JPH04280186A - Recording and reproducing system for digital - Google Patents

Abstract

PURPOSE:To preclude the possibility of disturbance in a reproduced pattern even when time axis correction is processed while plural kinds of digital video signals subject to vari-speed reproduction are distinguished and plural kinds of digital video signals are recorded in mixture at a different running speed onto a magnetic tape. CONSTITUTION:An information signal representing a running speed of a magnetic tape 1 at recording is inserted to plural kinds of digital video signals for each SYNC block as a discrimination data and the resulting signal is recorded onto the magnetic tape 1. The magnetic tape 1 on which plural kinds of digital video signals are recorded at a different running speed so as to form azimuth tracks is driven at a different running speed from that at recording and plural kinds of the digital video signals are reproduced by a rotary magnetic head 2. The time axis of the plural kinds of the digital video signals subject to vari-speed reproduction from the magnetic tape 1 is corrected by each time axis correction circuit in response to the discrimination data as the information signal of the running speed of the magnetic tape 1 at the recording for each SYNC block.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording and reproducing system for digital video signals.

0002

2. Description of the Related Art Hitherto, a helical scan type digital VTR has been proposed in which magnetic tapes are run at different running speeds and digital video signals are recorded by a rotating magnetic head so as to form inclined tracks. (Refer to Japanese Unexamined Patent Publication No. 1-258255).

0003

[Problem to be solved by the invention] Such a digital VTR
In this method, a magnetic tape on which multiple types of digital video signals are recorded so as to form inclined tracks at different running speeds is run at a different running speed than when recording, and the multiple types of digital video signals are transferred to a rotating magnetic tape. When playing back with the head, the rotating magnetic head scans across multiple inclined tracks, so near the boundaries of the recording areas of multiple types of digital video signals on the magnetic tape,
There is a possibility that multiple types of digital video signals may be mixed and reproduced. Therefore, if such a variable speed reproduction signal is supplied to a time axis correction device to correct the time axis error, and then the digital video signal with the time axis corrected is supplied to a television receiver for reproduction, the reproduction screen will be distorted. .

[0004] In view of the above, the present invention provides a method of running a magnetic tape on which a plurality of types of digital video signals are recorded so as to form inclined tracks at different running speeds than when recording. In this digital video signal recording and reproducing method in which multiple types of digital video signals are reproduced by a rotating magnetic head, we would like to propose a system that can distinguish and process multiple types of digital video signals that are reproduced at variable speeds. It is something to do.

[0005]

[Means for Solving the Problems] The present invention allows a magnetic tape 1 on which a plurality of types of digital video signals are recorded to form inclined tracks at different running speeds to be run at a different running speed from the time of recording. In the digital video signal recording and reproducing method in which the plurality of types of digital video signals are reproduced by the rotating magnetic head 2, the plurality of types of digital video signals are recorded on the magnetic tape along with an information signal of the running speed of the magnetic tape at the time of recording. 1, a plurality of types of digital video signals and an information signal of the running speed of the magnetic tape 1 are reproduced from the magnetic tape at variable speeds, and the plurality of types of digital video signals thus reproduced at variable speeds are reproduced from the magnetic tape. Each signal is processed separately according to the information signal of the traveling speed of the vehicle.

[0006]

According to the present invention, a plurality of types of digital video signals are recorded on the magnetic tape 1 together with an information signal of the running speed of the magnetic tape at the time of recording. Then, multiple types of digital video signals and information signals of the running speed of the magnetic tape 1 are reproduced from the magnetic tape at variable speeds, and the multiple types of digital video signals reproduced at variable speeds are reproduced at the running speed of the magnetic tape 1. Each signal is processed separately according to the information signal.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A digital VTR according to an embodiment of the present invention will be described in detail below with reference to the drawings. This digital VTR
The system uses two sets of closely spaced rotating magnetic heads attached to a rotating drum of a tape guide drum at an angle of 180 degrees to form predetermined tracks on a magnetic tape with alternately different recording azimuths. A digital video signal modulated (encoded) into a digital code is recorded, and it is reproduced and demodulated (decoded).

