JPH01277366A - Video tape recorder with audio signal noise reduction circuit - Google Patents

Abstract

PURPOSE:To omit the operation of a manual switch for selecting noise reduction processing at the time of reproducing by depressing a manual switch for selecting the validity of the noise reduction processing at the time of picture recording. CONSTITUTION:At the time of recording, the preprocessing noise reduction processing for an audio signal to be recorded in a magnetic tape 8 is executed or not in accordance with the validity of noise reduction processing selected by an operator through a selection switch 6 and a signal corresponding to the existence of the noise reduction processing is recorded in a video signal to be recorded. At the time of reproducing, the post processing of the noise reduction processing is applied to the audio signal to be reproduced in accor dance with a signal 33 indicating the existence of noise reduction processing so that the effect of the noise reduction processing appears. Consequently, it is unnecessary for the operator to depress the switch for selecting whether the noise reduction processing is to be executed or not.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video tape recorder that includes a noise reduction circuit in its audio circuit. In detail, the present invention is directed to a video tape recorder (hereinafter referred to as a VTR) with an audio signal noise reduction circuit that detects the presence or absence of noise reduction processing of an audio signal and automatically performs audio processing of the reproduced audio signal. omitted).

[Prior Art] Conventionally, some high-end home VTR models have a noise reduction circuit in their audio circuit.

Note that noise reduction processing is a well-known technology that compresses the dynamic range of audio signals when recording.
The opposite is true during playback, and this function reduces noise within the audio signal by widening the dynamic range.

When the operator wants to record the audio signal that has been subjected to noise reduction processing onto the magnetic tape loaded in the VTR, the operator turns on the selection switch installed in the VTR to select whether or not to perform the noise reduction processing. Operate to. Therefore, the audio signal is encoded by the noise reduction circuit and recorded on the magnetic tape. Furthermore, when noise reduction processing is not required, the selection switch may be turned off. In this case, the audio signal is recorded on the magnetic tape without passing through the noise reduction circuit.

Furthermore, when playing back a magnetic tape recorded with noise reduction processing, the operator must turn on the selection switch in order to decode the encoded audio signal, that is, to restore the compressed dynamic range. Must be. Furthermore, when reproducing a magnetic tape recorded without noise reduction processing, the operator must turn off the selection switch because there is no need to process the recorded audio signal.

As described above, in order to reproduce the recorded audio in the best condition, the operator needs to accurately operate the selection switch during reproduction, depending on whether or not noise reduction processing is performed during recording.

[Problems to be Solved by the Invention] However, in the conventional VTR as described above, when recording, the operator may, for example, add noise to the index provided on the magnetic tape cassette due to the operation of the selection switch during playback. It was necessary to state whether or not reduction processing was performed.

Then, during playback, there is a problem in that the operator has to operate the selection switch depending on whether or not the described noise reduction processing is to be performed. Furthermore, if there is no mention of the presence or absence of noise reduction processing, or if the same magnetic tape cassette being played contains both noise reduction processed and non-noise reduction processed sections, There is a problem in that it is difficult for the operator to operate the selection switch accurately, and therefore, the recorded audio signal is not reproduced in the best condition.

The present invention has been made to solve the above-mentioned problems, and is an audio signal noise reduction circuit material that eliminates the need for an operator to operate a switch to select whether or not to perform noise reduction processing when playing back a magnetic tape. The purpose is to provide VTR.

[Means for Solving the Problems] A first invention includes a manual switch for selecting whether or not noise reduction processing is necessary for an audio signal when recording a video signal and an audio signal, and a manual switch that selects whether or not to perform noise reduction processing on an audio signal by selecting the manual switch. The present invention is characterized by comprising a recording device that records on a recording medium a video signal to which a signal indicating presence/absence is added and an audio signal subjected to noise reduction preprocessing according to the selection of the manual switch. Furthermore, the second invention includes a detection means for detecting a signal indicating the presence or absence of noise reduction processing recorded on a recording medium, and a detection means for detecting a signal indicating the presence or absence of noise reduction processing recorded on a recording medium, and a detection means for detecting a signal after noise reduction processing for an audio signal reproduced from the recording medium according to the signal obtained by the detection means. The apparatus is characterized by comprising a noise reduction post-processing means for processing.

[Function] In the VTR of the first invention, according to the selection of the manual switch, the audio signal recorded on the magnetic tape is encoded, that is, pre-processed for noise reduction processing,
At the same time, a signal indicating the presence or absence of noise reduction corresponding to the selection of the manual switch is added to the video signal recorded on the magnetic tape. VT of the second invention
In R, when a detection means detects a signal indicating the presence or absence of noise reduction in a video signal recorded on a magnetic tape, decoding, that is, post-processing of noise reduction is performed on the audio signal to be reproduced from the magnetic tape. The means automatically operates to obtain a reproduced signal which has been subjected to noise reduction post-processing.

