JP2000013741A - Video recorder and video reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the volume of recording data without deteriorating picture quality by executing efficient thinning processing. SOLUTION: The moving amount of temporally continuous pictures as inputted video signals is detected by movement detection means 2 to 5 and a thinning ratio is set by a thinning ratio setting means 6 in accordance with the detected moving amount. The inputted video signal is thinned in each picture by a thinning processing means 7 based on the set thinning ratio. Then the thinned video signal is recorded in a recording medium by a recording means 9 together with the thinning ratio information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus for recording an input video signal on a recording medium such as a magnetic tape or an optical disk, and a reproducing apparatus for reproducing and outputting a video signal from the recording medium. is there.

[0002]

2. Description of the Related Art Various types of recording apparatuses and reproducing apparatuses for recording and reproducing video signals on recording media such as video tapes, video disks, and hard disks are known. When a video signal having a large amount of information is recorded on a recording medium, JPEG (Joint Photographic Experts Gr.
oup), MPEG1 (Moving Picture Experts Group Ph.
ase 1), MPEG2 (Moving Picture Experts Group
Image compression processing such as Phase 2) and image thinning-out in picture units (frame units or field units) are also used to compress the amount of information. When performing the picture thinning process, the thinning rate is fixed. For example, it is determined whether or not there is a certain amount of motion as a screen between temporally consecutive pictures, and if there is almost no motion, a process of thinning out a predetermined amount of pictures is performed.

[0003]

In a video recording apparatus, there is a demand for efficient recording on a recording medium (that is, efficient data amount reduction) to extend the recordable time of a moving image. However, in such a case, it is conceivable to reduce the data by increasing the image thinning rate, for example. However, if the amount of data is simply reduced by increasing the amount of the thinning process, the image quality naturally declines, which is not preferable.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention provides an image recording apparatus in which the image is thinned out efficiently without causing any visual problem so that the user can perform further recording without perceived deterioration in image quality. An object is to enable reduction of the data amount. It is another object of the present invention to provide a video reproducing apparatus capable of performing appropriate reproduction output from a recording medium on which a moving image video signal is recorded by such processing.

That is, a video recording device includes a motion detecting means for detecting the amount of motion between temporally consecutive pictures as an input video signal, and thinning-out in accordance with the amount of motion detected by the motion detecting means. Thinning rate setting means for setting a rate, thinning processing means for thinning the input video signal in picture units based on the thinning rate set by the thinning rate setting means, and thinning processing performed by the thinning processing means. Recording means for recording the video signal together with the thinning rate information on a recording medium.

A video reproducing apparatus performs a reproducing operation on a recording medium on which a video signal thinned out in picture units is recorded together with the thinning rate information based on a thinning rate variably set at the time of recording. Reading means for reading out the thinning rate information, storage means for storing the video signal read by the playing means, and a video signal read from the storage means at a timing based on the thinning rate information read by the playing means, Output control means for outputting a reproduced video signal.

That is, in the present invention, the thinning rate for a picture is variably set in accordance with the amount of motion between temporally consecutive pictures. For example, when pictures with little motion are continuous, a large number of pictures are thinned out so that the amount of information can be largely compressed without deteriorating image quality. In addition, information of a thinning rate that is variably set is simultaneously recorded, and at the time of reproduction, an output of a picture is controlled in accordance with the thinning rate so that an appropriate reproduced image signal is obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A recording / reproducing apparatus according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram of a recording / reproducing apparatus of the present example which can record and reproduce a moving image video signal on a predetermined recording medium 20 such as a disk or a tape.

An input video signal is converted into digital data by an A / D converter 1 and then taken into a frame memory 2 in picture units (fields or frames; in this example, picture units are frame units). It is. The video data output from the A / D converter 1 is also supplied to a subtractor 3.

The subtracter 3 performs a process of subtracting a luminance level from each pixel data (pixel) in a temporally continuous current frame and a previous frame. That is, in synchronization with the supply of the pixel data constituting the current frame to the subtractor 3 in a time series, the pixel data in the previous frame, that is, the frame taken in the frame memory 2 is read out in a time series. And supplied to the subtractor 3.

Accordingly, the difference between the luminance levels of the pixels in the preceding and succeeding frames is sequentially output from the subtracter 3, and the difference is supplied to the comparator 4. Comparator 4
Is supplied with a threshold value th1 as a comparison criterion, compares the luminance difference data sequentially supplied from the subtractor 3 with the threshold value th1, and outputs a comparison result. For example, if the luminance difference exceeds the threshold value th1, "1" is output.

The output of the comparison result of the comparator 4 is supplied to a counter 5. The counter 5 counts the number of comparison results “1” in a period corresponding to one frame. That is, the counter counts the number of pixels for which the difference in the luminance level has become larger than the threshold value th1 as a comparison of all the pixels in the preceding and succeeding frames. The count value n of the counter 5 is supplied to the comparator 6.

