JP2009289385A - Digital audio signal processing device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To smoothly reproduce an audio signal, by determining an optimal fade starting time point of time according to a data situation for a target point of time of time-sequential data to perform the minimum necessary fade processing. <P>SOLUTION: The digital audio signal processing device is one that performs fade processing based on the target point of time of a digital audio signal, and includes a fade execution period calculating part for detecting the level value of the digital audio signal in a predetermined period determined, according to the target point of time and calculating the fade execution period according to the level value, and a fade control part for controlling the fade processing based on the fade execution period. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a digital audio signal processing apparatus and method, such as a digital AV (Audio Visual) device, and more particularly to fade processing of a digital audio signal.

  In recent years, when an audio signal has been digitized and an error has occurred during the decoding process of a compressed digital audio signal, it is common to prevent noise by performing a mute process. In that case, if only the error data is muted, noise is generated when the output of normal data and error data is switched. As a means for avoiding this, the sound is gradually changed (fade process) when the output is switched. Therefore, there is a demand for a process that optimizes output data switching so that audio can be output as much as possible even in an environment where errors frequently occur due to the influence of radio wave conditions such as satellite broadcasting and one-segment broadcasting.

  Patent Documents 1 and 2 disclose digital signal processing apparatuses that reproduce 1-bit audio signals recorded on an optical disc. FIG. 13 is a block diagram showing a configuration of a 1-bit audio signal reproducing device in Patent Documents 1 and 2.

  The reproducing apparatus includes an optical pickup (PU) 12 that reads a signal recorded on the optical disc 11, a spindle motor (SPM) 26 that rotates the optical disc 11, a drive circuit 25 and a servo circuit 24 for driving and controlling the optical PU 12. An RF circuit 13 for shaping the waveform of the received signal, a digital signal DR for reproduction by demodulating the input signal, a first signal processing unit 14 for detecting data that could not be demodulated, and decoding processing on the demodulated data Second signal processing unit 15 that generates 1-bit digital audio data, 1-bit D / A converter 22 that converts 1-bit digital audio data into an analog audio signal, and time information demodulated by the first signal processing unit 14 The sub-code (Sub) etc. is decoded and each part is controlled and the second signal processing unit It comprises supplying a control signal CNT, the start of decoding, a display unit 28 connected thereto to the system controller 27 for controlling the stop or the like, a key operation unit 29 that receives an input operation from the user.

  Further, the second signal processing unit 15 performs a mute process with a fade on the digital signal DR when an error occurs based on the error flag fe received from the first signal processing unit 14 to obtain a constant rate. A buffer 16 for storing the digital signal DR and the error flag fe inputted from the first signal processing unit 14 for data output, a decoder 17 for decoding the digital signal DR, and the decoded audio data DA The fade processing unit 18 that performs a fade process for muting and the decoder 17 determines the state of the error flag fe included in the data Dd temporally before the digital signal DR acquired from the buffer 16, and the error determination result f The error flag determination unit 20 that outputs “e” and the fade processing unit 18 are controlled based on the error determination result f′e. It comprises a fade control portion 21 that. Further, the fade processing unit 18 includes an attenuator (ATT) counter 19 that controls the step width of the fade.

  Subsequently, an operation flow from the first signal processing unit 14 to the second signal processing unit 15 will be described. First, the first signal processing unit 14 controls the drive circuit 25 and inputs audio data from the optical disc 11. Next, the input audio data is demodulated to generate a digital signal DR for reproduction. If there is an error during data demodulation, the error flag fe is validated, and if there is no error, the error flag fe is invalidated. Then, the first signal processing unit 14 stores the digital signal DR and the error flag fe in the buffer 16.

  Next, the error determination unit 20 of the second signal processing unit 15 determines whether or not there is an error from the error flag fe. If it is determined that there is an error, the error determination flag f′e is validated, and the fade control unit 21 is notified. On the other hand, if the error flag determination unit 20 does not determine that an error has occurred, the error flag determination unit 20 invalidates the error determination flag f′e and notifies the fade control unit 21 of the error.

  Subsequently, the fade control unit 21 determines whether or not the error determination flag f′e is valid. If the error determination flag f′e is determined to be valid, the fade control unit 21 enables the mute flag fm. Further, it is determined whether the error flag is invalid for a certain period. If the error flag is invalid for a certain period, the mute flag fm is invalidated. As soon as the error flag changes from valid to invalid, the mute flag fm is kept valid.

After that, the fade processing unit 18 promptly differs from the playback stop time based on the mute flag fm and the step flag fs from the fade control unit 21 when an error occurs, that is, when the error determination flag f′e is valid. Fade for proper muting. The fade processing unit 18 incorporates an ATT counter 19 for controlling the sound volume in order to make the fade process for muting different between when playback is stopped and when an error occurs. The ATT counter 19 changes the step width (step width) for counting by the mute flag fm, the step flag fs and the control signal CNT. When the mute flag fm and the step flag fs become effective, the fade processing unit 18 sets the ATT counter 19 to a relatively large step size from 1.0 to 0.0, for example, a step size that takes 3 msec to count down. Count down and stop counting when it reaches 0.0. The count value of the ATT counter 19 is multiplied by the music data DA by a multiplier.
JP 2000-163888 A JP 2006-040529 A

  In Patent Documents 1 and 2, error data is detected when an audio signal is demodulated, and an error flag is stored in a buffer together with the demodulated data. Then, by performing a fade process at regular intervals from an audio signal a predetermined time before the time when the error flag is detected, a state in which the error data is reproduced can be muted.

