound will accumulate. Therefore, the cumulative time discrepancy from the point of time of start of the processing is stored in the time discrepancy storage  1555 . When the waveform is shortened by a constant value or more, a short pseudo waveform is prepared in the pseudo waveform generator  1554  and inserted to thereby stretch the total length.  
         [0167]     As shown at step  31  of  FIG. 11 , first, at the start of the processing, the time discrepancy storage  1555  resets the cumulative time discrepancy stored. The time discrepancy storage  1555  subtracts (X+P) from the cumulative time discrepancy stored at step  38  whenever the anomaly processing is carried out at steps  33  to  37 . When the time discrepancy storage  1555  detects that the cumulative time discrepancy exceeds a set value during the processing (step  39 ), the pseudo waveform detector  1556 , the pseudo waveform generator  1554 , and the waveform connector  1553  perform the pseudo waveform detection processing, pseudo waveform generation processing, and the pseudo waveform insertion processing shown at steps  40  to  42 . This set value may be for example 0 second. In that case, the waveform is always stretched in the initial processing and the signal is adjusted to maintain a slightly longer time than the original sound.  
         [0168]     The pseudo waveform generation and insertion processing will be explained below. An example of the waveform after the waveform connection processing is shown in  FIG. 16 .  
         [0169]     First, a waveform having a length l is taken in the front of the frontmost portion Tq of the connection point, and the mutual correlation coefficient with the waveform further in front from that by a length l is calculated.  
               R   ⁡     (   l   )       =         ∫   0   l     ⁢       g   ⁡     (     t   +     T   q     -   l     )       ⁢     g   ⁡     (     t   +     T   q     -     2   ⁢   l       )       ⁢           ⁢     ⅆ   t               ∫   0   l     ⁢         g   2     ⁡     (     t   +     T   q     -   l     )       ⁢           ⁢     ⅆ   t     ⁢       ∫   0   l     ⁢         g   2     ⁡     (     t   +     T   q     -     2   ⁢   l       )       ⁢           ⁢     ⅆ   t                         (   6   )             
 
         [0170]     This is calculated over a segment of l min ≦l≦l max . The  1  which becomes the maximum is determined as the pseudo waveform time length L.
 
 L={l|R ( l }-&gt;maximum,  l   min   ≦l≦l   max }  (7)
 
         [0171]     Here, the search range of the length l is made about the same degree as one pitch period of speech or music in the same way as the waveform connection portion. For example, l min  is made 4 ms and l max  is made 20 ms.  
         [0172]     After the pseudo waveform time length L is determined, as shown in  FIG. 17 , the waveform is divided at the time Tl=Tq−L. The back waveform is moved back by exactly L. When the front waveform is ga (t) and the back waveform after the movement is ga(t), they can be represented as follows by using g(t) of equation 5.  
                 g   a     ⁡     (   t   )       =     {             g   ⁡     (   t   )               0         ⁢             (     t   ≦     T   l       )     ,                 (     t   &gt;     T   l       )     ,                       (   8   )                   g   b     ⁡     (   t   )       =     {           0             g   ⁡     (     t   -   W     )             ⁢             (     t   ≦     T   q       )     ,                 (     t   &gt;     T   q       )     ,                       (   9   )             
 
         [0173]     Finally, as shown in  FIG. 18 , a pseudo waveform prepared by cross fading the waveform on the two sides shown in equation 10 is inserted in the segment Tl&lt;t&lt;Tq which becomes empty by the above processing,  
               F   ⁡     (   t   )       =     {             g   a     ⁡     (   t   )               (     t   ≦     T   l       )     ,                 {         (       T   q     -   t     )     ⁢       g   a     ⁡     (   t   )         +       (     t   -     T   l       )     ⁢       g   b     ⁡     (   t   )           }     /   L             (       T   l     &lt;   t   &lt;     t   q       )     ,                 g   b     ⁡     (   t   )               (     t   ≧     T   q       )     ,                     (   10   )             
 
         [0174]     The following can be realized by such a method.  
