JPH05334809A - Voice mode identification signal generating circuit - Google Patents

Abstract

PURPOSE:To satisfactorily transmit voice mode identification signals while preventing the occurrence of an erroneous voice output caused by a MUSE decoder. CONSTITUTION:A changeover switch 70 selects any one of changeover terminals (a) to (d) in accordance with 1350 counts which are equivalent to one frame of the MUSE bit string by a counter 62. A voice mode information is supplied to a control bit generator 66 from a microcomputer 38 of a VTR and the bit strings of voice mode identification signals are generated here. Bit strings of range bits and voice data are generated employing the changeover terminals (c) and (d) so that they respectively become '1' and '0'. By making these bit arrays, an error detection is made when an error correction code is decoded but no correction is made, no adverse effect is made on a digital voice reproduction and voice mode identification signals are transmitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a VTR for recording a high-definition signal, and in particular, a voice mode identification signal generating circuit for generating a voice mode identification signal for identifying a voice mode such as stereo, monaural, and bilingual. Regarding

[0002]

2. Description of the Related Art For high definition audio signals, 20 or more audio modes such as stereo, bilingual and surround are set. This audio mode identification signal is sent from the transmitting side, is decoded by the receiving side, and is used during reproduction. When a high-definition broadcast is once recorded and played back on a VTR, this audio mode identification signal must also be correctly recorded on the VTR. Therefore, some kind of audio mode identification signal is provided in addition to the video signal and the audio signal, and the audio signal is transmitted between devices. The need arises to interact.

A so-called MUSE (Multiple Sub-Nyquist S) is used as a voice mode identification signal in high definition.
ampling Encode) There is a MUSE bitstream output from the decoder. Describing based on the general high-definition broadcasting system of FIG. 5, the MUSE signal transmitted from the broadcasting station 10 includes a transmitting antenna 12 and a broadcasting satellite 1.
4, it is received by the satellite broadcast receiver 18 via the receiving antenna 16. On the one hand, the received signal is the MUSE decoder 2
0, and the analog video signal, audio signal, and digital MUSE bit stream are supplied to the CRT 22 after being decoded. In the CRT 22, the audio mode is identified based on the audio mode identification signal included in the MUSE bit stream, and the audio is reproduced based on the identified audio mode.

On the other hand, the MUSE signal output from the satellite broadcast receiver 18 or the MUSE bit stream output from the MUSE decoder 20 is also supplied to the MUSE / VTR 24 if it is necessary to record the signal. MUSE ・ V
The TR 24 is configured as shown in FIG. 6, for example,
By switching the switch unit 26, the satellite broadcast receiver 1
8 or MUSE decoder 20 output can be supported. The MUSE signal supplied from the satellite broadcast receiver 18 is decoded by the MUSE decoder, and each MUSE bit stream including a video signal, an audio signal, and an audio mode identification signal is output.

First, the recording operation will be described. MU
The video signal output from the SE decoder 20 or 28 is
The signal is supplied to the video signal processing circuit 30 via the switch unit 26, where processing such as pre-emphasis and FM modulation is performed and output to the recording amplifier 32. The audio signal output from the MUSE decoder 20 or 28 is transmitted to the switch unit 2
It is supplied to the audio signal processing circuit 34 via 6, and is subjected to processing such as encoding, and output to the recording amplifier 32.

The MUSE bit stream output from the MUSE decoder 20 or 28 is supplied to the MUSE bit stream / voice mode identification signal decoder 36 via the switch unit 26, where a voice mode control signal is detected and the entire MUSE bit stream is detected. It is output to the microcomputer 38 which controls the operation. This control signal is supplied from the microcomputer 38 to the recording amplifier 32 via the control signal generation / detection circuit 40. The input signal is amplified in the recording amplifier 32, and the amplified signal is recorded on the video tape 44 by the recording head 42.

