JP2667154B2 - Video signal recording and playback device - Google Patents

Description

The present invention relates to a video signal recording / reproducing apparatus. In particular, the present invention relates to a video signal recording / reproducing apparatus that changes the number of scanning lines to narrow the frequency band of a recording signal when converting an input video signal into a recording signal. 2. Description of the Related Art With the advent of the new media age, high-definition television has been actively developed. In Japan, the method called HDTV is particularly well known. This is being promoted by the Japan Broadcasting Corporation,
There are provisional standards shown in Table 1. To record a wideband video signal with a VTR in this way, (1) the video signal is recorded in multiple channels. (2) Increase the tape / head relative speed. There is a method. When trying to record a wideband video signal by introducing the above-mentioned method (1) or (2) into a VTR for the current television system such as the NTSC system, since the condition of H arrangement is limited, 1 If the number of horizontal scanning lines in the track is changed or the track pitch is changed, the horizontal synchronization signal recording positions are arranged between adjacent tracks, that is, the H arrangement is not established. However, considering that a signal to be recorded is a high-definition video signal, it is necessary to minimize crosstalk from an adjacent track, and it is important that H arrangement is established. Further, in order to easily perform special reproduction, it is necessary that the H arrangement is established. Conventionally, it has been attempted to mechanically achieve the H arrangement by changing the tape feed speed or the like. Problems to be Solved by the Invention Normally, when recording an input analog signal as it is,
Although all the scanning lines of the input signal are unavoidably recorded, if it is purely an information recording device, it is not necessary to record up to the part where there is no video signal such as vertical blanking, and even the information unnecessary in the conventional method You are recording. For general video signals such as NTSC, such redundancy is not a problem, but high-definition video signals with a bandwidth of 20 MHz or more are converted into narrow-band signals by channel division, and further divided into segments for VTR. In such cases, even a small amount of such redundancy has a significant effect on the final performance of the system. By the way, in the current television system VTR and the like, there is a problem of the crosstalk between adjacent tracks, particularly the influence of a horizontal synchronization signal. For this reason, an H arrangement method in which recording positions of the horizontal synchronization signals are aligned between adjacent tracks is employed. When recording a high-quality video signal, problems such as crosstalk are much more severely affected than those of the current system, and H arrangement between adjacent tracks is indispensable. Also, in order to enable special reproduction such as still, slow, etc., it is necessary to arrange H in order. Now, let us consider a case where a video signal is divided into two channels as shown in FIG. 2, the time axis is extended twice, and recorded on a tape in three segments. In FIG.
24 is the magnetic tape, 25 is the segment track, v _t is the tape feed speed, θ is the video track tilt angle when the tape is running, α
_HD is an inter-field H alignment, β _H is an inter-segment H alignment, and P is a segment track pitch. Assuming that one frame is thinned to 1046 lines as described later, the distance on the tape during one horizontal scanning period changes due to the channel division or the segment division, but 1046 (6 × 2) = 87 +
Since it is 1/6 line, α _H = (5/2) H, β _H = (5/6)
When it becomes H, the H arrangement is established as shown in FIG. In FIG. 3, 26 is a magnetic tape, 27 is a segment track, and 28 is a horizontal synchronization position. However, due to the parameter settings such as the number of scanning lines per segment track and tape feed speed v _t , β _H = 1H
, The recording pattern becomes as shown in FIG.
It will not line up. Parameters such as the tape feed speed v _t may be changed to establish the H arrangement.
In a VTR for recording high-definition video signals, the recording bandwidth, S /
The setting of N, recording time, and the like must be performed more strictly than a general VTR, and it is not possible to determine each parameter appropriately. In addition, the tape feed speed v _t , H between the fields
The parameters such as the alignment α _H and the track pitch P are mechanically related to each other, and cannot be determined independently of each other. If the value of one parameter is determined, it influences the other parameters. The degree is small,
It is very difficult to establish an H sequence after setting all parameters to optimum values. In view of the foregoing, the present invention eliminates unnecessary portions, such as blanking, of a video signal, extends the channel in the time axis, records the segment on a magnetic tape, and then electrically shifts the video signal data in the time axis direction. Accordingly, an object of the present invention is to provide a video signal recording / reproducing apparatus in which H arrangement is always established regardless of the number of horizontal scanning lines, the tape feed speed, and the like. Means for Solving the Problems The recording / reproducing apparatus of the present invention comprises NM (N and M are integers M) of input video signals composed of N scanning lines per frame.