         [0175]     1. Sound having periodicity in waveform like speech (vowels) or music has the maximum correlation in a whole multiple of the period, so the waveform is stretched while maintaining the periodicity.  
         [0176]     2. Even if not a periodic waveform, it can be connected by the portion having the highest correlation, that is, similar in waveform.  
         [0177]     3. Due to the cross fading, it can be smoothly connected without discontinuity in the waveform.  
         [0178]     Time Discrepancy Storage  
         [0179]     The time discrepancy storage  1555  stores the shortened time from the start of the processing and the cumulative time of the extension.  
         [0180]     The series of operation of the waveform connector  15  will be explained next by referring to  FIG. 11 .  
         [0181]     Step  31 : Before storing the audio signal in the signal buffer  152 , as the initial operation, the buffer controller  1551  in the signal processor  155  resets the cumulative time discrepancy storage data.  
         [0182]     Step  32 : The analog audio signal S 14  illustrated in  FIG. 12  demodulated in the FM demodulator  14  is converted to a digital audio signal in the A/D converter  151 . The converted digital audio signal S 151  is successively stored in the signal buffer  152  every sample time. The signal buffer  152  is configured by a ring buffer or FIFO. The digital data is given from its output end to the D/A converter  154  every sample time and output as an output audio signal S 15 .  
         [0183]     Step  33 : The buffer controller  1551  decides that an anomalous state occurred when receiving a track skip pulse S 13 , sets the anomaly flag at the position corresponding to that time in the signal buffer  152  ( FIG. 10 ), and proceeds to the processing of step  35  and the following steps. When it does not receive the track skip pulse S 13 , the operation routine shifts to the processing of step  34 .  
         [0184]     Step  34 : When there is no anomaly, the buffer controller  1551  does nothing. In that case, the audio signal successively stored in the signal buffer  152  is successively output to the D/A converter  154  after a predetermined time.  
         [0185]     Step  35 : When an anomalous state is detected at the buffer controller  1551 , the anomaly deleter  1552  deletes the data of the anomalous portion in the vicinity of the time T in  FIG. 12  described above. Namely, when the anomalous state is detected, the anomaly deleter  1552  deletes the signal before and after the processing center time as illustrated in  FIG. 13 . The noise, data loss, or the like to be eliminated by the present invention is instantaneous shot noise or discontinuity, so the deleted segment may be made for example about 5 ms.  
         [0186]     Steps  36  to  37 : When the anomalous data is deleted, the waveform connector  1553  connects the signal before and after the deleted segment in cooperation with the pseudo waveform detector  1556  and the pseudo waveform generator  1554 .  
         [0187]     The pseudo waveform detector  1556  searches for a similar portion by shifting the waveform data in back of the deletion portion as illustrated in  FIG. 14  and overlaps and adds it so that the parts of the waveform before and after the deleted portion resemble each other the most.  
         [0188]     The pseudo waveform generator  1554  detects the similar waveform of the data stored in the signal buffer  152  by utilizing the pseudo waveform detector  1556  again in order to compensate for the portion shortened in the total length of the data by the processing of the anomaly deleter  1552  and the waveform connector  1553 , generates the pseudo waveform for stretching the waveform, and inserts the generated waveform data into the portion deleted by the anomaly deleter  1552 .  
         [0189]     Step  38 : The time discrepancy storage  1555  adds and stores the time length of the shortening/extension of the waveform by the anomaly deleter  1552 , waveform connector  1553 , and the pseudo waveform generator  1554 .  
         [0190]     Step  39 : The time discrepancy storage  1555  decides whether or not the time discrepancy is within a constant value. When it is within the constant value, the operation routine shifts to the processing of step  34 .  
         [0191]     Steps  40  to  42 : When the time discrepancy exceeds the constant value, the above processing is repeated. Namely, the similar waveform detector  1556  evaluates the similarity of the waveform at a different time in the signal buffer  152  as explained above.  