Next, the operation during reproduction will be described. The signal reproduced from the video tape 44 by the reproducing head 46 is amplified by the preamplifier 48 and then supplied to the control signal generating / detecting circuit 40, the video signal processing circuit 50, and the audio signal processing circuit 52. The control signal generation / detection circuit 40 detects a control signal such as a voice mode from the input signal and sends the control signal to the microcomputer 38. In the microcomputer 38, information such as post-recording is further added to the control signal, and the control signal is sent to the voice mode identification signal generating circuit 54.

In the audio mode identification signal generating circuit 54, an audio mode identification signal is generated according to a predetermined format described above, and this is output together with the audio output of the audio signal processing circuit 52 and the MUSE bit stream encoder 56.
Entered in. The encoder 56 generates a MUSE bit stream based on the input signal and outputs it to another MUSE / VTR (not shown). The video signal processing circuit 50 performs processing such as FM demodulation and outputs the reproduced high-definition video signal. The audio signal processing circuit 52 also performs necessary processing, and outputs the processed audio signal.

As described above, the MUSE bit stream includes the MUSE decoder 20 together with the video signal and the audio signal.
Alternatively, the signal is a signal in which the time axis of the digital audio data signal time-compressed and multiplexed with the MUSE signal is expanded to form a continuous digital signal, and biphase mark modulation is performed on the continuous digital signal. Except for the bi-phase mark modulation, there are few additional circuits, which is convenient for digital audio data output. Moreover, since an error correction code is added, correct data transmission can be performed.

FIG. 7A shows the bit allocation of the MUSE bit stream in the case of the 8-bit 4-channel A mode, which is a frame synchronization signal of 16 bits from the beginning and a control code of 22 bits. In addition, 16 range bits, 512 data bits, 16 range bits, 512 data bits,
It has 128 bits of independent data and 128 bits of correction code. The total of these is 1350 bits, and these 1350 bits are called a frame, and 36 frames are called a master frame. Of these, the control contents of each bit of the control code are as shown in Table 1 below, for example, and the audio mode is represented by 6 bits of the audio format.

[0011]

[Table 1]

Next, the correction code BCH (82,7) is added to the voice data and the independent data in the MUSE bit stream.
4) is applied. The generation of this correction code is not performed in the order of the frame signals shown in FIG.
It is performed on the bit interleave matrix shown in.
That is, data is written as shown in the horizontal direction of FIG. 7 and is sent out in the vertical direction of FIG.
The MUSE bit stream shown in (1) is obtained, and is expressed in 16 lines excluding the control code. Here, the BCH (82, 74) has an 8-bit error correction code for 74 bits in each row (1 bit for each range bit, 16 bits for each of voices 1 to 4, and 8 bits for independent data). It means that it is added.

The generator polynomial of such a correction code is (X ⁸
+ X ⁷ + X ⁴ + X ³ + X + 1), and the correction code generator according to this is as shown in FIG. 9 (A). In the figure, “D” is a delay circuit that delays by 1 bit,
"+" Is an EXOR circuit that performs an exclusive OR operation,
These constitute a shift register. Further, the switches SW1 and SW2 are adapted to be interlocked and switched to a or b. First, the switches SW1,
Both SW2 are switched to the a side. Then, the input 74 bits are directly output to the corresponding part of the shift register while being output via the switch SW1 as they are.

When the output of the 74th bit is completed, the switches SW1 and SW2 are switched to the b side,
The correction code by the generator polynomial (X ⁸ + X ⁷ + X ⁴ + X ³ + X + 1) is generated and output. As a result, an 8-bit correction code is added after the 74-bit information bit.

Next, range bits (1, 2) corresponding to voices 1 and 2 and range bits (3, 3 corresponding to voices 3 and 4).
In 4), the correction code BCH (7,3) is applied independently of the voice data of voices 1 to 4. That is, FIG.
The range bits shown in (A) and FIG. 8 include range information and its correction code. The generator polynomial in this case is (X ⁴ + X ³ + X ² +1), and the correction code generator according to this is as shown in FIG. 9 (B). In the figure,
“D”, “+”, switches SW1 and SW2 are shown in FIG.
First, both the switches SW1 and SW2 are first switched to the a side. Then, the input 3
On the one hand, the bit is directly output via the switch SW1 and is input to the corresponding part of the shift register.

