JPS6098784A - Video recording and reproducing device - Google Patents

Abstract

PURPOSE:To compress a frequency band of a video signal without expanding/ compressing a time base by limiting each sample signal to a frequency band 1/2 that of a sampling signal frequency and by forming a record signal. CONSTITUTION:An input video signal S1 is sampled by sampling frequency fs in sample hold circuits 4 and 5 and separated into sample signals S30 and S3pi. At the time of sampling by the circuits 4 and 5, a folding signal of a high signal component and low signal component generates and this folding signal together with a signal component contained in the signal S1 are interred in the signals S30 and S3pi. As a result, even when the signals S30 and S3pi pass through LPFs 7 and 8, which hold cut-off frequency of 1/2fs, and when said signals are limited to half their bands, recording can be made on a tape of a VTR main unit 9.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a video recording and reproducing device, and is particularly suitable for use in a high definition video tape recorder (iD V'l'R). be.

[Background technology and its problems]

) II) Since a VTR has a large number of pixels arranged in the horizontal and vertical directions, the frequency of the video signal becomes high, and the VTR
Broadband frequency exceeding the allowable recording frequency range of TR & 2%
Therefore, it is necessary to compress the frequency band of the video signal before recording it on tape.

Conventional methods for frequency compression in VTRs include converting a video signal into a digital signal using an analog-to-digital conversion circuit, storing it in a memory, and extending the time axis by lengthening the reading cycle of the memory. It is conceivable to use a method in which the frequency VLa band is compressed by obtaining a signal. By the way, since the primary color signal G in one line has a wide band, the primary color video signal (divided into 1-2 channel signals and time axis expanded for each channel, then recorded as a component on each separate track at the same time as the other primary color signal RXB) There are ways to do this.

Therefore, a signal processing system such as an analog-to-digital conversion circuit, memory, and a digital-to-analog conversion circuit must be prepared. It is inappropriate to apply this method to JIIA-type compact VTRs.

[Purpose of the invention]

The present invention has been made in consideration of the above points, and it is an object of the present invention to make it possible to compress the frequency band of a video signal without performing expansion or compression processing on the time axis.

[Summary of the invention]

In order to achieve this objective, in the present invention, the input video No. 15 is sampled approximately at the upper limit frequency.

A sample signal of the "claw" channel is obtained by sampling with a sampling signal having a ring frequency v, and each of the above sample signals is limited to the range of t and i of the frequency of the above sampling signal. After forming a signal and reproducing the recorded signal and performing resampling at the frequency of the sampling signal, the plurality of resamples (fi, Z, and Z) are combined to obtain an output video signal.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a video recording and reproducing apparatus as a whole, in which an input video signal S applied to an input terminal 2 is received by a low-pass filter 3, and noise components in a frequency band above its cutoff frequency are removed. Video No. 48 S1) with the frequency components of the predetermined frequency components removed and shown in the second device! ! Get 1″.

This video signal S]i Sample and hold circuits 4 and 5 are sampling pulse generation circuit 6
The video signal 81 is sampled by two-phase sampling pulses S and S2π which are generated in synchronization with the 10.1 period signal of the video signal S1, respectively, and the first and second channels are sampled by sampling pulses S30 and S3π. Sending out. Here, the first and second sampling pulses 74
g signal 820 and S2π are two-phase sampling pulses having a phase difference of 1000 from each other as shown in FIG. 3 (11) and (B2), and the input video signal S signal (3 By sampling the values in Figure (A)) on an 11th order of magnitude, W, 3 O-phase and π-phase samples 4g, S) and S3π as shown in Figures (C1) and (C2) can be obtained. Thus, 0 liver! and the π-phase sandal signal 830 and S3π represent the contents of the pixels included in each scanning line, thus the first scan, the second scan, etc.
1η1J line for each set meal line al, C2...
...and bl, B2... are 111 and 11b,
and second channel sandals S30 and S3π.

The first and second channel sample signal signals S30 and S3π are passed through low-pass filters 7 and 8, respectively, to 0411 and π as shown in FIG. 3 (Dl) and (υ2).
VT as the first and second channel records 841 and 842 in which phase sample signals YIH are sequentially arranged.
R body 9 is given to each of the tracks of the male IJ1 fixed thus formed on the tape.

