JPS6217316B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital audio editing device for editing audio signals recorded by a digital recording/playback device.

In the past, in analog recorders (tape recorders), desired tapes could be obtained by manually cutting useful portions of recorded tapes and splicing them together to form one continuous tape. This situation is shown in FIG. In Figure 1, 1, 2
are each part of a recorded tape, and A of 1
Part B is a necessary part, part B is an unnecessary part, part C of 2 is an unnecessary part, and part D is a necessary part. A desired tape 3 can be obtained by cutting these tapes and mechanically joining them together. At this time, the cutting positions of tapes 1 and 2, that is, the boundaries between A and B and C and D (hereinafter referred to as editing points)
It was necessary to find the following, but to do so, the following tasks were required. That is, the tape recorder is put into a playback state, and while listening to the playback sound, the tape recorder is stopped at a position that appears to be an editing point. In order to find a more accurate editing point, the take-up reel and the supply reel of the tape recorder are manually rotated forward and reverse in the same direction, and the editing point is determined by listening to the reproduced sound. That is, when such fine adjustments are made and it is determined that the tape is at a desirable editing point, the position of the tape that is in contact with the reproducing head is set as the correct editing point, and the above-mentioned cutting is performed. The reason why the tape is cut diagonally as shown in FIG. 1 is to prevent the reproduced sound from becoming discontinuous at the editing point when the edited tape is played back. This is because the effect is that the sound of section A gradually becomes smaller (fade out) and the sound of section D gradually becomes louder (fade in). This connection processing is called crossfade.

Such editing work is indispensable when creating music tapes, etc., but difficult problems arise when applying it to digital recording and playback devices that have been put into practical use in recent years. In other words, since the recorded signal in a digital recording/playback device is a digital signal, cutting diagonally like an analog signal means that meaningless information continues for that period, and it is clear that this will have a harmful effect on the reproduced sound. be. On the other hand, even if the tape is cut perpendicular to the direction of tape progression in order to reduce the amount of information lost, digital recording and playback devices usually record several dozen samples of information bits as one PCM frame with error correction codes attached. In order to
Errors in information in 1PCM frame are inevitable. Therefore, (a) apply mutating to that part, (b)
Operations such as skipping that part and connecting the preceding and following information are required, and in any case, the deterioration in the sound quality of the original information at that part is essentially a problem.

The present invention provides an editing device suitable for a digital recording/playback device that does not cause the above-mentioned problems.

An embodiment of the present invention will be described below based on the drawings. First, an outline of the editing method of the editing device according to the present invention will be explained. In this method, the recorded tape is not cut mechanically, but two digital recording and playback devices are used. The first digital recording and playback device plays the first tape before editing, and the second digital A recording/playback device records only the necessary portions of the first tape onto a second tape to create one edited tape. This will be explained with reference to FIG. That is, in FIG. 2a, 1 and 2 are different parts of a first tape attached to a first digital recording/playback device, and 3 is a different portion of a first tape attached to a second digital recording/playback device. This is the second tape. Therefore, as an operation, first one of the first tapes attached to the first digital recording/playback device is
The part 1 is played back, and the part that passes the boundary between A and B in 1 and slightly enters the area B is recorded on a second tape attached to a second digital recording/playback device. This situation is shown in FIG. 2b. Next, the first tape is played back from a distance _L1 before the boundary between C and D in 2. At the same time, the second tape is played from _L2 before the boundary between A and B. Here, L ₁ L ₂ is assumed to be the same value as the boundary between A and B of the second tape at the moment when the playback head of the first digital recording/playback device comes into contact with the boundary between C and D of the first tape. The length may be sufficient to allow the first tape and the second tape to run synchronously so that the recording head of the second digital recording/playback device comes into contact with the tape. By running the first tape and the second tape synchronously in this manner, it is possible to record D on the first tape from the boundary between A and B on the second tape. This situation is shown in FIG. 2C. At this time A and D
At the boundary, A is faded out and D is faded in by digital calculation. These operations are performed using time codes recorded on separate tracks on the tape.