When the output of the third bit is completed, the switches SW1 and SW2 are switched to the b side, and the correction code by the generator polynomial (X ⁴ + X ³ + X ² +1) is generated and output. As a result, a 4-bit correction code is added after the 3-bit information bit.

M of FIG. 7A obtained as described above
The USE bit stream is output from the MUSE decoder together with the video signal and the audio signal. MUS like this
Since the E bit stream is also a signal intended for digital audio connection, it contains digital signals of audio data (audio 1 to 4 in FIG. 7A) and is interleaved as shown in FIG. Has been.

[0018]

Here, for example, when another MUSE / VTR is connected to the MUSE / VTR 24 shown in FIG. 6 to perform dubbing, the MUSE bit stream encoders 56 and M are considered due to the interleave relationship.
It is necessary to encode / decode the MUSE bitstream using the USE decoder 28. By this processing, the voice mode included in the control code can also be determined. However, in such a method, the MUSE decoder 28 and the MUSE bit stream encoder 56 are
Since it has to be provided in R, the circuit scale becomes large.

In particular, when voice dubbing is performed on a video tape recorded by the MUSE / VTR 24 and the voice mode is changed at this time, the voice mode information after the change must be transmitted to the VTR to be dubbed. I have to. In this case, when the conventional method is used, the control code including the changed voice mode information is generated, and the MUS
It is necessary to encode and decode the E bit stream.

Therefore, a method is conceivable in which the format of the MUSE bit stream (see FIG. 7A) is left unchanged and only the control code is changed without using the voice data (voices 1 to 4). However, in this case,
A problem arises as to what kind of data is used to fill the audio data area. The video and audio signals are normally supplied to the VTR on the dubbing side in analog,
Although the digital audio data in the MUSE bit stream is not used, when the digital audio data is used, the pseudo audio data is also decoded as the original audio data. Therefore, it is necessary to pay attention so that unnecessary sounds are not reproduced by such pseudo voice data.

For example, when all the range bits, voice data, and independent data are set to the logical value "0", FIG.
Due to the configuration of the correction code generator shown in (A), all correction codes are also "0". That is, a signal in which all the signals other than the synchronization code and the control code are "0" is the correction code BCH.
It is a pattern existing in (82,74), and is a correct code that is not an error. Therefore, there is a possibility that a meaningless voice is erroneously produced. The present invention focuses on these points, and provides a voice mode identification signal generation circuit having a simple configuration capable of favorably generating a voice mode identification signal that prevents erroneous voice output from a decoder. , And its purpose.

[0022]

One of the present inventions is to perform a voice mode identification signal generating means for generating a voice mode identification signal and a predetermined decoding process for a range bit signal and a voice data signal. In addition, pseudo signal generating means for generating pseudo signals of the range bit signal and the voice data signal so that error detection is possible but error correction is not possible by those error correcting codes, and by these signal generating means Signal sequence forming means for obtaining a signal sequence in a predetermined format by using the generated signal.

According to another aspect of the invention, the range bit signal is set to a minimum reproduction level when a predetermined decoding process is performed on the range mode signal and the range data signal and the voice mode identification signal generating means. And pseudo signal generating means for generating a pseudo signal of the audio data signal, and signal sequence forming means for obtaining a signal sequence of a predetermined format by using the signals generated by these signal generating means. Is characterized by.

[0024]

According to the present invention, the property of the error correction code attached to the range bit and the voice data is effectively used, and even if the voice data is decoded by mistake, the error detection and the error correction cannot be performed. Signal generation is performed so that the bit array of According to another invention, the property of the error correction code attached to the audio data is effectively used, and the signal generation is performed so that the bit arrangement is the minimum reproduction level even if the audio data is erroneously decoded. Is done.

