JPH08289321A - Video signal recording device and video signal recording-reproducing device - Google Patents

Abstract

PURPOSE: To provide a video signal recording device and a video signal recording-reproducing device which can suppress the conspicuousness of false signals and the blur of animation images with no adaptive control to be carried out based on the detection of the image movements. CONSTITUTION: A prefilter 5 which can switch the filter characteristics is prepared, together with a control part 6 which switches the characteristics of the prefilter 5 between the odd and even numbered fields, and a sub-Nyquist sampling processing circuit 7 which receives the chroma signals through the prefilter 5. The filter characteristics of the prefilter 5 are switched in every field, and a filtering operation is carried in a closed state secured by a frame. Then the circuit 7 sub-samples the chroma signals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal recording apparatus for recording a video signal by subsampling a chroma signal recorded by low-frequency conversion, and a video signal recording for recording / reproducing a video signal. The present invention relates to a playback device.

[0002]

2. Description of the Related Art Conventionally, in a video tape recorder (hereinafter referred to as VTR) that has been widely used for home use, a chroma component included in a video signal is converted into a low frequency band, and the low frequency band-converted chroma signal and frequency modulation The (FM) luminance signal is recorded together. For example, a chroma signal is converted into a low frequency band of about 600 to 750 KHz, and its bandwidth is about several hundred kHz. By recording the chroma signal, which has been converted to a low frequency band and has a relatively narrow band, on the video tape together with the frequency-modulated luminance signal, the video signal can be efficiently recorded on the video tape.

In a video signal recording apparatus for converting a chroma signal into a low frequency band for recording in this way, the chroma signal component of the reproduced signal is a luminance signal component because the bandwidth of the low frequency conversion chroma signal is relatively narrow. Will be inferior to.
In particular, when revising the standard for improving the picture quality of actual home-use VTRs, emphasis has been placed on expanding the frequency band of the luminance signal. In particular, it is necessary to improve the characteristics such as expanding the frequency band.

By the way, it is considered that the chroma signal is sub-sampled or sub-Nyquist sampled in order to substantially expand the frequency band of the chroma signal without changing the recording band on the recording medium such as a tape. There is. This sub-sampling is performed by adding an offset in the time axis direction such as a field offset or a frame offset, or a line offset or the like.
Sampling is performed by adding an offset on the dimensional plane.

[0005]

By the way, when subsampling with an offset in the time axis direction such as the above-mentioned field offset or frame offset is performed, when the screen image is a so-called still image, the image is stationary. The characteristics do not deteriorate because there is no change in the time axis direction,
In the case of a so-called moving image in which the image on the screen moves, there is a change in the time axis direction and the characteristics deteriorate, so image motion detection was performed, and the processing amount of subsampling with the offset in the time axis direction was detected. It is necessary to adaptively control according to the amount of movement.

Here, when the amount of movement changes abruptly,
The processing for moving images and the processing for still images are suddenly switched, which causes a problem such as edge flicker.

Further, adaptive control by motion detection is extremely complicated and it is difficult to obtain sufficient performance.

In view of the above-mentioned conventional circumstances, an object of the present invention is to provide a video signal recording apparatus and a video signal in which a false signal or a blur for a moving image is not noticeable without performing adaptive control by motion detection. It is to provide a signal recording / reproducing device.

[0009]

A video signal recording apparatus according to the present invention is a video signal recording apparatus for recording a video signal by sub-sampling a chroma signal recorded by low frequency conversion. A prefilter whose filter characteristic can be switched, a switching control means for switching the filter characteristic of the prefilter between an odd field and an even field, and a sub-Nyquist sampling means to which a chroma signal is supplied via the prefilter. , The filter characteristic of the pre-filter is switched for each field to perform filtering closed in a frame, and the sub-Nyquist sampling means sub-samples the chroma signal.

A video signal recording / reproducing device according to the present invention is a video signal recording / reproducing device for recording / reproducing a video signal by sub-sampling a chroma signal which is converted into a low frequency band and recorded. The recording system includes a prefilter whose filter characteristics can be switched, a switching control means for switching the filter characteristics of the prefilter between an odd field and an even field, and a sub-Nyquist sampling means to which a chroma signal is supplied via the prefilter. In preparation for this, a sub-Nyquist sampling means to which the chroma signal reproduced from the recording medium is supplied, a post filter whose filter characteristics are switchable to which the chroma signal is supplied via the sub-Nyquist sampling means, and a filter of the post filter Switch characteristics between odd and even fields Characterized in that it comprises a switching control means in the reproduction system.

[0011]

In the video signal recording apparatus according to the present invention, the filter characteristic of the pre-filter is switched between the odd field and the even field for filtering the chroma signal, and the filtering is performed by the sub-Nyquist sampling means. Apply sampling.