  However, since the fade processing in Patent Documents 1 and 2 is performed using an ATT counter with a preset time width, the fade processing period when an error occurs is a constant value. Further, since the audio output data has a small output level value in proportion to the audio data signal multiplied by the ATT counter when the signal level is low, no sound can be heard at an early stage of the fade processing period. Therefore, in Patent Documents 1 and 2, there is a problem that a state in which sound cannot be heard more than necessary continues for a long time.

  A digital audio signal processing apparatus according to a first aspect of the present invention performs a fade process based on a target time point of a digital audio signal, and the digital audio signal in a predetermined period determined according to the target time point A fade execution period calculation unit that detects a fade execution period according to the level value, and a fade control unit that controls the fade process based on the fade execution period.

  The digital audio signal processing apparatus according to the second aspect of the present invention performs a fade-out process or a fade-in process based on a target time point of the digital audio signal, and in a predetermined period determined according to the target time point. A processing timing determination unit that detects a level value of the digital audio signal and determines a processing start timing in the fade-out process or a processing end timing in the fade-in process according to the level value, and based on the processing start timing A fade control unit that controls the fade-in process based on the fade-out process or the process end timing.

  A digital audio signal processing device according to a third aspect of the present invention performs a fade process based on a target time point of a digital audio signal, and the digital audio signal in a predetermined period determined according to the target time point The level value is detected, and if the level value does not exceed a reference value for performing the fade process under a predetermined condition, the fade process is not performed.

  A digital audio signal processing method according to a first aspect of the present invention performs fade processing based on a target time point of a digital audio signal, and the digital audio signal in a predetermined period determined according to the target time point A fade execution period calculation step for detecting a fade execution period in accordance with the level value, and a fade control step for controlling the fade process based on the fade execution period.

  A digital audio signal processing method according to a second aspect of the present invention performs a fade-out process or a fade-in process based on a target time point of a digital audio signal, and in a predetermined period determined according to the target time point. A processing timing determination step for detecting a level value of the digital audio signal and determining a processing start timing in the fade-out processing or a processing end timing in the fade-in processing according to the level value, and the processing start timing based on the processing start timing A fade control step of controlling the fade-in process based on the fade-out process or the process end timing.

  A digital audio signal processing method according to a third aspect of the present invention performs fade processing based on a target time point of a digital audio signal, and the digital audio signal in a predetermined period determined according to the target time point The level value is detected, and if the level value does not exceed a reference value for performing the fade process under a predetermined condition, the fade process is not performed.

  According to the above-described digital audio signal processing apparatus and method of the present invention, for example, at a location where error data of a digital audio signal is generated, a fade execution period corresponding to a level value of the digital audio signal a predetermined period before the occurrence location is set. Since calculation or process start timing or process end timing can be determined, the fade execution period at the low signal level in the fade process is shortened, the process start is delayed at the fade-out process, and the fade-in process is By accelerating the end of processing, unnecessary fade processing can be reduced, and the sound can be heard longer.

  In addition, if there is no detected level value that exceeds the reference value when performing fade processing based on a predetermined condition, the state in which sound can be heard is lengthened by not performing fade processing itself. Can do.

  According to the present invention, a digital audio signal that performs smooth reproduction of an audio signal by performing a minimum necessary fade process by determining an optimum fade start point according to the data situation with respect to a target point of time-series data. A processing apparatus and method can be provided.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. In the drawings, the same elements are denoted by the same reference numerals, and redundant description will be omitted as necessary for the sake of clarity.

Embodiment 1 of the Invention
FIG. 1 shows a configuration diagram of a digital audio signal processing apparatus 1 according to a first embodiment of the invention. The digital audio signal processing apparatus 1 receives an input of a digital audio signal that is time-series data, and performs a fade-out process at a predetermined interval when there is error data in the digital audio signal. That is, the digital audio signal processing apparatus 1 performs a fade process based on a time point (target time point) when error data occurs.

  The digital audio signal processing apparatus 1 includes a decoder processing unit 110, a buffer unit 111, a fade execution period calculation unit 112, a step width calculation unit 113, a start address calculation unit 114, a fade start signal generation unit 115, and a fade. A processing unit 116 and a D / A converter 117 are provided.

  The decoder processing unit 110 performs decoding processing and error determination on the input digital audio signal data, outputs an audio signal DRA to the buffer unit 111, and outputs an error address to the fade execution period calculation unit 112 and the start address calculation unit 114. A1 is output (notified).

  The buffer unit 111 is a storage area, stores the audio signal DRA decoded by the decoder processing unit 110, outputs the audio signal DRA to the fade processing unit 116, and reads an address A3 that is an address of the audio signal DRA to be processed. Is output to the fade start signal generator 115.

  The fade execution period calculation unit 112 detects a level value of each digital audio signal DRA in a predetermined period determined according to the target time point, and performs a fade-out process according to the level value. Is calculated. Then, the calculated fade execution period fe1 is output to the step width calculation unit 113 and the start address calculation unit 114. That is, the fade execution period calculation unit 112 receives the notification of the error address A1 from the decoder processing unit 110, acquires the audio signal DRA before the time corresponding to the error address A1 from the buffer unit 111, and acquires the audio signal DRA The fade execution period fe1 is calculated based on the level value and a reference level that is a reference value for performing the fade process under a predetermined condition.

