JP3259396B2 - Digital mixer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital mixer, and more particularly to a digital mixer suitable for editing an audio signal of a digital VTR.

[0002]

2. Description of the Related Art When a plurality of input audio signals (hereinafter, referred to as input audio signals) are mixed (mixed), an audio program is created using a digital signal mixer (hereinafter, referred to as digital mixer) for performing a mixing operation digitally. It is being done.

The digital mixer obtains a digitized audio signal of a plurality of channels by mixing audio signals of a plurality of channels at a desired mixing ratio.

The principle of the digital mixer will be described with reference to FIG. FIG. 7 is a diagram showing a system of a mixing section of a digital mixer for obtaining audio output of 4 channels by adding audio inputs of 16 channels, for example.

[0005] In FIG. 7, input channels are audio signals # 1 to # 16 of 16 channels, which are input from an input unit 51. The 16-channel audio signals # 1 to # 16 are shown as INPUT # 1 to INPUT # 16 in the figure.

The input audio signals of the 16 channels pass through a mute switch section 52 for each signal, and the volume is adjusted by a channel fader section 53. Thereafter, the signals are added to the four buses via the assignment switch unit 54, and the four programmed outputs are taken out from the output unit 55. The four programmed outputs are:
PGM # 1, PGM # 2, PGM # 3, and PGM # 4 are shown inside the output unit 55.

Here, the mute switch section 52 includes:
This is a block including 16 mute switches for switching an input audio signal that is not required by the operator to be transmitted.

Further, the channel fader section 53
This block includes 16 channel faders having a function of adjusting the volume from T # 1 to INPUT # 16.

The assign switch 54 is a switch for determining whether or not to mix the sound whose volume has been adjusted by each channel fader of the channel fader section 53. When the switch is on, it is added, and the switch is turned off. In the case of (1), it has a function of not adding, and is an on / off switch for input to four mixing buses.

The sounds (for example, surround programs) added to the four mixing buses according to the assign switch 54 are respectively PGM # 1, PGM # 2, PGM # 3 and PGM #.
4 and is extracted from the output unit 55.

The digital mixer whose principle has been described with reference to FIG. 7 can be actually constructed using a DSP (digital signal processor). FIG. 8 is a block diagram of a digital mixer configured using a DSP. 8, the DSPs 61, 62, 63, 64, 65, 66, 67
And 68 input and output digital audio signals in the form of serial data.
Limited to one at a time.

That is, the DSP 61 inputs INPUT # 1 to IN
Up to PUT # 4, INPUT # 5 to INPUT # 8 to DSP62, INPUT # 9 to INPUT # 12 to DSP63, and INPUT # 13 to INPUT # 16 to DSP64. The DSP 65 has a first channel output of the DSP 61, a first channel output of the DSP 62,
The first channel output of the DSP 63, the first channel output of the DSP 64, the DSP 66 the second channel output of the DSP 61, the second channel output of the DSP 62, the DSP 6
3 and the second channel output of the DSP 64. The DSP 67 has the third channel output of the DSP 61, the third channel output of the DSP 62, and the DSP 63.
And the third channel output of the DSP 64, the fourth channel output of the DSP 61, the fourth channel output of the DSP 62, the DSP 63
And the fourth channel output of the DSP 64 are input.

Finally, the DSPs 65, 66,
Output PGM # 1 and PGM # of a total of 4 channels from 67 and 68
2, PGM # 3 and PGM # 4 are output.

The above-described four-channel outputs PGM # 1, PGM # 2, PGM # 3 and PGM # 4 output by the above-described digital mixer.
Will be described below.

First, in FIG. 7, the coefficient of each mute switch of the mute section 52 is M _X , the coefficient of the assign switch 54 to the four buses is S _{(X, Y)} , and each channel of the channel fader section 53 is _{Let the} fader coefficient be FX. It should be noted that the coefficient M _X of each mute switch, "0"
Alternatively, since the coefficient is internally used by interpolating the coefficient, there is an intermediate value between “0” and “1” only when each mute switch is turned on / off. Further, the coefficient S _{(X, Y)} is also “0” or “1”. Further, the coefficient F _{X of the} channel fader takes a value from “0” to “1” when there is no gain. Further, the subscript X of coefficients M _X and F _X indicates the value of the X channel, 1
≤ X ≤ 16 (X is an integer). Furthermore, S _{(X, Y)}
The subscripts X and Y indicate an input channel and an output channel, and 1 ≦ X ≦ 16 (X is an integer) and 1 ≦ Y
≦ 4 (Y is an integer).