[0025]

Embodiment 1 An embodiment of a voice mode identification signal generating circuit according to the present invention will be described below with reference to the accompanying drawings. It should be noted that the same components as those in the above-described conventional example or components corresponding to the conventional example are denoted by the same reference numerals.

FIG. 1 shows a voice mode identification signal generating circuit 60 according to this embodiment. As shown in FIG. 2, this circuit is provided in the VTRs 100 and 102, and has a function of outputting the audio mode identification signal of the above-mentioned signal format to the VTR 102 for dubbing. 1 and 2, the voice mode identification signal generating circuit 60 includes a counter 62, a sync pattern generator 64, and a control bit generator 66, respectively. A clock generator 68 is connected to the counter 62, the synchronization pattern generator 64, and the control bit generator 66.
For example, a clock of 1.35 MHz is commonly supplied.

The count output side of the counter 62 is connected to the changeover control side of the changeover switch 70, and the respective output sides of the synchronization pattern generator 64 and the control bit generator 66 are respectively connected to the changeover terminals a and b of the changeover switch 70. It is connected. The changeover terminal c of the changeover switch 70 is connected to the power supply V _CC , and a logical value "1" is generated. The changeover terminal 70 of the changeover switch 70 is connected to the ground so that a logical value "0" is generated. The output side of the changeover switch 70 is connected to the biphase mark modulator 72, and the output side of the biphase mark modulator 72 is the output side of the audio mode identification signal generating circuit 60.

Of the above units, the counter 62 is a MU.
1 to 1 corresponding to one frame of the SE bit stream
This is for repeatedly counting up to 350.
That is, the clock input from the clock generator 68 is counted, and when counting from 1 to 1350, it returns to 1 again. Next, the sync pattern generator 64 is for generating the bit pattern of the frame sync signal shown in FIG. Next, the control bit generator 66
Is for generating the bit pattern of the voice mode identification signal, and the voice mode information is supplied from the microcomputer 38 of the VTR 100.

Next, the changeover switch 70 has a counter 62.
Has a function of switching the switching terminal in accordance with the count value of the switch terminal. When the counter value is 1 to 16, the switching terminal a,
When the count value is 17 to 38, the switching terminal b, when the count value is 39 to 54, the switching terminal c, and the count value is 55.
To 566, the switching terminal d, the count value is 567 to 5
When it is 82, the switching terminal c and the count value are 583 to 135.
When it is 0, it can be switched to the switching terminal d.

Next, the VTRs 100 and 102 shown in FIG.
Has a configuration as shown in FIG. 3, for example. The output signal of the MUSE decoder 20 of FIG. 2 is input to the video signal processing circuit 30, the audio signal processing circuit 34, and the MUSE bit stream / audio mode identification signal decoder 36, respectively. Not provided. Further, the output of the audio mode identification signal generating circuit 60 is directly output to the outside, and no encoder is provided. The other parts are
It is similar to the device of FIG. 6 described above.

Next, the operation of the voice mode identification signal generating circuit 60 configured as described above will be described. In addition,
A case where dubbing is performed on the VTRs 100 to 102 in FIG. 2 will be described as an example. From the VTR 100, the audio mode identification signal is VTR along with the video signal and the audio signal.
It is output to 102. At this time, the audio mode identification signal is supplied from the audio mode identification signal generation circuit 60 of the VTR 100 to the MUSE bitstream / audio mode identification signal decoder 36 of the VTR 102.

This voice mode identification signal is shown in FIG.
More specifically with reference to (A) and (B), the count value of the counter 62 of the voice mode identification signal generating circuit 60 is 1
In the case of .about.16, the changeover switch 70 is connected to the changeover terminal a. Therefore, the bit string "000100110101" of the synchronization pattern output from the synchronization pattern generator 64 is output.
1110 ”is output from the changeover switch 70.