A circuit for dividing the video signal of the scanning line of ≧ 1) into n channels (n is an integer and n ≧ 2), and extending the video signal of each of the divided channels by approximately nN / (N−M) times. A circuit for dividing one field of the video signal of each channel extended in the time axis into L segments (L is an integer and L ≧ 2); and a track for adjoining the divided video signal on the magnetic tape. At least a circuit for shifting the time axis in the segment unit for a predetermined time so that the recording positions of the horizontal synchronizing signals are arranged in a line, and one field of the video signal of each channel shifted in the time axis is used as a helical recording track of an L segment. It is characterized in that the data is recorded on a recording medium by a scanning video tape recorder. According to the present invention, the input video signal composed of N scanning lines per frame, except for M scanning lines such as vertical blanking, in order to more efficiently narrow the bandwidth of one frame per frame. After forming NM scanning lines, the scanning lines are divided into n channels, and the video signal of each channel is expanded in time axis by approximately nN / (NM) times, and the expanded video signal of each channel is obtained. Is recorded on the magnetic tape in L segments. And even if the H sequence is not established due to the above operation, the recording bandwidth, S /
The H arrangement can be established by electrically shifting the recording signal of each segment by a predetermined time after freely performing tradeoffs such as N and recording time. Embodiment In this embodiment, a high-definition video signal having a frequency of 30 Hz per frame and 1125 scanning lines is considered. FIG. 5 shows one frame of a high-definition video signal and its processed. As shown in FIG. 5 (a), of the 1125 lines, the first field is 504 lines from No. 51 to No. 554, and the second field is 504 lines from No. 613 to No. 1116, for a total of 1008 lines. Is the active line. In order to narrow the signal band and lengthen the recording wavelength, this video signal is divided into two channels and recorded on a magnetic tape in three segments per field. It is also assumed that the mechanical inter-segment H alignment is β _H = 1H. FIG. 1 shows a block diagram of a video signal recording / reproducing apparatus according to an embodiment of the present invention. In FIG. 1, 1 is an input terminal of a video signal, 2 is an A / D converter, 3 is a blanking detection and removal circuit, 4 is a two-channel division and time base expansion circuit, 5 is a segment processing and time base shift circuit, 6 and 7 are D / A converters, 8 and 9 are FM modulators, 10 and 11 are recording heads, 12 is a magnetic tape, 13 and 14 are reproduction heads, 15 and 16 are FM demodulators, 17 and 18 are A / D converter, 19 is a time axis shift and segment processing circuit, 20 is a time axis compression and 2-channel synthesis circuit, 21 is a blanking addition circuit, and 22 is D /
The A converter 23 is a video signal output terminal. The operation of the video signal recording / reproducing apparatus of the present embodiment configured as described above will be described below. The high-definition video signal shown in FIG. 5A input from the input terminal 1 is converted into a digital quantity by the A / D converter 2 and then input to the blanking detection and removal circuit 3. Here, V necessary for head switching, segment processing, etc.
With the remaining 38 blanking lines remaining, 79 unnecessary V blanking lines are discarded and the number of recording lines is reduced to 1046 lines, as shown in FIG. 5 (b). Next, the two-channel dividing and time-base expanding circuit 4 first divides the data into two channels, and then expands the time base by 2 × 1125/1046 times, as shown in FIG. 5 (c). The segment processing and time axis shift circuit 5 is composed of a frame memory, and once the video signal as shown in FIG. 5 (c) is once written into the memory, 87 1/6 lines per frame per channel are converted into one segment. In one segment, 84 lines are set as active lines, and the preceding and following lines are set as blanking lines. The first segment of the video signal subjected to the segment processing as described above is used as is, the second segment is 1/6 H, the third segment is 2/6 H, the fourth segment is 3/6 H, and the fourth segment is 4 / H. The 6H and 5th segments are read out after being time-shifted (delayed in this case) by 5 / 6H respectively. By this operation, the video signal becomes the fifth
The timing relationship is as shown in FIG. D /
After conversion into analog quantities by the A converters 6 and 7 and recording on the magnetic tape 12 via the FM modulators 8 and 9 and the recording heads 10 and 11, if the time axis shift is not performed, it is shown in FIG. A recording pattern like this is one in which the H arrangement is established as shown in FIG. At the time of reproduction, the original video signal shown in FIG. 5A can be obtained by performing the operation completely opposite to that at the time of recording. That is, when the recording tracks shown in FIG. 6 are reproduced by the reproducing heads 13 and 14 and demodulated by the FM demodulators 15 and 16, the reproduced video signal at that time is as shown in FIG. 5D. This reproduced video signal is converted into a digital value by the A / D converters 17 and 18, and then the time axis shift and segment processing circuit.
