JPH04266277A - Video tape reproducing device - Google Patents

Abstract

PURPOSE:To attain special reproduction even in a segment recording video tape by storing a reproduction signal by a head from the video tape recorded in terms of a segment to a frame memory and reading the signal in a prescribed timing and order. CONSTITUTION:A video signal corresponding to each track obtained by a rotary head from a video tape subject to segment recording on plural tracks is stored in a frame memory 3 in a prescribed order depending on the drive speed of the video tape. Then each track signal read from the frame memory 3 under the read control of a control circuit 6 is converted into an analog signal by a D/A converter 4 and outputted as a reproduction analog signal. Thus, the video tape recorded in the segment recording system is used to attain reproduction of a still picture and vari-speed reproduction.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a videotape reproducing apparatus, and more particularly to a special reproducing apparatus for segment-recorded videotapes.

0002

[Prior Art] Conventionally, in video recording and playback devices such as VTRs, when recording information on a videotape, VH
In both the S and β systems, one field's worth of image signals is recorded on one track of the videotape. Therefore, special playback such as still image playback, double speed playback, etc. can be performed simply by varying the tape running speed. Furthermore, as an image signal recording method, a segment recording method is known in which one field of image data is recorded and reproduced over a plurality of tracks of a videotape.

0003

As described above, the segment recording method records one field's worth of image signals on a plurality of tracks. Therefore, when performing special playback of video signals from a videotape recorded using this method, it is not possible to obtain a sufficient image signal for one field by simply changing the tape running speed as in the conventional method. Unable to play.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a videotape playback device that is capable of playing back still images at double speed using a videotape recorded using the segment recording method.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, a videotape playback device according to the present invention provides video signals corresponding to each track obtained by a rotary head from a videotape in which segments are recorded on a plurality of tracks. The information is stored in a frame memory in a predetermined order determined by the running speed of the video tape, and is read out and played back. Furthermore, when the level of the RF reproduction signal obtained by the rotary head becomes equal to or less than a predetermined threshold, at least a horizontal synchronization signal stored in advance is stored in the frame memory.

[0006]

[Operation] In this invention, video signals corresponding to each track obtained by a rotary head from a video tape segment-recorded on multiple tracks are stored in a frame memory in a predetermined order determined by the running speed of the video tape, and are read out and played back. do. Furthermore, when the level of the RF reproduction signal obtained by the rotary head becomes equal to or less than a predetermined threshold, at least a horizontal synchronization signal stored in advance is stored in the frame memory.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a video tape playback apparatus according to the present invention. A videotape on which segments have been recorded is set in VTR1, and the A channel (ACH) head and B channel (B
A track signal recorded in segments using the two rotating heads of the CH) head is reproduced as a video signal,
The signal is input to the A/D converter 2.

In this embodiment, one field image signal is recorded on three tracks, and one frame image is composed of two field image signals, so a frame memory ( The special playback memory is divided into six parts. In Figure 1,
These frame memory groups are shown as one frame memory 3. The A/D converter 2 converts each track signal from the VTR 1 into a digital signal as a signal corresponding to each frame memory, supplies the digital signal to the frame memory 3, and stores the digital signal in the corresponding frame memory.

The RF level detection circuit 5 monitors the RF level of the reproduced video signal from the VTR 1, and outputs a signal indicating this to the control circuit 6 when the level falls below a predetermined threshold. That is, for example, when high-speed reproduction is performed, the area area over which the head scans the recording track becomes smaller, resulting in a deterioration of the S/N and noise becoming noticeable. Furthermore, if the S/N ratio is poor, the horizontal synchronization signal cannot be detected, resulting in loss of synchronization, making it impossible to obtain a normal reproduced image. Therefore, when the RF level detection circuit 5 detects that the RF level has become below the threshold, the control circuit 6 reads out the horizontal synchronization signal data and the black and gray intermediate color signals stored in the ROM 7 in advance, and It is output to the timing position and stored in the frame memory 3.

Under the read control of the control circuit 6,
Each track signal read from the frame memory 3 is D
The signal is converted into an analog signal by the /A converter 4 and output as a reproduced analog signal. Note that during the special playback operation, the audio is muted.

Next, the operations of still image playback, 1/2 speed playback, double speed playback, and quadruple speed playback in the case of 3-segment recording will be explained with reference to FIGS. 2 to 5. The frame memory 3 uses a frame memory divided into six parts, and during normal playback, video data is always played back through this frame memory. First, when playing back a still image, writing to the frame memory 3 is stopped in synchronization with the video frame. Reading from the frame memory 3 is always performed in the same order, and only the contents stored in the frame memory 3 are repeatedly reproduced, resulting in a still image.

FIG. 2 shows the pattern on the tape during still image playback. Numbers 1 to 6 at the top of the videotape indicate track numbers, and A and B at the bottom indicate the scanning trajectories of the ACH head and BCH head. It can be seen that the head is accurately scanning over the recording track.