  Further, the fade execution period calculation unit 112 calculates the fade execution period fe1 based on the peak level that is the maximum value among the detected level values. Further, the fade execution period calculation unit 112 calculates the fade execution period as the peak level is lower.

  Further, the fade execution period calculation unit 112 detects the maximum value as a peak level from the level values exceeding the reference level among the level values of the digital audio signal DRA in a predetermined period determined according to the target time point, When there is no level value exceeding the level, the fade execution period is calculated as 0.

  The step width calculation unit 113 calculates a step width De that is an update difference value of the increase / decrease coefficient of the digital audio signal DRA in the fade process based on the fade execution period fe1, and outputs the step width De to the fade start signal generation unit 115. .

  The start address calculation unit 114 calculates a fade process start address A2 that is a start point of the fade process based on the fade execution period fe1, and outputs it to the fade start signal generation unit 115.

  The fade start signal generation unit 115 receives the step width De and the fade process start address A2, generates a fade process control signal fc including the fade process start command and the step width De, and uses the fade signal control signal fc as the fade processing unit 116. Output to. That is, the fade start signal generator 115 controls and executes the fade process based on the fade process control signal fc.

  The fade processing unit 116 has an ATT counter 118 that controls the output during the fade process, performs a fade process by updating the value of the counter At of the ATT counter 118 from the step width De, and outputs the output signal Df after the fade process. Is output to the D / A converter 117.

  The D / A converter 117 converts the digital signal into an analog signal.

  In addition, the fade execution period calculation unit 112 and the start address calculation unit 114 in the digital audio signal processing device 1 detect the level value of the digital audio signal in a predetermined period determined according to the target time point, It can be said that it is a processing timing determination unit that determines the processing start timing in the fade-out processing according to the level value. The fade start signal generator 115 can be said to be a fade controller that controls the fade-out process based on the process start timing.

  An error address A1, a fade start address A2, and a read address A3 in FIG. 1 indicate address values stored in the audio signal DRA stored in the buffer unit 111. In the first embodiment of the present invention, the audio signal DRA stored in the buffer unit 111 is sequentially output according to the storage address, so that the storage address information corresponds to the time information when it is output.

  Hereinafter, the entire operation of the digital audio signal processing apparatus 1 of FIG. 1 is acquired from the time when the audio signal is input to the decoder processing unit 110 to the time when the audio signal is stored in the buffer unit 111. The operation until the audio signal is output from the D / A converter 117 to the outside will be described separately.

  FIG. 2 shows a process from when data is input to the decoder processing unit 110 until the data is stored in the buffer unit 111, that is, a process of storing data from the decoding of the digital audio signal to the buffer unit according to the first embodiment of the present invention. FIG.

  First, the maximum fade period is set in the fade execution period calculation unit 112 (S301). Next, the audio signal DRA is input to the decoder processing unit 110 (S302). Then, the decoder processing unit 110 performs a decoding process on the audio signal DRA (S303).

  Subsequently, the decoder processing unit 110 determines whether an error has occurred (S304). If no error has occurred, the process proceeds to S308. When an error occurs, the fade execution period calculation unit 112 calculates a fade execution period fe1 (S305). Next, the step width calculation unit 113 sets a step width De from the calculated fade execution period fe1 (S306). Then, the start address calculation unit 114 sets a value obtained by subtracting the fade execution period from the error time as the fade start time (S307).

  Thereafter, the decoded data is stored in the buffer unit 111 (S308). At that time, data at the time of error occurrence is stored with zero padding. Then, the end of the process is determined (S309). If the processing is not finished, the processing from step S302 to S309 is repeated.

  FIG. 3 is a flowchart showing processing for acquiring an audio signal from the buffer unit 111 and outputting the audio signal from the D / A converter 117 to the outside, that is, fading processing according to the first embodiment of the present invention. is there.

  First, as an initial setting, the fade state flag is set to OFF and the counter At is set to 1 (S401). Next, the fade processing unit 116 receives the audio signal DRA from the buffer unit 111 (S402). Then, the fade start signal generation unit 115 determines whether a fade start time is set (S403). If the fade start time is not set, the process proceeds to S407.

  When the fade start time is set in step S403, the fade start signal generation unit 115 compares the output data time when data is acquired in step S402 with the set fade start time (S404). If the output data time does not match the fade start time, the process proceeds to S407.

  In step S404, when the output data time and the fade start time coincide with each other, the fade start signal generation unit 115 outputs a fade process control signal fc to the fade processing unit 116 (S405). Then, the fade start signal generation unit 115 sets the fade state flag to ON (S406).

  Thereafter, the fade processing unit 116 determines whether the fade state flag is ON (S407). If the fade state flag is not ON, the process proceeds to S411. When the fade state flag is ON, the fade processing unit 116 updates the counter At with the value of the step width De (S408).

  Thereafter, the fade processing unit 116 determines the value of the counter At (S409). When the counter At is in the range of 0 to 1, the process proceeds to S411. If the counter At is not in the range of 0 to 1, the fade state flag is turned OFF and the counter At is set to 1 (S410).

