JPH07118161B2 - Digital signal recording method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recording a digital audio signal in a video tape recorder (hereinafter referred to as VTR) which records a digital audio signal together with a video signal by a rotary head.

[Conventional technology]

FIG. 6 is a block diagram showing a portion on the recording side of the VTR.
In the figure, 1 is a tape, 5 is an audio signal input terminal, 6 is an analog / digital (hereinafter referred to as A / D) converter I for converting an audio signal into a digital signal, 7 is an audio signal processing circuit, and 8 is a video signal. Input terminal, 9
Is an A / D converter that converts a video signal to a digital signal I
I and 10 are video signal processing circuits, 11 is a mixing circuit for mixing the video signal and the audio signal after the signal processing is performed, 12 is a modulation circuit I for modulating the video signal and the audio signal, and 13 is a modulated circuit. A recording amplifier I that amplifies the subsequent signal, a recording head I that records the amplified signal on the tape, a 15 is a modulation circuit II that modulates the video signal and the audio signal, and 16 amplifies the modulated signal. Recording amplifiers II and 17 are recording heads II and 20 for recording the amplified signal on the tape, and rotating head drums 20.

FIG. 7 shows a conventional recording format for recording a digital audio signal together with a video signal on a tape.
FIG. 3 is a schematic diagram of a format on a tape when the D-2 format TV signal, which is the third type, is of the NTSC system. In the figure, 1 is a video tape, 2 is a video sector in which a video signal is recorded, 18 is a tape upper end audio sector in which an audio signal is recorded, and 19 is a tape lower end audio sector in which an audio signal is recorded. As shown in the figure, since the track on the tape is made up of two tracks and one segment is formed, the recording signal is divided into two and simultaneously recorded on the two tracks.

Below, the audio signal is sampling frequency 48KHz, 16
Bit and the field frequency of the video signal is 59.94H
Let z.

At the time of signal recording, the audio signal input from the audio signal input terminal 5 is converted into a digital signal by the A / D converter I6, and then processed by the audio signal processing circuit 7 such as addition of error correction code. Mixed circuit
Entered in 11. On the other hand, the video signal is input from the video signal input terminal 8, converted into a digital signal by the A / D converter II9, and processed by the video signal processing circuit 10 such as adding an error correction code, and then input to the mixing circuit. Is entered. In the mixing circuit 11, the video signal and the audio signal are mixed, the mixed signal is modulated by the modulation circuit I12, amplified by the recording amplifier I13, and recorded in a certain segment on the tape 1 by the recording head I14. The signal mixed in the mixing circuit 11 is modulated in the modulation circuit II15 in the adjacent segment, amplified by the recording amplifier II16, and then recorded by the recording head II17. The above operation is repeated alternately, and tape 1
The signal is recorded continuously on top.

FIG. 8 is a diagram showing the recording timing of signals on the tape 1 when the tape winding angle is 180 ° in the conventional example. The audio tracks are arranged at both ends of each video track, and the audio signal is recorded before and after the boundary between the segments. FIG. 9 is a schematic diagram showing channel allocation at the time of recording in the audio sector of the conventional example. Since the number of samples recorded in one segment is 48000 / 59.94 × 3≅266.93 per channel, 267 samples are recorded in each audio sector, and one sample is reduced for every 15 tracks to match the fraction. In the same segment, 2 audio data
Double recording is performed, and the same data is recorded in the audio sectors at the upper and lower ends.

FIG. 10 is a diagram showing the data structure in the audio sector. The audio sector is actually divided into two by a gap. Each divided sector is # 0
It consists of 12 data blocks up to # 11. In addition, a sync signal (Syn
c.) ID, data, inner code C1, and outer code C2 are recorded in the format shown in FIG. At this time, the data and the outer code C2 are mixed.

FIG. 11 (a) is a schematic diagram showing the audio data structure in one field (excluding the header portion). First, in the inner code C1 block, an 8-byte check code is applied to 85-byte data, and it is possible to correct an error of up to 3 bytes in the block. Also, the outer code C2
The block applies a check code of 4 bytes to 8 bytes of data, and has a correction capability of up to 4 bytes for each block by the erasure flag from the inner code C1 decoder.

