JPH01152882A - Reproduction system for plural channel video signal - Google Patents

Abstract

PURPOSE:To reproduce moving part smoothly and to prevent deterioration in vertical resolution by extracting a one-channel video signal from a multiplex video signal and writing it intermittently in a picture memory and reading repetitively a signal of the same field for the picture moving part and the signal of the same frame for the part with less movement respectively for prescribed number of times. CONSTITUTION:When the movement of the picture of an A channel original video signal is less, since the picture correlation of each field is strong, odd and even fields parted timewise are combined and the result is reproduced as one-frame signal. Thus, the one-frame signal written in the picture memory is reproduced for four time repetitively in the unit of frames to obtain the reproduced video signal without deterioration in the vertical resolution. With a movement in the picture, after the odd number fields are read repetitively for four times, the even fields are reproduced repetitively for four times. Thus, the missing period of the signal is interpolated by using the one-field signal fetched in 2-frame period, then the reproduced picture not causing vibratory movement is obtained.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a method for reproducing a multi-channel video signal.
In particular, the present invention relates to a reproduction method for reproducing a video signal of one channel from a single multiplexed video signal in which original video signals of a plurality of channels are sequentially time-division multiplexed at predetermined intervals in units of frames.

BACKGROUND ART FIG. 4 shows a conventional example of a recording and reproducing system in which, for example, four channels of original video signals A to D are recorded on a recording medium by time division multiplexing and then reproduced. In the figure, four channels of original video signals A (a) to D (d) are extracted one frame at a time every four frames, and are sequentially time-division multiplexed to form a single multiplexed video signal (e). Edited. This edited multiplexed video signal (e) is recorded on a recording medium such as a video tape or a video disc.

FIG. 5 shows an example of a reproducing apparatus that reproduces a video signal of a specific channel, for example, the A channel, in the multiplexed video signal (e) read from the recording medium. In the figure, a read video signal from a recording medium is demodulated by a video signal demodulation circuit 1 and then supplied to a one frame memory 2 and a channel detection circuit 3. The channel detection circuit 3 detects the frame of the A channel of the multiplexed video signal and generates a low level signal for one frame period every four frames.

This low level signal is the write enable (W) signal (
f) to the memory 2.

As a result, only the video signal of the A channel is written to the memory 2 under the control of the write control circuit 4, while the video signal written to the memory 2 is continuously read out under the control of the read control circuit 5, and added. vessel 6
A synchronization signal is added at. As a result, a reproduced video signal (g) in which the reproduced image is updated every four frames is obtained.

Although FIG. 4 shows an example of a frame editing method in which the 4-channel original video signals A to D are edited one frame at a time in a four-frame cycle, a field editing method in which one field is edited in four-field cycles is also shown. There is also.

As mentioned above, in the frame editing method, the editing cycle is 4 frames (8 fields), so in scenes with intense movement, there are image differences due to movement even between the two fields that make up one frame, so such frames are By repeating the frame, the same movement is repeated four times,
The originally monotonous movement becomes a reproduced image with oscillating movement,
It becomes extremely unsightly.

On the other hand, in the field editing method, the editing cycle is 4 fields (2 frames), which is half the frame editing cycle, and the same field is played repeatedly, so it has the advantage that the reproduced image does not have oscillatory movement. However, on the other hand, for images with little movement, this method has the disadvantage that the vertical resolution deteriorates compared to the frame reproduction method, making it impossible to reproduce fine parts of the image.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide a reproduction method for multi-channel video signals that does not cause deterioration in vertical resolution and can smoothly reproduce moving parts.

The multi-channel video signal reproduction method according to the present invention extracts the video signal of one channel from the multiplexed video signal and writes it intermittently to the image memory, and when the video signal is continuously read from the image memory, It is characterized in that signals of the same field are repeatedly read out a predetermined number of times in moving parts of the image, and signals of the same frame are read out repeatedly a predetermined number of times in stationary parts or parts of the image with little movement.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

Although the reproduction method according to the present invention can also be applied to the reproduction of a multiplexed video signal having the configuration shown in FIG. do.

