JPH04368665A - Multichannel sound signal reproducing device - Google Patents

Abstract

PURPOSE:To able to reproduce present 2 channel stereophonic sound with a 4 channel sound signal reproducing device by outputting to convert a reproduced 3-1 system 4 channel stereophonic signal to a present 2 channel stereophonic signal. CONSTITUTION:The sound signals of the channel 1-the channel 4 of a HD-VTR are inputted respectively to D/A converters 25a-25d, are converted to the sound signals 12 of the CHI-the CH4 of an analog signal form and inputted to a selector 27 and a 2 channel converter 28. In the 2 channel converter 28, the 3-1 system 4 channel streophonic signal is converted to the 2 channel stereophonic signals L0, R0 and inputted to the selector 27. To the selector 27, in addition of a sound mode control code 16, the command signals of a 2 channel/4 channel switch 29 and a sound mode selecting switch 30 are inputted. Thus, when the 4CH/2CH switch 29 is switched to the 2 channel side, the L0, R0 converted to the present 2 channel stereophonic signals are outputted and the present 2 channel stereophonic sound is capable of listening.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording and reproducing apparatus for recording and reproducing four-channel audio signals.

0002

2. Description of the Related Art As an image recording and reproducing apparatus for recording and reproducing four-channel audio signals, for example, a high-definition V that records and reproduces a high-definition baseband signal sent from a high-definition receiver and a high-definition audio signal
There is a TR (hereinafter referred to as "HD-VTR"). The transmission format of this high-definition audio signal includes A mode and B mode.

FIG. 5 is a diagram showing the transmission format of high-definition audio signals in mode A and mode B. Mode A is a 4-channel mode with a sampling frequency of 32 KHz and a 15-bit quantized audio signal compressed to 8 bits. , B mode is a two-channel mode in which a 48KHz, 16-bit quantized audio signal is compressed to 11 bits. Hereinafter, this audio signal will be referred to as a "1.35 Mbps bitstream."

[0004] For high-definition audio sent in such a format, various audio modes are defined in addition to 3-1 system 4-channel stereo. Table 1
shows the TV audio mode that will be used for the time being.

[0005]

[Table 1]

[0006] In Table 1, L and R represent the left and right voices, respectively, and main and sub represent the main voice and sub-voice, respectively. In the case of the 3-1 system, L, R, C, and S indicate left front sound, right front sound, center front sound, and rear sound, respectively.

[0007] These audio modes include the above-mentioned 1.35M
It can be identified by the control code in the bps bitstream, and can be automatically selected from Channel 1 audio, Channel 2 audio, Channel 3 audio, and Channel 4 audio, or selected according to the viewer's wishes. I can hear it. Hereinafter, the audio signal after being selected will be referred to as a "selected audio signal." The audio of channels 1 to 4 mentioned above is the audio signal immediately after being decoded from the 1.35 Mbps bit stream by the audio decoder section of the MUSE decoder. called "audio signal".

[0008] H that records such high-definition audio
A D-VTR is configured to record and reproduce four-channel audio signals. FIG. 6 shows a connection diagram between this HD-VTR and a high-definition receiver. In the figure, 1 is MUS
E decoder, 2 is HD-VTR, 3 is display, 4
is a 4 channel audio amplifier, 5a, 5b, 5c
are a left speaker, a center speaker, and a right speaker, respectively, and 6a and 6b are rear speakers.

The MUSE decoder 1 receives a Y signal, a PB signal, and a PR signal 7 which are decoded from the MUSE signal and output in parallel, and which are decoded from a 1.35 Mbps bit stream by the audio decoder section of the MUSE decoder 1. The pre-selection audio signals 8 of channels 1 to 4 and the audio control signal 9 for identifying the aforementioned audio mode of the pre-selection audio signals 8 are output to the HD-VTR 2.

[0010] The HD-VTR 2 receives input Y, PB.
, PR signal 7 and pre-selection audio signal 8 are subjected to signal processing and then recorded on a magnetic tape. During reproduction, the reproduced Y, PB, PR signals 10 are output to the display 3, and the reproduced selected audio signal 11 is output to the four-channel audio amplifier 4. In the case of the 3-1 method, the selected audio signal 11 is
, R, C, and S audio signals.