         [0192]     Since the time discrepancy storage  1555  manages the amount of data of the audio signal in the deleted segment as time, so disconnection or overlap of the audio signal is eliminated.  
         [0193]     The above waveform connector  15  is able to delete the noise segment for shot noise superposed on the signal, signal skip, discontinuity, etc., smoothly connect the waveform before and after the deletion, and limit the time discrepancy from the original signal to the smallest level by inserting a pseudo waveform into the signal. Namely, the waveform connector  15  of the present embodiment can delete noise derived from shot noise or discontinuity of the audio signal without distorting the normal portion, smoothly interpolate the discontinuous portion, and reduce incongruity in sound.  
         [0194]     Further, the Hi-Fi video apparatus  1  of the embodiment of the present invention illustrated in  FIG. 1  generates an audio signal compensated for discontinuity even in the case where there is a discontinuity of the audio signal due to a track skip at the time of high speed reproduction or switching of the rotary head sat the head switch  12  and as a result can reproduce an audio signal without concern as to discontinuity.  
         [0195]     Second Example of Hi-Fi Video Apparatus  
         [0196]     A second example of the Hi-Fi video apparatus of the present invention will be explained by referring to  FIG. 19  to  FIG. 20 .  
         [0197]     The Hi-Fi video apparatus  1 A of the second example has a rotary head controller  11 , head switch  12 , track skip detector  13 , FM demodulator  14 , waveform connector  15 A, a rotary head drum  16  illustrated in  FIG. 2 , a fixed head  17  illustrated in  FIG. 2 , a not illustrated rotation drive controller of the rotary head drum  16 , a not illustrated running drive controller of the magnetic tape  18 , a not illustrated audio signal reproducing apparatus, and a not illustrated video signal reproducing apparatus.  
         [0198]     The Hi-Fi video apparatus  1 A illustrated in  FIG. 19  has a similar configuration to that of the Hi-Fi video apparatus  1  illustrated in  FIG. 1 , but the track skip pulse S 13  is not output from the track skip detector  13  to the waveform connector  15 An and the configuration of the waveform connector  15 A is different from that of  FIG. 9  as illustrated in  FIG. 20 . The other portions are similar to those of the Hi-Fi video apparatus  1  of  FIG. 1 , however. Accordingly, the following description will be made focusing on portions different from the first example.  
         [0199]     Waveform Connector  
         [0200]     The waveform connector  15 A will be explained by referring to  FIG. 20 .  
         [0201]     The waveform connector  15 A has an A/D converter  151 , signal buffer  152 , D/A converter  154 , signal processor  155 A, and anomaly detector  156 . When the audio signal is input in a digital form, the A/D converter  151  and the D/A converter  154  are unnecessary.  
         [0202]     The waveform connector  15 A does not use a track skip pulse S 13  generated in the track skip detector  13  unlike the waveform connector  15  of  FIG. 9 . For this reason, the anomaly detector  156  is provided in the waveform connector  15 A, and the processing of the signal processor  155 A is slightly different from the processing of the signal processor  155  illustrated in  FIG. 9 .  
         [0203]     Anomaly Detector  
         [0204]      FIG. 21  is a view of the configuration of the anomaly detector  156 .  
         [0205]     The anomaly detector  156  has a high pass filter  1561 , a power detector  1562 , a mean value calculator  1563 , and a power comparator  1564 .  
         [0206]     The anomaly to be eliminated by the present invention is short time shot noise or signal loss, short time signal skip (so-called sound skip), or discontinuity due to track skip, the switching of the rotary heads, etc. At the time of detection of an anomaly, the fact that a high frequency component is instantaneously largely generated due to the nature of the shot noise or skip is utilized. For example, in speech or music, the component up to about 10 kHz at most is dominant, but in contrast, in shot noise, a component up to near the Nyquist frequency is instantaneously generated.  