Further, in the recording system in the video signal recording / reproducing apparatus according to the present invention, the filter characteristic of the pre-filter is switched between the odd field and the even field for the chroma signal to perform the filtering closed by the frame.
Further, sub-Nyquist sampling means performs sub-sampling. Then, in the reproducing system, the chroma signal reproduced from the recording medium in which the video signal is recorded by the recording system is sub-sampled by the sub-Nyquist sampling means, and the filter characteristic of the post filter is divided into an odd field and an even field. Switching is performed and closed filtering is performed with a frame.

[0013]

Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the structure of a recording system of a video tape recorder (VTR) to which the present invention is applied. In this recording system, a composite color video signal is input terminal 1
Is supplied to the YC separation circuit 2 which is supplied via.

The YC separation circuit 2 separates the luminance signal Y and the chroma signal C from the composite color video signal. Then, the chroma signal C obtained by the YC separation circuit 2 is supplied to the color difference decoder 3.

The color difference decoder 3 converts the chroma signal C supplied from the YC separation circuit 2 into color difference signals R-Y, B.
-Generate Y. Then, the color difference signals RY and BY generated by the color difference decoder 3 are directly supplied to the prefilter 5 and are also supplied to the prefilter 5 through the first and second field memories 4a and 4b. It

Here, the first and second field memories 4a and 4b are connected in series, and the color difference signals (RY, B- supplied from the color difference decoder 3 are supplied.
Y), the color difference signal (R) delayed by one field by the first field memory 4a is delayed by one field.
-Y, BY) _1FDL is supplied to the pre-filter 5, and the second field memory 4b further delays by 1 field to delay the color difference signal (RY, BY) by 2 fields.
Y) _2FDL is supplied to the prefilter 5.

The pre-filter 5 comprises an input selection switch 5a and an adder 5b as shown in FIG.
The color difference signal (RY, BY) _1FDL delayed by one field from the first field memory 4a is added to the adder 5b.
Is supplied to the color difference decoder 3 and the color difference signals (R-Y, BY) from the color difference decoder 3 and the color difference signals (R-Y) delayed by two fields from the second field memories 4a and 4b.
Y, BY) _2FDL is selectively supplied to the adder 5b via the input selection switch 5a.

The input selection switch 5a is controlled by the control unit 6, and in the odd field ODD, the color difference signals (RY, BY) from the color difference decoder 3 are supplied to the adder 5b, and the even number is supplied. In the field EVEN, the color difference signals (RY, BY) _2FDL delayed by two fields from the second field memories 4a and 4b are supplied to the adder 5b.

In the pre-filter 5 having such a structure, the control section 6 controls the input selection switch 5a to be switched for each field, so that in the odd field ODD, one field from the first field memory 4a is selected. Delayed color difference signal (RY, BY) _1FDL and color difference signal (RY, BY) from the color difference decoder 3
Is performed, and in the even field EVEN, the color difference signals (RY, BY) delayed by one field from the first field memory 4a.
_1FDL and 2 from the second field memories 4a and 4b
A filtering process is performed to add the color lag signal (RY, BY) _2FDL with field delay. That is, in the pre-filter 5, the filter characteristics are switched between the odd field ODD and the even field EVEN as shown in FIG. 3, and in the odd field ODD, filtering is performed by adding only the subsequent field to the even field EDD.
In VEN, only the previous field is added to perform filtering, and the filter in the time direction is closed in the frame.

Then, the color difference signals (RY, BY) subjected to the filtering processing in the vertical direction and the time direction by the pre-filter 5 are supplied to the sub-Nyquist sampling processing circuit 7.

Here, the filtering process by the pre-filter 5 is low-pass in the time axis direction in order to prevent an error that occurs when sub-Nyquist sampling having an offset in the time axis direction is applied to a moving image. It is a process of applying a filter and is not necessary for a still image having no motion.

The sub-Nyquist sampling processing circuit 7 offsets the color difference signals (R-Y, BY) filtered by the pre-filter circuit 5 by 180 ° so that the sampling phase is inverted every field. It is given to perform sub-sampling of 2 field periods.

An outline of subsampling by the sub-Nyquist sampling processing circuit 7 is shown in FIG. FIG. 4A shows 4 fields (2 frames) of the original image. Further, FIG. 4B shows the sub-sampling performed by the sub-Nyquist sampling processing circuit 7 after the filtering processing is performed by the pre-filter circuit 5. Here, the sampling point is 1 from each line of the first field, the second field, the third field, and the fourth field in FIG.
Subsampled with a 180 ° offset between fields.

Then, the color difference signal sub-sampled by the sub-Nyquist sampling processing circuit 7 (R
-Y, BY) is supplied to the chroma signal recording processing circuit 8.