The display 3 displays the input Y, PB
, PR signal 10 is displayed. In addition, the selected audio signal 11 input to the 4-channel audio amplifier 4 is
In the case of the 3-1 method, L, R, C,
The audio signals of S are sent to the speakers 5a to 5c, 6a, 6, respectively.
b.

[0012] Dubbing is also one of the important functions of a VTR. FIG. 7 is a connection diagram of an HD-VTR 2 equipped with a signal output terminal for dubbing and a high-definition receiver.
It is configured to output a pre-selection audio signal 8 of channel 4 and an audio control signal 9 for identifying the audio mode of this pre-selection audio signal 8. This pre-selection audio signal 8
and the audio control signal 9 are for dubbing audio signals, and
It will be used as an output for future high-definition audio compatible amplifiers.

Next, the operation will be explained. In FIG. 6, when receiving a high-definition broadcast, Y, PB, and PR signals 7 are applied from the MUSE decoder 1 to the video input terminal of an HD-VTR 2 that records the high-definition broadcast. On the other hand, the pre-selection audio signal 8 from the MUSE decoder 1 is applied to the pre-selection audio signal input terminal of the HD-VTR 2, and at the same time, the audio control signal 9 of the 1.35 Mbps bit stream is applied to the audio control signal input of the HD-VTR 2. Added to the terminal.

Here, the reason why the pre-selection audio signal 8 is input to the HD-VTR 2 instead of the post-selection audio signal 11 is that the audio mode is two monaural main and sub audio systems, e.g.
In a multilingual program, when the main audio is Japanese and the secondary audio is a foreign language, if you select Japanese and record the audio after selection, it will not be possible to play back the audio in the foreign language. This is because it is necessary to record signal 8.

Next, Y and P input to the HD-VTR 2
B, PR signal 7 is subjected to recording signal processing and then FM
It is modulated and recorded on magnetic tape. Pre-selection audio signal 8
is A/D converted, an error correction code etc. are added, time axis compression is applied, and after digital modulation, the above F
It is time-division multiplexed with the M signal and recorded on the magnetic tape. The audio control signal 9 is digitally recorded together with the pre-selection audio signal 8. These are well known techniques.

[0016] At the time of playback, the process opposite to the above is performed,
The reproduction Y, PB, PR signals 10, the pre-reproduction selection audio signal 11, and the reproduction audio control signal are reproduced. Play Y, P
The B and PR signals 10 are input to the display 3 and a high-definition image is displayed. The audio mode of the playback pre-selection audio signal is identified by the playback audio control signal, and the playback post-selection audio signal 11 selected from the playback selection audio signal is automatically or manually selected from the playback selection audio signal according to the audio mode. Ru. In the case of the 3-1 system, L, R, C, and S audio signals are output as described above.

After the playback selection, the audio signals 11 are each input to a four-channel audio amplifier, amplified, and then output to the speakers 5a to 5c, 6a, and 6b.
In the case of high-definition broadcasting using this method, high-quality high-definition audio with a sense of realism is reproduced.

Next, the dubbing operation according to the conventional example shown in FIG. 7 will be explained. As mentioned above, HD-VTR2 has
A pre-selection audio signal 8 and an audio control signal 9 are recorded. In order to dub the reproduced audio signal of the HD-VTR 2, it is necessary to output the reproduced pre-selection audio signal 12 as is and output the reproduced audio control signal 13.

The audio signals 12 of channels 1 to 4 are outputted from the pre-reproduction selection audio signal output terminal, and the reproduced audio control signal 13 is outputted from the reproduced audio control signal output terminal. When dubbing, these playback pre-selection audio signals 12 and playback audio control signals 13 are transferred to the other party's HD.
-It is input to a VTR and dubbed. Note that the dubbing of the reproduced video signal is based on the Y, PB reproduced by the HD-VTR2.
, PR signal 10 is input to the other party's HD-VTR and dubbed.

[0020]

[Problems to be Solved by the Invention] Since the conventional HD-VTR is configured as described above, it is difficult to use an HD-VTR for viewing using a 4-channel audio amplifier, or for recording and playing back 4-channel audio signals. There is no problem with dubbing between them. However, from a format point of view, even if a VTR can record and play back 4-channel audio signals, it is better to listen to high-definition audio in the current 2-channel stereo format than in the 3-1 system, which is cheaper. Based on this idea, it is expected that an HD-VTR that records and plays only two channels of audio will be realized.