The comparator 6 is supplied with threshold values th2 and th3 as a comparison reference. The comparator 6 compares the threshold values th2 and th3 with the count value n to determine the amount of motion between two consecutive frames in three stages. That is, a) n <th2, b) th2 ≦ n <th3, c) th3 <n, and the amount of motion is detected. Then, the thinning rate S1 is set according to the amount of the movement. If the amount of motion detected and set in three stages and the thinning rate are large,
If it is expressed by medium and small, in the case of a), the amount of motion is “small” → the thinning rate is “large” In the case of b), the amount of motion is “medium” → the thinning rate is “medium” In the case of c) And the motion amount is “large” → the thinning rate is “small”.

The comparator 6 calculates the thinning rate S set as described above.
1 is supplied to the picture thinning processing section 7. The picture thinning processing unit 7 sets the thinning timing according to the supplied thinning rate, and reads the frame image from the frame memory 2 at that timing. Then, the data is supplied to the JPEG compression circuit 8. As a result, the JPEG compression circuit 8 includes:
A video signal thinned out at a thinning rate corresponding to the amount of motion is supplied, and JPEG data compression processing is performed on such a video signal. Then, the compressed data is supplied to the recording / reproduction drive 9 as recording data. Further, the picture thinning processing section 7 supplies thinning rate information corresponding to the compressed data to the recording / reproducing drive 9 in accordance with the timing of the compressed data.

The recording / reproducing drive 9 is capable of performing a recording operation and a reproducing operation on a recording medium 20 such as a disk or a tape, and records the compressed data supplied from the JPEG compression circuit 8 on the recording medium 20 at the time of recording. I will do it. The thinning rate information is also recorded in correspondence with the compressed data. For example, the thinning rate information may be recorded as management information for each video signal (each frame image as compressed data) that is continuous in time series.

The above-described thinning processing in the recording system is shown in FIG.
4 to 4 are conceptually shown. FIG. 2 shows an input video signal in a frame unit image. F1, F2 ...
Indicates frames that are temporally continuous at intervals of time t1. For example, it is assumed that, as a result of continuously detecting the motion of the image in the preceding and succeeding frames for such a video signal, the portions of the motion amounts “large”, “medium”, and “small” are detected as shown in FIG. .

For example, during a period from frames F1 to F4,
It is assumed that the motion amount is determined to be “large” in the previous and subsequent frames, and the thinning rate is set to “small”. For example, if the thinning rate is “small”, the thinning is not performed, and the thinning is not performed on the frames F1 to F4 as shown in FIG. On the other hand, when comparing the frames F4 and F5, it is assumed that the motion amount is determined to be “medium” and the thinning rate is set to “medium”. For example, when the thinning rate is “medium”, if the thinning for one frame is to be performed, the frame F5 is thinned as indicated by a broken line. Further, the frame F
7 and F8, it is assumed that the motion amount is determined to be “small” and the thinning rate is set to “large”. For example, when the thinning rate is “large”, if the thinning for two frames is to be performed, the frames F8 and F9 are thinned as shown by the broken lines.

For example, by performing thinning in accordance with such a motion amount, a video signal which is JPEG-compressed and recorded on the recording medium 20 is converted into frames F5, F8,
F9 is removed. That is, a video signal whose data amount is efficiently compressed according to the amount of motion is recorded.

Next, the reproducing system will be described. Recording medium 2
In 0, a video signal that has been subjected to the decimation process and the JPEG compression process as described above is recorded, and decimation ratio information is also recorded together with the video signal. During playback,
The video signal read out by the recording / reproduction drive 9 performing a reproduction operation on the recording medium 20 is supplied to a JPEG decompression circuit 10 and decompression processing for JPEG compression is performed. Then, each frame image data as a video signal subjected to the decompression processing is stored in the memory 11. On the other hand, the recording / reproducing drive 10 reads the corresponding thinning-out rate information from the recording medium 20 in synchronization with the reading of the video signal or prior to the reading of the video signal, and supplies the information to the transmission timing generating unit 12.

The transmission timing generation section 12 causes each frame image data stored in the memory 11 to be read out at a timing corresponding to the thinning rate information corresponding to each frame. Further, the read timing of the next frame is transmitted to the recording / reproducing drive 9, and the reading operation of the frame image data in the recording / reproducing drive 9 is controlled.

The frame and timing read from the memory 11 are controlled according to the thinning rate. This is schematically shown in FIG. As described above, the video signal recorded on the recording medium 20 is as shown in FIG. 4, and the frames F5, F8, and F9 are thinned out.
Therefore, there is no data of the frames F5, F8, and F9 as frames read from the recording medium and stored in the memory 11.

Here, the transmission timing generation unit 12 determines that the frame F5 following the frame F4 has been thinned and that the two frames F8 and F9 following the frame F7 have been skipped according to the thinning rate information corresponding to the video signal to be read. You can recognize that it is being pulled. Therefore, the transmission timing generation unit 12 sends the frames F1 to
Until F4, reading is executed at regular timing intervals, and control is performed so that the video signals of the frames F1 to F4 are also sequentially read and output from the memory 11 at t1 intervals. On the other hand, at the next timing of the transmission of the frame F4, the recording / reproducing drive 9 is made to temporarily wait for reading (if necessary depending on circumstances such as the capacity of the memory 11 and the transfer rate). Frame F
4 is read and output.