  The fade processing unit 116 multiplies the audio signal DRA obtained from the buffer unit 111 by the value of the counter At, and outputs the result to the outside via the D / A converter 117 (S411). Thereafter, the end of the process is determined (S412). If not finished, the processes in steps S402 to S412 are repeatedly executed.

  FIG. 4 is a flowchart showing details of the fade execution period calculation processing in step S305 of FIG. First, the fade execution period calculation unit 112 uses, as parameters, the data search position as a position obtained by subtracting the maximum fade period from the error position, the detection level value as 0, the reference level value as the maximum level value, The data search flag is set within the reference level (S501).

  Next, the fade execution period calculation unit 112 determines whether the data search flag is within the reference level (S502). When the data search range is within the reference level, the fade execution period calculation unit 112 compares the reference level value with the signal level value at the data search position (S503). If the reference level value is equal to or greater than the signal level value at the data search position, the fade execution period calculation unit 112 sets the signal level value at the next data search position as the reference level value (S504).

  In step S503, if the signal level value at the data search position is greater than the reference level value, the fade execution period calculation unit 112 sets the data search flag outside the reference level (S505). Then, the fade execution period calculation unit 112 sets the detection level value to the signal level value at the data search position (S506).

  If the data search flag is not within the reference level in step S502, the fade execution period calculation unit 112 compares the detection level value with the signal level value of the data search position (S507). If the signal level at the data search position is greater than the detection level, the fade execution period calculation unit 112 sets the value of the detection level to the signal level value at the data search position (S506).

Thereafter, the fade execution period calculation unit 112 moves the data search position to the position of the next data search (S508). The fade execution period calculation unit 112 determines whether the data search position is equal to the error position (S509). If the data search position is not equal to the error position, the process returns to step S502. Further, when the data search position is equal to the error position, the fade execution period calculation unit 112 calculates the fade execution period fe1 according to the equation (1) (S510).
Fade execution period = detection level × maximum fade period / maximum signal level

                                                                  ... (1)

  FIGS. 5A, 5 </ b> B, and 5 </ b> C are diagrams illustrating a schematic example of a fade implementation period using a digital audio signal. Here, the waveform AN is an analog image of the audio signal DRA input to the fade processing unit 116. Time T2 indicates an error occurrence position, and time T1 indicates a position obtained by subtracting the maximum fade period femax from the error position. The line connecting the maximum signal level MAX and the signal level 0 at the position of time T2 from the position of time T1 is a line indicating the reference level, and the value of the reference level at the data search position is the signal indicated by the line of reference level This is the level value.

  In FIG. 5A, the data search is performed from the position of the time T1 until the time T2, and the signal level value of the audio signal at the data search position is compared with the value of the reference level at the data search position. The signal level value at the time T3, which is the maximum value of the signal level value among the signal levels of the audio signal exceeding the reference level in FIG.

  Here, when the line is extended horizontally from the signal level value at the time T3 with respect to the line indicating the reference level, the time T4 at the point where the reference level line intersects becomes the fade start time, and from the time T4 A period fe1a up to time T2 is a fade implementation period.

  In FIG. 5B, the comparison is performed in the same manner as in FIG. 5A, and the signal level value at time T5 is set as the detection level value. Here, when the line is extended horizontally from the signal level value at the time T5 with respect to the line indicating the reference level, the time T6 at the point where the reference level line intersects becomes the fade start time, and from the time T6. A period fe1b until time T2 is a fade execution period.

  In FIG. 5C, the data search is performed from the position of time T1 until time T2, and the signal level value of the audio signal at the data search position is compared with the value of the reference level at the data search position. Since there is no signal level value exceeding the value of, the detection level value is zero. Therefore, time T2 is the fade start time, and the fade execution period is zero.

  FIG. 6 is a schematic diagram for explaining the result of the fading process of the present invention. In particular, FIG. 6 shows the audio signal output when the audio signal is constant 50% of the Max value. Then, by applying the fade execution period calculation process of FIG. 4, the fade execution period becomes a period from time T7 to T2.

  During a period feo from time T1 to time T7, the original sound is output without performing the fade process, the fade process is started from time T7, and the fade process is completed at time T2. In this way, since the optimum fade period is set according to the level value of the audio signal, the period during which the original sound can be output can be increased, and the sound reproducibility is improved.

In Embodiment 1 of the present invention, the attenuation value is determined and fade processing is performed by the method of updating the value of the counter At with the value of the step width De. However, the value of the counter At is expressed by the equation (2). By obtaining the attenuation amount using an arbitrary function f (t) that monotonously decreases, various fade processes can be handled.
At = f (t) (2)

  As described above, the digital audio signal processing device 1 according to the first exemplary embodiment of the present invention includes the fade execution period calculation unit 112, the step width calculation unit 113, the start address calculation unit 114, and the fade start signal generation unit 115. And fading processing.

  The digital audio signal processing apparatus 1 can be applied to a digital AV device or the like. At that time, the fade execution period calculation unit 112 detects the audio signal peak level during the maximum fade period from the position of the error data using steps S501 to S509 in FIG. 4, and the audio signal peak level detected using step S510. The fade execution period is calculated from the value.

