JPH077483B2 - Magnetic recording / reproducing device - Google Patents

Description

Detailed Description of the Invention

[Field of Industrial Application] The present invention relates to a video tape recorder for professionals used in broadcasting stations and the like. SUMMARY OF THE INVENTION The present invention, for example, in a video tape recorder called the SMPTE-C type format, when a digital audio signal is recorded on a so-called synchronous track instead of the synchronous signal, a reproducing head for the digital audio signal is recorded. This is provided in advance of the time required for processing during reproduction, and during reproduction, digital signal processing other than reproduction processing can be performed during this preceding time. [Prior Art] In a so-called SMPTE-C type video tape recorder, two heads are provided on a rotating drum, and this drum is rotated at a rate of one rotation per one field, and at the same time, the circumference of the drum is rotated. The magnetic tape is wound diagonally over nearly 360 degrees of the surface and transported at a predetermined speed. The video period of the video signal is recorded in one of the two heads described above, and the signal is recorded in the other head during the period (synchronization period) in which the head is separated from the magnetic tape. Has been done. That is, FIG. 4 shows a recording pattern of the magnetic tape thus recorded. In the figure, the magnetic tape is divided into two in the width direction, a signal in the video period is recorded on an oblique track by the above-mentioned one head in the divided wide portion, and the other in the divided narrow portion. The signal of the synchronization period is recorded on the diagonal track by the head. A control track, a first audio track, a second audio track, and a third audio signal track, which are recorded by a fixed head, are provided between these parts and on both side edges of the magnetic tape. By the way, in such a format, if a so-called time base collector is used for the reproduction signal, even if the signal in the synchronization period is lost, a regular video signal can be reproduced without trouble as long as the signal in the video period is obtained. . Therefore, in the above-mentioned format, it was considered to record a digitized audio signal instead of the signal of the synchronization period on the diagonal track of the narrow portion. That is, in the above-mentioned conventional format, the audio signal is analog-recorded by the fixed head, but in such analog recording, the deterioration is remarkable especially when the dubbing is repeated. On the other hand, if the recording is performed digitally, the problem of deterioration during dubbing can be solved. However, in that case, there is no problem if the digital signal is simply dubbed, but if you try to process the digital signal with a transversal filter for editing, etc., the signal will be delayed by one to several sampling cycles. Will occur. On the other hand, since the signal processing is performed in units of one field, for example, there is a possibility that the edited recording may not be normally performed if the small delay as described above occurs. By the way, when recording / reproducing is performed digitally, a signal is delayed by time due to AD / DA conversion and error correction during recording and reproduction. This delay is 1 field at the time of recording, and is 1 field or more at the time of recording for error correction etc. when processing is performed in units of 1 field. Therefore, in the above-described recording apparatus, the recording head and the reproducing head are independent of each other, and the reproducing head is provided ahead of the time delay so that the timing of the reproduced audio signal coincides with that at the time of recording. Is being done. [Problems to be Solved by the Invention] As described above, in the related art, when a digital signal is processed for editing or the like, there is a problem that a signal is delayed and normal recording cannot be performed. . [Means for Solving the Problems] The present invention has a rotary drum provided with a first head for recording a video signal and a second head for recording an audio signal, and the circumference of the rotary drum. A magnetic tape in which the video signal is recorded by the first head and the audio signal is recorded by the second head in each recording area obtained by dividing the magnetic tape whose surface is slanted into two in the width direction. In the recording / reproducing apparatus, the head (10A) (10B) corresponding to the second head is supplied with an audio signal which has been subjected to recording processing (encoder (7)) including AD conversion and time base compression for recording. Along with the head corresponding to the second head provided on the rotary drum, reproduction including time axis extension and DA conversion corresponding to the time required for the recording processing at the time of recording and the recording processing at the time of reproduction. Processing (decoder 17) (1
8)) is provided with a third head (12 [(36A) (36B)]) at a position preceding by a time which is a sum of the necessary time and a reproduced audio signal reproduced by the third head during the reproduction. Is subjected to the above-mentioned reproduction processing, and the reproduction audio signal thus subjected to the reproduction processing is written in the memory (5), and the reproduction audio signal is reproduced from the memory at an arbitrary timing of a time corresponding to the time of the sum or more. A magnetic recording / reproducing apparatus is characterized in that the read reproduction audio signal is read and subjected to digital signal processing (editing control circuit (26)) other than the reproduction processing. According to this, since the signal can be taken out in advance for the time required for the processing, it is possible to solve the problem of delay caused by the processing [Example] In the block diagram of FIG. ) Supply The analog audio signal is supplied to the AD conversion circuit (3) through the IO circuit (2) and converted into digital data, which is supplied to the data bus (4). The data stored in the memory (5) is supplied to the encoder (7) via the data bus (6) and is encoded by adding a predetermined error correction code and rearrangement. Then, the data from the memory (5) is supplied to the modulation circuit (8), and the signal of the modulated data is supplied to the recording head (10) through the recording amplifier (9),
It is recorded on an oblique track of a narrow portion corresponding to the above-mentioned synchronous track of the magnetic tape (11). The structure of the rotary drum provided with the recording head (10) is shown in FIG. In the figure, the drum is rotated clockwise and its peripheral edge is spaced at an angle of 30 degrees.
Individual heads are provided. The digital audio signals are recorded and reproduced by two heads, respectively, and the audio signal recording heads (10A) (10A) are rotated counterclockwise from the position at 3 o'clock in the figure.
B), video signal erasing head (31), video signal recording / reproducing head (32), dummy head (33), audio signal recording confirmation reproducing heads (34A) (34B), variable speed reproduction of video signal Head (35), one playback head for audio signals (36
A), one playback head of the audio signal for variable speed playback (37
A), the other corresponding head (36B), (37B)
Is provided. During playback, the tape (11) to the playback head (12)
[(34A) (34B) (36A) (36B] (37A) (37B)] The signal reproduced by the demodulation circuit (1
The digital data supplied to and recorded in 4) is demodulated. The demodulated data is supplied to the data buses (15) and (16), the data of the data buses (15) and (16) is supplied to the memory (5), and the first and second decoders (17) are provided. ) (18). Demodulator circuit (14)
The address of the data detected at is supplied to the memory (5) through the address bus (19). Then, the data subjected to predetermined rearrangement, error correction, and other decoding are supplied from the memory (5) to the data bus (4). The data of the data bus (4) is supplied to the DA conversion circuit (20) to be an analog audio signal, and this signal is taken out to the output terminal (21) through the IO circuit (2). Further, the signal from the digital signal input terminal (22) is supplied to the data bus (4) through the digital IO circuit (23), and the signal from the data bus (4) is output as a digital signal through the IO circuit (23). It is taken out to the terminal (24). Further, at the time of editing, data from another video tape recorder or the like is supplied to the editing control circuit (26) through the terminal (25), and the data from this circuit (26) is transferred to the data bus (4).
And the control signal detected by the circuit (26) is supplied to the memory (5) through the auxiliary bus (27). Further, FIG. 3 shows a time chart of the recording / reproducing operation of this apparatus. Vertical lines in the figure are field boundaries. In this figure, first, A is a recording operation,