Furthermore, when dubbing from a conventional HD-VTR to a two-channel audio HD-VTR, the following problems occur. That is, in order to be able to reproduce 3-1 system 4-channel stereo as the current 2-channel stereo, the 2-channel stereo outputs LO and RO and the 3-1 system 4-channel stereo outputs L, The following relationship is required between R, C, and S: LO = L + 0.7C + 0.7S RO = R + 0.7C + 0.7S.

However, the audio signal 11 after playback selection has the following:
Since only the L, R, C, and S audio signals are output, no matter which two terminals are selected, the LO and RO outputs cannot be obtained.
The current 2-channel stereo outputs LO and RO cannot be supplied to a 2-channel audio HD-VTR.

[0023] This invention has been made to solve the above-mentioned problems, and the invention of claim 1 is capable of reproducing the current two-channel stereo even if a two-channel audio amplifier is connected to an HD-VTR. In addition, for this purpose, it is an object of the present invention to provide an HD-VTR that does not require an increase in the number of output terminals for pre-selection audio signals of the HD-VTR.

[0024] Furthermore, the invention of claim 2 provides a system for converting a 4-channel audio HD-VTR to a 2-channel audio HD-VT
The purpose of this invention is to obtain a 4-channel audio HD-VTR that can output the current LO, RO 2-channel stereo audio when dubbing to R.

[0025]

[Means for Solving the Problems] A multi-channel audio signal reproducing device according to the invention of claim 1 includes a four-channel audio signal and an audio control signal including an audio mode control code for identifying the mode of the audio signal. a means for reproducing the four-channel audio signal and the audio mode control code from a recording medium on which is recorded; means for creating a current 2-channel stereo signal from a signal; a selector that receives the created 2-channel stereo signal and the reproduced 4-channel audio signal as input; and an output signal selected by the selector that is a 2-channel stereo signal. 4 channels or 4 channels specified by the selector based on the reproduced audio mode control code;
It is configured to output an audio signal in the audio mode specified by the channel.

[0026] The multi-channel audio signal reproducing device according to the invention of claim 2 is the multi-channel audio signal reproducing device according to the invention of claim 1,
A second selector that inputs the audio signal of the channel and the current 2-channel stereo signal created from the 3-1 system 4-channel stereo signal, and a second selector that inputs the current 2-channel stereo signal created from the audio signal of the channel and the 3-1 system 4-channel stereo signal, and the output signal selected by this selector is the main stereo signal or the sub-stereo signal. and means for creating and outputting an original audio control signal from the reproduced audio mode control code, and when a four-channel output signal is designated from the second selector, It is configured to output four-channel input signals, and when a two-channel output signal is specified, to output the specified main stereo signal or sub-stereo signal.

[0027]

According to the invention of claim 1, when a 3-1 system 4-channel stereo signal is being reproduced, the signal converted to the current 2-channel stereo signal is selected and output by the selector, and other audio modes are played. When reproducing an audio signal, it is possible to select and output an audio signal that matches the number of channels and audio mode of the audio output system.

Further, according to the invention of claim 2, apart from the audio output system, the four-channel audio signal input to the second selector is adapted to the number of channels and audio mode of another audio recording device. In addition to outputting the audio signal, it also outputs an audio control signal to identify the audio mode of the audio signal, so you can use another recording device, separate from the audio output system, to output the originally recorded audio signal as it is. Can be dubbed.

[0029]

[Embodiment] An embodiment of the invention according to claim 1 will be described below. The signal input from the MUSE decoder is recorded on the magnetic tape in the same manner as in the conventional example.

FIG. 1 is a block diagram of the reproduction signal processing system of the HD-VTR according to this embodiment, in which reference numeral 21 denotes a reproduction amplifier to which a time division multiplexed signal reproduced from a magnetic tape is added;
2 is a separation circuit that separates the time-division multiplexed FM signal and the digital modulation signal, and 23 is a separation circuit that separates the FM signal from the Y, PB signal.
, a video reproduction processing circuit for reproducing the PR signal; 24 is an audio reproduction processing circuit for reproducing the pre-selection audio signal and the audio control signal from the digital modulation signal; 25a, 25b, 25c;
, 25d is a D/A conversion circuit, 26 is a voice control decoder,
27 is a selector that selects and outputs the selected audio signal from the pre-selected audio signal, 28 is a 2-channel conversion circuit that converts 3-1 system 4-channel stereo to 2-channel stereo, and 29 is a 2-channel or 4-channel selection. 2-channel/4-channel switch for selecting the rear audio signal, and 30 is an audio mode selection switch.