Then, PGM # 1, PGM # 2, PGM # 3 and PGM #
4 is represented by the following equations (1), (2), (3) and (4). _{PGM # 1 = M 1 × F} 1 × S (1,1) × INPUT # 1 + M 2 × F 2 × S (1,2) × INPUT # 2 + ...... ...... + M 15 × F 15 × S (1 _{, 15) × INPUT # 15 +} M 16 × F 16 × S (1,16) × INPUT # 16 ··· (1) PGM # 2 = M 1 × F 1 × S (2,1) × INPUT # 1 + M 2 × F ₂ × S _(2,2) × INPUT # 2 + ………… + M ₁₅ × F ₁₅ × S _(2,15) × INPUT # 15 + M ₁₆ × F ₁₆ × S _(2,16) × INPUT # 16 ··· (2) PGM # 3 = M 1 × F 1 × S (3,1) × INPUT # 1 + M 2 × F 2 × S (3,2) × INPUT # 2 + ...... ...... + M 15 × _{F 15 × S (3,15) ×} INPUT # 15 + M 16 × F 16 × S (3,16) × INPUT # 16 ··· (3) PGM # 4 = M 1 × F 1 × S (4,1) × INPUT # 1 + M ₂ × F ₂ × S _(4,2) × INPUT # 2 + _………… + M ₁₅ × F ₁₅ × S _(4,15) × INPUT # 15 + M ₁₆ × F ₁₆ × S _{( 4,2) 16)} × INPUT # 16 ・ ・ ・ (4)

When the PGM # 1, PGM # 2, PGM # 3 and PGM # 4 expressed by the above equations (1), (2), (3) and (4) are to be calculated by the DSP shown in FIG. Since only four channels of audio input can be connected to the DSP, the calculation is as follows.

That is, in the DSP 61, M ₁ × F ₁ × S _(1,1) × INPUT # 1 + M ₂ × F ₂ × S _(1,2) × INPUT # 2 + M ₃ × F ₃ × S _{(1 , 3)} × INPUT # 3 + M ₄ × F ₄ × S _(1,4) × INPUT # 4 ・ ・ ・ (5) M ₁ × F ₁ × S _(2,1) × INPUT # 1 + M ₂ × F ₂ × S _(2,2) × INPUT # 2 + M ₃ × F ₃ × S _(2,3) × INPUT # 3 + M ₄ × F ₄ × S _(2,4) × INPUT # 4 ・ ・ ・ (6) M ₁ × F ₁ × S _(3,1) × INPUT # 1 + M ₂ × F ₂ × S _(3,2) × INPUT # 2 + M ₃ × F ₃ × S _(3,3) × INPUT # 3 + M ₄ × F ₄ × S _(3,4) × INPUT # 4 ・ ・ ・ (7) M ₁ × F ₁ × S _(4,1) × INPUT # 1 + M ₂ × F ₂ × S _(4,2) × INPUT # 2 + M ₃ × F ₃ × S _(4,3) × INPUT # 3 + M ₄ × F ₄ × S _(4,4) × INPUT # 4 ... (8)

Further, in the _{DSP62, M 5 × F 5 ×} S (1,5) × INPUT # 5 + M 6 × F 6 × S (1,6) × INPUT # 6 + M 7 × F 7 × S (1 _{, 7) × INPUT # 7 +} M 8 × F 8 × S (1,8) × INPUT # 8 ··· (9) M 5 × F 5 × S (2,5) × INPUT # 5 + M 6 × F 6 × S _(2,6) × INPUT # 6 + M ₇ × F ₇ × S _(2,7) × INPUT # 7 + M ₈ × F ₈ × S _(2,8) × INPUT # 8 ・ ・ ・ (10) M _{5 × F 5 × S (3,5} ) × INPUT # 5 + M 6 × F 6 × S (3,6) × INPUT # 6 + M 7 × F 7 × S (3,7) × INPUT # 7 + M 8 × F ₈ × S _(3,8) × INPUT # 8 ・ ・ ・ (11) M ₅ × F ₅ × S _(4,5) × INPUT # 5 + M ₆ × F ₆ × S _(4,6) × INPUT # 6 + M ₇ × F ₇ × S _(4,7) × INPUT # 7 + M ₈ × F ₈ × S _(4,8) × INPUT # 8 ... (12)