The present invention realizes an editing device based on the above idea, and a detailed description of the embodiments will be given below. In Figure 3, 4 is a CPU (microcomputer) that controls this device;
5 stores the program for CPU4
ROM, 6 is a data bus (the address bus is omitted in the figure), 7 is an operation input section that gives control commands to this device, and 7' is a CPU that receives operation inputs.
4 is a control output section for outputting a display to show that it has been received or a control signal for controlling other parts of this device;
This is an interface element for interfacing with the CPU 4. On the other hand, P and R are digital signal input terminals from first and second digital recording and reproducing devices (hereinafter referred to as PCM tape recorders), respectively. 9 is a memory for writing and storing digital data from the input terminal P; 10 is a memory 9;
address counter, 11 is address counter 1
12 is a memory that similarly writes and stores digital data from the input terminal R, 13 is an address counter of the memory 12, and 14 is an interface element that interfaces the address counter 13 and the CPU 4. It is. 15, 15' are switches controlled by the output of the control output unit 7' from the CPU 4 via the interface element 8; 16 is the digital data from the first PCM tape recorder input from the input terminal P and the input terminal R; 18 is a D/A converter; 18 is a D/A converter; 18 is a D/A converter; 18 is a D/A converter; 19 is a low-pass filter,
20 is an amplifier, and 21 is a monitor speaker. W is an output terminal to the second PCM tape recorder (recording tape recorder). 22 is a clock pulse generation circuit, 23 is a manual clock pulse generator, and 24 is a changeover switch that selects and outputs either the output of the clock pulse generation circuit 22 or the manual clock pulse generator 23 according to the output of the control output section 7'. It is. The T _P terminal was played by the first PCM tape recorder connected to the P terminal.
SMPTE time code input terminal, 25 is the interface between the above time code input and CPU4, T _R
The terminal is an input terminal for the SMPTE time code reproduced by the second PCM tape recorder connected to the R terminal, and 26 is an interface between the time code input and the CPU 4.

Next, the operation of this embodiment will be explained based on FIG. 3 as well. As a premise, the first
The tape attached to the PCM tape recorder is the first tape explained in FIG. 2, and the second PCM tape recorder connected to the R terminal is also the second tape. These are called a playback tape recorder and a recording tape recorder, respectively. First, use the playback tape recorder to play back one part (parts A and B) of FIG. 2. Make a second tape as shown in Figure b. Next, Figure 2 a-2
Play back the parts (C and D parts), and play the parts A and B in Figure 2b.
D is recorded while performing crossfade processing from the boundary of
It is necessary to find the exact location of the boundary of B and the boundaries of C and D.

Next, the operation for determining the editing point will be explained.
First, in order to determine the boundary between C and D, part 2 of the first tape is played back by a tape recorder on the playback side and inputted to the P terminal. When PCM data is input to the P terminal, this data is cyclically recorded in the memory 9. In other words, when writing to the last address of memory 9 is completed, writing starts again from the first address.As a result, if we take a certain moment, the PCM data recorded in memory 9 will always be stored for a certain period of time from that moment. The previous data will be stored continuously. This memory 9
The address is controlled by an address counter 10. The clock pulses of the counter 10 are supplied with the clock pulses generated from the clock pulse generating circuit 22 by turning df of the switch 24 ON. Furthermore, switch 15 has b-c turned on, and the input PCM data is sent to crossfade processing circuit 1.
6, is converted into the original analog signal by the D/A converter 18, the high frequency component is cut by the low frequency filter 19, is amplified by the amplifier 20, is supplied to the speaker 21, and is output to the tape recorder on the playback side. Audio is monitored. Control of each of the above sections, such as the polarity of the switches 15 and 24, and disabling of the crossfade processing circuit 16, are all performed by signals from the control output section 7'. That is, a signal from an operation input section 7 consisting of a keyboard pushbutton, etc. is transmitted to the CPU 4 via an interface element 8 and a bus line 6.
A corresponding control signal is outputted from the control output section 7' from the CPU 4 via the bus line 6 and the interface element 8, and the control is performed based on this signal.
In FIG. 3, control lines from the control output section 7' to other parts than the switch are omitted.

The editor inputs a signal from the operation input section 7 indicating that it is the desired timing to edit while monitoring the output audio from the speaker 21. This signal is transmitted to the CPU 4 through the above-mentioned path, and the following control is performed via the control output section 7'. First, the operation continues for a certain period of time from an editing point desired by the editor, and after the certain period of time, writing to the memory 9 is stopped. Thereafter, tape running in the playback tape recorder is stopped. Tape recorder control
This is executed by an instruction from the CPU 4, but is omitted from the diagram. Now, the contents of the memory 9 at this time are as shown in FIG. Here, the specifications are assumed as follows. Audio data is 16 bits/sample, sampling frequency is 50kHz, memory is 256KW (1W = 16
In this way, the audio data stored in the memory 9 is approximately 5 seconds, as 256k÷50k≈5 seconds. Of course, in order to save memory, the data may be stored in memory every other sample (this means that the sampling frequency is halved). Alternatively, a method such as reducing the number of bits per sample using a bit compression method may be applied. Here, in order to simplify the explanation, such processing will not be performed at all. In Figure 4, a 256kw memory is simulated, but the audio data is written sequentially from left to right and is 2FFFF.
If you write up to 00000, you will have to write again from 00000.
This is repeated. The memory address corresponding to the timing desired by the editor is represented by _XP in the figure. Then, the writing is completed at a timing corresponding to the memory address of Y _P delayed by, for example, 4 seconds within the repetition cycle as a fixed period of time. As a result, memory 9 contains (Y _P +1) → 2FFFF → 00000 → Y _P
The audio will be recorded in this order.