Enter in 19. Here, once the reproduced video signal has been written to the memory, the first segment is 5/6 H, and the second segment is 4/6 H
H, the third segment is 3 / 6H, the fourth segment is 2 / 6H,
The fifth segment is read with a delay of 1 / 6H. The sixth segment is read as it is. This time axis shift processing makes the distances of all the horizontal synchronization periods equal. Then, the order of the active line and the blanking line is exchanged and the active line and the blanking line are separated to form the video signal of FIG. This signal is multiplied by 1046/2 × 1125 by the time axis compression and two-channel synthesizing circuit 20, and then two channels are synthesized into one channel, as shown in FIG. 5 (b). The blanking addition circuit compensates for the missing blanking and adds up
If the analog signal is returned to the D / A converter 22 after the 1125 lines, the video signal shown in FIG. In this example, the mechanical segment H alignment β _H
There has been described a IH, beta values of _H There much even by appropriately selecting the time-axis shift amount in the time-axis shift and the segment processing circuit 5,9 can be established the H line. In this embodiment, the input video signal is a high-definition video signal having 1125 scanning lines, of which 79 lines are blanked and 1046 lines are recorded. However, in general, a video signal having N scanning lines is used. Of these, only the M lines are deleted and the NM scanning lines are recorded. Further, in the present embodiment, the case where the video signal is extended in two-channel division time axis and recorded in three segments is considered. However, in general, even when the n-channel division time axis is extended and recorded in L segments per field, the time axis shift amount is It is clear that the H arrangement of the recording pattern can be established by appropriately selecting. As described above, according to the present invention, when a wide-band signal such as a high-definition video signal is recorded on a VTR by a channel division time-axis expansion segment method, unnecessary portions such as V blanking of an input video signal are previously removed. By removing and increasing the time axis expansion rate by that amount, more efficient signal narrowing can be achieved. When the H arrangement of the recording pattern is not established by the above operation or the like, the H arrangement is established without changing the tape feed speed or the like by electrically shifting the video signal for a predetermined time in the segment unit. Can be. Conversely, when determining parameters such as the tape feed speed and the track pitch, it is not necessary to take the H arrangement into consideration, so the degree of freedom in setting the parameters is greatly expanded, and the effect is large.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a video signal recording / reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a pattern diagram showing a general recording track on a magnetic tape, and FIG. FIG. 4 shows a recording track pattern when the H arrangement is mechanically established.
Recording track pattern diagram when the arrangement is not established,
FIG. 5 is a diagram showing the change in the time axis of the video signal input to the video signal recording / reproducing apparatus of FIG. 1 and the video signal after being subjected to processing such as channel division, and the positional relationship between the active line and blanking. FIG. 6 and FIG. 6 are recording track pattern diagrams in the case where H arrangement is established by electrical processing. 1 ... input terminal, 2, 17, 18 ... A / D converter, 3 ... blanking detection and removal circuit, 4 ... 2 channel division and time axis expansion circuit, 5 ... segment processing and time axis shift Circuit, 6,7,22 …… D / A converter, 8,9 …… FM modulator, 10,1
1 ... Recording head, 12 ... Magnetic tape, 13,14 ... Reproduction head, 15,16 ... FM demodulator, 19 ... Time axis shift and segment processing circuit, 20 ... Time axis compression and 2-channel synthesis Circuit, 21 ... Blanking addition circuit, 23 ... Output terminal, 24,26 ... Magnetic tape, 25,27 ... Segment track, 28 ... Horizontal synchronization position.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Kiyoshi Sasaki               1006 Kadoma Kadoma Matsushita Electric Industrial               Inside the corporation (72) Inventor Tatsushi Sakauchi               1006 Kadoma Kadoma Matsushita Electric Industrial               Inside the corporation (72) Inventor Katsuya Yokoyama               1-10-11 Kinuta, Setagaya-ku, Tokyo Japan               The Broadcasting Corporation Broadcasting Research Institute (72) Inventor Hiromichi Shibatani               1-10-11 Kinuta, Setagaya-ku, Tokyo Japan               Broadcasting Society Broadcast Technology Laboratory                (56) References JP-A-61-196407 (JP, A)                 JP-A-53-36210 (JP, A)                 JP-A-60-209970 (JP, A)

Claims (1)

(57) [Claims] 1. Of the input video signals composed of N scanning lines in a frame, NM video signals (N and M are integers and M ≧ 1) are input to n channel ( n is an integer and n≥2, and a circuit for dividing the video signal of each of the divided channels into approximately nN / (N
-M) a circuit for extending the time axis by a factor of two, a circuit for dividing one field of the video signal of each channel extended for the time axis into L segments (L is an integer and L ≧ 2), and an image for each of the divided channels. At least a circuit for shifting a signal on a time axis basis for a predetermined time in the segment unit so that recording positions of horizontal synchronization signals are arranged between adjacent tracks on a magnetic tape; A video signal recording / reproducing apparatus characterized in that a field is recorded on a recording medium by a helical scan video tape recorder as an L segment recording track.