JPH04295653A - Recording and reproducing system for digital image signal - Google Patents

Abstract

PURPOSE:To shorten mode switch over time required when reproducing digital image signals in a plurality of modes successively from the magnetic tapes where digital signals in a plurality of modes are successively recorded by changing a standard traveling speed. CONSTITUTION:In a digital image signal recording system where a first digital image signal is recorded on a magnetic tape traveling at a first traveling speed as if forming a slanting track and then a second digital image signal is recorded on a magnetic tape traveling at a second traveling speed as if forming a slanting track by means of a rotary magnetic head, both the first digital image signal and an information signal which shows the second traveling speed are recorded on the magnetic tape traveling at the first traveling speed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video signal recording and reproducing system suitable for use in a digital VTR.

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). This digital VTR has a rotating drum for the tape guide drum.
The magnetic tape is modulated (encoded) into a predetermined digital code by two sets of closely spaced rotating magnetic heads installed at an angle of 80 degrees so as to form inclined tracks of alternately different recording azimuths on the magnetic tape. It records digital video signals, and also reproduces and demodulates (decodes) them. This digital VTR has LP mode (long-term recording video signal mode), SD mode (NT
Video signal modes such as SC system and PAL system) and HD
There are three modes (modes for high-quality video signals such as MUSE video signals), and three types of standard running speeds for magnetic tape are set for these modes, the ratio of which is 1:2:4, and at least , HD mode and SD mode video signals, and HD mode and LP mode video signals have different signal formats. Note that the rotation speed of the rotating magnetic head is constant for each mode. Also, L
The recording rates of digital video signals in P, SD and HD modes are 15MBPS, 30MBPS and 60MB, respectively.
It is PS. In the LP mode and the SD mode, all of the two sets of rotating magnetic heads described above are used for recording and reproduction, and in the HD mode, one set of rotating magnetic heads arranged close to each other is used.

0003

[Problem to be Solved by the Invention] In such a digital VTR, digital video signals in a plurality of modes are sequentially recorded on one magnetic tape at different standard running speeds, and the magnetic tape is played back. think about it. For example, a magnetic tape is run at the standard running speed in HD mode to record a digital video signal in HD mode, and then the running speed of the magnetic tape is changed to the standard running speed in SD mode to record the digital video signal in SD mode. Considering signal recording, the magnetic tape running speed will be changed to the SD mode standard running speed after recording of the digital video signal in HD mode is completed, so the transition period of the magnetic tape running speed will be , the signal cannot be recorded (therefore, the signal cannot be reproduced in that part), and the SD mode digital video signal is recorded only after the magnetic tape is running stably at the SD mode standard running speed. That's a big deal. Therefore, when reproducing such a magnetic tape, first reproduce an HD mode digital video signal from the magnetic tape,
Next, when reproducing a digital video signal in SD mode, there is a drawback that mode switching takes a long time.

In view of the above, the present invention provides a method for sequentially reproducing digital video signals of a plurality of modes from a magnetic tape on which digital video signals of a plurality of modes are sequentially recorded at different standard running speeds. This paper attempts to propose a recording method and a reproducing method for digital video signals that can shorten mode switching time.

[0005]

[Means for Solving the Problems] A digital video signal recording system according to the present invention uses rotating magnetic heads Ha to Hd to form a first inclined track on a magnetic tape TP running at a first running speed. In a digital video signal recording method, a digital video signal is recorded, and subsequently a second digital video signal is recorded so as to form an inclined track on a magnetic tape TP running at a second running speed, A second digital video signal is transmitted along with a first digital video signal onto a magnetic tape TP running at a first running speed.
An information signal indicating the running speed of the vehicle is recorded.

The digital video signal reproducing method according to the present invention records a first digital video signal by means of rotating magnetic heads Ha to Hd so as to form an inclined track on a magnetic tape TP running at a first running speed. Subsequently, a second digital video signal is recorded on the magnetic tape TP running at a second running speed so as to form an inclined track, and the first digital video signal is recorded on the magnetic tape TP running at a first running speed. from a magnetic tape TP on which an information signal indicating a second running speed is recorded together with a digital video signal of
The rotating magnetic heads Ha to Hd reproduce the first and second digital video signals and also reproduce the information signal indicating the second running speed, and drive the tape running with the information signal indicating the second running speed. Means PR, CP, CM, 1, 2,
3.