Next, in order to search for the correct edit point, the contents of the memory 9 are repeatedly read out, and the editor can control each section by setting the device to edit point search mode from the operation input section 7. The signal will look like this: Switch 15 has a-c on
However, the switch 24 turns df ON. After the contents of the memory 9 are played back in the order of X _P →Y _P (in this case, for about 4 seconds), the address counter 10 is stopped to temporarily stop the playback, and there is no sound for a certain period of time, for example, 2 seconds. Then, reading starts again from _XP , but only during this silent state, switch 24 d-e is turned on. Reference numeral 23 denotes a manual clock pulse generator composed of a rotary encoder or the like, and the larger the amount of movement, the more clock pulses are generated. If a clock pulse is generated manually, e.g. by rotating a dial, during silence, the address counter 1
This clock pulse is input to 0. At this time, by simultaneously supplying rotational direction information to the address counter 10 and operating it as an up-down counter, the values X _P +M and X _P -M can be created from the value of X _P. Here, X _P +M occurs when the dial is rotated to the right and M clock pulses are generated, and X _P -M occurs when the dial is rotated to the left and M clock pulses are generated.
After this 2 seconds of silence, the switch 24 df is automatically turned ON according to the command from the CPU 4, and the contents of the memory 9 are changed from X _P + M _P (or X _P - M _P ) to Y _P Play in this order. Then, mute the sound again and repeat the above routine. By doing this, you can change the first address of the memory 9 to be played during the silent state, and at the same time change the starting point of the played audio, so specify that point as the editing point. be able to. This method is more accurate because it allows you to specify edit points while listening to the playback sound at normal speed, compared to the conventional analog tape recorder, which searches for edit points while listening to the playback sound when the reel is rotated by hand. Edit points can be specified. In this way, during the silent state, the CPU 4 is
A signal indicating that the audio sample corresponding to the value of the address counter 10 at that time is an editing point is given to the address counter 10 at that time. This means that the position of the boundary between C and D in Figure 2a has been determined. In order for the CPU 4 to recognize this position, the following process is performed. First, the CPU 4 reads the time code input signal from the T _P terminal, which is input simultaneously with the PCM data, via the time code interface 25 and the bus line 6 at the timing of the editing point given by the editor. In SMPTE time code, the minimum signal unit is a frame (1/30th of a second), so if you want to increase the editing accuracy beyond this, you need to count the audio sampling pulses within the frame and calculate the number of samples within the frame. Also includes information on whether there is
Although the CPU 4 needs to read the counter, this counter is omitted in FIG. 3 and is included in the time code interface 25. Therefore, at this point, the CPU 4 reads information on hours, minutes, seconds, frames, and samples. Next, in the edit point search mode, the counter in the time code interface 25 operates together with the address counter 10 by the output of the manual clock pulse generator 23, and the time code information of the correct manually corrected edit point and the more detailed frame unit are operated. The CPU 4 reads the sample point information within, that is, hour, minute, second, frame, and sample information. In this way,
The CPU 4 has information on the exact position of the sample point in the memory 9 and on the tape. Let the address in the memory 9 of the edit point determined at this point be X _P +N _P .

Next, determine the boundary between A and B of the second tape in FIG. 2b. The recording side tape recorder is played back, and PCM data is input to the R terminal. This data is recorded cyclically in memory 12. At this time, the operations of the memory address counter 13, switch 24, switch 15, crossfade processing circuit 16, D/A converter 18, low-pass filter 19, amplifier 20, and speaker 21 are the same as in the playback side tape recorder, so no explanation will be given. Omitted. Editor is speaker 21
While monitoring the output audio from the tape, a signal to that effect is inputted from the operation input section 7 at the timing when editing is desired, that is, near the boundary between A and B of the second tape, as described above. Thereafter, writing continues in the memory 12 for a certain period of time, and the process is the same until it stops.
However, in this case, the capacity of memory 12 is
Assuming that there is approximately 5 seconds as in the case of , writing to the memory 12 is stopped when, for example, 1 second has elapsed from the designated point. The state inside the memory 12 at this time is shown in FIG. X _R and Y _R correspond to X _P and Y _P in FIG. 4, respectively. Furthermore, to search for the correct editing point in the memory 12, switch 15' is turned on with a'-c' turned on, as in the case of the playback tape recorder.
The contents of memory 12 are (Y _R +1) → 2FFFF →
It is played in the order of 00000→X _R , and then again (Y _R +
There will be about 2 seconds of silence between 1) and the time it starts playing. During this silent state, the switch 24
e is turned ON, and X _R becomes X _R + by rotating the dial.
M _R (or X _R - M _R ). In this way, the point at which the reproduced audio ends changes as the dial is rotated, so this point can be designated as an editing point. The position information at this point is read into the CPU 4 by the same operation as in the case described above. Let the address of this point on the memory be X _R +N _R .