FIG. 11 (b) shows the error correction capability of the D-2 format of 2
It is the figure shown in comparison with the divided audio sector. With the correction code, it is possible to correct burst errors up to 1.3 mm in the track direction, 1.29 mm in the tape running direction, and 0.14 mm in the tape width direction.

[Problems to be Solved by the Invention]

Since the conventional recording format is configured as described above, redundancy is increased because double writing is performed on both the upper and lower axes of the audio signal, but if double writing is not performed, the position of the audio track will change. Since they are arranged in the tape running direction, there is a problem that a satisfactory error correction capability cannot be obtained for burst errors in the tape running direction.

The present invention has been made to solve the above-mentioned problems, and when an audio signal is recorded on a tape by a rotary head together with a video signal in a VTR, a higher error than a burst error in the tape running direction is produced. An object of the present invention is to obtain a digital signal recording method that has a correction capability and that can obtain a recording format in which a tape can be used efficiently without increasing redundancy.

[Means for Solving the Problems]

According to the digital signal recording method of the present invention, a certain n (m is an integer of 3 or more) tracks (n is an integer of 3 or more) forming one field of an audio signal recorded on a part of all tracks are used. An integer of 2 or more, but m>
The recording is performed on the track n), and at least the odd number sample and the even number sample are separated on another track and are dispersed and recorded in the tape width direction.

[Action]

In the present invention, the number of audio sectors per field is n to increase the audio sector length to improve the data error correction capability, and the n sectors are dispersed in the tape width direction to provide an odd number of audio signals. Since the data is divided into samples and even-numbered samples for recording, even if a burst error occurs in the tape running direction due to clogging of the head, half of the data can be secured and error correction capability can be improved. Does not increase the redundancy during recording.

〔Example〕

Hereinafter, as an embodiment of the present invention, a case of recording a 4-channel digital audio signal in a VTR will be described.

FIG. 1 is a schematic diagram of a recording format on a tape in a digital signal recording method according to an embodiment of the present invention. Reference numeral 1 is a video tape, 2 is a video sector in which a video signal is recorded, 3 is a tape upper end side audio sector in which an audio signal is recorded, and 4 is a tape lower end side audio sector in which an audio signal is recorded. On the tape, two tracks form one segment, and signals are simultaneously recorded on two tracks of the same segment. Also,
One field is composed of three segments, and therefore one frame is composed of six segments (= 12 tracks).

As a device for recording a signal on a tape, a conventional device as shown in FIG. 6 can be used. At the time of recording the signal, the audio signal input from the audio signal input terminal 5 is converted into a digital signal by the A / D converter I6, processed by the audio signal processing circuit 7 such as error correction coding, and input to the mixing circuit 11. To do. On the other hand, the video signal is input from the video signal input terminal 8, converted into a digital signal in the A / D converter II9, input to the video signal processing circuit 10 and subjected to processing such as error correction coding, and then mixed. Input to circuit 11.

After the video signal and the audio signal are mixed in the mixing circuit 11, the mixed signal is modulated in the modulation circuit I12, amplified by the recording amplifier I13, and recorded in a certain segment by the recording head I14. In the adjacent segment, the signal mixed by the mixing circuit 11 is modulated by the modulation circuit II15, amplified by the recording amplifier II16, and then recorded by the recording head II17. By repeating this operation alternately, signals are continuously recorded on the tape.

FIG. 2 is a diagram showing recording timing of signals on the tape 1 in the embodiment of the present invention. 1 audio sector
It is arranged at the end of one of the two adjacent fields in the frame and at the beginning of the other, and an audio signal is recorded before and after the boundary between the fields.

When the sampling frequency is 48 KHz and the field frequency of the video signal is 60 Hz, the number of samples of the audio signal recorded in one field is 48,000 / 60 = 800. According to this embodiment, since there is one audio sector in one field, 800 samples of audio signals are recorded per channel in that one area.