[0007]

[Operation] In the digital video signal recording method according to the present invention, the first digital video signal is recorded by the rotating magnetic heads Ha to Hd so as to form an inclined track on the magnetic tape TP running at the first running speed. Subsequently, a second digital video signal is recorded so as to form an inclined track on the magnetic tape TP running at a second moving speed. Then, an information signal indicating the second running speed is recorded together with the first digital video signal on the magnetic tape TP running at the first running speed.

In the digital video signal reproduction method according to the present invention, a first digital video signal is recorded on the rotating magnetic heads Ha to Hd so as to form an inclined track on a magnetic tape TP running at a running speed of 1; The second following
recording a second digital video signal so as to form an inclined track on a magnetic tape TP running at a running speed of
A first digital video signal is recorded on the magnetic tape TP, which is running at a first running speed, and an information signal indicating a second running speed. The first and second digital video signals are reproduced, and at the same time, an information signal indicating the second traveling speed is reproduced. Then, the information signal indicating the second running speed is sent to the tape running drive means PR, CP, CM, 1, 2.
, 3.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, referring to FIG. 4, the rotating magnetic head and the like will be explained. Ha, Hb, Hc, Hd are two sets of rotating magnetic heads which are arranged close to each other and have gaps of opposite azimuths, and the tape consists of a fixed drum and a rotating drum so as to alternately form inclined tracks of different recording azimuths. They are attached to the rotating guide drum SLD of the guide drum device with an angular interval of 180 degrees. TP is a magnetic tape, which is guided by a pair of guide pins GP to be wound around a stationary drum and a rotating drum with each winding angle of 180 degrees. These rotating magnetic heads H
a, Hb, Hc, and Hd record a digital video signal modulated (encoded) into a predetermined digital code on the magnetic tape TP, and also reproduce and demodulate (decode) it. This magnetic tape TP has a capstan C
P and pinch roller PR to make it run. CM is a motor that rotationally drives the capstan CP. A frequency generator 1 generates a frequency signal having a frequency corresponding to the rotation of the capstan CP. 2 is a servo circuit for the capstan motor CM, and frequency generator 1
and a magnetic tape running speed command signal (here, H
The rotation of the capstan motor CM is controlled in response to command signals of standard running speeds in D mode, SD mode, and LP mode.

[0010] This digital VTR has an HD mode (M
There are four modes: high-quality video signal mode (USE system, etc.), SD mode (video signal mode, NTSC system, PAL system, etc.), and LP mode (long-term recording video signal mode).
For these modes, there are standard running speeds for the three types of magnetic tapes mentioned above, namely HD mode, SD mode and LP mode, and the ratio thereof is 4:2:1. Note that the rotation speeds of the rotating magnetic heads Ha, Hb, Hc, and Hd are constant regardless of the difference in the standard running speed of the magnetic tape TP. Also, the recording rate of digital video signals in HD, SD and LP modes is 60MBPS and 30MB, respectively.
PS, 15MBPS. In HD mode, a pair of rotating magnetic heads Ha, Hb (or Hc, H
d) is used for recording and reproduction, and in the SD mode and LP mode, all of the above-mentioned two sets of rotating magnetic heads Ha, Hb and Hc, Hd are used for recording and reproduction.

As shown in FIG. 6, a digital video signal in HD mode is recorded on a magnetic tape TP running at a standard running speed V-HD in HD mode, so as to form an inclined track, and then the running speed of the magnetic tape TP is When changing the running speed of the magnetic tape TP to the SD mode standard running speed V-SD without stopping the magnetic tape TP, and recording an SD mode digital video signal so as to form an inclined track on the magnetic tape TP. The operation will be explained with reference to the flowchart in FIG.