Next, the operation will be explained. The time division multiplexed signal reproduced from the magnetic tape is amplified by the reproduction amplifier 21 and then input to the separation circuit 22, where the time division multiplexed FM signal and the digital modulation signal are separated.
The signal is input to the video reproduction processing circuit 23, and the digital modulation signal is input to the audio reproduction processing circuit 24. In the video reproduction circuit 23, after the FM signal is demodulated, the Y, PB, PR signals are reproduced by performing the reverse processing to that during recording.
Reproduction Y, PB, and PR signals 10 are output in parallel from the video signal output terminal.

The digital modulated signal input to the audio reproduction processing circuit 24 is demodulated, then subjected to time axis expansion and error correction to be converted into channels 1 to 1 in the form of a digital signal.
The pre-selection audio signal of channel 4 is output. The audio signals of channels 1 to 4 are each D/A
The signals are input to converters 25a to 25d and converted into audio signals 12 of channels 1 to 4 in analog signal form. The audio reproduction processing circuit 24 simultaneously reproduces a 1.35 Mbps bit stream recorded as an audio control signal, and this signal 13 is input to the audio control decoder 26.

The audio signals 12 of channels 1 to 4 outputted from the D/A converters 25a to 25d are input to the selector 27 and the 2-channel conversion circuit 28,
The 2-channel conversion circuit 28 converts the 3-1 system 4-channel stereo into 2-channel stereo LO, RO, and inputs it to the selector 27.

On the other hand, the audio control decoder 26 extracts the 6-bit audio mode control code 14 for identifying the audio mode shown in Table 1 from the control code of the input 1.35 Mbps bit stream 13 and inputs it to the selector 27. . In addition to this audio mode control code 14, the selector 27 receives a command signal from an audio mode selection switch 28 for manually selecting an audio mode, and a selected audio signal outputted from the selector 27 for 2 channels or 4 channels. A designation signal from the 2-channel/4-channel switch 29 is input to designate the channel.

FIG. 2 is a block circuit diagram showing the configuration of the selector switch portion of the selector 27 and the two-channel conversion circuit 28 in order to explain the operation of the selector 27. In the figure, SW1 to SW6 are switches 1a, 1b,
1c, 2a, 2b, 2c, 3a, 3b, 4a, 4b, 5
a, 5b, 6a, and 6b are switching terminals of SW1 to SW6, respectively. These switches SW1 to SW6 are switched by the audio mode control code 14, a designation signal from the 2-channel/4-channel switch 29, and a command signal from the manual audio mode selection switch 28.

The two-channel conversion circuit 28 includes an adder 31
, 32 and amplifiers 33 and 34 with a gain of 0.7, and as described above, this circuit converts 3-1 system stereo so that it can be reproduced as the current 2-channel stereo. The operation will be explained below. In the case of 3-1 stereo, L, R, C, and S audio signals are input;
is input to the adder 31, R is input to the adder 32, C is input to the amplifier 31, and S is input to the amplifier 34, and the output of the amplifier 33 multiplied by 0.7 is input to the adders 31 and 32, The outputs of are also input to adders 31 and 32.

As a result, the outputs of the adders 31 and 32 are as follows:
L+0.7C+0.7S R+0.7C+0.7S In other words, 2 channel stereo output LO, RO
is obtained. The output LO of the adder 31 is input to the switching terminal 3a of SW3, and the output of the adder 32 is input to the switching terminal 4b of SW4.

Channel 1 audio of pre-selection audio signal 12,
The audio modes for Channel 2 audio, Channel 3 audio, and Channel 4 audio are shown in Table 1. Among these audio modes, the two monaural systems require at least manual selection of main and sub audio. With two stereo systems, manual selection of main and sub stereo is required.

Channel 1 audio is switched to switch terminal 1 of SW1.
Channel 2 audio is applied to the switching terminal 1b of SW1 and switching terminal 2b of SW2, and channel 3 audio is applied to the switching terminal 5a of SW5.
is applied to the switching terminal 1c of SW1, and the channel 4 audio is applied to the switching terminal 6a of SW6 and the switching terminal 2c of SW2.