  Next, the step width calculation unit 113 calculates the step width using step S306 in FIG. 2, and the start address calculation unit 114 calculates the fade start address using step S307. Then, the fade start signal generation unit 115 can control the ATT counter 118 of the buffer 16 from the step width and the fade start address using steps S401 to S411 in FIG. 3 to perform the fade process.

  Also, the fade execution period calculation unit 112 determines whether the audio signal level is outside the reference level using step S502 in FIG. 4, and if it is outside the reference level, searches for the signal level using step S507, The audio signal peak level can be determined.

  From the above, the first embodiment of the invention can improve the problem that the state in which sound cannot be heard becomes longer by shortening the fade period at the time of a low signal level. This is because the fade execution period calculation unit 112 detects the audio signal peak level during the maximum fade period from the position of the error data, and calculates the fade execution period based on the detected audio signal peak level value.

Embodiment 2 of the Invention
In the second embodiment of the present invention, a digital audio signal processing apparatus capable of recovering to a normal volume more quickly by shortening the fade-in process time after the mute process is performed will be described. The digital audio signal processing apparatus according to the second embodiment of the present invention has the same configuration as the digital audio signal processing apparatus 1 in FIG.

  FIG. 7 is a flowchart showing processing for storing data from the decoding of the digital audio signal to the buffer unit in the fade-in processing according to the second embodiment of the present invention. The same processes as those in the flowchart shown in FIG.

  First, the maximum fade period is set in the fade execution period calculation unit 112, and the value of the sample count is set to 0 (S601). Next, the audio signal DRA is input to the decoder processing unit 110 (S302). Then, the decoder processing unit 110 performs a decoding process on the audio signal DRA (S303).

  Subsequently, the decoder processing unit 110 determines whether the error data has changed to normal data as a result of decoding (S602). If the error data does not change to normal data, the process proceeds to step S604. When the error data changes to normal data, the fade execution period calculation unit 112 sets the number of multiplications during the maximum fade period as the sample count value (S603).

  Thereafter, the fade execution period calculation unit 112 determines whether or not the sample count is greater than 0 (S604). If the sample count is 0, the process proceeds to step S308. If the sample count is greater than 0, the fade execution period calculation unit 112 decreases the sample count by 1 (S605).

  Then, the fade execution period calculation unit 112 determines whether or not the sample count is 0 as a result of step S605 (S606). If the sample count is other than 0, the process proceeds to step S308. When the sample count becomes 0, the fade execution period calculation unit 112 calculates the fade execution period fe1 from the audio signal stored in the buffer unit 111 from the normal change from the error to the maximum fade period. (S607). Next, the step width calculation unit 113 sets a step width De (S306). Then, the start address calculation unit 114 performs fade start time setting (S608).

  Thereafter, the decoded data is stored in the buffer unit 111 (S308). At that time, data at the time of error occurrence is stored with zero padding. Then, the end of the process is determined (S309). If the processing is not finished, the processing from step S302 to S309 is repeated.

  FIG. 8 is a flowchart showing details of the fade execution period calculation process at the time of fading in step S607 of FIG. The same processes as those in the flowchart shown in FIG.

  First, the fade execution period calculation unit 112 uses, as parameters, the data search position to a position where error data has changed to normal data, the detection level value is set to 0, the reference level value is set to 0, and the data search flag is set to the reference level. (S701).

  Next, the fade execution period calculation unit 112 performs the processing of steps S502 to S508 as in FIG. After step S508, the fade execution period calculation unit 112 determines whether the data search position is equal to the data output start position + the maximum fade period (S702). If the data search position is not equal to the error position, the process returns to step S502. Further, when the data search position is equal to the error position, the fade execution period calculation unit 112 performs the same process as in step S510.

  As described above, in the second embodiment of the present invention, the fade execution period calculation unit 112 detects the audio signal peak level during the maximum fade period from the position of the return data from the error, and uses the detected audio signal peak level value. Calculate the fade implementation period. Next, the step width calculation unit 113 calculates the step width and the start address calculation unit 114 calculates the fade start address from the fade execution period, and the fade start signal generation unit 115 calculates the ATT counter of the fade processing unit 116 from the step width and the start address. By controlling 19, the fade period at the time of low signal level can be shortened at the time of recovery from the error as well as at the time of error occurrence. Also, by completing the fade earlier than before, the period for outputting the original sound becomes longer and the sound reproducibility is improved.

  That is, in the second embodiment of the present invention, the same effect as in the first embodiment of the present invention can be obtained by applying the fade execution period calculation process of the fade-out process in the fade-in process.

Embodiment 3 of the Invention
In the third embodiment of the present invention, the digital audio signal processing apparatus 1 according to the first embodiment of the present invention is improved, and an error flag fe is added to the digital audio signal, so that the error occurrence position and the fade start position are set. It is characterized by calculating.

  FIG. 9 is a block diagram showing a configuration of the digital audio signal processing apparatus 2 according to the third embodiment of the present invention. The digital audio signal processing apparatus 2 includes a decoder processing unit 110, a buffer unit 111, a fade execution period calculation unit 112, a start address calculation unit 114, and a fade start signal generation unit 115 in FIG. And a buffer unit 211, a fade execution period calculation unit 212, a start timing generation unit 214, and a fade start signal generation unit 215.

  The decoder processing unit 210 performs decoding processing and error determination on the input digital audio signal data, and outputs the audio signal DRA and the error flag fe to the buffer unit 211.

