JPH0273502A - Digital signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain multiplex recording, to heighten operability and to prevent the degradation of sound quality by executing only an after recording further. CONSTITUTION:When a sound signal from the outside is supplied to an encoder ENC9 not through a mixer 7, the sound signal is recorded to channels corresponding to input terminals 1a-1d by magnetic heads 21b and 22b. The sound signal reproduced from a magnetic tape by the head 21b and 22b is added to another sound signal from the outside in adders 6a-6d if necessary. The mixer 7 mixes the signals for the number of the channels of an addition output and sends it to the ENC9 as an arbitrary channel signal. The ENC9 encodes the reproduced signal by the heads 21b and 22b and sends it to heads 21a and 22a. Thus, the sound signal recorded first on the magnetic tape is recorded on the tape again without disappearing and a mixed signal is also recorded newly.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a digital signal recording and reproducing device, and particularly to a rotary head type digital audio tape recorder (hereinafter abbreviated as RDAT or DAT), which is used to record audio signals that have already been recorded. The present invention relates to a digital signal recording and reproducing apparatus that enables so-called after-recording, in which another audio signal is recorded overlappingly with the audio signal.

2. Description of the Related Art Conventionally, there have been known recording and reproducing apparatuses that are capable of reproducing a previously recorded audio signal while recording another audio signal in an overlapping manner. According to this, for example, the performances of a plurality of musical instruments can be gradually added and recorded, and in the end, the same effect can be produced as if all the musical instruments had been played and recorded at the same time.

The above-mentioned recording and reproducing apparatus has been proposed, for example, in Japanese Patent Laid-Open No. 60-656 and Japanese Patent Laid-Open No. 61-246961.

In the former case, in addition to providing first and second magnetic heads having opposing angles of 180 degrees on the head cylinder, the first and second magnetic heads are provided on the head cylinder.
The tape winding is shifted by an angle or more in the rotational angular direction with respect to the magnetic head, and a third and third tape are placed ahead of the tape feeding side by a distance equivalent to one to several tracks in the track width direction. 4 magnetic heads are provided, and the signal reproduced from the tape by the third and fourth magnetic heads and the external signal are mixed and recorded again at the same position by the first and second magnetic heads. It is.

In the latter case, a first magnetic head plays back a tape on which PCM signals are sequentially recorded serially (time-divisionally) for each of a plurality of channels, and the PCM signals are divided into channels, and the PCM signals corresponding to each channel are reproduced. A switch means is provided to enable the insertion of another PCM signal, and the PCM signals of the plurality of channels in which another PCM signal is inserted into the channel selected by the switch means are serially converted and recorded again by the second magnetic head. It is something to do.

Problems to be Solved by the Invention However, in RDAT, since the signals of each channel are interleaved and recorded in one frame consisting of two tracks, partial signals of each channel are mixed in each track.

For this reason, in RDAT, JP-A-61-24696
Re-recording for only one channel as shown in No. 1 is not possible.

Furthermore, in the device shown in JP-A No. 60-656, a preceding reproduction-only head is provided, and by reproducing the audio signal recorded on the magnetic tape in advance, this reproduced audio signal and an external audio signal can be combined. It is possible to mix and re-record. However, if, for example, the performance fails during this re-recording, the already recorded signals will not be left on the magnetic tape. Therefore, if the re-recorded performance fails, it is necessary to restart the entire performance from the beginning, or to anticipate such a situation and make a backup recording on another recording/playback device, etc., which saves time. , which is disadvantageous in terms of cost.

The present invention has been made in view of the above points, and is based on the RDA
To provide a digital signal recording and reproducing device capable of leaving the previously recorded audio signal as it is even when re-recording is performed after mixing audio using a so-called after-recording. purpose.

Means for Solving the Problems The present invention has first and second magnetic heads having different azimuth angles and facing angles of 180 degrees, and forming linear tracks on a magnetic tape to generate digital signals. In a helical scan type digital signal recording and reproducing apparatus for recording or reproducing a magnetic head, the first and second magnetic heads are at rotational angular positions that differ by an angle of 90 degrees or 270 degrees, or an angle in the vicinity thereof; A third magnetic head and a fourth magnetic head are provided at positions where the track is scanned in advance of the second magnetic head.
a magnetic head, a decoding means for decoding the digital signal reproduced by the third and fourth magnetic heads, and outputting it as a signal for each channel; Adding means for adding signals for each channel; mixing means for mixing the signals of each channel from the adding means and outputting the signal as a signal of an arbitrary channel; and encoding the signal from the adding means or the signal from the mixing means, encoding means for supplying the encoded recording signal to the second magnetic head, and mixing the signals reproduced by the third and fourth magnetic heads with the externally supplied signal, The configuration is such that re-recording is performed on the same track using two magnetic heads.