         [0207]     The high pass filter  1561  passes the high frequency component of an audio signal S 151  output from the A/D converter  151  therethrough. The power detector  1562  calculates the power of the signal passed through the high pass filter  1561 , that is, the square of the signal passed through the high pass filter  1561 . The mean value calculator  1563  calculates the mean value of the power over for example past 50 ms of the audio signal of the high frequency component. The power comparator  1564  compares the mean value of the power calculated at the mean value calculator  1563  and the power of the audio signal calculated at the power detector  1562 . When the power value is larger than the mean power value, the time is detected as the time of generation of instantaneous noise or a skip.  
         [0208]      FIG. 12  illustrates an example of a waveform having an anomalous portion due to the disturbance of the waveform on the periphery of the time T. When the audio signal behaves as in the period T of  FIG. 12 , the value deviates from the mean value of the audio signal, so the anomalous state can be detected at the power comparator  1564 .  
         [0209]     The anomalous state detected at the anomaly detector  156  is notified to the signal buffer  152  illustrated in  FIG. 10 . The signal buffer  152  sets the anomaly flag in the corresponding data.  
         [0210]     The signal buffer  152  is similar to the signal buffer  152  explained above. Namely, as illustrated in  FIG. 10 , it comprises for example a 16-bit signal buffer and a 1-bit anomaly flag. The content of the signal buffer  152  is shifted rightward every sample time. New data is added to the input position and the data at the output position is output. The output position and the processing center position do not vary, but the input position varies in accordance with the time discrepancy due the processing of the signal processor.  
         [0211]     In the present example, the anomaly flag is set in accordance with not the track skip pulse S 13 , but the detection of the anomaly detector  156 .  
         [0212]     Signal Processor  
         [0213]     The signal processor  155 A illustrated in  FIG. 20  has a buffer controller  1551 A, anomaly deleter  1552 , waveform connector  1553 , pseudo waveform generator  1554 , time discrepancy storage  1555 , and pseudo waveform detector  1556 .  
         [0214]     The signal processor  155  monitors the anomaly flag stored in the signal buffer  152  by the anomaly detector  156 , performs no operation where the anomaly flag is “0” (where there is no anomaly), and performs a series of processing of anomalous segment deletion, waveform connection, and pseudo waveform insertion where the anomaly flag is “1” (where there is an anomaly).  
         [0215]      FIG. 22  is a flow chart of the processing of the signal processor  155 A.  
         [0216]     Buffer Controller  
         [0217]     The buffer controller  1551 A monitors the anomaly flag at the processing center for the data stored in the signal buffer  152  illustrated in  FIG. 10 . Namely, the track skip pulse S 13  is not input to the buffer controller  1551 A, so the set state of the anomaly flag set by the anomaly detector  156  is achieved by the buffer controller  1551 A. Accordingly, the decision of the anomaly by the buffer controller  1551 A of step  33 A in  FIG. 22  becomes the monitoring of the set state of the anomaly flag of the signal buffer  152 .  
         [0218]     The buffer controller  1551 A further shifts and replaces the data in the buffer along with the series of processing for the signal with the waveform shown in  FIG. 12  to  FIG. 18 .  
         [0219]     Anomaly Deleter, Waveform Connector, Pseudo Waveform Generator, Time Discrepancy Storage  
         [0220]     The anomaly deleter  1552 , waveform connector  1553 , pseudo waveform generator  1554 , and time discrepancy storage  1555  perform similar processing to that explained above by referring to  FIG. 9 .  
         [0221]     As explained above, the waveform connector  15  of  FIG. 9  and the waveform connector  15 A of  FIG. 20  are different in only the method of detection of the anomalous state. Accordingly, the waveform connector  15 A of  FIG. 20  can perform similar waveform connection processing to that of the waveform connector  15  of  FIG. 9 .  