Thereafter, frames 6 and F7 are read from the recording medium 20, stored in the memory 11, and stored in the memory 1
The read output is performed at time intervals of t1 from 1, and the next timing of the transmission of the frame F7 and the period of the next timing are recorded / reproduced if necessary according to circumstances such as the capacity of the memory 11 and the transfer rate. The drive 9 is made to temporarily wait for reading, and the image data of the frame F7 is read out from the memory 11 again and again and output.

The video data read from the memory 11 as described above is converted into an analog video signal by the D / A converter 13 and output as a reproduced video signal. In other words, interpolation processing is performed according to the amount of frames thinned out during recording,
A reproduced video signal is obtained as a time-series signal similar to the input video signal at the time of recording.

As described above, in the recording / reproducing apparatus of the present embodiment, at the time of recording, a video signal whose data amount is efficiently compressed according to the amount of motion of the preceding and following frames is recorded. Thus, for example, when a still image state continues due to a video with little motion, for example, a flip or CG in a news program, the thinning rate increases, and only one or a few frames as a representative image are recorded. Can be Also,
If the screen changes to a relay screen and the movement becomes large,
The thinning rate is reduced, and the number of frames to be thinned is reduced to a small number or zero so that the image quality does not deteriorate. That is, the recording data amount can be efficiently reduced according to the screen condition, and efficient recording can be realized without deteriorating the image quality. This also makes it possible to extend the recordable time. Further, at the time of reproduction, since the interpolation processing is performed according to the thinning rate variably set at the time of recording and the reproduction video signal is output, the reproduction video can be output in a high quality and appropriate time state. That is, it is possible to output a reproduced video that does not cause the user to feel the image quality degradation.

The above is an example, and various modifications of the recording apparatus and the reproducing apparatus according to the present invention can be considered. For example, in the above example, the motion detection and the thinning rate are determined / set in three steps, but may be four or more steps. An example is also considered in which the motion detection / thinning rate is set in units of fields, instead of the motion detection / thinning rate in units of frames before and after. Further, the motion detection may be performed with three or more consecutive pictures instead of the motion detection with two preceding and succeeding pictures (frames or fields). Note that, for example, when performing motion detection in three frames, two frame memories are required.

With respect to interpolation during reproduction, in the above-described example, the representative frames are continuously output. However, the representative frames or the representative frames and the frames read out next are thinned out by the motion prediction calculation processing. May be generated by interpolation.

Although the data compression process uses the JPEG method as an example, MPEG1, MPEG2, etc.
Other image compression processing may be adopted.

[0029]

As described above, according to the present invention, at the time of recording, the thinning rate is set in accordance with the amount of motion of the picture of a temporally continuous video signal, and the picture thinning process is performed. According to the content, the recording data amount can be efficiently reduced without lowering the image quality. Therefore, for a video with little motion, the recording time length on the recording medium can be increased. Furthermore, at the time of reproduction, an interpolation process according to the thinning rate is performed, and a reproduced video signal is output. Therefore, there is an effect that a reproduced video that does not cause deterioration in image quality for a user can be output.

[Brief description of the drawings]

FIG. 1 is a block diagram of a recording and reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an input video signal according to the embodiment.

FIG. 3 is an explanatory diagram of a thinning process according to the embodiment;

FIG. 4 is an explanatory diagram of a video signal recorded according to the embodiment.

FIG. 5 is an explanatory diagram of a reproduced video signal according to the embodiment;

[Explanation of symbols]

1 A / D converter, 2 frame memory, 3 subtractor,
4, 6 comparator, 5 counter, 7 picture thinning processing section, 8 JPEG compression circuit, 9 recording / playback drive,
10 JPEG decompression circuit, 11 memory, 12 transmission timing generator, 13 D / A converter

Claims (2)

[Claims] 1. A motion detecting means for detecting an amount of motion between temporally consecutive pictures as an input video signal, and a thinning rate is set according to the amount of motion detected by the motion detecting means. Thinning rate setting means, thinning processing means for thinning out an input video signal in picture units based on the thinning rate set by the thinning rate setting means, and a video signal thinned by the thinning processing means Recording means for recording the information together with the thinning rate information on a recording medium. 2. A reproducing operation is performed on a recording medium on which a video signal thinned out on a picture basis based on a thinning rate variably set at the time of recording is recorded together with thinning rate information indicating the thinning rate, A reproducing unit that reads out the video signal and the thinning-out ratio information; a storage unit that stores the video signal read out by the reproducing unit; and a timing based on the thinning-out ratio information that is read out by the reproducing unit. An output control means for reading a video signal and outputting the read video signal as a reproduced video signal.