[Embodiment] In the audio signal noise reduction circuit material VTR of the present invention, FIG. 1 shows an embodiment of the constituent parts for recording video and audio on a magnetic tape loaded in the VTR.

A video input terminal l to which a video signal is input is connected to a vertical synchronization signal separation circuit 2 and an adder 3, which separate the vertical synchronization signal from the video signal. A delay circuit 4 connected to the output side of the vertical synchronization signal separation circuit 2 is a circuit that delays the synchronization signal output from the vertical synchronization signal separation circuit 2 and converts it into a pulse signal. The video switch circuit 5 is the delay circuit 4
The encoder 7 and the adder 3 are connected only while a signal is being output from the adder 3. Note that the encoder 7 is
The code corresponds to the state in which the selection switch 6 is on, that is, the noise reduction processing of the audio signal to be recorded on the magnetic tape 8 is executed, or the selection switch 6 is in the off state, that is, the state in which the noise reduction processing of the audio signal is not performed. It outputs a converted signal. The output side of the adder 3 is F for recording the video signal on the magnetic tape 8.
It is connected via an FM modulator 9 that performs M modulation to a video head 10 that records video signals on the magnetic tape 8 and reproduces video signals recorded on the magnetic tape 8.

On the other hand, an audio input terminal 11 to which an audio signal is input is connected to a noise reduction circuit 12 that reduces noise in the audio signal.
and is connected to the audio switch circuit 13. The audio switch circuit 13 that performs an off or on operation in response to the on state or off state of the selection switch 6 described above is connected to a bypass line of the noise reduction circuit 12. A recording amplifier 14 that amplifies the encoded audio signal output from the noise reduction circuit 12 records the audio signal on the magnetic tape 8 together with a bias oscillation circuit 15 that applies an AC bias to the audio signal output from the recording amplifier 14. It is also connected to an audio head 16 that plays back audio signals recorded on the magnetic tape 8.

In the VTR with the audio signal noise reduction circuit configured as described above, the video signal as shown in FIG.
and is input to the adder 3.

The vertical synchronization signal separation circuit 2 separates only the vertical synchronization signal 31 included in the input video signal, and outputs the vertical synchronization signal 31 to the delay circuit 4. The delay circuit 4 delays the vertical synchronizing signal 31 to a portion 32 of the vertical blanking period 30 where there is no vertical synchronizing signal, and outputs the vertical synchronizing signal 31 as shown in FIG.
The pulse signal 33 is converted into a pulse signal 33 having an opposite phase, and is output to the video switch circuit 5. Furthermore, as shown in Fig. 4,
Although the pulse signal 33 is output to a portion of the portion 32 where there is no vertical synchronization signal, the pulse signal 33 is not limited to this, and may be output during the entire period of the portion 32 where there is no vertical synchronization signal. Since the video switch circuit 5 brings the encoder 7 and the adder 3 into conduction state only while the delay circuit 4 is outputting the signal, the selection switch 6 is in the ON state as shown in FIG. 5(a). Alternatively, the signal 34 indicating whether noise reduction processing is to be performed on the encoded audio signal output by the encoder 7 in response to the off state is input to the adder 3 only when the video switch circuit 5 is in the conductive state. Ru. Therefore, the signal appearing on the output side of the video switch circuit 5 is synchronized with the pulse signal 33, as shown in FIG. 5(b). Therefore, the adder 3 receives the video signal shown in FIG. 3 and the video signal shown in FIG. 5(b).
A video signal 36 as shown in FIG. 5(e) to which the pulse signal 35 shown in FIG. 5 is added is output to the FM modulator 9. Therefore, this video signal 36 is FM modulated by the FM modulator 9 and then recorded on the magnetic tape 8 by the video head 10. Therefore, in the video signal recorded on the magnetic tape 8, it is determined whether noise reduction processing is being performed on the audio signal recorded on the magnetic tape 8, depending on whether the selection switch 6 is on or off. Contains signals to indicate.

Further, when the operator selects the noise reduction ON state of the selection switch 6, that is, the state that reduces the noise of the audio signal recorded on the magnetic tape 8, the audio switch circuit 13 turns the bypass line of the noise reduction circuit 12 into the OFF state. do. On the other hand, when the operator selects the noise reduction OFF state of the selection switch 6, that is, the state in which the noise of the audio signal is not reduced, the audio switch circuit 13 turns on the bypass line of the noise reduction circuit 12 and switches the noise reduction circuit 12 to the ON state. does not operate.