         [0222]     As a result, the Hi-Fi video apparatus  1 A illustrated in  FIG. 19 , similar to the Hi-Fi video apparatus  1  of  FIG. 1 , can perform signal processing to eliminate anomalous due to track skip, switching of the rotary heads, or the like. Namely, the Hi-Fi video apparatus  1 A using the waveform connector  15 A illustrated in  FIG. 19  generates an audio signal compensated for anomaly even when there is an anomaly of the audio signal due to track skip at the time of high speed reproduction and the switching of the rotary heads in the head switch  12  and as a result can reproduce an audio signal without concern as to anomaly.  
         [0223]     Third Example of Hi-Fi Video Apparatus  
         [0224]     The method of detection of the anomalous portion in the waveform connectors  15  and  15 A is not limited to the examples explained above. Other various methods can be employed.  
         [0225]     For example, in the same way as a track skip being detected at the track skip detector  13  and a track skip pulse S 13  being output to the waveform connector  15 , a signal indicating an anomalous state in the apparatus using the waveform connector  15  from that apparatus and an auxiliary signal can be input to for example the buffer controller  1551  of the signal processor  155  illustrated in  FIG. 9 .  
         [0226]     As such an auxiliary signal, use can be made of for example an error correction code used at the time of reproduction of a CD etc. By this, the time of generation of the anomaly becomes clear, and the processing in the waveform connector  15  becomes possible.  
         [0227]     The waveform connectors  15  and  15 A can be applied to not only a Hi-Fi video apparatus, but also various other apparatuses handling audio signals. As such apparatuses, there are for example CD audio signal players, MD players, DVD players, cellular phones, 8 mm video apparatuses, and audio signal communication devices.  
         [0228]     When the present invention is applied to such apparatuses, even if there is noise or skips due to scratches or dust on the magnetic tape, noise or skips due to scratches or dust on the magnetic disk, noise or skips due to scratches or dust on the optical disk, noise or skips due to scratches or dust on the analog record disk, noise or signal loss occurring in the air or apparatus, etc., the influence of them can be eliminated and the incongruity in sound can be reduced.  
         [0229]     Further, the present invention is not limited to the Hi-Fi video apparatuses explained above and can be applied to the signal processing of an anomaly caused when reproducing an audio signal recorded on a magnetic tape or a rotary recording medium such as a magnetic disk.  
         [0230]     Digital Video Signal Recording and/or Reproducing Apparatus  
         [0231]     As another embodiment of the present invention, a digital video signal recording and/or reproducing apparatus will be explained. The explanation of the processing in the Hi-Fi video apparatuses also applies to a digital video signal recording and/or reproducing apparatus, but a Hi-Fi video apparatus and digital video signal recording and/or reproducing apparatus have the following differences.  
         [0232]     1. A digital video signal recording and/or reproducing apparatus is controlled to follow a track by a dynamic tracking head even at the time of high speed reproduction, so skips occur also in units of tracks.  
         [0233]     2. A digital video signal recording and/or reproducing apparatus can easily judge a track skip since an ID is recorded at the track head.  
         [0234]      FIG. 23  is a view of the configuration of a digital video signal recording and/or reproducing apparatus  2  taking into account the above conditions.  
         [0235]     The digital video signal recording and/or reproducing apparatus  2  has a not illustrated rotary drum with rotary heads An and B mounted thereon, a digital signal demultiplexer  21 , a track skip detector  22 , and a waveform connector  23 .  
         [0236]      FIG. 24  is a view of the track structure of the recording surface of a consumer-use digital video tape, and  FIG. 25  is a view of the head scanning trace at the time of high speed reproduction.  
         [0237]     In this example, the tracks are read skipping one out of three tracks.  
         [0238]     The rotary heads An and B are arranged facing each other at 180 degrees in the same way as illustrated in  FIG. 2 , but the digital video signal recording and/or reproducing apparatus is controlled to scan along a track by a not illustrated auto tracking control mechanism.  
         [0239]     The digital signal demultiplexer  21  reads a recording signal comprised by insert and track information (ITI), an audio signal, a video signal, and a sub code and demultiplexes the same as the digital data.  
         [0240]     The digital signal demultiplexer  21  transmits the video signal to a not illustrated usual video processor and transmits the audio signal to the waveform connector  23 .  