In FIG. 1, for example, a 4-channel original video signal A
(a) to D (d) are time-division multiplexed frame by frame every four frames and edited as a single multiplexed video signal (e). The two fields constituting one frame of the multiplexed video signal (e) are not adjacent fields in the original video signal, but are a combination of two fields separated by a predetermined period of time. When reproducing the video signal of a specific channel from the multiplexed video signal (e) having such a configuration, the reproduction method according to the present invention detects the movement of the image and reproduces the signal of the same field a predetermined number of times in the moving part of the image. The video signal of a specific channel is reproduced by repeatedly reading out from the image memory, and in a still part of the image or a part with little movement, the signal of the same frame is read out a predetermined number of times from the image memory.

One method for detecting image motion is to insert a code or flag into the video signal on the recording side to determine whether it is a moving image or a still image on a field-by-field or frame-by-frame basis based on the magnitude of the movement, the ratio to the still part, etc. A conceivable method is to detect moving parts on the playback side, separate the moving parts and static parts, and process them differently.

FIG. 2 shows a memory output configuration for a multiplexed video signal in a memory read mode when there is little image movement. When there is little movement in the image of the A channel original video signal, the image correlation between each field is strong, so the odd number (ODD) field and the even number (E V E
N) No vibrational movement occurs even when the fields are combined and reproduced as a frame signal. Furthermore, since frames are reproduced using odd and even fields, there is no deterioration in vertical resolution compared to a field reproduction method in which fields of the same type are combined and reproduced. Therefore, one frame signal written in the image memory is divided into four signals in one frame unit.
By repeating the reproduction several times, a reproduced video signal (memory output signal) without deterioration in vertical resolution can be obtained.

However, if there is movement in the image, the difference in movement between the two fields that make up one frame becomes large, so as mentioned above, if this one frame is repeatedly played back four times, it will not be possible to reproduce the originally monotonous movement. However, the reproduced image moves in a vibrating manner, which is extremely unsightly. Therefore, when there is movement in the image, the video signal of one frame imported into the image memory is not read out frame by frame, but after reading out the odd field repeatedly four times as shown in Figure 3. Even-numbered fields are reproduced four times. One frame of the multiplexed video signal is a combination of images of frames two frames apart in time, so by reading it out in this way, the missing period of the signal can be interpolated with one field signal captured at a cycle of two frames. Therefore, it is possible to obtain a reproduced image that does not generate vibrational motion, which is an advantage of the field reproduction method, and at the same time,
Since images are captured at half the frame period, a reproduced image with smoother motion can be obtained.

In the image memory readout control method described above, if the image movement exceeds a predetermined value, the entire screen is played back as a field, so moving parts coexist with still parts, which would normally be better played by frame. If it is, field playback will occur, and deterioration of vertical resolution is unavoidable.However, on the other hand, the recording side must decide whether the image memory read mode is field playback or frame playback, and the code is not included in the video signal. Or by inserting it with a flag signal,
Since there is no need to judge image movement on the playback side,
This has the advantage that the circuit configuration of the playback device can be simplified.

Next, a reproduction method in which image motion detection is performed on the reproduction side will be described.

For example, to determine whether there is a moving part in the image of the A channel, it is sufficient to calculate the difference between each frame of the A channel. It is obtained by taking the difference at M+1.

FIG. 6 shows an embodiment of a partial motion adaptive type image memory read control section using frame difference detection.

In FIG. 6, the reproduced video signal of the A channel is sequentially written into the frame memory 11. Frame memory 11
A video signal of M frames reproduced one frame before is written in , and when (M+1) frames are reproduced, the frame memory 11 operates in read-modify-write mode.

In other words, while reading the video signal of M frames (M+
1) Write the frame video signal.

(M+1) frame video signals are output to memory 1 at the same time.
After writing for one frame is completed, under the control of the readout control circuit 14, as described above, a moving part is played back as a field, and a part without movement is played back as a frame.