In the DSP 63, M ₉ × F ₉ × S _(1,9) × INPUT # 9 + M ₁₀ × F ₁₀ × S _(1,10) × INPUT # 10 + M ₁₁ × F ₁₁ × S _{(1, 11) × INPUT # 11 + M} 12 × F 12 × S (1,12) × INPUT # 12 ··· (13) M 9 × F 9 × S (2,9) × INPUT # 9 + M 10 × F 10 × S _{(2,10) × INPUT # 10 +} M 11 × F 11 × S (2,11) × INPUT # 11 + M 12 × F 12 × S (2,12) × INPUT # 12 ··· (14) M 9 × F 9 _{× S (3,9) × INPUT #} 9 + M 10 × F 10 × S (3,10) × INPUT # 10 + M 11 × F 11 × S (3,11) × INPUT # 11 + M 12 × F 12 × S (3 _{, 12)} × INPUT # 12 ・ ・ ・ (15) M ₉ × F ₉ × S _(4,9) × INPUT # 9 + M ₁₀ × F ₁₀ × S _(4,10) × INPUT # 10 + M ₁₁ × F ₁₁ × S _(4,11) × INPUT # 11 + M ₁₂ × F ₁₂ × S _(4,12) × INPUT # 12 (16)

Further, in the _{DSP64, M 13 × F 13 ×} S (1,13) × INPUT # 13 + M 14 × F 14 × S (1,14) × INPUT # 14 + M 15 × F 15 × S (1,15 _{) × INPUT # 15 + M 16} × F 16 × S (1,16) × INPUT # 16 ··· (17) M 13 × F 13 × S (2,13) × INPUT # 13 + M 14 × F 14 × S (2 _{, 14) × INPUT # 14 +} M 15 × F 15 × S (2,15) × INPUT # 15 + M 16 × F 16 × S (2,16) × INPUT # 16 ··· (18) M 13 × F 13 × S _{(3,13) × INPUT # 13 +} M 14 × F 14 × S (3,14) × INPUT # 14 + M 15 × F 15 × S (3,15) × INPUT # 15 + M 16 × F 16 × S (3,16) × INPUT # 16 ··· (19) M 13 × F 13 × S (4,13) × INPUT # 13 + M 14 × F 14 × S (4,14) × INPUT # 14 + M 15 × F 15 × S (4, ₁₅₎ × INPUT # 15 + M ₁₆ × F ₁₆ × S _(4,16) × INPUT # 16 ... (20) is calculated.

Therefore, in the digital mixer using the DSP shown in FIG. 8, the DSPs 61, 62, 63 and 64 calculate intermediate values as shown in the above equations (5) to (20). From the above DSPs 65, 66, 67
And 68, the above PGM # 1, PG
M # 2, PGM # 3 and PGM # 4 are obtained.

As described above, like the analog mixer, the digital mixer has a configuration in which any input can be added to any output, and has a function of arbitrarily outputting all inputs to an output bus.

However, an analog mixer uses an operational amplifier (operational amplifier) to add audio signals. Even if a configuration is used in which all inputs are added to all outputs, if the resistance is increased one by one, Good,
In the digital mixer, as described above, the number of channels that can be added is limited to one DSP, and thus the number of DSPs increases as the number of input channels increases.

As input signals to the digital mixer, there are a plurality of audio signals recorded by a number of microphones and the like. That is, as in a recording studio, recording is performed by inputting one or more sounds of a guitar, a trumpet, a drum, or the like.

Heretofore, the above-mentioned digital mixer has also been used for editing an audio signal of a video tape recorder (hereinafter, referred to as VTR). In this VTR editing, the number of images to be edited is two in many cases. The editing of the audio signal used in the editing of the VTR is two in many cases because the audio signal is attached to the image.