Here, the frequency f8 of the O-phase and π-phase sampling pulse signals 820 and S2π of the sampling pulse generation circuit 6
is the upper limit frequency of the input video signal 81 (and therefore the input video signal 81N) obtained at the output of the low-pass filter 3 as shown in the second device? tt'! The same frequency is selected. By performing K in this way, the energy distribution of the frequency components of the sample signals S30 and S3π can be transformed as follows.

That is, the sample signals S30 and S3π include the frequency #y signal component of pixels in the 0-phase and π-phase sections of the input video signal S1, respectively, and the energy distribution of this frequency V signal component is the same as that of the input video coefficient S1. They are distributed discretely from the frequency O toward the upper limit frequency f8 centered on the frequency V, which is an integral multiple of the horizontal loop I frequency, and the magnitude thereof gradually decreases. The sample signals 83L+ and S3π are sampled by the sampling pulse signals S20 and S2π in addition to the first group of frequency signal components, so that the distribution of the first # frequency signal component p1 is changed from the sampling periodic mantissa f8. A second group of frequency signal components similar to those folded back in the 00 direction are generated. This second group of folded frequency signal components has a sampling frequency f
Depending on how you select
As shown in , the input signal Sl or t 77-link circumference v'1lir8, no circumference && The m-component component is the signal component in the O-phase and π-phase sections. component n/ton, which is formed by folding back 1° (high frequency component and high frequency component), and the h frequency component B of the input video signal S1 on the high frequency side.
. and low frequency side component L1t of low frequency measurement 81 and high frequency ia+
IJX component h1r includes a single return component HIIC, and includes a high-frequency side component H2r of the input video signal S1 as a high-frequency component H2r, a low-frequency O1!1 component, and a return component L of r; Become.

The high-frequency components of the first and second channel samples S30 and S3π having such a configuration are removed by the low-pass filters 7 and 8, and the first and second channel samples S30 and S3π having such a configuration are removed as shown in FIG. 2 (C1) and (C2). 2 channel sun 7” signal S3
0 and S3π low frequency side signal components. .

Recording signals S41 and S42'i including 1-1'o and H'jr are sent out. Here, the cutoff period mantissas of filters 7 and 8 are selected to be 2 i s for sampling frequency f8.

In this way, the frequency bands of the first and second channel recording numbers S41 and 842 are limited to the low frequency range of the input video signal 81, but this limited low frequency range includes the frequency range of the input video signal S1. Frequency component H included in the high range side
The signal component corresponding to 6 and B9 is the folded component H1o.
In the end, all the information of the human-powered video signal S1 could be stored in the input video signal S1'1kVTR body 9 in a recording manner equivalent to compressing it into half the frequency band. It turns out.

The first and second channel reproduction signals 851 and S 52 respectively reproduced from the VTR body 9 are provided to the resampling circuit 10. Resampling circuit 10i Sample hold circuit 11 and 12'@i, reproduced signal 851
The O-phase and π-phase sampling pulse signals S titl and S6π generated in the resampling pulse generation circuit 13 in synchronization with each synchronous issue of
Resample and hold. Here, the resampling pulse signal Sα) and 86π are generated by the sampling pulse generation circuit 6.
and the same frequency f8 and phase difference as S2π (=180°)
has. Therefore, in the same way as described above for FIGS. 2 (B1) and (B2), the 1H component distributed from frequency 0 to resampling frequency f81 is
A frequency signal component similar to that when folded back in the 0 direction is generated.

However, the frequency signal components of the first and second channels are 1 raw signals 851 and S52 as shown in FIG. 2 (CI) and (C2).
Since it has the same frequency distribution as described above, in Figure 2 (C1) and (C2), the same signal components are obtained by folding the folded frequency signal components n5 and H- again in the high frequency region, respectively. is included, and ρ of the input video signal 81 is included.

Frequency components included in the region side. Thus, as shown in FIG. 2, the sample signals S'70 and S7π, which are sent out from the sample and hold circuits 11 and 12, have signal components, respectively. , Ho and l, , r, H,r will be included.

Note that unnecessary feedback frequency components are generated due to the aliasing effect that occurs when resampling is performed in the sample and hold circuits 11 and 12, but these unnecessary frequency components are removed by the filters provided in the sample and hold circuits 11 and 12. be done.

