JPH0527191B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a signal reproducing device for reproducing audio signals recorded on a recording medium, and in particular, to a so-called digital tape recorder so that the level of the reproduced signal can be easily displayed. This is what I did. [Background technology and its problems] Conventionally, in order to display the signal level of a transmitted signal in a signal transmission system that handles digital signals such as a digital tape recorder, data processing such as absolute value detection and peak hold is required for all data of the transmitted signal. The envelope information of the transmission signal is obtained by performing the above steps, and the display device is operated based on this envelope information. In addition, when displaying a signal level as a bar graph using a multi-segment display element instead of a so-called analog meter to display the level, it is also possible to perform level conversion such as logarithmic conversion to correspond to each display segment for the envelope information. It required encoding processing, etc. The block diagram of FIG. 1 shows a conventional general configuration of a level display system for a reproduced audio signal in a digital tape recorder. In the conventional example shown in FIG.
A digital audio signal converted into PCM (Pulse Code Modulation) is recorded in the recording head 2, and the reproduced PCM signal obtained by the reproduction head 2 is supplied to a decoder 4 via a reproduction amplifier 3. Then, the decoder 4 performs a predetermined decoding process on the reproduced PCM signal to obtain, for example, 16-bit reproduced audio data, and converts this data into an analog The reproduction audio signal is outputted from the signal output terminal 6. Furthermore, the reproduced audio data obtained by the decoder 4 is supplied to an absolute value detection processing circuit 11, and this processing circuit 11 performs absolute value detection on all data. Further, the absolute value data obtained by the absolute value detection processing circuit 11 is supplied to a level encoder 12. This level encoder 12 reduces the number of bits by performing polygonal approximation processing such as logarithmic conversion on the absolute value data to form segment display data with a number of bits corresponding to the number of display segments in the level display section 20. It's getting old. That is, for example, the level display section 20
When the signal level of the reproduced audio signal is displayed as a bar graph using the 16 segment display elements ID _o , 4-bit segment display data is formed by the level encoder 12. The segment display data obtained by the level encoder 12 is supplied to a peak hold circuit 13.
The peak value is detected by , and certain decay processing and hold processing are performed. Then, the segment display data corresponding to the envelope of the absolute value data outputted from the peak hold circuit 13 is selected via the decoder 14 to each segment display element ID ₁ , ID ₂ , ..., ID _o of the level display section 20. The level display unit 20 displays the signal level of the reproduced audio signal as a bar graph. Incidentally, in the conventional digital tape recorder having the above-mentioned configuration, in order to display the level of the reproduced audio signal, there are dedicated level display circuits such as the absolute value detection processing circuit 11, the level encoder 12, the peak hold circuit 13, and the decoder 14. Either hardware is required, or it is necessary to time-divisionally process the audio signal by cutting out the processing time of the software for data processing to reproduce the audio signal. Generally, during playback operation, error correction processing, correction processing, etc. of the playback audio data are performed by software, and when the level display is time-divisionally processed by software, the ability to correct errors, etc. of the playback audio data is increased. must be lowered. In addition, in the conventional example described above, since segment display data was formed for all absolute value data of the reproduced audio data, the level encoder 1
If you try to process the operation of 2 with software, you will need a processing unit with a large processing capacity, and in order to perform an accurate level encoder, a dedicated level encoder equipped with an extremely large capacity ROM (Read Only Memory) is required. hardware was required. [Object of the Invention] Therefore, in view of the problems of the prior art as described above, an object of the present invention is to make it possible to easily display the level of the reproduced audio signal when reproducing the audio signal recorded on the recording medium. The present invention provides a signal reproducing device that makes it possible to effectively utilize an arithmetic processing unit for error correction processing, etc., which is generally required in a reproducing system, especially in a digital tape recorder. [Summary of the Invention] In order to achieve the above-mentioned object, a signal reproducing device according to the present invention comprises a reproducing means for reproducing a signal from a recording medium on which an audio signal and a signal indicating envelope information of the audio signal are recorded. and level display means for displaying the level of the reproduced audio signal based on the signal representing the envelope information reproduced by the reproduction means. [Embodiments] Hereinafter, specific embodiments of the signal reproducing device according to the present invention will be described in detail with reference to the drawings. In the embodiments shown in FIGS. 2 to 8, the present invention is applied to a rotary head type digital tape recorder. In the block diagram of FIG. 2 showing the general configuration of the entire recording and reproducing system in this embodiment, the input audio signal of the left channel is supplied to the first signal input terminal 31, and the input audio signal of the left channel is supplied to the second signal input terminal 32. is fed with the right channel input audio signal. The input audio signals of the left and right channels are supplied to an analog-to-digital A/D converter 33 via signal input terminals 31 and 32, and are digitized by the A/D converter 33. The A/D converter 33 quantizes the input audio signal and supplies the 16-bit digital audio signal as serial data to the signal processing section 50, for example. The signal processing unit 50 has an addition function, a subtraction function,
A logical operation processing section 34 has various operation processing functions such as an exclusive OR function and a data comparison function, and a RAM (Bandum Access) that temporarily stores various data.