FIG. 3 shows a pattern during 1/2 speed playback. During 1/2 speed playback, the tape running speed is halved, so the video data is not played back in the same order as in normal playback. In this embodiment, the following memory processing is performed using azimuth recording. In FIG. 3, the thin solid line L is the recording pattern on the tape, and the solid line M is the ACH
The running trajectory of the head, the dotted line N is the running trajectory of the BCH head,
Diagonal lines O indicate areas where recording signals can be picked up by the ACH head, and dots P indicate areas where recording signals can be picked up by the BCH head. As is clear from FIG. 3, signals can only be picked up by either the ACH head or the BCH head during one revolution of the drum. When the signal cannot be picked up, it is indicated by ×, and for each track number (1 to 6) of the pattern, 1→×→×→
The signals are reproduced in the order of 2→3→×→×→4→5→×→×→6. The signals reproduced in this way are stored in the memory allocated in this order in the frame memory 3. Note that x indicates a period in which the data is not stored in any memory. Since the readout of the frame memory 3 is constant, the video is switched in units of ⅓ field. Here, since there is a correlation between each field, the break in the video does not pose a practical problem.

FIG. 4 shows a double speed playback pattern for explaining the double speed playback operation. In FIG. 4, thin solid lines indicate recording track patterns, and thick solid lines indicate A and B.
The traveling locus of the CH head is shown, and vertically hatched areas and dotted areas indicate areas that can be read from the recording track pattern. As is clear from FIG. 4, the reproducible track area of each head is about half, and the order of output tracks is 1→4→5→2→3→6. Since it is necessary to change the order of writing into the frame memory 3, writing is performed in this order.

[0015] During high-speed playback such as double speed playback, the area scanned by the head becomes narrower as described above, and the S
/N deteriorates and it may become impossible to detect the horizontal synchronizing signal, so the RF level detection circuit 5 in Fig. 1 detects this bad condition and detects the horizontal synchronizing signal prepared in advance from the ROM 7 or the black and white signals. It outputs a gray intermediate color signal. When viewed in units of fields, the video appears to be missing in this area, but when viewed in units of frames, the video signal of this area is output in the next field, so visually the brightness and resolution of this area are , although it decreases.
Since the horizontal synchronization signal is not lost, a stable reproduced image can be obtained.

FIG. 5 shows a pattern during quadruple speed reproduction, and the area over which the head scans the recording tracks 1 to 6 is even narrower than that during double speed reproduction. Furthermore, since there are two tracks in one scan, including a track on which a signal can be picked up and a track on which no signal can be picked up, it is necessary to switch frame memories in the middle of one scan. As is clear from Figure 5, the order of the output tracks is (1 bottom → 3 top)
→ (6 down → 2 up) → (3 down → 5 up) → (2 down → 4 up) →
(5 down → 1 up) → (4 down → 6 up). Here, the number in parentheses indicates one scan, and since each track is divided into two, the track numbers are distinguished by adding upper and lower numbers. Therefore, the frame memory to be written is changed according to the order of output tracks.

[0017]

As explained above, the videotape playback device according to the present invention stores the playback signal from the head from the videotape on which segment recording has been performed in the frame memory and reads it out at a predetermined timing and order.
Special playback is also possible on segment recording video tapes. Furthermore, since the level of the reproduced RF signal from the head is monitored and when the level falls below the threshold level, a synchronization signal prepared in advance is used, so it is possible to prevent synchronization loss due to S/N deterioration.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram showing an embodiment of a video tape playback device according to the present invention.

FIG. 2 is a diagram showing a recording track of a video tape and a traveling locus pattern of a head when a still image is played back by the video tape playback device according to the present invention.

FIG. 3: 1/2 of the videotape playback device according to the present invention
FIG. 3 is a diagram showing a recording track of a video tape and a travel locus pattern of a head during double-speed playback.

FIG. 4 is a diagram showing a recording track of a video tape and a travel locus pattern of a head during double speed playback of the video tape playback device according to the present invention.

FIG. 5 is a diagram showing a recording track of a video tape and a travel locus pattern of a head during quadruple speed playback of the video tape playback apparatus according to the present invention.

[Explanation of symbols]

1 VTR 2 A/D converter 3 Frame memory 4 D/A converter 5 RF level detection circuit 6 Control circuit 7 ROM

Claims (2)

[Claims] 1. Video signals corresponding to each track obtained by a rotary head from a video tape segment-recorded on a plurality of tracks are stored in a frame memory in a predetermined order determined by correspondence to the running speed of the video tape, and are read out and played back. A videotape playback device characterized by: 2. When the level of the RF reproduction signal obtained by the rotary head becomes below a predetermined threshold, at least a horizontal synchronization signal stored in advance is stored in the frame memory. The videotape playback device described in .