Next, a case will be explained in which the HD-VTR outputs 4-channel audio. In this case, by setting the 4 channel/2 channel switch 29 to the 4 channel side, the designated signal of the 4 channel is sent to the selector 27.
is input. From the audio control decoder 26, the audio mode control code 14 identified as described above is input to the selector 27, and SW1 to SW6 in the selector 27 are input from the audio mode control code 14 and the 4 channel/2 channel switch 29. The switching is performed based on the four-channel designation signal from the audio mode selection switch 28 and the designation signal from the audio mode selection switch 28 for manually selecting main/sub audio and main/sub stereo. Table 2 shows the switching modes of each switch in each audio mode.

[0041]

[Table 2]

In Table 2, the circles indicate the switching terminals of each SW. By switching control of this switch, when four channel audio is output, channel 1 audio (main audio) is output from the output terminals 14a and 14b in the case of one monaural system. In addition, 1 stereo system (L,
R) and two monaural systems (main and sub), channel 1 audio and channel 2 audio are output from output terminals 14a and 14b, respectively.

In addition, in the case of main audio selection of two monaural systems, channel 1 audio (main audio) is output from the output terminals 14a and 1.
It is output from 4b. In addition, when selecting monaural 2 channels of sub audio, channel 2 audio (sub audio) is output from output terminal 1.
It is output from 4a and 14b. In addition, in the case of main stereo selection of two stereo systems, channel 1 audio (main L) and channel 2 audio (main R) are output from the output terminal 14.
It is output from a and 14b.

In addition, in the case of sub-stereo selection of two stereo systems, channel 3 audio (sub-L) and channel 4 audio
Audio (sub-R) is output from output terminals 14a and 14b, respectively. In addition, in the case of 3-1 method, channel 1
Audio L, channel 2 audio R, channel 3 audio C, and channel 4 audio S are output terminals 14a and 14b, respectively.
, 14c, and 14d.

Next, a case will be explained in which the HD-VTR outputs two-channel audio. In this case, by switching the 4-channel/2-channel switch 29 to the 2-channel side, the 2-channel designated signal is input to the selector 27, and the audio mode control code 14 is input from the audio control decoder 26 to the selector 27. be done.

Hereinafter, similarly to the above-mentioned 4-channel audio output, SW1 to SW6 in the selector 27 are connected to the audio mode control code 14 and the 4-channel/2-channel switch 2.
9, and main/sub audio selection from the manually switched audio mode selection SW 28.
It is switched based on the main and sub-stereo designated signals. Table 3 shows the switching modes of each switch in each audio mode.

[0047]

[Table 3]

In Table 3, the circles indicate the switching terminals at which each switch is switched. By switching control of this switch, 1 monaural system, 1 stereo system (L, R), and 2 monaural systems (main/sub) when outputting 2-channel audio.
, 2 monaural main audio selections, 2 monaural auxiliary audio selections, 2 stereo main stereo selections, and 2 stereo sub stereo selections The switch switching modes are the same as when outputting 4-channel audio. Yes, the desired post-selection audio is output from the output terminals 14a and 14b, respectively.

[0049] In addition, in the case of the 3-1 system, channel 1
Audio L, channel 2 audio R, channel 3 audio C, and channel 4 audio S are input to the 2-channel conversion circuit 28 as described above, and the 2-channel conversion circuit 28 converts 3-1 stereo into 2-channel stereo. The converted LO and RO are output. This LO,RO
are input to the switching terminal 3h of SW3 and the switching terminal 4b of SW4, respectively, and after selection through SW3 and SW4, LO and LO are input from the audio output terminals 14a and 14b, respectively.
RO is output.

As described above, when connecting the selected audio signal output of the HD-VTR 2 to a 4-channel audio amplifier, the 4-channel/2-channel SW 29
If you set it to the channel side, you can listen to high-definition audio in all audio modes, including 3-1 4-channel stereo. Also, when connecting to a 2-channel audio amplifier, by setting the 4-channel/2-channel switch 29 to the 2-channel side, LO and RO, which are converted from 3-1 system 4-channel stereo to current 2-channel stereo, will be output. , you can hear this.

In the above embodiment, when outputting 2-channel audio, the audio output terminal 14a is selected after selecting 4 channels.
, 14b are shared, but a 2-channel audio output terminal and a 4-channel post-selection audio output terminal may be provided separately. Furthermore, 2-channel stereo output LO, RO
and 3-1 system 4 channel stereo output L, R, C
, S is not limited to the equation of this embodiment.