In the editing of a VTR, techniques generally called AB roll editing and cut editing are employed.

First, AB roll editing refers to AV for playback.
The TR and the reproduction B-VTR are alternately reproduced, and the reproduced material is recorded on the recording VTR.

For example, three VTRs (a first VTR, a second VTR,
(A), (b) and (c) of FIG. 9 recorded on a VTR and a third VTR are combined into a single recording VTR. 9 (d)
This is editing such as recording and editing as shown in FIG.

[0030] In FIG. 9 (d), and material that is recorded in the material and the third VTR was recorded in the second VTR at point P ₁ is switched, point P ₂ in the third V
And the material which is recorded in the material of the first VTR was recorded in TR is switched, and the material which is recorded in the material and the third VTR was recorded in the first VTR at point P ₃ is switched .

That is, looking at each point P ₁ , P ₂ , P ₃ , only two materials can be switched.

[0032] The AB role of audio mixer in roll editing, for example, in the case of two material switching sandwiching the point P _1, a second of the recording VTR audio VTR
After recording, the sound of the third VTR is recorded on the recording VT.
R is to record.

Here, the audio signal of the currently reproduced VTR, such as the audio of the second VTR, is referred to as a program (PGM) audio signal, and the third VTR.
A VTR audio signal to be reproduced next, such as a TR sound, is called a preset (PST) audio signal.

Therefore, it can be said that the audio editing in the AB roll editing is performed between the PGM audio signal and the PST audio signal.

In the audio editing in the AB roll editing described above, not only the cut-out and cut-in as shown in FIG. 10 but also the points P ₁ , P ₂ and P ₃ (referred to as switching points) shown in FIG. Processing such as fade-out and fade-in is also performed as needed.

The switching point P shown in FIG.
Cutout in _1, illustrating the cut-in and fade-out, the processing of the fade-less.

As shown in FIG. 10, the cut-out and the cut-in are performed when the sound of the second VTR and the sound of the third VTR, which are set in advance with the same volume (level), are switched. Instantaneously set the audio level to zero,
Of the VTR is instantaneously brought to a preset level.

Fade-out and fade-in are shown in FIG.
Second VT with the same volume (level) as shown in FIG.
When switching between the audio of R and the audio of the third VTR,
This refers to a process of gradually lowering the audio level of the second VTR and gradually increasing the audio level of the third VTR. Here, the process of increasing the level of the third audio before the level of the audio of the second VTR becomes zero is called cross-fade processing.

Next, cut editing refers to an A-VTR for reproduction.
And a playback B-VTR at the same time, and the editing is performed by switching the material being played back, for example, by a switch operation of a routing switcher.

For example, three VTRs (a first VTR, a second VTR,
And the third VTR) are reproduced at the same time, and the materials shown in FIGS. 12A, 12B and 12C are switched and connected, and one recording is performed. VT for
The editing is such that recording and editing are performed in R as shown in FIG.

Therefore, in the audio editing in the cut editing, only the currently reproduced PGM audio signal is used, and the PST audio signal to be reproduced next is not used.

[0042]

When a VTR is edited using the digital mixer described above, the function of arbitrarily outputting all the inputs of the digital mixer to an output bus is useless.

In the VTR editing, a method called AB roll editing as described above is employed. Therefore, in the VTR audio editing, as can be seen from FIG. The source of the audio signal is only the audio input from the two VTRs at that switch point.

Therefore, as described above, a digital mixer having a function of arbitrarily outputting all inputs to an output bus is used only for audio editing of a VTR because the digital mixer is composed of a large number of DSPs as described above. Since the DSP is expensive, the cost increases.

Also, the time (processing time) from the input of an audio signal to the DSP to the output thereof is, for example, about 20 μs per word, so that a digital mixer composed of a large number of DSPs requires a processing time. Becomes longer.

Also, by incorporating a routing switcher, a maximum of eight VTRs capable of inputting, for example, four channels can be connected and a digital mixer capable of connecting 32 channels of input can be used.
Attempting to perform the cut editing indicated by 0 causes loss of continuity of data at the switching point, resulting in noise.