When the inputted external audio signal is supplied to the encoding means without passing through the mixing means, the &re signal is recorded by the first and second magnetic heads in the channel corresponding to the input terminal.

The audio signal reproduced from the magnetic tape by the third and fourth magnetic heads is added to another audio signal from the outside in an adding means as necessary, and the output of this adding means is encoded as is. and on the other hand to the mixing means. The mixing means mixes the output signals of the number of channels from the adding means and supplies the mixed signals as an arbitrary channel signal to the encoding means.

The encoding means generates (encodes) a recording signal so that the signals reproduced by the third and fourth magnetic heads are recorded on the same channel, and the signal mixed by the mixing means is recorded on an unused channel, The magnetic head is supplied to the first and second magnetic heads.

Through the above procedure, the audio signal originally recorded on the magnetic tape is recorded on the magnetic tape again without being erased, and the signal mixed with the external audio signal is also newly recorded.

In addition to the modes of ■2 channels/48kHz (sampling frequency)/16-bit linear quantization, the example DAT has two modes: ■2 channels/44.1kllz (or 32kHz)
) / 16 bit linear quantization ■ 4 channels / 32 kHz / 16 bits → 12 pit compression and tape speed, head drum rotation speed is halved ■ 2 channels / 32 kHz / 16 bits → 12 bit compression mode available has been done. In this embodiment, mode (4) of 4 channels/32 kHz/16 bits→12 bits compression (this will be referred to as 4 channel mode) will be explained as an example.

FIG. 1 is a block diagram of an embodiment of the present invention, which corresponds to an RDAT device with a 90-degree magnetic head arrangement, which will be described later. Figure 2 shows the arrangement of two types of magnetic heads that are possible in the present invention, and Figure 3 (A) (8) shows the relationship between the magnetic heads in Figure 2 and tracks formed on the magnetic tape. . Here, the relative transition of the magnetic heads 21 and 22 is shown assuming that the magnetic tape is fixed as shown on the left side of the figure (Δ).

As shown in FIGS. 2(A) and 2(B), in this embodiment, two recording/reproducing heads 21a and 22a are mounted on the rotating cylinder 23.
and two reproduction-only heads 21b.

22b is provided. In the same figure (A), the read-only heads 21b and 22b are the corresponding recording/playback heads 21a.
, 22a in the rotational direction of the cylinder, and 270 degrees in advance in the figure (B).
) arrangement is called the 270 degree type).

Further, as shown in FIG. 3, in the 90-degree type, the read-only heads 21b and 22b are replaced by the recording/playback heads 21a and 22a.
4.5 in the axial direction of the cylinder (in the width direction of the track)
Tp (Tp indicates track pitch), 27
In the 0 degree type, it is set higher by 5.5 Tp. As a result, the read-only head 21b is read over the magnetic tape prior to recording.

22b first reproduces the audio signal to be mixed.

When performing normal recording or reproduction, the recording/reproducing heads 21a and 22a are used. In RDAT, two adjacent tracks constitute one frame, and each channel is interleaved and recorded within this one frame.

First, a case will be described in which an audio signal supplied from the input terminal 1a in FIG. 1 is recorded from a state where nothing is recorded on the magnetic tape. The audio signal supplied from the input terminal 1a is adjusted to an appropriate level by a variable resistor 2a, passes through a low-pass filter 3a, and then is supplied to an A/D converter 4a, where it is converted into a digital signal. Gain control 5 sets only 5a to an appropriate value (usually 1), and controls the other 5b to 5h.
is zero. Further, the data selector 8a selects the A side, and the digital audio signal is supplied to the encoder 9.

The encoder 9 performs processing such as interleaving based on the data from the first channel to the fourth channel.
A DAT recording signal is generated, but since there is no sound from the second channel to the fourth channel, this recording signal includes only the signal supplied to the input terminal 1a.

Therefore, apparently only the upper first channel is recorded.

The digital mixer 7 is used to digitally remix the audio signals input to the input terminals 1a to 1d and to monitor the audio signals during recording. During the recording, the output of the gain control 5a is taken out to the outside via the digital mixer 7, the D/A converter 11, and the low-pass filter (LPF) 12, and is monitored.