         [0241]     The digital signal demultiplexer  21  inputs the head signal to the track skip detector  22 .  
         [0242]     The track skip detector  22  detects the ID number of the track from the head signal, compares the same with the ID number of the track reproduced immediately before that, and determines the existence of a track skip. The track skip detector  22  sets “0” when the ID numbers continue, while sets “1” when they do not continue, and transmits a track skip pulse S 22  to the waveform connector  23 .  
         [0243]     The waveform connector  23  has a similar configuration to that of the waveform connector  15  illustrated in  FIG. 9  as illustrated in  FIG. 26 .  
         [0244]     The waveform connector  23  is configured by a signal buffer  231  and a signal processor  232 . The signal processor  232  is configured by a buffer controller  2321 , an anomaly deleter  2322 , a waveform connector  2323 , a pseudo waveform generator  2324 , a time discrepancy storage  2325 , and a pseudo waveform detector  2326 .  
         [0245]     The signal buffer  231  of the waveform connector  23  corresponds to the signal buffer  152  of the waveform connector  15 . The signal processor  232  of the waveform connector  23  corresponds to the signal processor  155  of the waveform connector  15 . The buffer controller  2321 , anomaly deleter  2322 , waveform connector  2323 , pseudo waveform generator  2324 , time discrepancy storage  2325 , and pseudo waveform detector  2326  correspond to the buffer controller  1551 , anomaly deleter  1552 , waveform connector  1553 , pseudo waveform generator  1554 , time discrepancy storage  1555 , and pseudo waveform detector  1556 .  
         [0246]     Note that the digital video signal recording and/or reproducing apparatus  2  performs digital signal processing, so the A/D converter  151  and the D/A converter  154  are not provided.  
         [0247]     The signal buffer  231  receives as input a digital audio signal S 21 A detected and demultiplexed at the digital signal demultiplexer  21 .  
         [0248]     The buffer controller  2321  performs processing equivalent to the decision processing at step  33  of  FIG. 11  when the track skip pulse S 22  is “1”.  
         [0249]     The buffer controller  2321 , anomaly deleter  2322 , waveform connector  2323 , pseudo waveform generator  2324 , time discrepancy storage  2325 , and pseudo waveform detector  2326  perform similar processing to that of the buffer controller  1551 , anomaly deleter  1552 , waveform connector  1553 , pseudo waveform generator  1554 , time discrepancy storage  1555 , and pseudo waveform detector  1556  explained above.  
         [0250]     As explained above, the digital video signal recording and/or reproducing apparatus  2  can repair an audio signal having an anomaly due to a track skip or the like even in the case of high speed reproduction in the same way as a Hi-Fi video apparatus.  
         [0251]     8 mm Video Apparatus  
         [0252]     The present invention can also be easily applied to an 8 mm video apparatus.  
         [0253]     The track structure of an 8 mm video tape is shown in  FIG. 27 .  
         [0254]     An audio signal is digitally recorded on the magnetic tape by a rotary head as a PCM audio signal. An FM modulated analog signal (in the same way as a Hi-Fi signal) is recorded multiplexed on the video signal.  
         [0255]     When the 8 mm video apparatus uses an FM audio signal using a dynamic tracking head, the processing is the same as in a Hi-Fi video apparatus. Further, when the 8 mm video apparatus uses a PCM audio track using the dynamic tracking head, a similar configuration to that of the case of the digital video apparatus is employed.  
         [0256]     In this way, the 8 mm video apparatus can utilize the audio signal of a PCM or FM track at the time of high speed reproduction.  
         [0257]     Magnetic Disk Apparatus  
         [0258]     The data skip in the case of a magnetic disk apparatus has the following characteristic features unlike a track skip in a Hi-Fi video apparatus or a digital video signal recording and/or reproducing apparatus explained above.  
         [0259]     1. The random accessibility of the data is high, so a skip due to limitations of physical arrangement of the tracks on a tape does not occur.  