[0052] Although the above embodiment describes an HD-VTR, it is not limited to an HD-VTR, and may be applied to an image recording and reproducing device using a magnetic recording or magneto-optical recording method, a reproduction-only HD-VTR, or a video disc player. It may also be an image reproduction device such as.

Next, an embodiment of the invention according to claim 2 will be described. FIG. 3 is a block circuit diagram of the reproduction signal processing system of the HD-VTR according to this embodiment. In the figure, the same reference numerals as in FIG. 1 indicate the same parts, and 35
36 is a selector for selecting and outputting a post-selection audio signal from pre-selection audio signals, and 36 is for selecting and outputting a 4-channel or 2-channel pre-selection audio signal and identifying the audio mode of the pre-selection audio signal. A selector 37 that outputs an audio control signal is a main/sub stereo selection switch that selects either main stereo or sub stereo.

Next, the operation of the parts different from the embodiment shown in FIG. 1 will be explained. The audio signal 12 before playback selection is input to the selector 35, and the audio signal after selection, such as main audio, sub audio, 3-1 system 4-channel stereo, etc., is selected and output from the output terminals 14a, 14b, 14c, and 14d. be done.

The selector 36 has the audio signal 1 before playback selection.
2, when this audio signal 12 is a 3-1 system 4-channel stereo, a 2-channel stereo conversion circuit 28
2-channel stereo LO, RO converted by
The audio mode control code 16 extracted by the audio control decoder 26 and the 2 channel/4 channel selection switch 2
9 and the main/sub stereo selection switch 37
A specified signal from the input terminal is input.

FIG. 4 is a diagram for explaining the operation of the selector 36, and is a block circuit diagram showing the configuration of the changeover switch portion of the selector 36 and the two-channel conversion circuit 28. In the figure, SW7 to SW10 are switches of the selector 36, 7a to 7c, 8a to 8c, 9a, 9b, 10.
a and 10b are switching terminals of SW7 to SW10, respectively.

These switches S7 to S10 are switched by the input audio mode control code 16, a designation signal from the 2-channel/4-channel selection switch 29, and a designation signal from the main/sub stereo selection switch 37.

Channel 1 audio goes to the switching terminal 7b of SW7, channel 2 audio goes to the switching terminal 8b of SW8, channel 3 audio goes to the switching terminal 7c of SW7 and switching terminal 9a of SW9, and channel 4 audio goes to the switching terminal 7c of SW8. The signal is input to the switching terminal 8c and the switching terminal 10a of the SW 10, respectively.

Next, a case will be described in which the HD-VTR 2 outputs pre-selection audio signals for four channels. In this case, use the 2 channel/4 channel selection switch 2.
9 to the 4 channel side, the 4 channel designation signal is input to the selector 36, and SW7 to SW1
0 is switched based on the 4 channel designation signal and the audio mode control code 16. Table 4 shows the switching modes of each switch for each audio mode.

[0060]

[Table 4]

In Table 4, the circles indicate the switching terminals at which each switch is switched. By controlling the switching of the switch, when outputting the 4-channel pre-selection audio signal, the playback pre-selection audio signal 12 is output as is. That is,
Audio of channels 1 to 4 is output from pre-selection audio signal output terminals 18a to 18d, respectively.

Next, a case will be explained in which the HD-VTR outputs a pre-selection audio signal for two channels. In this case, the 2 channel/4 channel selection switch 29
By switching to the 2-channel side, a 2-channel designation signal is input to the selector 36, and the audio mode control code 16 is input from the audio control decoder 26.

The main/sub stereo selection switch 37 is used only when the pre-reproduction selection audio signal 12 is of two A-mode stereo systems, and is used to send a designation signal specifying which of the main stereo and sub stereo to be selected. It is sent to the selector 36. SW7 to SW10 in the selector 36 are switched based on the input 2-channel designation signal, the audio mode control code 16, and the main/sub stereo designation signal. Table 5 shows the switching modes of each switch for each audio mode of the audio signal before playback selection.

[0064]

[Table 5]

In the figure, circles indicate switching terminals at which each switch is switched. With this switch control, 2
When outputting the audio signal before channel selection, the audio mode of the audio signal 12 before playback selection is monaural 1 system, monaural 2
system, in the case of one stereo system and in the case of two stereo systems, and by the main/sub stereo selection switch 37,
When main stereo is selected, channel 1 audio and channel 2 audio are output from pre-selection audio signal output terminals 18a and 18b, respectively.