Also, the A side of the data selectors 8b to 8d is selected except during remixing.

Next, superimpose it on the audio signal recorded by the above operation,
The operation of recording another audio signal (so-called after-recording) will be explained. This method is used, for example, when the performance of one musical instrument is recorded, and while the recorded audio signal is being played back, the audio of another musical instrument being played along with the recorded audio signal is recorded. In this case, in order to retain the previous audio signal even after recording the second audio signal, in this embodiment, in addition to the recording/playback heads 21a and 22a, playback-only heads 21b and 22b are used as shown in FIG. In addition to the arrangement, the circuit configuration shown in FIG. 1 was adopted.

FIGS. 4(A) and 4(B) show timing charts of 90-degree type and 270-degree type magnetic head arrangements, respectively. In the reproduction signal and recording signal portions in the same figure, the portion marked with 10 indicates the audio signal recorded by the plus azimuth head (in this case, the magnetic head 21a), and the portion marked with - indicates the audio signal recorded by the minus azimuth head (also the magnetic head 21a). magnetic head 22
represents the audio signal recorded by a). In this embodiment, the audio signal reproduced from each track and another audio signal from the outside are mixed and then re-recorded on the magnetic tape. Since it is necessary to maintain the continuity of the audio signal in the preceding part, the track on which the mixed audio signal is re-recorded must be the same track and the same azimuth as the track on which it was recorded before being mixed. It must be recorded with a head with horns.

Furthermore, as mentioned above, in RD AT, the signals of each channel are interleaved and recorded within one frame consisting of two adjacent tracks, so the signals of each channel cannot be recorded until the entire frame has been played back. cannot be separated.

Considering the above conditions and considering the time required to mix the reproduced audio signal with the external audio signal, the re-recording that follows from the preceding playback in the case of the 90-degree type As shown in Fig. 4(A), the minimum distance is 4.5 tracks (180 mm of the head cylinder).
1 degree rotation corresponds to 1 track). Correspondingly, the reproducing heads 21b and 22b are provided above the recording/reproducing heads 21a and 22a by 4.5 Tp on the head cylinder, as shown in FIG. 3(A). Therefore, the audio signal reproduced by the reproduction-only head 21b during the period t1 in FIG. Re-recording takes place at t IQ. Further, in this case, three RAMs are required as shown in FIG. 4(A).

This corresponds to RAM25, 26, and 27 in FIG.

On the other hand, in the case of the 210-degree type, the same conditions as in the case of the 90-degree type must be satisfied, but compared to the case of the 90-degree type, the read-only head 21b.

22b and the recording/reproducing heads 21a and 22a are further 18
Since they are separated by 0 degrees, 5. as shown in Figure 4 (B).
Re-recording is performed at intervals of five tracks. Correspondingly, the playback heads 21b and 22b are arranged as shown in FIG. 3(B).
The recording/playback head 21 is mounted on the head cylinder as shown in
8.22a above by 5.5 Tp.

Also, in this case, as shown in Figure 4 (B), at least four RAMs are required, which is disadvantageous in terms of cost compared to the 90-degree type, but there is a time margin created by adding one RAM. Another advantage is that it can be used for error detection and correction of reproduced audio signals.

In addition, the period indicated by the X in the RAM in Figure 4 (B) is the RA
Since M is temporarily inactive, it is a waste of time, and if a 270-degree type is used, the read-only head 2
1b and 22b further advance 180 degrees, and further ITp above the cylinder axis (i.e. 6 points above the recording/playback head).
．． 5Tp above), it is possible to eliminate the idle time of this RAM, which can be further used for error detection and correction of digital audio signals.

Returning again to the block diagram corresponding to the 90-degree type in FIG.
2b, and the reproduction amplifier (Pa amplifier) 13
The signal is input to the decoder 14 via the . Here, the reproduced audio signal including the first channel is demodulated, code errors are detected and corrected in the error detection/correction circuit 15, and then supplied to the gain control 5e. At this time, the first channel is in the playback mode, so the gain control 5a is set to the gain output, and the gain of the gain control 5e is set to 1. As a result, the adder 6a outputs the digital audio signal reproduced from the first channel as it is.