This is because the digital mixer shown in FIG. 8 uses the DSP to perform a very short time (for example, 5 m).
This is because, while the fade-out and fade-in are performed in s), since the routing switcher is a mere switching element, the fade-out and fade-in processing cannot be performed.

The present invention has been made in view of the above circumstances, and is suitable for editing an audio signal of a VTR.
It is an object of the present invention to provide a digital mixer that can be configured with a reduced number of Ps, and to provide a digital mixer that can perform cut editing without generating noise without deteriorating the continuity of audio signals.

[0049]

A digital mixer according to the present invention includes a selector for selecting two of a currently reproduced audio signal and a next reproduced audio signal from a plurality of input audio signals; A digital signal processing unit for performing a cross-fade process for lowering the level of the currently reproduced audio signal selected in step 1 and intersecting it while raising the level of the next reproduced audio signal. And extracting a cross-faded audio signal based on the currently reproduced audio signal and the next reproduced audio signal.

[0050]

Further, the digital mixer according to the present invention
A switching selector for switching and selecting one of the currently reproduced audio signals from the plurality of input audio signals; and a digital signal processor for varying the level of one of the currently reproduced audio signals selected by the switching selector. Switching from one of the currently reproduced audio signals to another one of the currently reproduced audio signals in the switching selection section is performed by selecting one of the currently reproduced audio signals in the digital signal processing section. The above-mentioned object is achieved by lowering one level to zero and then raising another level of the currently reproduced audio signal switched from zero.

[0052]

In the digital mixer according to the present invention, the selection section selects the currently reproduced audio signal and the next reproduced audio signal from the plurality of input audio signals, and the digital signal processing section selects the selected audio signal. Cross-fade processing is performed to lower the level of the currently reproduced audio signal selected by the section while crossing it while raising the level of the next reproduced audio signal, and to reproduce the currently reproduced audio signal and the next reproduced audio signal Extract a cross-fade audio signal based on the audio signal.

Further, the digital mixer according to the present invention
After the digital signal processing unit lowers the level of the currently reproduced audio signal switched and selected from among the plurality of input audio signals by the switching selection unit to zero, the switching selection unit outputs another currently reproduced audio signal. One is switched and then the other switched level is increased from zero.

[0054]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a digital mixer according to the present invention will be described below with reference to the drawings.

First, a first embodiment of the digital mixer according to the present invention will be described. FIG. 1 is a block diagram showing the configuration of the first embodiment. This first embodiment is:
A matrix switcher 2 which is a selector for selecting two from a plurality of input audio signals supplied from a video tape recorder (hereinafter, referred to as a VTR), and two input audio signals selected by the matrix switcher 2 are mixed. And a digital signal processor (DSP) 3 for processing.

[0056] The matrix switcher 2, the program from among the plurality of input audio signal INPUT # 1 ~INPUT # N of VTR supplied via the input terminal 1 ₁ to 1 _N currently being played (PGM) audio signal And a preset (PST) audio signal to be reproduced next.

The DSP 3 has a function of mixing the PGM audio signal and the PST audio signal selected by the matrix switcher 2 so as to perform a cross-fade process, for example.

The cross-fade process is a process of lowering the level of one input audio signal while crossing it while raising the level of the other input audio signal.
The GM audio signal is faded out, and the level of the PST audio signal is increased before the volume (level) becomes zero.

That is, in the DSP 3, the volume of the channel of the PGM audio signal and the volume of the channel of the PST audio signal are subjected to cross-fade processing and are derived from the output terminal 4.

As described above, in the first embodiment, the VTR
The audio editing of the VTR in the AB roll editing can be realized with a simple configuration using the matrix switcher 2 and the DSP 3.

In the first embodiment, the PGM audio signal output from the matrix switcher 2 and the PST
The audio signal is one channel each, and a specific example in the case where the PGM audio signal and the PST audio signal each have four channels is described in the second example.
An example will be described with reference to FIG.

In the second embodiment, four VTRs outputting audio output of four channels are connected as sources,
This is a digital mixer that adds audio inputs of 16 channels and outputs audio of 4 channels.