The sample signals 87fJ and S obtained in this way
7π is given to the switch circuit≠14. The switch circuit 14 has a resampling pulse 56UX of S6π.
On the other hand, for example, S6π is applied to a doubling circuit J5 and the frequency is multiplied by two.
The switching circuit 14 passes through the O-phase signal S'10 in the interval corresponding to 1 and -18, and in the interval e corresponding to the half-height of the sampling period, the π-phase lissangle signal H is passed. Pass the number S7π. (Then, the rezange signal 57t is sent from the Kiriki circuit 14 to the song of one sandal period)
and S7πY 111th order resampling output information +-qS9 is obtained, which causes the low-pass filter 16 to
...and output stopper 1 as video output No. S 10
7). Here, the cutoff frequency of the filter 16 is selected to correspond to the upper limit frequency of the human input video signal S1 (FIG. 2 (4)), and thus there are many noise components above the upper limit frequency. It is designed to remove the burden.

In the above definition, one person was Kavideo Count No. 81 (Fig. 2 (A)
) is sampled by sampling pulse No. 18 820 of sampling frequency fB and S2π in sample and hold circuits 4 and 5.
! It is separated into two channel sample signals S30 and S3π. Here, sampling pulse S21. ) and S2π
are two-phase signals with mutually opposite holes, thus the first and second channel sample signals S30 and S3π are mutually @
The content of the data of adjacent pixels is distributed alternately,
As a result, all the information of the input video input S30 and S is corrected in the first and second channel sample signals S30 and S30.
This means that it has been converted to 3π.

At the same time, during the sampling process in the sample and hold circuits 4 and 5, the folded signals of the high frequency signal component and the low frequency coefficient component are addressed, and this folded signal is the signal component included in the input video signal S1. The signal is interleaved with the first and second samples 830 and S3π.

As a result, even if the first and second channel sample signals 7 and 53() and S3π or i- pass through the low-pass filters 7 and 8, the frequency band is limited to half. In the first and second channel recording numbers 841 and S42 obtained from the above, high frequency signals can be recorded together with the low frequency signal components of the human-powered video signal 81.

This V '1' l (first and second channel writing signals S51 and 852 reproduced from the main body 9 are resampled in the re-sandal circuit 10, and similar to the above-mentioned sandal operation, a frequency component folding effect occurs and the reproduced signal S
51 and S52, the 0-phase and π-phase samples S'10 and 87π, which are obtained by expanding the human video signal 81 twice, are obtained, and these samples are rearranged in time series in the switching circuit 14 to be resandled output. Tsukuda-1) i9y
! - is traced through the filter 16 and sent to the output terminal 17 as an output video signal 810'1-.

In this way, when recording on the VTR main body 9, recording signals S41 and 842 are obtained which have a frequency band half of the frequency band V of the input video signal S1 and contain all the information of the input video signal SL. and input video signal S based on the reproduced signals S 51 and 852.
An output video signal 810 having the same frequency band as 1 and 101 and containing all the information can be obtained, and thus can be recorded and reproduced with the same frequency band.

In the above, an example has been described in which the sampling pulse signal and the resampling pulse signal are selected to have two phases, 0 phase and π phase, but the number of phases can be increased to three or more as necessary. reactor.

[The young fruits of invention]

As described above, according to the present invention, a human video signal is sampled using a sampling pulse signal VC to obtain sample signals of a plurality of channels, and then the band of the sample signal is limited to form a recording signal. By doing this, it is possible to obtain a recording signal that is located in a frequency band that contains too much or too little information of the signal, and thus it is possible to reliably record and play back the video in the local band on the Qi2. In this way, it can be put to practical use with a sample-and-hold circuit having a much simpler configuration than a logger-type configuration that uses a gauge digital memory to increase the width of the time axis pressure by 1-1.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the video recording and reproducing apparatus according to the present invention, and FIGS. 2 and 3 are frequency characteristic diagrams and graphs showing signals of each part thereof. 4, 5, 11, 12...sample hold circuit, 6...sampling pulse generation circuit, 9...VT
R body, 10... resampling circuit, 13... resampling pulse generation circuit, 14... switching circuit. Agent 1) Figure 2

Claims (1)

[Claims] The input video signal is sampled with a sampling signal having a sampling frequency approximately equal to the upper limit frequency to obtain a plurality of channel sample signals, and the frequency of each sample signal is limited to a frequency band approximately as shown in the figure and recorded. 15, reproduces the recorded signal and converts the reproduced signal into 8tf of the sampling signal.
A video recording and reproducing apparatus characterized in that, after resampling at t, the plurality of sampled signals are combined to obtain an output video signal.