FIG. 3 is a diagram showing allocation of recording channels in the audio sector. The audio sector is actually divided into two by a gap, and thus is divided into four parts. Therefore, signals of different recording channels are recorded in the four parts. Furthermore, odd-numbered (odd) data is recorded in the upper audio sector 3 of the tape, and even-numbered (even) data is recorded in the lower audio sector 4 of the tape, and either one of the data bursts on the tape 1. Even if data is lost due to an error, at least half of the data is secured and error correction is possible. In the audio sector 3 on the upper side of the tape, the data of channels 1 and CH3 is recorded on the side of the video sector, and the data of CH2 and CH4 is recorded on the side of the tape. Conversely, in sector 4, CH2 and CH4 data are recorded on the video track side, and CH1 and CH3 data are recorded on the tape end side.
By this processing, even if a burst error occurs at both ends of the tape 1, if the error has a certain width or less, half of the data can be secured and error correction can be performed.

FIG. 4 is a diagram showing the data structure in the audio sector in the embodiment of the present invention. Here, for comparison, it is considered that the redundancy is the same as that of the conventional example. The audio sector divided into two by the gap is from # 0 to # 29, respectively.
It consists of 30 data blocks. Further, in one data block, a sync signal (Sync.) Block address ID, parity, data, inner code C1 and outer code C2 are recorded in a format as shown in the figure. 80 bytes between the parity and the inner code C1 record data in the blocks # 0 to # 19, and the outer code C2 in the blocks # 20 to # 29.
To record.

FIG. 5 (a) is a schematic view showing the audio data structure of one field in the embodiment of the present invention (excluding the header part).

First, the inner code C1 block is 8 for 80-byte data.
The check code of bytes is applied, and an error of up to 3 bytes can be corrected in the block. The outer code C2 block applies a check code of 10 bytes to 20-byte data, and has a correction capability of up to 4 bytes for each block by the erasure flag from the inner code C1 decoder.

FIG. 5 (b) is a diagram showing the error correction capability of the format according to the present invention in comparison with the audio track divided into two. Length in track direction due to correction code 3.
Error correction is possible for burst errors up to 9 mm, 3.87 mm long in the tape running direction, and 0.42 mm long in the tape width direction. Each length is shorter than the conventional case in Fig. 11 (b). It has tripled.

In the above embodiment, the audio sector is shown at the beginning and the end of each field, but the n audio sectors are in different segments in the same field and do not overlap when viewed from the tape running direction. It suffices if it is at a position, and the same effect as that of the above-described embodiment is exhibited in the arrangement satisfying these conditions.

[Effects of the Invention] As described above, according to the present invention, the audio sector is provided only in a certain video sector, not in all the video sectors. Therefore, the audio sector length is increased, the error correction capability is improved, and the audio sector is improved. Since the sectors are distributed in the tape width direction and the digital audio signal is recorded by dividing it into an odd number sample and an even number sample, the redundancy on the tape is not increased and the burst error in the tape running direction is prevented. There is an effect that a recording format that exhibits high error correction capability can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a recording format on a tape according to an embodiment of the present invention, FIG. 2 is a diagram showing a recording timing of a signal on the tape in the above embodiment, and FIG. 3 is an audio in the above embodiment. FIG. 4 is a diagram showing allocation of recording channels to sectors, FIG. 4 is a diagram showing a digital structure in the audio sector in the above embodiment, and FIG. 5 (a) is a one field audio data structure in the above embodiment. FIG. 5 (b) is a diagram showing the error correction capability of the format according to the above embodiment, FIG. 6 is a block diagram showing the recording side portion of the digital VTR, and FIG. 7 is a conventional recording format. FIG. 8 is a schematic diagram of the format on the tape of the D-2 format which is one, FIG. 8 is a diagram showing the recording timing of the signal on the tape in the D-2 format, FIG. 9 is a diagram showing channel allocation to audio sectors during recording in D-2 format, FIG. 10 is a diagram showing data structure in audio sectors in D-2 format, and FIG. 11 (a) is D −
FIG. 11B is a schematic diagram showing the data structure of one field in the two formats, and FIG. 11B is a diagram showing the error correction capability of the D-2 format. Reference numeral 1 is a tape, 2 is a video sector, 3 is an audio sector on the upper end side of the tape, and 4 is an audio sector on the lower end side of the tape. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A digital signal recording method for recording a digital audio signal obtained by converting an analog audio signal into a digital signal on the same track together with a video signal by a rotary head. M constituting one frame (m is an integer of 2 or more) A digital signal recording method characterized in that a digital audio signal is recorded on a fixed number n (n is an integer of 1 or more and m> n) for each track of the book.