Next, the count value of the counter 62 is 17 to
In the case of 38, the changeover switch 70 is connected to the changeover terminal b. Therefore, the bit string "XXXX ... XX" of the voice mode identification signal output from the control bit generator 66 is output from the changeover switch 70. Next, when the count value of the counter 62 is 39 to 54, the changeover switch 70 is connected to the changeover terminal c. Therefore, the pseudo bit string "111 ... 11" of the logical value "1" corresponding to the range bit (1, 2) is output from the changeover switch 70.

Next, the count value of the counter 62 is 55-55.
At 566, the changeover switch 70 is connected to the changeover terminal d. Therefore, the pseudo bit string “000 ... 00” of the logical value “0” corresponding to the sounds 1 and 2 is output from the changeover switch 70. Next, when the count value of the counter 62 is 567 to 582, the changeover switch 70 is connected to the changeover terminal c. Therefore, the pseudo bit string "111 ... 11" of the logical value "1" corresponding to the range bit (3, 4) is output from the changeover switch 70. Next, when the count value of the counter 62 is 583 to 1350, the changeover switch 70 is connected to the changeover terminal d. Therefore, the pseudo bit string "0000 ... 00" of the logical value "0" corresponding to the voice 3, 4, the independent data, and the check bit is changed to the changeover switch 70.
Will be output from.

That is, the counter 62 is set to 1 to 1350.
Counting up to, the changeover switch 70 to FIG.
Is output as a bit stream, which is bi-phase modulated by the bi-phase mark modulator 72 to produce VTR1.
No. 02 MUSE bit stream / audio mode identification signal decoder 36. Explaining the bit stream of FIG. 4B further, the synchronization code and the control code are still the MUSE bit stream of FIG. 7A, and the range bits in the data area are all logical values “ 1 ", and all other data have a logical value of" 0 ".

Of these, all the range bits are "1".
Is a nonexistent pattern, and the correction code portion is a code in which 2 bits of the correct code are incorrect.
Therefore, even if this is decoded by the MUSE bitstream / audio mode identification signal decoder 36, the error can be detected but the error cannot be corrected. Regarding the check bits which are the correction codes of the voices 1 to 4, similarly, 2 bits of the correct code become an erroneous code, and the MUSE bit stream / voice mode identification signal decoder 36 can detect the error but cannot correct it.

Therefore, the voice mode identification signal generating circuit 60
The audio data portion in the bit stream supplied from the MUSE to the MUSE bit stream / audio mode identification signal decoder 36 is determined to be uncorrectable erroneous data and will not contribute as audio data. For this reason, the inconvenience of unnecessary sound being reproduced by the pseudo bit stream shown in FIG. 4B can be effectively prevented.

Even if it is erroneously decoded as voice data, all "0" s of voices 1 to 4 correspond to "no difference" in DPCM, so that only DC (direct current) is output and no sound is produced. I won't. Furthermore, since the DC component is cut by the high-pass filter (HPF) provided in the decoder, no particular inconvenience occurs. Other than that, the processing of the video signal and the audio signal is similar to that of the apparatus of FIG.

The present invention is not limited to the above embodiments, and includes, for example, the following. (1) In the above-mentioned embodiment, the case where the voice transmission is performed in the 8-mode 4-channel (32 KHz sampling) A mode is described as an example, but the 11-bit 2-channel (48 KHz) is used.
The present invention is also applicable to the B mode of (sampling). FIG. 7B shows the bit allocation of the MUSE bit stream in the B mode, which is a frame synchronization signal of 16 bits from the beginning, a control code of 22 bits, and a range bit. 16 bits, voice 1
Data bits of 528 bits, voice 2 data bits of 528 bits, independent data of 112 bits, and correction code of 12
It has 8 bits. These total 1350 bits in total.

If the above embodiment is applied as it is in the case of the B mode, the bit stream shown in FIG. 4B is the MUSE bit stream / audio mode identification signal decoder 36 (see FIGS. 2 and 3) of the VTR 102. B mode
It will be decoded in the standard format. Therefore, the data of "1111 ... 11" corresponding to the range bit (3, 4) of FIG. 4A becomes a part of the B-mode voice 1 shown in FIG. 4C. However, since the LSB of the voice 1 is only "1", even if it is decoded by the MUSE bit stream / voice mode identification signal decoder 36, it can be suppressed with a minimum influence.