The magnetic tape TP running at the standard running speed V-HD in HD mode is
When recording a D-mode digital video signal, in step ST-1, the mode conversion command [recording mode A] is executed.
mode, here a command to convert from HD mode to a different B mode, here SD mode] is input, and if NO, wait; if YES, step ST-2 to move to. Step ST
At step ST-2, the input of the digital video signal for recording signal processing of the digital video signal in the A mode, that is, the HD mode is stopped, and then the process proceeds to steps ST-3 and ST-8 in parallel. In step ST-3, information on the B mode, that is, the SD mode (this is the standard running speed of the magnetic tape TP) is written in the "next recording mode information area" of the subcode over several inclined tracks or ten inclined tracks. and signal format information), and record the count ID for each inclined track in the "count ID area" of the subcode as X, X-1,
, 3, 2, 1, 0 are recorded. Further, in step ST-8, recording signal processing of a digital video signal in B mode, that is, SD mode is started.

Referring to FIG. 5, one inclined track (one segment) of the digital video signal recorded on the magnetic tape TP by the rotating magnetic heads Ha to Hd.
The data structure of is explained. In FIG. 5, 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. PRA (preamble) or PO
In A (postamble), a pulse having a frequency equal to the data bit frequency is recorded, and this is reproduced during playback and supplied to the PLL for bit clock extraction. ATF pilot is a pilot for automatic tracking. Video and audio data consists of a series of multiple sync blocks, each of which has an ID.
It consists of data and parity. In addition, there is an area for audio data and a subcode, and this subcode includes the above-mentioned "next recording mode information area" and "count ID area" to record SD mode information and count ID, respectively. .

[0014] In step ST-4, A mode, ie,
It is determined whether or not the digital recording signal processing in HD mode has been completed. If NO, it waits; if YES,
The process moves to step ST-5. In step ST-5,
The servo of the capstan CP is changed from A mode, that is, HD mode servo, to B mode, that is, SD mode servo, and the running speed of the magnetic tape TP is changed from the standard running speed V-HD of HD mode to SD. Change the mode to standard traveling speed V-SD. In step ST-6, the servo (
It is determined whether or not the B mode (ie, SD mode servo) is locked. If NO, the process waits; if YES, the process moves to step ST-7. Also, step ST-8
After that, the time required for servo lock in step ST-9,
That is, the running speed of the magnetic tape TP changes from the standard running speed V-HD in HD mode to the standard running speed V-SD in SD mode.
After a delay of the time required to transition to step ST
-Move to 7. The dot area in FIG. 6 indicates a portion of the magnetic tape TP where signals are not recorded.
It shows a region where the traveling speed of P changes and the servo of the capstan motor CM is not yet locked. Step ST
At -7, recording of a digital video signal in B mode and SD mode is started.

Next, the standard running speed V-HD in HD mode
An HD mode digital video signal is recorded on a magnetic tape TP running at a speed such that an inclined track is formed, and then,
The running of the magnetic tape TP is temporarily stopped, the magnetic tape (cassette tape) TP is loaded into the digital VTR, and the running speed of the magnetic tape TP is set to V-.
The recording operation when an SD mode digital video signal is recorded on the magnetic tape TP by running the magnetic tape TP in such a manner as to form an inclined track will be described with reference to the flowchart of FIG.

In this case, the magnetic tape TP is a digital VT.
After R is loaded, the operation starts from the point where it is rewound by several to ten inclined tracks and stopped. In step ST-1, it is determined whether a B mode, ie, SD mode, recording command has been input. If NO, the process waits; if YES, the process moves to step ST-2.

In step ST-2, the magnetic tape is run at the A mode, that is, the standard running speed V-HD of the HD mode, and the recorded signal is reproduced. In step ST-3, it is determined whether the phase servo of the capstan motor CM is locked, that is, whether the magnetic tape TP is running at the A mode, that is, the standard running speed V-HD of the HD mode. , if NO, it waits; if YES, it moves to step ST-4. In step ST-4, information on the B mode, that is, the SD mode, is recorded in the "next recording mode information area" of the subcode of the magnetic tape TP over several inclined tracks or over ten inclined tracks.