As described above, the time code on the tape, the position information based on the PCM sample point, and the information based on the address on the memory regarding the boundaries of C and D and the boundaries of A and B in Figure 2 are stored in the register in the CPU. .

Next, the contents of the memory 12 and the memory 9 are continuously read out using the editing point determined above as a boundary point to monitor the audio in the actually edited state. At this time, crossfade processing is performed at the editing point to obtain a natural sound connection. This series of actions is called rehearsal here. At the time of rehearsal, the editor gives a rehearsal instruction to the CPU 4 from the operation input section 7. The CPU 4 controls the initial value of the address counter 13 through the address counter interface element 14 and also controls the address counter 10 through the address counter interface element 11.

The crossfade time is given from the operation input section 7. For example, 1ms, 10ms, 100ms,
This is done by selecting one of the operation buttons such as 300ms and 500ms. FIG. 6 shows the operation when the crossfade time is F seconds. Memory playback in the case of rehearsal is performed in the following order based on instructions from the CPU 4. The rehearsal starting point is Y _R +1 in the memory 12 and is played back in the order of 2FFFF→00000→X _R , but the crossfade starts from X _R +N _R -1/2Z. Here, Z is the number of memory addresses advanced in F seconds, which corresponds to 50×10 ³ (kHz)×F seconds. When the memory 12 reaches X _R +N _R -1/2Z, the memory 10 starts playing back from X _P +N _P -1/2Z and a crossfade period begins. Thereafter, the memories 9 and 12 are simultaneously reproduced for F seconds, that is, Z memory addresses, and a crossfade process is performed. Memory 12 is X _R +N _R +1/2
Z, the crossfade period ends when the memory 9 progresses to X _P +N _P +1/2Z, and only the memory 9 is played back to Y _P and the rehearsal ends.

Here, the above-mentioned crossfade processing will be specifically described. FIG. 7 is a detailed block diagram of the fade processing circuit 16 in FIG. 3. Fi1 is the input from switch 15' in Figure 3, Fi2
is also an input from the switch 15. CK is the sampling clock pulse input. 27 is a fade curve generation circuit that digitally generates coefficients of a crossfade curve, and includes a counter,
Alternatively, it may be configured by a combination of an address counter and ROM. An example of the output of this circuit is shown at 32 in FIG. Here, the vertical axis represents the above coefficient D/
This is the size when converted to A. 28 is a multiplication circuit, which combines the output of the fade curve generation circuit 27 and Fi
Digitally multiplies the PCM audio signal input from 1. As a result, the output of the multiplier circuit 28 is
This is the input from Fi1 faded out. 29 is a fade curve generating circuit similar to 27, and an example of its output is shown at 33 in FIG. 30
is a multiplication circuit that multiplies the input of Fi2 and the output of 29, and the output of the multiplication circuit 30 fades in the input from Fi2. Reference numeral 31 denotes an adder circuit that adds the outputs of the multiplier circuits 30 and 28, and this output FO provides a digitally crossfaded signal. In this way, a signal crossfaded at the editing point is obtained at the output of the fade processing circuit 16. Through the above process, if the rehearsal is completed and there is a problem with the connection of sounds near the editing point, repeat the process starting from the step of determining the editing point in memory, and if a suitable editing point is obtained, proceed to the next editing step. .

Editing involves recording the same signal that has been rehearsed in memory onto the actual tape, but the signal played back by the playback head that precedes the recording head of the recording tape recorder and the tape on the playback side are combined. The timing of the signals reproduced by the playback head of the recorder is adjusted by appropriate delay circuits, and the recording head of the recording tape recorder has just come into contact with the first position of the crossfade period shown in Fig. 2b. At the moment when the signal is reproduced from the first position of the crossfade A of the second tape in FIG. 2b on the recording tape recorder and the D section of the first tape in FIG. 2a on the playback tape recorder. The signal reproduced from the first position of the crossfade period is the crossfade processing circuit 1 of FIG.
6 and is output to the W terminal and supplied to the recording head, so that the signal previously recorded near the editing point and the signal newly recorded by editing work are correctly connected. . At this time, switches 15 and 15' naturally have b-c and b'-c'.
It is ON.