This digital audio signal is supplied to the data selector 8a, and also to the digital mixer 7, and the D/A converter 11. The signal is outputted to the outside via a low-pass filter (LPF) 12 for monitoring. In the case of overdubbing a musical instrument performance, another performance is performed in accordance with this output audio signal, and this is input to, for example, the input terminal 1b.

The audio signal input to the input terminal 1b is input to the gain control 5b through the variable resistor 2b, the low-pass filter 3b, and the A/D converter 4b, similar to the audio signal originally recorded from the input terminal 1a, and the gain is adjusted. Adjusted (usually set to 1). At this time, gain controls 5a and 5f
, 5c, 5Q.

The gains of 5d and 5h are narrowed down to the gap, and therefore the gain of the booster 6b
The audio signal supplied from the input terminal 1b to the data selector 8b is only the second audio signal input from the input terminal 1b. Six inputs are selected for both data selectors 8a and 8b, so that the first audio signal is input from the data selector 8a and the second audio signal is input from the data selector 8b to the encoder 9.

The encoder 9 interleaves the first audio signal from the data selector 8a as a first channel and the second audio signal from the data selector 8b as a second channel, thereby generating a recording signal conforming to the RD8 standard. This recording signal is amplified via the recording amplifier 10, and the first recording signal on the magnetic tape is amplified by the recording/reproducing heads 21a and 22a.
will be recorded on the same track where the audio signal was recorded.

Furthermore, when recording the third audio signal on the third channel, 5cm5e=5f=1.5a=5b=5d=5g=
5h=O, data selectors 8a to 8d all select six inputs, and the operation mode is set to the recording mode for the third channel and the playback mode for the other channels, thereby transmitting the third audio signal to the third channel 17. It can be recorded in synchronization with the audio signals recorded on the first and second channels.

At this time, the reproduced audio signal is monitored by the digital camera.7. D/A converter 11. This is done by taking out the signal to the outside via the low-pass filter 12.

The digital mixer 7 outputs a right channel (R channel) and a left channel (
There are two outputs (L channel).

This digital mixer 7 can adjust the sound image localization of the monitor audio using a panpot, and can also adjust the level of each channel.

Additionally, a master volume is provided that simulates the mix of both R and R channels, allowing you to adjust the monitor audio.

Next, a case will be described in which the audio signals of the first to third channels are tracked down to the fourth channel. When performing a trackdown, there are two cases in which the first to third channels are simply mixed and recorded on the fourth channel.
There are cases where a new fourth audio signal is added and the first to fourth audio signals are mixed and recorded on the fourth channel.
Since the latter includes the contents of the former, the latter case will be explained here.

In this case, the gain control is 5a=5b=5c=5
h=0.5e=5f=5g-5d=1, input terminal 1
A fourth audio signal is input to d, and its level is adjusted by variable resistor 2d.

The first to fourth audio signals are sent from the adders 6a to 6d respectively to the first to fourth audio signals.
~The signal is input to the digital mixer 7 as the fourth channel, where the volume balance of each channel is adjusted and track down is performed. As a result, a sound signal in which the first to fourth audio signals are mixed is extracted from the R output of the digital mixer 7, and is supplied to the data selector 8d. Here, the data selector 3d i,tB input is selected.

Therefore, the encoder 9 receives the first audio signal as the first channel and the second audio signal as the second channel.
A third audio signal is input as the third channel, and first to fourth audio signals are input as the fourth channel, and these audio signals are encoded by the encoder 9,
Recording/playback heads 21a, 22 via recording amplifier 10
A is recorded on the same track on the magnetic tape as the previously recorded track.

By performing the trackdown according to the above procedure, the first to third fame signals are also left in the first to third channels. Therefore, even if, for example, the performance fails when recording the fourth audio signal, only the track down portion after R needs to be redone.

Another method is to mix only the first to third audio signals to the fourth channel and track down, or record the fourth audio signal independently to any of the first to third channels. However, the same result can be obtained by mixing this with the first to third audio signals of the fourth channel and recording it on another channel. Since the signals handled here are digital signals, even if one audio signal is recorded and reproduced multiple times as described above, there is no signal deterioration and high sound quality is maintained.

Further, when an external audio signal is superimposed on an already recorded audio signal and recorded as a signal of the same channel, the following procedure is performed. For example, if audio signals have already been recorded on the first and second channels, the gain control is set to 5a = 5b - 5e = 5f = 1/2, the others are set to zero, and the external audio signals are input to input terminals 1a and 1b. As a result, the previously recorded sound angle signal and the external audio signal are recorded in the first and second channels in a superimposed manner.