Therefore, when the operator selects the noise reduction ON state of the selection switch 6, the encoded audio signal, that is, the pre-processed noise reduction processing, is amplified by the recording amplifier 14, and the bias oscillation circuit 1
An alternating current bias is applied to the output of 5, and the signal is recorded on the magnetic tape 8 by the audio head 16. Further, when the operator selects the off state of the selection switch 6, the audio signal that is not encoded, that is, the audio signal that is not subjected to the noise reduction preprocessing is transferred to the magnetic tape 8 by the same effect as described above.
recorded in

- In this way, when the operator selects the noise reduction ON state of the selection switch 6, the magnetic tape 8
The audio signal recorded on the magnetic tape 8 is pre-processed for noise reduction processing, and the video signal recorded on the magnetic tape 8 includes a signal indicating that the audio signal has been subjected to noise reduction processing. Further, when the operator selects the noise reduction off state of the selection switch 6, the audio signal recorded on the magnetic tape 8 is not subjected to noise reduction processing, and the video signal recorded on the magnetic tape 8 is A signal indicating that the audio signal is not subjected to noise reduction processing is included.

FIG. 2 shows the structure of an embodiment of a reproducing section of a VTR with an audio signal noise reduction circuit according to the present invention which reproduces a magnetic tape on which audio signals and video signals are recorded as described above. Components that are the same as those shown are given the same reference numerals.

The video head 1O is connected to an FM demodulator 17 that demodulates the FM-modulated video signal into the original state video signal.
The output side of the M demodulator 17 is connected to the video signal output terminal 18, the input side of the vertical synchronizing signal separation circuit 2' and the video switch circuit 5'.
connected to the input side of the The video switch circuit 5° includes a code decoder 19 and an FM demodulator 17 that decode the encoded signal indicating the presence or absence of noise reduction processing into the original signal only while the signal is output from the delay circuit 4°. Connecting. Note that the delay circuit 4° has the same configuration as the delay circuit 4 described above, and delays the vertical synchronization signal output from the vertical synchronization signal separation circuit 2'' by the same time as the delay circuit 4, and has an opposite phase. It outputs as a pulse signal.Also,
The code decoder 19 has an audio noise reduction output terminal 22
connected to.

On the other hand, the audio head 16 is connected to the input side of a reproduction amplifier 20 that amplifies the reproduced audio signal, and the output side of the reproduction amplifier 20 is connected to the noise reduction circuit 12° that decodes the encoded audio signal. The audio switch circuit 13, which is connected to the bypass line of the noise reduction circuit 12, uses the signal output from the encoder decoder 19 indicating that noise reduction processing is present, that is, the signal that the selection switch 6 is in the noise reduction ON state during recording. It turns off and puts the bypass line in a non-conductive state. In addition, the switch 13 is turned on in response to a signal with no noise reduction processing, that is, a signal in which the selection switch 6 is in the noise reduction off state during recording, and the bypass line is made conductive, thereby disabling the noise reduction circuit 12. The output terminals of the noise reduction circuit 12° and the audio switch circuit 13' are the audio signal output terminal 2.
Connected to 1.

In the reproducing section of the audio signal noise reduction circuit configured as described above, the video signal recorded on the magnetic tape 8, which includes a signal indicating whether noise reduction processing is to be performed on the audio signal, is reproduced by the video head 10. , F.M.
The demodulator 17 demodulates the FM signal and outputs the video signal to the output terminal 18. It is output to the vertical synchronization signal separation circuit 2° and the video switch circuit 5°. The vertical synchronizing signal of the video signal input to the vertical synchronizing signal separation circuit 2° is separated, and the separated vertical synchronizing signal is output to the delay circuit 4′. The delay circuit 4° and the video switch circuit 5° have the same function as the delay circuit 4 and the video switch circuit 5 described above, and the delay time of the delay circuit 4° is the same as that of the delay circuit 4. Therefore, the timing at which the video switch circuit 5' turns on is F
Synchronizing with the input of the encoded signal indicating the presence or absence of noise reduction processing in the video signal outputted from the M demodulator 17 to the video switch circuit 5', the encoder decoder 19 receives the signal indicating the presence or absence of the noise reduction processing in the video signal. Only the signal indicating this is input. Then, the code decoder 19 decodes the signal and outputs it to the audio noise reduction output terminal 22. The signal output to the audio noise reduction output terminal 22 is used to indicate whether the noise reduction process is on or off.