The exact edit point on the tape is determined by the CPU as described above.
4, the synchronous running of the tape, the delay amount of the delay circuit, the crossfade timing, etc. are all performed by commands from the CPU 4. Crossfade processing circuit 1
The operation in step 6 is exactly the same as in the case of rehearsal. When the above process is completed, the second tape shown in FIG. 2c is completed, and the editing work is completed.

In this way, since editing is done at the audio PCM signal stage itself, regardless of the recording format of the tape deck, information may be missing due to hand-cut editing when newly reconstructed and recorded on the recording tape recorder. It doesn't happen at all.

As detailed above, according to the present invention, (i) the editing work of a PCM tape recorder, which conventionally involved some kind of missing information, can be performed without any errors; (ii) the editing work can be performed without any errors; Even when making a decision, since the audio is played back at the speed at which normal audio is played, it is easy to determine which point in the actual audio the specified editing point corresponds to. (iii) It can be rehearsed in memory before actually being recorded on tape, and revisions can be made in memory as many times as the editor is satisfied; (iv)
It is possible to obtain a digital audio editing device having features such as being able to edit sampling pulse accuracy by using a time code and a sampling pulse in combination.

[Brief explanation of the drawing]

Figure 1 shows the concept of conventional analog editing.
FIG. 2 is a diagram showing the concept of the system adopted in the digital audio editing device according to the present invention, FIG. 3 is a block diagram of the digital audio editing device according to the present invention, and FIG.
This figure shows the writing state of the memory 9 in FIG. 3, FIG. 5 shows the writing state of the memory 12 in FIG. 3, and FIG. 6 shows the temporal correspondence of the memories in FIGS. 4 and 5. 7 is a detailed block diagram of the crossfade processing circuit shown in FIG. 3, and FIG. 8 is a diagram showing how the output of the fade curve generating circuit shown in FIG. 7 is D/A converted. 4... CPU, 5... ROM, 7... operation input section, 7'... control output section, 9... first memory,
10... first memory address counter, 12...
... second memory, 13 ... address counter of second memory, 15, 15' ... first and second switching means, 16 ... crossfade processing circuit,
18...D/A converter, 21...Speaker, 22
... clock generation circuit, 23 ... manual clock generator, 27 ... fade curve generation circuit (fade-out means), 29 ... fade curve generation circuit (fade-in means).

Claims (1)

[Scope of Claims] 1. A digital audio editing device that creates an edited tape by editing a digital recording tape recorded by a digital recording/playback device and recording the output by the digital recording device,
means for reproducing the first tape to be edited, converting it into an audio signal, and monitoring it; a first memory means for storing the digital signal of the reproduced first tape; means for controlling writing and reading of the memory; means for converting and monitoring the reproduction signal of the second tape to be edited into an audio signal; and a second memory means for storing the digital signal of the reproduced second tape. ,
means for controlling writing/reading of the second memory by an external timing signal; means for reading the first memory and the second memory at substantially the same speed as when writing; manual control means for specifying an edit point by controlling a read end address of the first memory corresponding to an edit point on the tape and a read start address of the second memory corresponding to an edit point on the second tape; means for storing the address specified by the manual control means; means for successively reading out the contents of the first memory and the second memory and converting them into audio signals based on the contents of the storage means; means for specifying positions on the tape corresponding to editing points of the first memory and the second memory; means for storing positional information corresponding to the positions;
a first switch means for selecting either the digital signal reproduced from the tape or the output of the first memory; and means for receiving the output of the first switch means and digitally fading out the signal; a second switch means for selecting either the digital signal reproduced from the second tape or the output of the second memory; and means for digitally fading the signal into which the output of the second switch means is input. , when the first and second switch means select memory output, the timing for operating the fade-out means and the fade-in means is generated based on the output of the address storage means; The digital audio editing device is characterized in that when the switch means selects a digital signal reproduced from a tape, the timing for operating the fade-out means and the fade-in means is generated based on the output of the position information storage means. 2. The manual control means that controls the read end address of the first memory and the read start address of the second memory and specifies the editing point is configured to operate at a finite time interval when repeatedly reading the first memory or the second memory. 2. The digital audio editing device according to claim 1, further comprising manual control means for creating a silent state by providing a soundless state and changing an editing point during this silent state.