When simply tracking down the audio signals of the first to third channels to the fourth channel, the gain control is 5e=5f=5g=1. All @ characters are used as mouths. Furthermore, the problem of not being able to redo mix recording, which was not possible with conventional equipment, is resolved by recording audio signals in advance on the first and second channels, and recording external audio signals on the third and fourth channels. can. In this case, the gain control is 5a=5b=5q=5h=0°5e
=5 r=5c=5d=1, data selector 8a~
8d selects input to all, and selects input to 1st. The second channel is in playback mode, the third channel is in playback mode, and the third channel is in playback mode. The fourth channel is set to recording mode.

In this embodiment, the output and R output of the digital mixer 7 are connected to data selectors 8a, 8c, 8b, and 8d, respectively, but this is because the device of this embodiment can be used as a multi-track table recorder. This is to make it a unique Noh performance. That is, for example, if a stereo audio signal is recorded in which the first and second channels are the upper channel and the R channel, respectively, a stereo audio signal is externally applied to the input terminals 1a and 1b and transmitted to the third and fourth channels. Can be mixed down. If you use this method, you can mix the stereo audio signal by repeating the process of draining the first and second channels, recording a new stereo audio signal there, and mixing it down further. It can be used as a 4-channel multi-recorder that allows re-recording.

Furthermore, when all channels are played simultaneously, the playback-only head 21
It is also possible to perform a so-called bunch-in-bunch-out operation in which recording/reproduction is performed from the middle on the magnetic tape by reproducing data using the magnetic tapes b and 22b.

In FIG. 5, the four A/D converters 4a to 4d in FIG. 1 are replaced with two A/D converters 4a to 4b, simplifying the circuit configuration. In the same figure, the components before low-pass filters (LPF) 38 to 3d are the same as those in FIG. 1, and latches 20a to 20. The output of Od is supplied to gain controls 5a to 5d in FIG. 1, respectively. The configuration shown in the figure is provided with zumble holds (S/H) 18a to 18d, interlocking switches 19a to 19d, and n-bit (n is the number of quantization bits of the audio signal) latches 20a to 20d.

With this configuration, the number of A/D converters can be reduced.

In the above embodiment, digital mixers such as those shown in FIG. 1 6a to 6d were used, but D/A converters were added to the outputs A to D in FIG. You can also mix at analog level. At this time, it can be realized using a well-known analog mixer configuration, and 5a to 5h and 6a to 6d are unnecessary.

Effects of the Invention As described above, according to the present invention, even when performing so-called after-recording in which another audio signal is recorded over the audio signal recorded on a magnetic tape, the previously recorded audio signal remains unchanged. For example, even if a performance fails during after-recording, there is no need to re-record the first audio signal, and multiplex recording can be done by performing only after-recording again. This improves operability, and since it is digital recording, the g quality does not deteriorate even if the above operations are repeated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing two types of magnetic head arrangement possible in the present invention.
FIG. 3 is a diagram showing the relative positional relationship between the magnetic head and seven tracks on the magnetic tape, FIG. 4 is a timing chart for performing after-recording, and FIG. 5 is a block diagram of another embodiment of the present invention. .

Claims (1)

[Scope of Claims] A first lens whose azimuth angles are different from each other and whose opposing angles are 180 degrees.
and a second magnetic head, in a helical scan type digital signal recording and reproducing apparatus that records or reproduces digital signals by forming linear tracks on a magnetic tape, the first and second magnetic heads having 90 degrees or 270 degrees
third and fourth magnetic heads, which are provided at rotational angular positions that differ by an angle of or near the angle, and are provided at positions that scan the track in advance of the first and second magnetic heads; decoding means for decoding the digital signals reproduced by the third and fourth magnetic heads and outputting them as signals for each channel; and a signal from the outside for the output signal of the decoding means as necessary. an adding means for adding the signals of each channel from the adding means, a mixing means for mixing the signals of each channel from the adding means and outputting it as a signal of an arbitrary channel, and a signal from the adding means or a signal from the mixing means is arbitrary. and encoding means for encoding the encoded recording signal to be recorded on the first and second magnetic heads, and supplying the encoded recording signal to the first and second magnetic heads, and the signal reproduced by the third and fourth magnetic heads. 1. A digital signal recording and reproducing apparatus characterized in that a signal is mixed with an externally supplied signal and re-recorded on the same track by the first and second magnetic heads.