  The buffer unit 211 is a storage area, stores the audio signal DRA decoded by the decoder processing unit 210, and outputs the audio signal DRA to the fade execution period calculation unit 212 and the fade processing unit 116.

  The fade execution period calculation unit 212 calculates the fade execution period fe1, and outputs the fade execution period fel to the step width calculation unit 113 and the start timing generation unit 214.

  The start timing generation unit 214 generates a fade start timing signal fst and outputs it to the fade start signal generation unit A215.

  The fade start signal generation unit A215 receives the step width De input from the step width calculation unit 113 and the fade start timing signal fst input from the start timing generation unit 214, and includes a fade process start command and a fade including the step width De. A processing control signal fc is generated, and the fade signal control signal fc is output to the fade processing unit 116. Since the subsequent configuration is the same as that of the first embodiment of the present invention, description thereof is omitted.

  FIG. 10 is a timing chart of the fade process according to the third embodiment of the present invention. First, the decoder processing unit 210 decodes the input audio signal and outputs it as an audio signal DRA.

  Here, the audio signal D0 is normal data, and the audio signal D1 is error data. The period from time T1 to time T2 is a period until the audio signal DRA decoded by the decoder processing unit 210 is output by the fade process. The preset maximum fade period is also the period from time T1 to time T2.

  Furthermore, the time when the fade execution period calculation unit 212 detects that the error flag fe stored in the buffer unit A211 becomes valid is set as time T1. At this time, it is assumed that the fade end time is a time T2 obtained by adding a period from the time T1 when the error flag fe becomes valid to the actual output.

  Next, the fade execution period calculation unit 212 sets time T1 obtained by subtracting the maximum fade period from time T2. Then, the fade execution period calculation unit 212 detects the maximum value of the audio signal level from the pre-fade audio signal during the period from time T1 to time T2, and calculates the fade execution period fe1 from the detected level. Since this operation is the same as that of Embodiment 1 of the present invention, detailed description thereof is omitted.

  Thereafter, the start timing generation unit 214 waits for a period Tw obtained by subtracting the fade execution period fe1 from the period from time T1 when the audio signal is decoded to time T2 when the audio signal is output to the outside, and at time T8 the fade start timing signal Enable fst.

  The fade start signal generation unit A215 performs a fade process from the fade start timing signal fst and the calculated step width De. Thereafter, the D / A converter 117 outputs the analog output after the fade process.

  As described above, in the third embodiment of the present invention, the start timing generation unit 214 only has to wait for the period Tw until the fade starts, and each time an audio signal is output as in Patent Documents 1 and 2, Since it is not necessary to perform the comparison function for synchronization, the configuration of the apparatus is simplified. That is, Embodiment 3 of the invention can also be applied by improving Patent Documents 1 and 2.

  As described above, in the third embodiment of the present invention, it is not necessary to monitor timing and compare for synchronization every time an audio signal is output, so that the circuit scale can be reduced. This is because the error occurrence position and the fade start position are calculated using not the address but the error flag fe and the delay value from decoding to output.

Embodiment 4 of the Invention
Embodiment 4 of the present invention is characterized in that fade-out processing or fade-in processing start position designation information is input to the fade execution period calculation unit in place of error position information, and fade processing is performed.

  In the fourth embodiment of the present invention, for example, in the decoder processing unit 110 of FIG. 1, information on designation of arbitrary fade processing start position or timing based on information in the audio signal such as when the sampling frequency is changed or when AV is synchronized. By accepting an input and replacing the error address A1 with the address corresponding to the designation information as an input to the fade execution period calculation unit 112, the same configuration as in the first embodiment of the present invention can be realized.

  As described above, according to the fourth embodiment of the present invention, the fade period is optimized in the fade-out process or the fade-in process from the designated position of the audio signal, such as when the sampling frequency is changed or AV synchronization is performed, in addition to the occurrence of an error. it can. This is because the fade execution period is calculated by outputting to the fade execution period calculation unit 112 the address at which the fade-out process or the fade-in process is started instead of the error address A1.

Embodiment 5 of the Invention
In the fifth embodiment of the present invention, the digital audio signal processing apparatus 1 according to the first embodiment of the present invention is improved, a table data storage unit is added, and table data is used instead of the counter At at the time of fade processing. Then, a fade process is performed.

  FIG. 11 is a block diagram showing a configuration of the digital audio signal processing apparatus 3 according to the fifth embodiment of the present invention. The digital audio signal processing apparatus 3 includes a fade execution period calculation unit 112, a fade processing unit 116, and an ATT counter 118, a fade execution period calculation unit 312, a fade processing unit 316, and a table data holding unit 301 in FIG. And a start timing generation unit 214 and a fade start signal generation unit 215, and a table data storage unit 300 is added.

  The table data storage unit 300 stores the increase / decrease coefficient value of the digital audio signal in the fade process for each of a plurality of predetermined periods. For example, the table data storage unit 300 stores in advance the value of the counter At in the fade-out for each fade period shown in FIG. 12 as table data.