Furthermore, when the audio mode of the pre-selection audio signal 12 is two stereo systems, and when sub-stereo is selected by the main/sub stereo selection switch 37, channel 3 audio and channel 4 audio are respectively pre-selected. The audio signals are output from the audio signal output terminals 18a and 18b.

Furthermore, when the audio mode of the reproduced pre-selection audio signal 12 is 3-1 system 4-channel stereo, channel 1 audio L, channel 2 audio R, channel 3 audio C, and channel 4 audio S are as follows. As mentioned above, 2
The channel conversion circuit 28 converts the 3-1 system 4-channel stereo into 2-channel stereo LO and RO. 2-channel stereo LO and RO are connected to SW7 and switching terminal 8, respectively, which are switched to switching terminal 7a.
The pre-selection audio signal is output from the pre-selection audio signal output terminals 18a and 18b via SW8 which is switched to a.

As described above, the desired playback pre-selection audio signal is output when outputting the 4-channel and 2-channel pre-selection audio signals. Then, the selector 36 creates a 1.35 Mbps bitstream audio control signal 15 for identifying the audio mode of the 4-channel and 2-channel pre-selection audio signal outputs, and generates a 1.35 Mbps bitstream audio control signal 15 when outputting the 4-channel and 2-channel pre-selection audio signals. , are simultaneously output from the audio control output terminal 19.

Table 6 shows the respective audio modes when the 4-channel and 2-channel pre-selection audio signals are output.

[0070]

[Table 6]

[0071] When outputting the audio signal before selecting 4 channels,
Since the pre-selection audio signal 12 reproduced from the magnetic tape is output as is, the audio control signal 15 is output in the same audio mode as the audio mode of the pre-selection audio signal reproduced from the magnetic tape. .

Furthermore, when outputting the 2-channel pre-selection audio signal, if the playback pre-selection audio signal 12 is of two stereo systems, the main/sub stereo selection switch 37 selects and outputs the main or sub stereo. In addition, in the case of 3-1 system 4-channel stereo, 2-channel stereo will be output, and the audio mode will be A mode and 1 stereo system.

In the case of an audio mode other than the above, the audio mode is the same as the audio mode of the pre-reproduction selection audio signal 12. Therefore, when outputting the audio signal before selecting 2 channels,
There are audio modes shown in Table 6 for audio output before 2-channel selection. The audio mode control output terminal 19 outputs an audio control signal 15 corresponding to the audio mode of the 2-channel pre-selection audio signal.

Therefore, when dubbing is performed from an HD-VTR that reproduces 4-channel audio signals to an HD-VTR that records 4-channel audio signals, the reproduction side H
Set the 2-channel/4-channel selection switch 29 of the D-VTR to the 4-channel side, and connect the audio signal output terminals 18a to 18d and the audio control signal output terminal 19 before playback selection.
If these are connected to the pre-selection audio signal input terminal and the audio control signal input terminal of the recording HD-VTR to be dubbed, audio signals can be dubbed.

[0075] Furthermore, when dubbing is performed from an HD-VTR that reproduces 4-channel audio signals to an HD-VTR that records 2-channel audio signals, the reproduction side HD-VTR is
VTR 2 channel/4 channel selection switch 2
9 to the 2 channel side, and the pre-reproduction selection audio signal output terminals 18a, 18b and the audio control signal output terminal 19,
It is sufficient to connect to the 2-channel audio input terminal and the audio control signal input terminal of the HD-VTR on the recording side to be dubbed.

Furthermore, if the audio signal 12 before playback selection is a 3-1 system 4-channel stereo, the audio signal converted to the current 2-channel stereo may also be a stereo 2-system (
In the case of main/sub stereo selection switch 37, one system of stereo selected by the main/sub stereo selection switch 37 can be dubbed, and also in the case of other audio modes.

In the above embodiment, a 1.35 Mbps bit stream is used as the audio control signal, but the signal is not limited to this as long as the audio mode of the pre-selection audio signal can be identified.

In the above embodiment, the audio control signal is also output when the 2-channel pre-selection audio signal is output, but in an HD-VTR that records and plays back the 2-channel audio signal, Current household V
Unlike TR, it is not necessary to input the audio control signal, and it is not necessary to output the audio control signal when outputting the audio signal before 2-channel selection.