Referring to FIG. 2, the second embodiment has a VT
A matrix switcher 15 for selecting a PGM audio signal and a PST audio signal each having a 4-channel output from 16-channel input audio signals supplied from R11, VTR12, VTR13 and VTR14, and a PGM selected by the matrix switcher 15 It has DSPs 16 and 17 for receiving and mixing outputs of two channels each from an audio signal and a PST audio signal.

The DSP 16 is supplied with the output of the channel 1 (CH1) of the PGM audio signal, the channel 2 (CH2) of the PGM audio signal, the channel 1 (ch1) of the PST audio signal, and the channel 2 (ch2) of the PST audio signal. Is done. On the other hand, the DSP
17 includes channel 3 (CH) of the PGM audio signal.
3), channel 4 of the PGM audio signal (CH
4), PST audio signal channel 3 (ch3)
And the output of the channel 4 (ch4) of the PST audio signal.

Then, the DSP 16 is connected to CH1, CH
2, ch1 and ch2 are mixed, and PGM # 1 and PGM # 2 are derived from output terminals 18a and 18b. In addition, the above DS
P17 mixes CH3, CH4, ch3 and ch4, and derives PGM # 3 and PGM # 4 from output terminals 19a and 19b.

These PGM # 1, PGM # 2, PGM # 3 and PGM #
4 outputs are outputs of four channels of one output in which the PGM audio signal and the PST audio signal are mixed.

Therefore, the second embodiment can greatly reduce the number of DSPs as compared with the digital mixer shown in FIG. Since the DSP generally costs the most in the signal processing portion, the second embodiment can achieve a significant cost reduction as compared with the digital mixer shown in FIG.

In digital signal processing, the delay involved in the processing of audio and video may be a problem. In digital signal processing, however, how many signals mainly pass through a signal processing LSI such as a DSP is required. Therefore, in the first and second embodiments, the delay can be minimized.

Next, a third embodiment of the digital mixer according to the present invention will be described with reference to FIG. In the third embodiment, one of a plurality of input audio signals supplied from a VTR is used.
A routing switcher 22 which is a switching selector for switching and selecting one of them, and a DSP 23 which varies a level of one input audio signal switched and selected by the routing switcher 22 or another one which is switched and selected next. ing.

[0070] The routing switcher 22, one PGM from a plurality of input audio signal INPUT # 1 ~INPUT # N of VTR supplied via the input terminal 21 ₁ through 21 _N
The audio signal is switched and selected according to an external channel switching signal.

The routing switcher 22
Is one PG according to an external channel switching signal.
The switching selection from the M audio signal to another PGM audio signal is also performed. Hereinafter, one PGM audio signal is referred to as a first PGM audio signal, and another PGM audio signal is referred to as a second PGM audio signal.

Conventionally, when a PGM audio signal is switched by a selection switch such as the routing switcher 22, a first PGM audio signal and a second PGM audio signal are switched.
If the GM audio signal is simply switched, the continuity of the audio signal is lost and noise is generated.

For this reason, it is conceivable that the crossfade is performed in a short time at the time of switching. However, as shown in FIG. 4, the audio signal has already been changed from the first PGM audio signal to the second PGM audio signal at the switching point p. The switching is performed, and the first PGM audio signal cannot be faded out even if the second PGM audio signal can be faded in (the hatched portion in FIG. 4).

Therefore, in the third embodiment, as shown in FIG. 5, the switching selection timing of the routing switcher 22 (switching point s) is, for example, based on the timing (switching point p) of an externally output channel switching signal. The first PGM audio signal is faded out by about 5 ms, switched to the second PGM audio signal, and then switched to the second PGM audio signal.
Is faded in.

That is, in the third embodiment, the above D
The level change processing for the first PGM audio signal by the SP 23 is performed so as to go to zero before the timing (switching point s) of the selection of switching to the second PGM audio signal by the routing switcher 22, and the DSP 23 performs the processing. The level change processing for the second PGM audio signal is performed so as to increase from zero after the switching point s.

The procedure of the level changing process performed in the third embodiment will be described with reference to the flowchart of FIG.

First, in step S1, a channel switching signal is supplied to the routing switcher 22.

In step S2, the multiplication coefficient (= k) in the DSP 23 from the time when the channel switching signal is supplied to the routing switcher 22 (switching point p) is Δk
Only decrease. This is because the fade-out performed by the DSP 23 on the first PGM audio signal reduces the level.