In step ST-5, it is determined whether the magnetic tape TP has reached the position at which it was loaded into the digital VTR (LD: loading), in other words, it has reached the recording end position of the digital video signal in the A mode, that is, the HD mode. If it is NO, it waits, and if it is YES, it goes to step S.
Move to T-6. In step ST-6, the recording block end ID indicating the end of the recording area of the A mode of the magnetic tape TP, that is, the HD mode digital video signal, is set to the "recording block end ID" of the subcode of the last inclined track. Record it in "Elijah" of ID. Note that instead of recording the recording block end ID, a count ID may be recorded in the subcode and 0 as the count ID may be recorded in the subcode of the last inclined track, as in the case of FIG. . In step ST-7, the recording mode is changed from A mode, that is, HD mode, to B mode and SD mode, that is, the running speed of the magnetic tape is changed from the standard running speed of HD mode, V-HD, to the standard running speed of SD mode. Change to V-SD. In step ST-8, it is determined whether the phase servo is locked, that is, whether the running speed of the magnetic tape TP has reached the standard running speed V-SD of the SD mode. If so, proceed to step ST-8. In step ST-9, recording of a B mode, ie, SD mode, digital video signal is started so as to form an inclined track on the magnetic tape TP.

Next, as shown in FIG. 1 or 2, the HD
The HD mode digital video signal is recorded on the magnetic tape TP running at the standard running speed V-HD of the mode, and then the magnetic tape TP is run at the standard running speed of the SD mode, and the SD mode digital video signal is recorded. The operation of sequentially reproducing digital video signals in HD mode and SD mode from the magnetic tape TP on which the signals are recorded will be explained with reference to the flowchart in FIG.

In step ST-1, the A mode, ie, HD mode digital video signal on the magnetic tape TP is reproduced. In step ST-2, it is determined whether or not B mode, that is, SD mode information is detected from the "next recording mode information area" of the subcode. If NO, standby; if YES, step ST-2. Move to ST-3. In step ST-3, it is determined whether the magnetic tape TP has reached a mode change point, that is, whether a count ID of 0 or a recording block end ID has been detected;
If NO, wait; if YES, step ST
-Move to 4. In step ST-4, the running speed of the magnetic tape is changed from the standard running speed V-HD of the A mode, that is, the HD mode, to the standard running speed V-SD of the B mode, that is, the SD mode. Also, at this time, the reproduction signal processing circuit for the digital video signal is changed from the HD mode circuit to the S
Switch to D mode circuit. This magnetic tape TP
During the transition period of the running speed, the rotating magnetic head scans the dot area on the magnetic tape shown in FIG. Step ST
-5, whether or not the phase servo of the capstan motor CM is locked, that is, whether the running speed of the magnetic tape TP is SD
It is determined whether the standard running speed of the mode has been reached, and NO
If so, it waits, and if YES, it moves to step ST-6. In step ST-6, B on the magnetic tape TP is
mode, that is, playback of the digital video signal in SD mode is started.

Next, as described above, the mode switching time when sequentially reproducing digital video signals of a plurality of modes from a magnetic tape on which digital video signals of a plurality of modes have been sequentially recorded is shorter than usual. This will be explained with reference to FIG. On the magnetic tape TP, an HD mode digital video signal and an SD mode digital video signal are recorded via a seam (unrecorded portion). In a normal case, first, a digital video signal in HD mode is reproduced from a magnetic tape TP running at a standard running speed V-HD in HD mode, and the magnetic tape continues at the standard running speed V-HD in HD mode. After passing the seam at time t0 to t1 and decoding the recording mode ID of B mode, that is, SD mode, the magnetic tape is in SD mode.
The speed changes toward the standard running speed V-SD of the mode (capstan motor CM speed servo period), then the speed servo of the capstan motor CM locks, and immediately thereafter the phase servo locks, and the magnetic tape The traveling speed becomes the standard traveling speed in SD mode.