The signal AD-converted in the period of [0] is encoded in the first half of the next field [1], time-axis-compressed and read in the latter half of this field [1], and the recording heads (10A) (10B) Will be recorded at. On the other hand, B is a reproducing operation. For example, the signals reproduced by the reproducing heads (36A) and (36B) in the first half of the field [-2] are from the second half of the field [-2] to the next field. [-
1] is decoded in the first half, and the next field

The time axis is expanded during the period [0], DA converted, and taken out. Therefore, in the device described above, the same field

In order to extract the signal with [0], the reproducing heads (36A) and (36B) must be provided three fields or more ahead of the recording heads (10A) and (10B). And in the case of the above-mentioned device, since the mounting position of the reproducing heads (36A) (36B) on the rotary drum precedes the recording heads (10A) (10B) by 120 degrees, the actual preceding amount is Is. On the other hand, one field for AD-DA conversion and one field for encoding and recording at the time of recording are almost completely necessary, but for reproduction and decoding (error correction) at the time of reproduction. About 1 field is actually needed, and the remaining 1 /
3 fields are extra. Therefore, in the above-mentioned time chart, about 1/3 field from the end of decoding to the start of DA conversion is in a stopped state only because the data is held in the memory (2). Therefore, when the data is processed by the above-mentioned editing or the like, it is possible to speed up the reading of the data from the memory (5) for the time required for the processing and eliminate the time delay due to the processing. That is, in the above block diagram, the reading of the memory (5) is controlled by the control signal from the editing circuit (26), the reading is started from the beginning of the next field during normal reproduction, and the reading is performed from the beginning of the next field during editing. Start reading from an early point. Thus, according to the above-described device, the data can be read out early at the time of editing or the like, and thus, the processing of the data having the time delay can be performed while eliminating the time delay. The reading of the memory (5) can be delayed until the end point of one field is just before the reproduction of the next field. This makes it possible to deal with a case where the video signal is processed to cause a delay in the video signal. The arrangement of the heads on the rotating drum is not limited to the above example. [Advantages of the Invention] According to the present invention, since the time and signal required for the processing can be taken out in advance, the problem of the time caused by the processing can be solved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an example of the present invention, FIGS. 2 and 3 are diagrams for explaining the same, and FIG. 4 is a diagram for explaining a conventional technique. (1) is an input terminal, (2) is an IO circuit, (3) is an AD conversion circuit, (4), (6), (15) and (16) are data buses, (5) is a memory, (7) is an encoder, (8) is a modulation circuit,
(9) is a recording amplifier, (10) is a recording head, (11) is a magnetic tape, (12) is a reproducing head, (13) is a reproducing amplifier,
(14) is a demodulation circuit, (17) and (18) is a decoder, (19) is an address bus, (20) is a DA conversion circuit, (21) is an output terminal, (22) is a digital input terminal, and (23) is Digital IO circuit, (24) is digital output terminal, (25) is terminal, (26)
Is an edit control circuit, and (27) is an auxiliary bus.

Claims (1)

[Claims] 1. A magnetic tape having a rotary drum provided with a first head for recording a video signal and a second head for recording an audio signal, the magnetic tape being transported obliquely on the peripheral surface of the rotary drum. In the magnetic recording / reproducing apparatus, the video signal is recorded by the first head and the audio signal is recorded by the second head in each recording area divided into two in the width direction. A head corresponding to the second head provided on the rotating drum is provided with a sound signal which has been subjected to a recording process including A / D conversion and time axis compression for recording to a head corresponding to the head. Therefore, the third head is located at a position preceding by a time equal to or more than the sum of the time required for the recording process at the time of recording and the time required for the reproducing process including the time axis extension and DA conversion corresponding to the recording process at the time of reproducing. The above At this time, the reproduction processing is performed on the reproduction audio signal reproduced by the third head, the reproduction audio signal subjected to the reproduction processing is written in the memory, and the time corresponding to the sum time or more is arbitrarily set. The magnetic recording / reproducing apparatus is characterized in that the reproduced audio signal is read from the memory at the timing, and the read reproduced audio signal is subjected to digital signal processing other than the reproducing processing.