In step S3, it is determined whether or not the multiplication coefficient k has become zero. That is, whether or not the level of the first PGM audio signal has become zero. Where N
When O is determined, the process returns to step S2, and when YES is determined, the process proceeds to step S4.

In step S 4, receiving the result of the determination in step S 3, the routing switcher 22 sends the second P
The GM audio signal is switched and selected.

In step S5, in order to fade in the level of the second PGM audio signal, the multiplication coefficient in the DSP is increased by Δk.

In step S6, it is determined whether or not the multiplication coefficient has become 1. Here, if NO is determined, the process returns to step S5, and if YES is determined, the process ends.

As described above, in the third embodiment, the switching in the routing switcher 22 can be apparently performed using only fade-out and fade-in, so that the continuity of the audio signal is not impaired. Thus, cut editing can be performed without generating noise.

The embodiment of the digital mixer according to the present invention is not limited to the above-described first to third embodiments. For example, the number of input audio signals is limited to 16 channels. The audio signal that can be output is not limited to four channels.

[0085]

In the digital mixer according to the present invention, the selection section selects the currently reproduced audio signal and the next reproduced audio signal from the plurality of input audio signals, and the digital signal processing section Cross-fade processing is performed to lower the level of the currently reproduced audio signal selected by the above selection section, cross it, and raise the level of the next reproduced audio signal. Since the cross-fade audio signal based on the audio signal to be extracted is extracted, the number of digital signal processing units to be used can be reduced,
Significant cost reduction and downsizing can be achieved. Further, even if the number of input channels increases, the number of inputs that can be mixed is only two. Therefore, in terms of hardware, the number of input / output devices is increased, and the cost does not increase significantly. Further, the delay time from the input of the audio signal to the output thereof can be minimized because the number of DSPs is greatly reduced.

Further, the digital mixer according to the present invention
After the digital signal processing unit lowers the level of the currently reproduced audio signal switched and selected from among the plurality of input audio signals by the switching selection unit to zero, the switching selection unit outputs another currently reproduced audio signal. One is switched and selected, and then the other switched level is raised from zero, so that the cut editing can be performed without deteriorating the continuity of the audio signal and without generating noise.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a digital mixer according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a second embodiment.

FIG. 3 is a block diagram showing a configuration of a third embodiment.

FIG. 4 is a diagram for explaining a conventional switching operation by a routing switcher.

FIG. 5 is a diagram for explaining the operation of the third embodiment.

FIG. 6 is a flowchart for explaining the operation of the third embodiment.

FIG. 7 is a system diagram for explaining the principle of a general digital mixer.

8 is a block diagram in which the digital mixer shown in FIG. 7 is constituted by a DSP.

FIG. 9 is a diagram for explaining AB roll editing.

FIG. 10 is a diagram for explaining cut-out and cut-in.

FIG. 11 is a diagram for explaining fade-out and fade-in;

FIG. 12 is a diagram for explaining cut editing.

[Explanation of symbols]

 2, 15,... Matrix switcher 3, 16, 17, 23,... DSP 11, 12, 13, 14,. Switcher

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/268 G11B 27/038 H04N 5/7826 H04N 5/91

Claims (2)

(57) [Claims] 1. A current playback from a plurality of input audio signals
Audio signal and a selector for selecting two of the audio signal to be reproduced next, the audio signal to be reproduced next by intersecting thereto while lowering the level of the audio signal reproduced currently selected by the selector A digital signal processing unit for performing a cross-fade process for increasing the level of the audio signal, and an audio signal currently reproduced from the digital signal processing unit.
And the next faded audio signal
Digital mixer, characterized in that retrieving the audio signal. 2. A current playback from a plurality of input audio signals
Has a switching selection unit for one switching selecting an audio signal and a digital signal processing unit for varying the level of the audio signal reproduced currently selected by the switching selecting portion, it is currently being played in the switching selecting portion From one of the audio signals
Switching selection to one of the other audio signal currently being reproduced, the first sound signal reproduced currently the digital signal processor
One level is reduced to zero the performed from the digital mixer, characterized in that raising the other one level of the subsequent switching is audio signal currently being reproduced from zero.