         [0260]     2. Rather, at the time of high speed reproduction, there are data segments which are intentionally not read so as to keep the data within the readable speed.  
         [0261]      FIG. 28  is a view of the hardware configuration of a magnetic disk apparatus taking into account the above circumstances.  
         [0262]     The magnetic disk apparatus  3  has an address controller  31 , a fixed disk drive  32 , and a waveform connector  33 .  
         [0263]     The fixed disk drive  32  stores the audio signal and the video signals as digital data. At the time of reproduction, the data is read according to the address designated by the address controller  31  and input to the waveform connector  33 .  
         [0264]     The address controller  31  compares the reproduction speed designated by the user and the reading speed of the fixed disk, determines the data read segments and the nonread segments so as to be within the range of the read speed, and designates the read addresses to the fixed data drive  32  accordingly. Further, it generates a data skip signal at the end of continuous read segments (immediately before a nonread segment) and inputs the same to the waveform connector  33 .  
         [0265]      FIG. 29  is a graph of the operation timing of the magnetic disk apparatus  3 .  
         [0266]     For convenience, assume that successive recording data ( FIG. 29A ) given numbers D 1  to D 15  are recorded in the fixed disk drive  32 .  
         [0267]     At the time of reproduction, assume that the address controller determines the read segments and the nonread segments as illustrated in  FIG. 29B . At that time, the data actually read from the fixed disk drive  32  become as illustrated in  FIG. 29C , and discontinuity of data occurs between D 5  and D 8  and between D 12  and D 15 . The data skip signal generated by the address controller  31  detecting such discontinuity becomes as shown in  FIG. 29D .  
         [0268]     The waveform connector  33  has the equivalent circuit configuration to the waveform connector  23  illustrated in  FIG. 26 .  
         [0269]     Accordingly, the waveform connector  33  receiving the data skip signal from the address controller  31  performs repair processing similar to that explained above for the audio signal input from the fixed disk drive  32 .  
         [0270]     As explained above, the present invention is not limited to the high speed reproduction of an audio signal recorded on a recording medium like a magnetic tape and can be applied to also the high speed reproduction of an audio signal recorded on a random access type recording medium such as a magnetic disk and an optical disk.  
         [0271]     Further, the present invention is not limited to the embodiments explained above. The present invention can be applied to various other types of audio signal processing apparatuses. As such audio signal processing apparatuses, there are the compact disk players, MD players, DVD players, etc.  
         [0272]     The present invention can not only be applied to apparatuses such as Hi-Fi video apparatuses, digital video signal recording and/or reproducing apparatuses, 8 mm video apparatuses, and magnetic disk apparatuses, but also can use elements configuring these apparatuses alone.  
         [0273]     For example, the waveform connectors  15 ,  23 , and  33  shown in the various embodiments are not limited to the waveform connection of the audio signals explained above, but can also be applied to other signal processing.  
         [0274]     Summarizing the effects of the present invention, the audio signal processing method and the audio signal processing apparatus of the present invention delete the audio signal in the noise segment due to shot noise superposed on the signal, signal skip, and discontinuity and smoothly connect the waveform before and after the deletion. Particularly, it can keep the time discrepancy from the original audio signal to a minimum level by inserting a pseudo waveform into the signal.  
         [0275]     The audio signal processing apparatuses such as Hi-Fi video apparatuses, digital video signal recording and/or reproducing apparatuses, 8 mm video apparatuses, and magnetic disk apparatuses can reproduce a high quality audio signal with little incongruity by eliminating the influence of the sound skip (skip) occurring at the time of high speed reproduction, the noise at the switching of the heads, etc.  
         [0276]     As a result, for example, in a Hi-Fi video apparatus, even when trying to save time while fully viewing and listening to the content by reproduction at 1.2× speed, a high quality audio signal can be reproduced. In a magnetic disk apparatus, it becomes possible to obtain a greater margin in the access time and therefore perform time division processing with other tasks without exceeding the limit of the access time.