The chroma signal recording processing circuit 8 performs desired signal processing such as chroma emphasis and frequency conversion on the color difference signals (RY, BY) supplied from the sub Nyquist sampling processing circuit 7. Then, the low-frequency conversion chroma signal is supplied from the chroma signal recording processing circuit 8 to the mixer 11.

The luminance signal Y separated from the composite color video signal by the YC separation circuit 2 is supplied to the luminance recording processing circuit 10 via the field memory 9.

The luminance recording processing circuit 10 performs desired signal processing such as emphasis and frequency modulation on the luminance signal Y supplied from the YC separation circuit 2 via the field memory 9. Then, the frequency-modulated luminance signal YFM is supplied from the luminance recording processing circuit 10 to the mixer 11.

The mixer 11 mixes the low frequency conversion chroma signal supplied from the chroma signal recording processing circuit 8 and the luminance signal YFM supplied from the luminance recording processing circuit 10 to generate a recording signal. Then, the video signal as the recording signal generated by the mixer 11 is the recording head 1
It is recorded on the recording track on the magnetic tape 13 via the recording medium 2.

The field memory 9 functions as a delay circuit for adjusting the timing of the luminance signal YFM and the low frequency conversion chroma signal.

In the recording system having such a configuration, for the chroma signal C, the filter characteristic of the pre-filter 5 is switched between the odd field ODD and the even field EVEN to perform the filtering closed in the frame, and the sub-Nyquist sampling is performed. Since the processing circuit 7 performs sub-sampling, a false signal or blurring is less noticeable in the reproduction system, and the false signal or blurring of a moving image can be made less noticeable without performing adaptive control by motion detection. .

A reproducing system of a VTR to which the present invention is applied is constructed as shown in FIG. 5, for example.

In the reproducing system of the VTR shown in FIG. 5, the reproducing head 21 traces the recording track on the magnetic tape 14 on which the luminance signal YFM and the low frequency conversion chroma signal are recorded by the recording system as described above. The obtained reproduced signal is supplied to the chroma signal reproduction processing circuit 22 and the luminance signal reproduction processing circuit 28.

The chroma signal reproduction processing circuit 22 subjects the reproduced signal reproduced by the reproducing head 21 to desired signal processing such as chroma de-emphasis and color difference decoding to generate color difference signals RY and BY. To do. Then, the color difference signals RY and BY generated by the chroma signal reproduction processing circuit 22 are directly supplied to the sub-Nyquist sampling processing circuit 14 and also via the first and second field memories 23a and 23b. It is supplied to the sub-Nyquist sampling processing circuit 24.

Here, the first and second field memories 23a and 23b are cascade-connected to each other, and the color difference signals (RY, BY) supplied from the chroma signal reproduction processing circuit 22 are supplied. On the other hand, the 1-field delayed color difference signal (RY, BY) _1FDL delayed by 1 field by the first field memory 23a is supplied to the sub-Nyquist sampling processing circuit 24, and the second field memory 23b is supplied. The color difference signal (RY, BY) _{2FDL is} delayed by 1 field and delayed by 2 fields by
Is supplied to the sub-Nyquist sampling processing circuit 24.

The sub-Nyquist sampling processing circuit 24 receives the color difference signals (RY, BY) directly supplied from the chroma signal reproduction processing circuit 22 and one field supplied from the first field memory 13a. The above-mentioned _recording is performed for the delayed color difference signal (RY, BY) _1FDL and the two field delayed color difference signal (RY, BY) _2FDL supplied from the second field memory 23b. Subsampling is performed in the same pattern as the system sub-Nyquist sampling processing circuit 7 with an offset of 180 ° for each field.

The sub-Nyquist sampling processing circuit 24 sub-samples the color difference signals (RY, BY), (RY, BY) _1FDL , (R
-Y, BY) _2FDL is supplied to the post filter 25.

As shown in FIG. 6, the post filter 25 is composed of an input selection switch 25a and an adder 25b, and is 1-sampled from the first field memory 23a subsampled by the sub-Nyquist sampling processing circuit 24. Field-delayed color difference signals (RY, B
-Y) _1FDL is supplied to the adder 25b, and
The chroma signal reproduction processing circuit 22 subsampled by the sub-Nyquist sampling processing circuit 24.
From the second field memory 23b and the color difference signal (RY, BY) _2FDL delayed by two fields from the second field memory 23b is the input selection switch 25a.
And is selectively supplied to the adder 25b via.

The input selection switch 25a is
Controlled by the control unit 26, the color difference signals (RY, BY) are supplied to the adder 25b in the odd field ODD, and the color difference signals (RY, B- delayed by the two fields in the even field EVEN. Y) _2FDL is added to the above adder 2
Supply to 5b.

That is, the post filter 25 has the same structure as the recording system pre-filter 5, and the control unit 16 controls the input selection switch 25a to be switched field by field. The field is added to perform filtering, the even field EVEN is added to only the previous field to perform filtering, and filtering is performed by closing the frame in the time direction. The post filter 25 functions as an interpolation filter for interpolating the pixels thinned out in the recording system as shown in FIG. 4C as shown by hatching in FIG. 4D.