Image motion detection is performed by the motion detection circuit 12 by calculating the difference between the video signal of M frames and the video signal of (M+1) frames. Since this type of motion detection circuit is well known, its details will be omitted. Motion detection circuit 1
The detection output of step 2 is 1-bit information indicating the presence or absence of movement.
It is written into the motion memory 13 in correspondence with the image. Then, in response to the readout output of the motion memory 13, the readout control circuit 14 operates as described above. For motion detection, the output video signal is delayed by a period equivalent to one frame compared to the input video signal, so each output of the output frame memory 15 and the frame memory 16 attached thereto is alternately switched by the switch 17. By selecting, an output video signal can be obtained without interruption.

As another example of partial motion adaptation, as shown in FIG. 7, it is also possible to perform image motion detection between two fields constituting one frame. The input video signal is written into the memory 21 starting from the odd field.
From the time when the next even field is input, the subtractor 23
The difference between the even field signal and the odd field read signal written earlier is calculated. After passing through the vertical spatial low-pass filter 24, this subtracted output is supplied to the readout control circuit 14 via the motion detection circuit 12 and motion memory 13, as in the previous embodiment. and,
After writing one frame into the memory 21 is completed, the video signal is read out from the memory 7 under the control of the readout control circuit 14 so that the moving portion is reproduced in the field.

In the case of motion detection based on inter-field differences, if there is a change in the signal level in the vertical direction of the image, a large level will be output from the subtracter 23 even when there is no motion, and it will be determined that the mode is motion. In order to prevent this, a low-pass filter 24 is provided in the vertical spatial direction, thereby avoiding erroneous detection of movement. memory 2
2 is provided for alternately writing and using one frame signal of the A channel, which is intermittently inputted, as in the case of the above-mentioned embodiment.

In the above embodiment, the case of a video signal with four channels has been described, but the present invention is not limited to this, and can be similarly applied to a case of a video signal with two channels, for example.

In addition, there are various known techniques for detecting image motion, and new techniques may be devised, but the present invention is applicable to image memory reading for interpolating and reproducing multi-channel video signals depending on the presence or absence of motion. The present invention has characteristics, and any method other than the embodiment can be applied as a motion detection method.

Further, the recording medium may be a video disk or a magnetic tape (videotape).

As described in detail, the multi-channel video signal reproduction method according to the present invention switches between field repeat playback and frame repeat playback according to the movement of the image, so there is no deterioration in vertical resolution. Moreover, a reproduced image with smooth movement can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a multiplexed video signal for a 4-channel original video signal to which the reproduction method according to the present invention is applied;
Figure 2 shows the configuration of each signal in the memory read mode when there is little movement in the image, Figure 3 shows the configuration of each signal in the memory read mode when there is movement in the image, and Figure 4 shows the configuration of each signal in the memory read mode when there is movement in the image. A diagram showing the configuration of each signal in a conventional method for recording and reproducing 4-channel original video signals by time division multiplexing. FIG. 5 shows an example of the configuration of a reproducing device that reproduces, for example, an A-channel video signal. Block diagram: FIG. 6 is a block diagram showing an embodiment of a partial motion adaptive type image memory read control unit using frame difference detection; FIG. 7 is a block diagram showing an embodiment of a partial motion adaptive type image memory read control unit using field difference detection. FIG. Explanation of symbols of main parts 2...1 Frame memory 3...Channel detection circuit 4...Write control circuit 5.14...Read control circuit 12. ...Motion detection circuit 13.Old...Motion memory applicant Pioneer Corporation

Claims (2)

[Claims] (1) The video signal of one channel is extracted from a single multiplexed video signal obtained by sequentially time-division multiplexing the original video signals of multiple channels at a predetermined period in units of frames and stored in the image memory intermittently. By continuously reading out the video signal from the image memory while writing to the image memory,
A reproduction method for reproducing the video signal of the first channel, in which the signal of the same field is read out repeatedly from the image memory a predetermined number of times in the moving part of the image, and the same frame is read out in the static part or the part with little movement of the image. A method for reproducing a multi-channel video signal, characterized in that the signal is read out from the image memory repeatedly a predetermined number of times. (2) For fields containing moving parts of the image, 1
2. The method for reproducing a multi-channel video signal according to claim 1, wherein the same field is read out from the image memory repeatedly a predetermined number of times on a field-by-field basis.