(2) In the above embodiment, as shown in FIG.
As shown in (B), the range bit is set to the logical value "1" and the audio data is set to the logical value "0", but this may be appropriately changed as necessary. BCH (8
(2,74) correction code is capable of 1-bit error correction and 2-bit error detection, and when it is decoded by setting any 2 bits to logical value "1" and the rest to "0" The error correction cannot be performed. Therefore, BC
Arbitrary 2 of 74 bits of data in H (82,74)
In the case of a pattern in which the bits are "1" and the rest are all "0", or a pattern in which any two bits of the error-free correction code are inverted, the same effect as the above embodiment can be obtained. it can.

(3) The above embodiment is a case of a general MUSE bit stream, but the digital signal string is not necessarily limited to the above-mentioned format, but can be applied to various kinds. (4) In addition, the circuit configuration can be modified in various ways so as to achieve the same operation, for example, software processing by a microcomputer.

[0043]

As described above, the voice mode identification signal generating circuit according to the present invention has the following effects. (1) A simple circuit configuration is made by using the property of the error correction code attached to the voice data, and using a fail-safe bit array that enables error detection and error correction even if the voice data is erroneously decoded. With this, there is an effect that erroneous voice output is favorably prevented. (2) Since the bit arrangement is such that the minimum reproduction level is obtained even if audio data is erroneously decoded, erroneous audio output can be favorably reduced with a simple circuit configuration.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a voice mode identification signal generating circuit according to the present invention.

FIG. 2 is an explanatory diagram showing an example of a high-definition broadcasting system to which the embodiment is applied.

3 is a block diagram showing an example of a VTR in the system of FIG.

FIG. 4 is a pseudo bit string and M generated in the embodiment.
It is explanatory drawing which shows the relationship with the format of a USE bit stream.

FIG. 5 is an explanatory diagram showing an example of a conventional general high-definition broadcasting system.

6 is a block diagram showing an example of a VTR in the system of FIG.

FIG. 7 is an explanatory diagram showing a format of a MUSE bit stream.

FIG. 8 is an explanatory diagram showing a relationship between code correction and interleaving in a MUSE bitstream.

FIG. 9 is a circuit diagram showing a correction code generation circuit for a MUSE bit stream.

[Explanation of symbols]

30, 50 ... Video signal processing circuit, 32 ... Recording amplifier, 3
4, 52 ... Audio signal processing circuit, 36 ... MUSE bit stream / audio mode identification signal decoder, 38 ... Microcomputer, 40 ... Control signal generation / detection circuit, 42
... recording head, 44 ... video tape, 46 ... reproducing head, 48 ... preamplifier, 60 ... audio mode identification signal generating circuit, 62 ... counter, 64 ... synchronization pattern generator, 6
6 ... Control bit generator (voice mode identification signal generating means), 68 ... Clock generator, 70 ... Changeover switch (signal string forming means), 72 ... Biphase mark modulator, 1
00, 102 ... VTR, V _CC ... Power supply (pseudo signal generating means).

Claims (2)

[Claims] 1. When a predetermined decoding process is performed on a range bit signal and a voice data signal, a voice mode identification signal generating means for generating a voice mode identification signal and error detection can be performed by those error correction codes. However, it is predetermined using pseudo signal generating means for generating pseudo signals of the range bit signal and the voice data signal and the signals generated by these signal generating means so that error correction is impossible. And a signal sequence forming means for obtaining a signal sequence of a certain format. 2. A voice mode identification signal generating means for generating a voice mode identification signal, and a minimum reproduction level when a predetermined decoding process is performed on the range bit signal and the voice data signal. Pseudo signal generating means for generating pseudo signals of the range bit signal and the voice data signal, and signal sequence forming means for obtaining a signal sequence of a predetermined format by using the signals generated by these signal generating means. A voice mode identification signal generating circuit characterized by being provided.