Furthermore, in the above embodiment, when outputting the 2-channel pre-selection audio signal, the 4-channel pre-selection audio output terminals 18a and 18b are shared; An audio signal output terminal may also be provided separately.

[0080] In the above embodiment, when the pre-selection audio signals for reproduction are two stereo systems, when the 2-channel pre-selection audio signal is selected, either the main or sub stereo is selected by the main/sub stereo selection SW. However, the main/sub stereo selection switch may not be provided and the main stereo may be output. Note that the relational expressions between the outputs LO, RO of the two-channel stereo and the outputs L, R, C, and S of the 3-1 system four-channel stereo are not limited to the expressions of this embodiment.

Further, in the above embodiments, the HD-VTR was explained, but the invention is not limited to the HD-VTR, and can be applied to image recording/reproducing apparatuses using magnetic recording or magneto-optical recording methods, reproduction-only HD-VTRs, etc. It may also be an image playback device such as a video disc player.

[0082]

As described above, according to the invention of claim 1, in a device for reproducing a 4-channel audio signal, the audio signal after selecting 4 channels and the 3-1 system 4-channel stereo can be reproduced from the current 2-channel audio signal. Since the configuration is configured to output the audio signal after selecting 2 channels including the audio signal converted to a stereo signal, it can be connected to both a 4-channel audio amplifier and a 2-channel audio amplifier. You can listen to channel stereo. Also, 4
Since the post-channel selection audio signal output terminal and the 2-channel selection audio signal output terminal are made common, the number of output terminals can be reduced, which has the effect of making the device cheaper.

According to the second aspect of the invention, since the device is configured to output the 2-channel and 4-channel pre-selection audio signals and the audio control signal separately from the output signal to the audio amplifier, Current 2-channel stereo signal converted from 3-1 system 4-channel stereo,
For two stereo systems (main/sub), one system of stereo signals desired by the user and other audio modes are
This is a recording device that can record and play back 2-channel audio signals, and has the advantage of being able to be dubbed.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of a reproduced signal processing system according to an embodiment of the invention.

FIG. 2 is a block circuit diagram showing the configuration of a selector and a two-channel conversion circuit, which are the main parts of this embodiment.

FIG. 3 is a block circuit diagram of a reproduced signal processing system according to an embodiment of the invention according to claim 2;

[Fig. 4] Two selectors, which are the main parts of this embodiment, and 2
FIG. 2 is a block circuit diagram showing the configuration of a channel conversion circuit.

FIG. 5 is a transmission format diagram of a high-definition signal.

FIG. 6 is a connection diagram between a conventional HD-VTR and a high-definition receiver.

[Figure 7] Conventional HD-V with output terminal for dubbing
It is a connection diagram of a TR and a high-definition receiver.

[Explanation of symbols]

24 Audio reproduction processing circuits 25a to 25d D/A converter 26 Audio control decoders 27, 36 Selector 28 2-channel conversion circuit 29 2-channel/4-channel selection switch 30
Audio mode selection switch 37 Main/sub stereo selection switch

Claims (2)

[Claims] Claim 1: The four-channel audio signals and the audio mode control code are extracted from a recording medium on which the audio signals of the four channels and the audio control signal including the audio mode control code for identifying the mode of the audio signal are recorded. means for reproducing a current 2-channel stereo signal from this signal when the reproduced 4-channel audio signal is a 3-1 system 4-channel stereo signal; A selector receiving the channel stereo signal and the reproduced 4-channel audio signal as input, means for specifying whether the output signal selected by the selector is 2 channels or 4 channels, and means for specifying the audio mode of the output signal. and a multi-channel audio signal configured to output an audio signal of a designated audio mode of four channels or two channels designated by the selector based on the reproduced audio mode control signal. playback device. 2. In claim 1, the second selector receives as input the reproduced 4-channel audio signal and the current 2-channel stereo signal created from the 3-1 system 4-channel stereo signal; and means for specifying whether the output signal to be outputted is a main stereo signal or a sub-stereo signal, and means for creating and outputting an original audio control signal from the reproduced audio mode control code, When a 4-channel output signal is specified from the selector 2, the 4-channel input signal is output, and when a 2-channel output signal is specified, the specified main stereo signal or sub stereo signal is output. A multi-channel audio signal reproducing device.