It is program-controlled by a microprogram controller (not shown) and functions as a PCM encoder in the recording operation mode and as a PCM decoder in the reproduction operation mode. This signal processing section 50
In the recording operation mode, the digital audio signal supplied as serial data from the A/D converter 33 is converted into 16-bit parallel data by the first serial/parallel S/P converter 36, and the parallel data is converted into 16-bit parallel data. The logic operation processing unit 34 performs PCM encoding processing to convert the data into PCM data, and the PCM data is converted back to serial data by the first parallel-serial P/S converter 37 and output as a PCM audio signal. Then, in the recording operation mode, the signal processing section 5
The PCM audio signal outputted from PCM 0 is supplied from a modulator 38 via a recording amplifier 39 to a rotating magnetic head 40, and is recorded on a recording track on a magnetic tape 41 by the rotating magnetic head 40. Here, the rotating magnetic head 40 rotates once every 1/60 seconds, as shown in FIG. It is now possible to trace. Further, the recording track 70 is divided into 2n data blocks, and the n-th data block, that is, the data block at the center position is used as the control data block 71. And each data block is
As shown in the data arrangement in Figure 4, the block synchronization word SYNC, block address address word
ADRS, PCM audio words L ₁ , R ₁ , L ₂ , R ₂ , L ₃ , R ₃ , L ₄ , R ₄ for each left and right channel, parity words P, Q, and error correction word CRC each have 1 word and 16 bits. It consists of In addition, the control data block also includes SYNC, ADRS, and control words, similar to the data block above.
CW ₁ , CW ₂ , . . . , CW ₈ , P, Q, and CRC each consist of 16 bits. In the control words CW ₁ and CW ₂ , level data VPK·L and VPK·R of each channel, which are formed by the signal processing section 50 in the following manner, are recorded. That is, in this embodiment, in the recording operation mode, the signal processing section 50 not only functions as the PCM encoder described above, but also functions as the PCM encoder for each recording track 7.
Envelope data is formed for each PCM audio signal for each 0, and signal processing for level display is also performed to form level data VPK.L and VPK.R for each channel indicating the maximum value. The configuration for performing the signal processing for level display is shown in the block diagram of FIG. 5, and its operation is shown in the flow chart of FIG. That is, the signal processing section 50 in this embodiment
The processing mode for level display is preprogrammed in the microprogram controller 80 during the recording operation mode, and the maximum value data VPK is detected as follows for the PCM audio signal recorded for each recording track 70. I'm starting to do that. When this processing mode is entered, first in a first step, an initial setting operation is performed in which the contents of the maximum value data VPK storage location in the RAM 35 are set to "0" and the RAM address n is set to "1". here,
In the second step following the RAM 35, the envelope data D(n) previously written to the envelope data storage location of the RAM 35 is transferred to the envelope data D(n).
It is read at RAM address n and transferred to the data register B.Reg 81 via the logical operation processing section 34, and also transfers sign flag data Sing Flag indicating the polarity of the envelope data D(n) to the flag register 82. In the next third step, the polarity of the sign flag data Sing Flag is determined. Then, in the third step, if it is determined that the envelope data D(n) has positive polarity, the fourth step
The envelope data D(n) read from B.Reg 81 is processed by the logical operation processing section 34.
If it is determined that the envelope data D(n) has negative polarity, the process moves to the fifth step and returns to B.Reg81.
Envelope data D(n) read from Reg81
The polarity of is inverted in the logic operation processing section 34 and (n)
is returned to B.Reg 81 above. 4th and 5th above
By the operation of the step, the absolute value data |D(n)| of the above envelope data D(n) becomes B・Reg81
is temporarily stored in Then, in the next 6th step, the above RAM
Read the maximum value data VPK from 35 and read the contents of B.Reg81, that is, the absolute value data |D(n)
The logic operation processing unit 34 performs an operation to subtract | from the maximum value data VPK, transfers the subtraction data to the B-Reg 81, and also sends sign flag data indicating the polarity of the subtraction data.
Sing Flag is transferred to the flag register 82. In the next seventh step, the polarity of the subtracted data is determined, and if the subtracted data has positive polarity, the process moves to an eighth step and the RAM 3 is
Read the maximum value data VPK from 5 and perform the above B.
If the subtraction data is of negative polarity, the process moves to the ninth step and the contents of B.Reg81, that is, the absolute value data |D(n)
| is returned to the corresponding B・Reg81 as it is. Then, in the above 10th step, the above B.
The contents of Reg81 are the maximum value data of RAM35 VPK
Write to memory location. In the next eleventh step, it is determined whether the RAM address n is equal to the final number of words of PCM audio data for one recording track. The judgment result in this 11th step is NO.