The color difference signals (RY, BY) interpolated by the post filter 25 are supplied to the modulator 27. The modulator 27 uses the color difference signals (RY, B-).
Y) is converted into a carrier color signal C and supplied to the mixer 30.

Further, the luminance signal reproduction processing circuit 28 is
The luminance signal Y is generated by subjecting the reproduced signal reproduced by the reproducing head 21 to desired signal processing such as de-emphasis or FM demodulation. The luminance signal Y generated by the luminance signal reproduction processing circuit 28 is supplied to the mixer 30 via the field memory 29.

The mixer 30 mixes the carrier color signal C supplied from the modulator 27 with the luminance signal Y to generate and output a composite color video signal.

In the reproducing system having such a configuration, the sub-Nyquist sampling processing circuit 14 sub-samples the color difference signals (RY, BY) reproduced from the magnetic tape 13 to obtain the filter characteristics of the post filter 15. Is switched between an odd field ODD and an even field EVEN to perform filtering closed in a frame to interpolate pixels thinned out in the recording system, so that false signals and blurring are less noticeable, and adaptive control by motion detection is performed. It is possible to make the false signal and the blurring of the moving image inconspicuous even without performing.

[0045]

As described above, in the video signal recording apparatus according to the present invention, the filter characteristic of the pre-filter is switched between the odd field and the even field for the chroma signal to perform the filtering closed by the frame. Since sub-Nyquist sampling processing means performs sub-sampling, spurious signals and blurring are less noticeable in the playback system.
It is possible to make false signals and blurring of a moving image inconspicuous without performing adaptive control by motion detection.

Further, in the recording system in the video signal recording / reproducing apparatus according to the present invention, the filter characteristic of the pre-filter is switched between the odd field and the even field for the chroma signal to perform the filtering closed by the frame. Further, the sub-Nyquist sampling means performs sub-sampling, and in the reproducing system, the chroma signal reproduced from the recording medium on which the video signal is recorded by the recording system is sub-sampled by the sub-Nyquist sampling means. By switching the filter characteristic between the odd field and the even field and performing filtering closed in a frame, by interpolating the pixels thinned out in the recording system, false signals and blurring are less noticeable, and adaptive by motion detection. Without any control , It is possible to make the false signal and the blur for the moving image inconspicuous.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a configuration of a recording system of a VTR to which the present invention is applied.

FIG. 2 is a block circuit diagram showing a configuration of a pre-filter in the recording system.

FIG. 3 is a diagram for explaining characteristics of filtering processing by the prefilter.

FIG. 4 is a diagram for explaining sub-Nyquist sampling processing in the VTR.

FIG. 5 is a block circuit diagram showing a configuration of a VTR reproducing system to which the present invention is applied.

FIG. 6 is a block circuit diagram showing a configuration of a post filter in the recording system.

[Explanation of symbols]

 1 Input Terminal 2 Y / C Separation Circuit 3 Color Difference Decoder 4a, 4b Field Memory 5 Pre-filter 6 Control Unit 7 Sub Nyquist Sampling Processing Circuit 8 Chroma Signal Recording Processing Circuit 12 Recording Head 13 Magnetic Tape 21 Playback Head 22 Chroma Signal Playback Processing Circuit 23a, 23b Field memory 24 Sub Nyquist sampling processing circuit 25 Post filter 26 Control unit

Claims (2)

[Claims] 1. A video signal recording device for recording a video signal by sub-sampling a chroma signal recorded by low-frequency conversion, the pre-filter having switchable filter characteristics, and the pre-filter. A switching control means for switching the filter characteristic of the pre-filter to an odd field and an even field, and a sub-Nyquist sampling means to which a chroma signal is supplied via the pre-filter, and switching the filter characteristic of the pre-filter for each field A video signal recording device characterized in that the filtering closed by the above is performed, and the chroma signal is sub-sampled by the sub-Nyquist sampling means. 2. A video signal recording / reproducing apparatus for recording / reproducing a video signal by sub-sampling a chroma signal recorded by low-frequency conversion, comprising a pre-filter having switchable filter characteristics, The recording system is equipped with a switching control means for switching the filter characteristic of the prefilter between an odd field and an even field, and a sub-Nyquist sampling means to which a chroma signal is supplied through the prefilter, and the video signal is recorded by the recording system. Sub-Nyquist sampling means to which the chroma signal reproduced from the recorded recording medium is supplied, a post filter whose filter characteristics can be switched via the sub-Nyquist sampling means, and a filter characteristic of the post filter. To switch between an odd field and an even field. Video signal recording and reproducing apparatus characterized by a control means in the reproduction system.