  The fade execution period calculation unit 312 uses the table data Ta1 from the table data storage unit 300 to calculate the reference level used when detecting the audio signal peak level during the maximum fade period from the position of the error data. For example, when the maximum fade period is set to 100 ms, the fade execution period calculation unit 312 acquires the table data Ta1 for 100 ms in FIG. 12 from the table data storage unit 300, and based on the table data Ta1 The level is calculated and output to the table data storage unit 300 in addition to the step width calculation unit 113 and the start address calculation unit 114. Further, the fade execution period calculation unit 312 acquires table data Ta1 corresponding to the fade execution period fe1 from the table data storage unit 300 during the fade-in process, and sets the reference level during the fade-in process based on the table data Ta1. The fade execution period fe1 is calculated using the reference level, and similarly output to the table data storage unit 300.

  Further, the table data storage unit 300 outputs the table data Ta2 corresponding to the fade execution period fe1 input from the fade execution period calculation unit 312 to the fade processing unit 316 and stores it in the table data holding unit 301 for each fade period. . Note that the table data storage unit 300 selects the closest one in the table data storage unit 300 when there is no fade period corresponding to the fade execution period fe1. For example, when the fade execution period fe1 is 40 ms, the table data for 50 ms shown in FIG. 12 is selected and transmitted to the fade processing unit 316. Note that the table data stored in the table data storage unit 300 can be updated as necessary.

  The fade processing unit 116 uses the table data Ta2 stored in the table data holding unit 301 instead of the counter At when starting the fade processing based on the fade processing control signal fc. Other configurations and processes are the same as those of the first embodiment of the present invention, and thus description thereof is omitted.

  As described above, when the reference level in the fade process is expressed by a complicated expression, the processing amount can be reduced because the process can be executed by using the previously calculated table data without calculating the complicated expression. be able to.

  As described above, in the fifth embodiment of the invention, the calculation amount of the counter At can be reduced. This is because a table data storage unit is added, table data is previously stored instead of the counter At at the time of fade processing, and the value of the counter At is referred to from the table data.

Other Embodiments of the Invention
Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention described above.

It is a block diagram which shows the structure of the digital audio signal processing apparatus concerning Embodiment 1 of this invention. It is a flowchart figure which shows the process which stores data in the buffer part from decoding of the digital audio signal concerning Embodiment 1 of this invention. It is a flowchart figure which shows the fade process concerning Embodiment 1 of this invention. It is a flowchart figure which shows the fade implementation period calculation process concerning Embodiment 1 of this invention. (A), (b) and (c) is a figure which shows the schematic example of the fade implementation period by a digital audio signal. It is a schematic diagram for demonstrating the fade process result of this invention. It is a flowchart figure which shows the process which stores data from the decoding of the digital audio signal concerning Embodiment 2 of this invention to a buffer part. It is a flowchart figure which shows the fade implementation period calculation process concerning Embodiment 2 of this invention. It is a block diagram which shows the structure of the digital audio signal processing apparatus concerning Embodiment 3 of this invention. It is a timing chart figure of the fade process concerning Embodiment 3 of this invention. It is a block diagram which shows the structure of the digital audio signal processing apparatus concerning Embodiment 5 of this invention. It is an example of the table data which the table data storage part concerning Embodiment 5 of this invention stores. It is a block diagram which shows the structure of the audio disc player of related technology.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital audio signal processing apparatus 110 Decoder processing part 111 Buffer part 112 Fade execution period calculation part 113 Step width calculation part 114 Start address calculation part 115 Fade start signal generation part 116 Fade processing part 117 D / A converter 118 ATT counter 2 Digital Audio signal processing device 210 Decoder processing unit 211 Buffer unit 212 Fade execution period calculation unit 214 Start timing generation unit 215 Fade start signal generation unit 3 Digital audio signal processing device 312 Fade execution period calculation unit 316 Fade processing unit 301 Table data holding unit 300 Table data storage unit 11 Optical disk 12 Optical PU
DESCRIPTION OF SYMBOLS 13 RF circuit 14 1st signal processing part 15 2nd signal processing part 16 Buffer 17 Decoder 18 Fade processing part 19 ATT counter 20 Error flag discrimination | determination part 21 Fade control part 22 1 bit D / A converter 23 Output terminal 24 Servo circuit 25 Drive circuit 26 SPM
27 System Controller 28 Display Unit 29 Key
DRA audio signal A1 error address A2 fade start address A3 read address fe1 fade execution period De step width fc fade processing control signal Df output signal AN waveform T1 time T2 time T3 time T4 time T5 time T6 time T7 time femax maximum fade period Implementation period fe1b Fade implementation period fe0 period fe Error flag fst Fade start timing signal Ta1 Table data Ta2 Table data DR Digital signal Dd Data D'R Digital signal DA Audio data f'e Error judgment result fm Mute flag fs Step flag CNT Control signal Sub subcode

Claims (22)