In this digital VTR, the rotational speed of the rotating magnetic head is constant, but there are three standard running speeds of the magnetic tape during recording and reproduction: LP mode, SP mode, and HD mode. ,V,2V,4
V (where V is a predetermined speed value). In this case, the recording digital video signal is in LP mode, SP
The band is compressed according to the mode and HD mode, and
The transmission rate of the digital video signal is set to R, 2R, and 4R depending on the LP mode, SP mode, and HD mode, respectively.
(However, R is set to a predetermined transmission rate value).

In FIG. 3(A), the rotating magnetic head
The data structure of one inclined track (one segment) of a digital video signal recorded on a magnetic tape is shown. Figure 3
In (A), the left end is the entry side of the rotating magnetic head, and the right end is the separation side. MG (margin) and IBG (interblock gap) are non-recorded sections of the signal. P
A pulse with a frequency equal to the data bit frequency is recorded in the RA (preamble) or POA (postamble), and this is used as the P for bit clock extraction during playback.
LL is supplied. ATF pilot is a pilot for automatic tracking. Video and audio data are
It is composed of a plurality of consecutive sync blocks, and each sync block has a sync, ID (
identification data) and parity.

[0010] When recording a digital video signal on a magnetic tape, the standard running speed of the magnetic tape at that time is L.
Discrimination data ID-LP, ID-SP or ID depending on whether the mode is P mode, SP mode or HD mode.
- HD is recorded in each sync block of video and audio data.

Next, referring to FIG. 1, this digital VT
The main parts of the R recording circuit will be explained. Reference numeral 1 indicates a magnetic tape on which the above-mentioned modulated (encoded) digital video signal is recorded, 2 indicates the above-mentioned two sets of rotating magnetic heads, and the magnetic tape 1 is moved at a different speed than the recording speed (several times the recording speed, The rotary magnetic head 2 reproduces the modulated (encoded) digital video signal recorded on the magnetic tape at variable speeds (cue reproduction, review reproduction, etc.), and outputs it to the reproduction amplifier. 3 and an equalizer 4, and is supplied to a demodulator 5 for demodulation (decoding).

The digital video signal from the demodulator 5 is LP
It is commonly supplied to the time axis correction circuit 6 of the mode, the time axis correction circuit 7 of the SD mode, the time axis correction circuit 8 of the HD mode, and the discrimination data detection circuit 9. The time axis correction circuits 6, 7 and 8 each include a memory, a write clock generation circuit,
Although it is equipped with a read clock generation circuit, etc., the frequency of the write clock signal and read clock signal is
F, 2F, and 4F (where F is a predetermined frequency value) are selected depending on the P mode, SD mode, and HD mode, respectively.

The detection signal of the discrimination data detection circuit 9 controls the writing of digital video signals into the memories of the time axis correction circuits 6, 7, and 8, and the detection signal of the discrimination data ID-LP is controlled by the discrimination data detection circuit 9. The sync block of video and audio data is written only to the memory of the time axis correction circuit 6 in LP mode, and the discrimination data I
The sync block of the detected video and audio data of D-SD is written only to the memory of the time axis correction circuit 7 in the SD mode, and the sync block of the detected video and audio data of the discrimination data ID-HD is written as follows. It is written only to the memory of the time axis correction circuit 8 in HD mode. To further explain this with reference to FIG. 2, as shown in FIG. 2(A), on the magnetic tape, for example, there is an area where a digital video signal in SD mode is recorded, and an area where a digital video signal in HD mode is recorded. The modulated digital video signal from the rotating magnetic head 2 when the rotating magnetic head scans diagonally across the boundary line when the two areas border each other is as shown in FIG. 2(B). signal part a,
b, c are SD modes, followed by signal parts d, e
is in HD mode. Therefore, as shown in FIG. 2(C), the discrimination data for the sync blocks in the signal portions a, b, and c in the SD mode is ID-SD, and the discrimination data for the sync blocks in the signal portions d and e in the HD mode is ID-SD. - Since it is HD, signal portions a, b, and c are demodulated (decoded) and then written only to the memory of the time axis correction circuit 7 in SD mode, and signal portions d and e are demodulated (decoded). It can be seen that the data is written only to the memory of the time axis correction circuit 8 in HD mode.