That is, if the maximum value detection has not been completed for all the envelope data D(n) of the PCM audio signal for one recording track, the process moves to the 12th step, advances the RAM address n by one, and performs the above-mentioned second step. Return to step operation. By repeating the operations of the second to twelfth steps described above, the contents of the maximum value data VPK storage location of the RAM 35 are sequentially rewritten to the maximum value data by the operation of the tenth step.
When the maximum value is detected for all the envelope data D(n) of the PCM audio signal for one recording track, the determination result in the twelfth step becomes YES, and the process shifts to another processing mode. Then, level data VPK・L, VPK・L, and VPK・L are formed by signal processing for level display as described above.
R is the modulator 3 along with the above PCM audio signal.
8, and recording on the magnetic tape 41 is performed in the data format shown in FIG. 4 above. Next, in the reproduction operation mode, the reproduction signal reproduced from the magnetic tape 41 by the rotating magnetic head 40 is supplied to the demodulator 43 via the reproduction amplifier 42, and the reproduction PCM audio signal obtained by the demodulator 43 is The signal is supplied to the signal processing section 50.
This signal processing section 50 then processes the reproduction PCM
The audio signal is converted into parallel data by the second S/P converter 44, and the parallel data is subjected to PCM decoder processing by the logic operation processing section 34, and then sent via the second P/S converter 45. A reproduced digital audio signal is obtained and the reproduced digital audio signal is supplied to the digital-to-analog D/A converter 46. The D/A converter 46 includes the signal processing section 50
Converts the reproduced digital audio signals supplied from the input terminals into analogs, and outputs the reproduced audio signals of the right and left channels to the first and second signal output terminals 47 and 4.
Output from 8. Further, the signal processing section 50 displays the level data VPK.L, VPK.R reproduced by the control data block in the reproduction operation mode, that is, the maximum value data of the reproduced PCM audio signal for each recording track 70, on the level display 60. supply. The level display device 60 performs level encoding processing on the maximum value data of the envelope data supplied from the signal processing section 50, peak-holds the encoded output, and uses the decoder to send each segment display element 101, 102, . . .
116 to display the signal level of the reproduced audio signal in a bar graph. The level indicator 60 of this embodiment is configured as shown in FIG. 7, and the signal processing section displays the maximum value data VPK of the envelope data of the reproduced PCM audio signal for one recording track at a cycle of 1/60 seconds. 50, microcomputer 8
3, the following display control operation is performed according to the flowchart of FIG. Here, the ROM 85 of the level display 60
stores level comparison data TH(N) in each storage location specified by level address N and peak address P.
Level display data LEVEL(N) and peak display data PEAK(P) are stored, forming a conversion table as shown in Table 1.

〔Effect of the invention〕

As is clear from the description of the embodiments described above, in the signal reproducing apparatus according to the present invention, the reproducing means reproduces an audio signal and a signal indicating envelope information of the audio signal from a recording medium, and a signal indicating the envelope information is converted into a signal indicating the envelope information. Based on this, the level of the reproduced audio signal can be displayed by the level display means. In other words, the level of the reproduced audio signal can be displayed without requiring large-scale hardware or software dedicated to level display such as absolute value detection or peak hold to form a signal representing the envelope information from the reproduced audio signal. can be easily done. Therefore, according to the present invention, when applied to a playback system such as a digital tape recorder that handles digital audio signals, the burden of calculation processing for level display can be reduced, and errors in playback audio data can be reduced. This makes it possible to prevent a decline in correction ability, etc.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the general configuration of a level display system for reproduced audio signals in a digital tape recorder. FIG. 2 is a block diagram showing a schematic configuration of an embodiment in which the present invention is applied to a rotary head type digital tape recorder, and FIG.
The figure is a schematic diagram showing the tape format of the magnetic tape in the above embodiment, FIG. 4 is a schematic diagram showing the arrangement of data blocks of signals recorded on the magnetic tape, and FIG. 5 is a schematic diagram showing the signal processing for level display. 6 is a flowchart showing the operation of the signal processing section, FIG. 7 is a block diagram showing the overall structure of the level display, and FIG. 8 is a block diagram showing the structure of the signal processing section. 3 is a flowchart showing a display control operation on a display device. 31, 32...Signal input terminal, 36, 44...
Serial/parallel converter, 37, 45... Parallel/serial converter, 34... Logical operation processing circuit, 40... Rotating magnetic head, 41... Magnetic tape, 60... Level indicator, 81... Data register , 82...Flag register, 83...Microcomputer, 100...Display section.

Claims (1)

[Scope of Claims] 1. Reproducing means for reproducing a signal from a recording medium on which an audio signal and a signal indicating envelope information of the audio signal are recorded, based on the signal indicating the envelope information reproduced by the reproducing means. 1. A signal reproducing device comprising: level display means for displaying the level of a reproduced audio signal.