On the other hand, the audio signal recorded on the magnetic tape 8 is reproduced by the audio head 16, amplified by the reproduction amplifier 20, and inputted to the input ends of the noise reduction circuit 12' and the audio switch circuit 13°. Audio switch circuit 13
° is in an on state when the output signal of the code decoder 19 is subjected to noise reduction processing, and the code decoder 19
When the output signal of the noise reduction process is "no", it is in the on state. Therefore, according to the signal indicating the presence or absence of noise reduction processing included in the video signal and recorded when recording the video signal, if the noise reduction processing is "yes", the audio signal is decoded by the noise reduction circuit 12° and output as audio. If the noise reduction process is "no", the audio signal is output to the audio output terminal 21 via the audio switch circuit without going through the noise reduction circuit 12°.

As described above, during recording, preprocessing for noise reduction processing is performed or not performed on the audio signal depending on whether noise reduction processing is necessary or not selected by the operator for the audio signal to be recorded on the magnetic tape. ,
A signal depending on whether or not noise reduction processing has been performed is recorded in the video signal to be recorded. Furthermore, during playback, the reproduced audio signal is subjected to post-noise reduction processing in accordance with the signal recorded on the video signal to indicate whether noise reduction processing has been performed or not, so that the effect of the noise reduction processing appears.

Therefore, when playing back a recorded magnetic tape, even if it is unclear whether noise reduction processing was performed at the time of recording, the effect of noise reduction processing will automatically appear on the recorded audio signal when the magnetic tape is played back. will be played. Furthermore, even in the case of a magnetic tape in which audio signals are recorded with and without noise reduction processing, the audio signals can be accurately reproduced by the above-described operation.

In this embodiment, the output signal of the selection switch 6 is encoded by the encoder, but the encoder is not limited to this, and for example, only the detection pulse may be used. Also, the audio switch circuits 13 and 13° were used to switch between the noise reduction circuits 12 and 12' and the bypass line, but when switching electrically inside the noise reduction circuits 12 and 12', the audio switch Circuits 13 and 13° do not need to be used.

[Effects of the Invention] As detailed above, according to the VTR of the first invention, the pre-processing of the noise reduction processing of the audio signal can be performed by operating the manual switch that selects whether or not the noise reduction processing of the audio signal is necessary during recording. The audio signal can be recorded on the recording medium by selecting whether or not to perform the process. Further, according to the VTR of the second aspect of the invention, the presence or absence of noise reduction recorded on the recording medium can be detected by the detection means, and execution of the post-processing of noise reduction processing of the audio signal can be automatically selected. Therefore, the operator does not need to operate a manual switch for selecting whether or not to perform post-processing of noise reduction processing on the audio signal during playback.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the configuration of the recording section in the audio signal noise reduction circuit material VTR of the present invention, and FIG. 2 is a block diagram showing the configuration of the reproducing section in the VTR with audio signal noise reduction circuit of the present invention. 3 is a block diagram showing an embodiment, FIG. 4 is a diagram showing a video signal, FIG. 4 is a diagram showing an output signal of a delay circuit in a VTR with an audio signal noise reduction circuit of the present invention, and FIG. ) is a diagram showing the output signal of the vertical synchronizing signal separation circuit in the VTR with the audio signal noise reduction circuit of the present invention, and FIG. A diagram showing the output signal of the circuit, FIG. 5(c),
FIG. 3 is a diagram showing an output signal of an adder in a VTR with an audio signal noise reduction circuit according to the present invention. 2... Vertical synchronization signal separation circuit, 3... Adder, 5... Video switch circuit, 6... Selection switch, 7... Encoder, 8... Magnetic tape, lO... - Video head, 12... Noise reduction circuit, 13... Audio switch circuit, 16... Audio head.

Claims (2)

[Claims] (1) a manual switch for selecting whether or not to perform noise reduction processing on the audio signal when recording the video signal and the audio signal; and a video signal to which a signal indicating the presence or absence of noise reduction processing is added by selecting the manual switch; A video tape recorder with an audio signal noise reduction circuit, comprising a recording device for recording onto a recording medium an audio signal that has been subjected to noise reduction preprocessing according to the selection of the manual switch. (2) A detection means for detecting a signal indicating the presence or absence of noise reduction processing recorded on a recording medium, and post-processing of noise reduction on the audio signal reproduced from the recording medium according to the signal obtained by this detection means. 1. A video tape recorder with an audio signal noise reduction circuit, characterized in that it is equipped with a noise reduction post-processing means.