The digital video signals in LP, SD, and HD modes whose time axis errors have been corrected from the time axis correction circuits 6, 7, and 8 have clock signal frequencies of f, 2f, and 4f (respectively) for signal processing. f is a predetermined frequency value) is supplied to the digital video signal processing circuits 10, 11, and 12 in LP, SD, and HD modes and subjected to signal processing. and 12, and using a timing signal generated from the timing generation circuit 13 according to the discrimination data from the discrimination data detection circuit 9, for each sync block for band compression,
written to the correct address in its memory, LP, S
Interpolation processing is performed for each D and HD mode digital video signal. Note that the interpolation circuit 14 is provided separately for digital video signals in LP, SD, and HD modes, and when the mode of the digital video signal changes midway, the discrimination mode before the change is changed until the mixed section ends. The digital video signal may be played back, and when the mixed section ends, the digital video signal of the changed discrimination mode may be played back.

According to the digital VTR of the above-described embodiment, the magnetic tape 1 on which a plurality of types of digital video signals are recorded so as to form inclined tracks at different running speeds is run at a different running speed from that at the time of recording. Then, the multiple types of digital video signals are sent to the rotating magnetic head 2.
In a variable speed reproduction method for digital video signals, a plurality of types of digital video signals are reproduced on a magnetic tape 1 along with an information signal of the running speed of the magnetic tape at the time of recording.
A plurality of types of digital video signals and an information signal of the running speed of the magnetic tape 1 are recorded on the magnetic tape 1 at variable speeds, and the plurality of types of digital video signals thus reproduced at variable speeds are reproduced from the magnetic tape 1 at variable speeds. Since each signal is processed separately according to the information signal of the traveling speed of the vehicle, it is possible to distinguish between multiple types of digital video signals reproduced at variable speeds and supply them to the time axis correction circuit for time axis correction processing. Even if a plurality of types of digital video signals are mixedly recorded on a magnetic tape at different running speeds, there is no possibility that the playback screen will be disturbed.

[0016]

According to the present invention described above, a magnetic tape on which a plurality of types of digital video signals are recorded so as to form inclined tracks at different running speeds can be run at a different running speed from that during recording. In a digital video signal recording and reproducing method in which multiple types of digital video signals are reproduced by a rotating magnetic head, multiple types of digital video signals are recorded on a magnetic tape together with an information signal of the running speed of the magnetic tape at the time of recording. Then, multiple types of digital video signals and information signals of the running speed of the magnetic tape are reproduced from the magnetic tape at variable speeds, and the multiple types of digital video signals reproduced at variable speeds are reproduced at different speeds of the running speed of the magnetic tape. Since each signal is processed separately according to the information signal, it is possible to distinguish between multiple types of digital video signals reproduced at variable speeds and perform signal processing. Even if video signals are mixed and recorded, there is no risk that the playback screen will be distorted.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention.

[Figure 2] Explanatory diagram of variable speed playback

[Figure 3] Diagram showing the data structure of a digital video signal

[Explanation of symbols]

1 Magnetic tape 2 Rotating magnetic head 6-8 Time axis correction circuit 9 Discrimination data detection circuit 10-12 Signal processing circuit 13 Timing generation circuit 14 Interpolation circuit

Claims (1)

[Claims] [Claim 1] A magnetic tape on which a plurality of types of digital video signals are recorded so as to form inclined tracks at different running speeds is run at a running speed different from that at the time of recording, and the plurality of types of digital video signals are recorded. In a digital video signal recording and reproducing method in which the digital video signals are reproduced by a rotating magnetic head, the plurality of types of digital video signals described above are recorded on a magnetic tape together with an information signal of the running speed of the magnetic tape at the time of recording, and the above-mentioned video signals are recorded from the magnetic tape. A plurality of types of digital video signals and information signals of the running speeds of the magnetic tapes are reproduced at variable speeds, and the plurality of types of digital video signals thus reproduced at variable speeds are reproduced according to the information signals of the running speeds of the magnetic tapes reproduced at variable speeds. , a digital video signal recording and reproducing method characterized by processing each signal separately.