A digital audio signal processing apparatus that performs fade processing based on a target time point of a digital audio signal,
A fade execution period calculation unit that detects a level value of the digital audio signal in a predetermined period determined according to the target time point, and calculates a fade execution period according to the level value;
A digital audio signal processing apparatus comprising: a fade control unit that controls the fade process based on the fade execution period.   The digital audio signal processing apparatus according to claim 1, wherein the fade execution period calculation unit calculates a fade execution period based on a peak level which is a maximum value among detected level values.   The digital audio signal processing apparatus according to claim 2, wherein the fade execution period calculation unit calculates the fade execution period as the peak level is lower.   The fade execution period calculation unit detects the peak level from level values exceeding a reference value when performing the fade process under a predetermined condition among the level values of the digital audio signal in the predetermined period. 4. The digital audio signal processing apparatus according to claim 2, wherein the digital audio signal processing apparatus is a digital audio signal processing apparatus.   5. The digital audio signal processing apparatus according to claim 4, wherein the fade execution period calculation unit calculates a fade execution period as 0 when there is no level value exceeding the reference value. The digital audio signal processing apparatus includes:
A step width calculation unit that calculates a step width that is an update difference value of an increase / decrease coefficient of the digital audio signal in the fade processing based on the fade execution period;
A start point calculation unit that calculates a start point of the fade process based on the fade execution period;
6. The fade control unit according to claim 1, wherein the fade control unit generates a fade process control signal including the step width and the start position, and causes the fade process to be executed based on the fade process control signal. A digital audio signal processing apparatus according to claim 1. The digital audio signal processing apparatus includes:
A storage unit that previously stores the increase / decrease coefficient value of the digital audio signal in the fade process for each of a plurality of predetermined periods;
The fade execution period calculation unit obtains an increase / decrease coefficient value corresponding to the predetermined period from the storage unit, calculates a reference level in the fade process, detects the peak level using the reference level,
The said fade control part controls the said fade process based on the increase / decrease coefficient value corresponding to the said fade implementation period stored in the said storage part, The Claim 1 characterized by the above-mentioned. Digital audio signal processing device. A digital audio signal processing apparatus that performs fade-out processing or fade-in processing based on a target time point of a digital audio signal,
A processing timing for detecting a level value of the digital audio signal in a predetermined period determined according to the target time point and determining a processing start timing in the fade-out processing or a processing end timing in the fade-in processing according to the level value A decision unit;
A digital audio signal processing apparatus comprising: a fade control unit that controls the fade-out process based on the process start timing or the fade-in process based on the process end timing. A digital audio signal processing apparatus that performs fade processing based on a target time point of a digital audio signal,
The level value of the digital audio signal in a predetermined period determined according to the target time point is detected, and if the level value does not exceed a reference value for performing the fade process under a predetermined condition, the fade process is performed. There is no digital audio signal processing device.   10. The digital audio signal processing apparatus according to claim 1, wherein the target time is a time when an error occurs during the decoding process of the digital audio signal.   11. The digital audio signal processing apparatus according to claim 10, wherein the target time point is a time point of a digital audio signal corresponding to the error address when a notification of an error address is received. A digital audio signal processing method for performing fade processing based on a target time point of a digital audio signal,
A fade execution period calculating step of detecting a level value of the digital audio signal in a predetermined period determined according to the target time point, and calculating a fade execution period according to the level value;
A digital audio signal processing method comprising: a fade control step of controlling the fade processing based on the fade execution period.   13. The digital audio signal processing method according to claim 12, wherein the fade execution period calculation step calculates a fade execution period based on a peak level which is a maximum value among detected level values.   14. The digital audio signal processing method according to claim 13, wherein the fade execution period calculation step calculates the fade execution period as the peak level is lower.   The fade execution period calculating step detects the peak level from level values exceeding a reference value when performing the fade process under a predetermined condition among the level values of the digital audio signal in the predetermined period. 15. The digital audio signal processing method according to claim 13, wherein the digital audio signal is processed.   16. The digital audio signal processing method according to claim 15, wherein the fade execution period calculation step calculates the fade execution period as 0 when there is no level value exceeding the reference value. The digital audio signal processing method includes:
A step width calculation step of calculating a step width that is an update difference value of an increase / decrease coefficient of the digital audio signal in the fade processing based on the fade execution period;
A start point calculating step of calculating a start point of the fade process based on the fade execution period;
The fade control step generates a fade process control signal including the step width and the start point, and executes the fade process based on the fade process control signal. 2. A digital audio signal processing method according to claim 1. The digital audio signal processing method includes:
A storage unit that previously stores the increase / decrease coefficient value of the digital audio signal in the fade process for each of a plurality of predetermined periods;
The fade execution period calculation step obtains an increase / decrease coefficient value corresponding to the predetermined period from the storage unit, calculates a reference level in the fade process, detects the peak level using the reference level,
18. The fade control step according to claim 12, wherein the fade control step controls the fade process based on an increase / decrease coefficient value corresponding to the fade execution period stored in the storage unit. Digital audio signal processing method. A digital audio signal processing method for performing fade-out processing or fade-in processing based on a target time point of a digital audio signal,
A processing timing for detecting a level value of the digital audio signal in a predetermined period determined according to the target time point and determining a processing start timing in the fade-out processing or a processing end timing in the fade-in processing according to the level value A decision step;
A digital audio signal processing method comprising: a fade control step of controlling the fade-out process based on the fade-out process based on the process start timing or the process end timing. A digital audio signal processing method for performing fade processing based on a target time point of a digital audio signal,
The level value of the digital audio signal in a predetermined period determined according to the target time point is detected, and if the level value does not exceed a reference value for performing the fade process under a predetermined condition, the fade process is performed. There is no digital audio signal processing method.   21. The digital audio signal processing method according to claim 12, wherein the target time is a time when an error occurs during the decoding process of the digital audio signal.   The digital audio signal processing method according to claim 21, wherein the target time point is a time point of a digital audio signal corresponding to the error address when an error address notification is received.

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