On the other hand, in the case of the embodiment, at the end of the recording area of the HD mode digital video signal of the magnetic tape TP running at the standard running speed V-HD, the subcode "next recording mode information" is displayed. Elijah's B mode,
That is, since the SD mode information is reproduced and detected, the speed of the magnetic tape changes toward the standard running speed of the HD mode immediately after the magnetic tape enters the joint of the magnetic tape (t0) (the speed of the magnetic tape changes toward the standard running speed of the HD mode). speed servo period),
After that, the speed servo of the capstan motor CM is locked, and immediately thereafter the phase servo is locked, and the magnetic tape T
The traveling speed of P becomes the standard traveling speed V-SD in the SD mode. Therefore, the mode switching time can be shortened by a time approximately equal to the time during which the magnetic tape TP travels through the joint portion (between times t0 and t1).

Next, an example of application will be explained with reference to FIG. In a digital VTR, for example, an S
When recording a D-mode digital video signal, in step ST-1, for example, the remaining amount of the magnetic tape at that time is detected from the time code signal recorded on the magnetic tape TP, and the standard running speed V is detected. -Calculate (calculate) the recording time Trest, which is how many hours and minutes can be recorded using the remaining amount of the magnetic tape TP running in SD. Step ST-2
Now, set the time T that you want to record on the digital VTR from that point forward.
Enter rec. In step ST-3, the time Tre
Compare st and time Trec, and find that Trest>Tre
If it is YES, it is the end, that is, the recording of the digital video signal is continued,
If NO, the process moves to step ST-4. In step ST-4, when the digital video signal is recorded by running the magnetic tape TP in another mode with a lower standard running speed than the SD mode, for example, the standard running speed V-LP in the LP mode, then The recording time of how many hours and minutes can be recorded using the remaining amount of the magnetic tape TP is calculated (calculated). In step ST-5, both the remaining recording time of the magnetic tape in the original mode, ie, SD mode, and in another mode, ie, LP mode, are displayed on the display. Step S
At T-6, the user determines whether or not to change the mode; if NO, the process ends, that is, the recording of the digital video signal continues; if YES, the process ends.
The process moves to step ST-7. In step ST-7,
When the magnetic tape TP is running at the standard running speed V-SD in the SD mode, the LP mode information is stored in the "next recording mode information area" of the subcode over several inclined tracks or ten inclined tracks. After recording, the running speed of the magnetic tape TP is changed from the standard running speed V-SD in the SD mode to the standard running speed V-LP in the LP mode.

[0024]

According to the present invention described above, when digital video signals of a plurality of modes are sequentially reproduced from a magnetic tape on which digital video signals of a plurality of modes are sequentially recorded at different standard running speeds. mode switching time can be reduced.

[Brief explanation of drawings]

[Figure 1] Flowchart of recording in the example

[Figure 2] Flowchart of other recording in the embodiment

[Figure 3] Flowchart of playback according to the embodiment

[Fig. 4] Diagram showing the rotating magnetic head, etc. of the embodiment

[Figure 5] Diagram showing the data structure of a digital video signal

[Fig. 6] Explanatory diagram of the record of the example

[Figure 7] Explanatory diagram of changes in running speed of magnetic tape

[Figure 8]
Application example flowchart

[Explanation of symbols]

Ha~Hd Rotating magnetic head TP magnetic tape CP capstan CM Capstan motor PR Pinch roller 1 Frequency generator 2 Servo circuit 3 System controller

Claims (2)

[Claims] Claim 1: A first digital video signal is recorded by a rotating magnetic head so as to form an inclined track on a magnetic tape running at a first running speed, and subsequently running at a second running speed. In the digital video signal recording method, the second digital video signal is recorded so as to form an inclined track on the magnetic tape, wherein the first digital video signal is recorded on the magnetic tape running at the first running speed. A digital video signal recording method characterized in that an information signal indicating the second traveling speed is recorded together with the video signal. 2. A first digital video signal is recorded by a rotating magnetic head so as to form an inclined track on a magnetic tape running at a first running speed, and subsequently running at a second running speed. A second digital video signal is recorded on the magnetic tape so as to form an inclined track, and the second digital video signal is recorded on the magnetic tape running at the first running speed together with the first digital video signal. A rotary magnetic head reproduces the first and second digital video signals from a magnetic tape recording an information signal indicating the second running speed, and reproduces the information signal indicating the second running speed. 1. A digital video signal reproducing system characterized in that an information signal indicating a running speed of No. 2 is supplied to a tape running drive means.