JPH02143791A - Coder and decoder - Google Patents

Abstract

PURPOSE:To attain coding in a bit rate a half that of the studio standards while keeping the definition of a video signal by using a carrier of a frequency a half the sampling frequency so as to apply frequency multiple to a color signal subjected to line sequencing in the case of coding a high definition television signal. CONSTITUTION:A luminance signal Y and color signals PB, PR inputted from input terminals 100-102 are filtered at a prescribed band width at a low frequency respectively. After the color signals PB, PR subjected to line sequencing are used for amplitude-modulating a carrier having a frequency being a half the sampling frequency fS, the result is added to a luminance signal Y. Thus, the video signal of the high definition television is coded in a bit rate at a half the studio standards while the resolution is kept sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an encoding device and a decoding device used to digitize and transmit or record video signals.

2. Description of the Related Art In recent years, efforts have been made to improve the quality of television images, and among these, the Japan Broadcasting Corporation has proposed a high-definition television system that is completely different from the current television system (for example, High-Definition Television], Journal of the Society of Television Engineers, Vol. 36, No. 10, 1982), this system is being further standardized as an international standard, and studio standards are currently being published (e.g. , Broadcast Technology Development Council Standard BTA 5-001 rl
125/60 High Definition Television System Studio Standard (Broadcast Technology Development Council, established in August 1987), this standard defines the basic parameters and video signals used in the studio for the 1125/60 High Definition Television System. , synchronization signals, colorimetric parameters, etc. According to this, the main basic specifications include 1125 scanning lines, 2:1 interlaced scanning, and an aspect ratio of 16:9. The field frequency is determined to be 60 Hz, and the line frequency is determined to be 33.75 KHz. Also,
The video signal band is YPB.

In the case of RR format, the luminance signal Y is 30MHz, and the color signal P
B and P are 15 MHz, and when digitally sampled, they are each 74.25 M1 (z, 37.1
It is to be sampled at a frequency of 25 MHz.

Now, if we sample the video signal at the above frequency,
When quantized in bits, temporally multiplexed, and serially transmitted, the bit rate is 1188Mbit/
It becomes super fast with sec. Such high transmission speeds make hardware difficult and expensive to implement, and at the same time, it is almost impossible to use coaxial cables as transmission lines, and it is also difficult to use optical fibers. The transmission distance becomes shorter. Furthermore, when used in a recording system, the recording density on a magnetic tape or the like becomes extremely high.

Therefore, HLO-PAL (Ha If-1ine
A possible method is to digitally encode and transmit a decoded color television signal of the 0ffset PAL system (see [Reference Special Feature on High Definition Television JP 882-88]).
B.3. (See Signaling and Transmission).

The frequency spectrum of the decoded color television signal of this HLσ-PAL system is as shown in Figure 8, and the total band is 30
M1 (in z, the bandwidths of the luminance signal Y and color signals C1 and Cn are 20 MHz and 6.5 M, respectively) lz, 5.5 MHz
It becomes. The sampling frequency when digitally encoding this decoded color television signal is three times the color subcarrier frequency r5c (24,3 MHz) (72,9 MHz).
) or four times the frequency (97,2M7) is used,
583.2 Mbit/se when quantized with 8 bits
c or 777.6 Mbit/sec.

In this example, the bit rate can be reduced to about half of the studio standard, but since the sampling frequency is different from the studio standard, digital interfacing with studio equipment becomes difficult. Further, the bandwidths of the luminance signal and the chrominance signal are narrowed because the chrominance signal is orthogonally two-phase modulated and has both side bands and occupies a wide band.

Another method to reduce the bit rate while maintaining sufficient video signal bandwidth is to use band compression (high-efficiency coding), but high-definition television requires a high-speed arithmetic circuit, and the circuit size is large. The disadvantage is that it is large and complex. (For example, intra-frame/inter-frame adaptive extrapolation predictive coding of rHDTV signals, IEICE Transactions 87/IVo1.J70-B No. 196
~page 104).

Problems to be Solved by the Invention As described above, when a high-definition television signal is encoded using the conventional encoding method, when the luminance signal and color signal are temporally multiplexed in accordance with the studio standard, the bit rate increases. The bandwidth of decoded color television signals is too high, the bandwidth is narrow in the form of decoded color television signals, it is difficult to digitally interface with studio-standard equipment, and band compression makes circuit implementation difficult and complicated.

In view of the above problems, the present invention provides an encoding device and a decoding device that reduce the bit rate to 1/2 of the studio standard while ensuring sufficient video signal bandwidth, and that are easy to implement as a circuit. be.

Means for Solving the Problems In order to solve the above problems, the encoding device of the present invention performs low-pass filtering on the luminance signal and the chrominance signal each with a predetermined bandwidth, and filters the luminance signal and the chrominance signal with a frequency of 1/2 of the sampling frequency f5. The present invention has a configuration in which a frequency carrier wave is amplitude-modulated with the color signal and then calculated into the luminance signal.

Further, the decoding device inputs the video signal encoded as described above, separates the luminance signal by low-pass filtering the video signal in a predetermined band, and adds the video signal to the video signal at a sampling frequency f5. A configuration is obtained in which color signals are separated by multiplying carrier waves of 1/2 frequency and performing low-pass filtering in a predetermined bandwidth.

Effect: With the above-described configuration, the present invention can encode a high-definition television video signal at half the bit rate of the studio standard while maintaining sufficient resolution, and at the same sampling rate as the studio standard. Therefore, a digital interface with the studio standard can be easily established, and the circuit scale of the encoding device and decoding device is small, making it easy to realize hardware.

Embodiment Below, the configuration of an encoding device and a decoding device in an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of an encoding device and a decoding device in a first embodiment of the present invention.

In FIG. 1, 100 is an input terminal for the luminance signal Y;
1 is an input terminal for the color signal PB, 102 is an input terminal for the color signal PR, and 103 is a low-pass filter L (hereinafter abbreviated as LPF T).
, 104, 105 are low-pass filters (hereinafter abbreviated as LPF11), 106, 107, 108 are analog-digital converters (hereinafter abbreviated as A/D converters), 109, 110, 1
11 are digital luminance signals DY and color signals DP, respectively.
B and DPR input terminals, 112 is a delay circuit, 113
114 is a line sequential circuit, 114 is an adder circuit, 115 is an amplitude circuit, and 116 is an output terminal for an encoded video signal, and the above is the configuration of the encoding device. Also, in the same figure, 117
is an input terminal for the encoded video signal, 118 is a delay circuit, 119 is a demodulation circuit, 120 is a line interpolation circuit,
121, 122 and 123 are output terminals for digital luminance signal DY and color signals DPB and DP, respectively; 124, 1
25, 126 are Digicrew analog conversion circuits, 127
128 and 129 are LPF I, 128 and 129 are LPF II, 130 is an output terminal for a luminance signal Y, 131 is an output terminal for a color signal PB, and 132 is an output terminal for a color signal PR. The above is the configuration of the decoding device.

The encoding device and decoding device configured as described above will be explained below with reference to FIGS. 1, 2, 3, and 4. Here, FIG. 2 is a frequency characteristic diagram of LPF I and LPF II used in FIG. 1, FIG. 3 is a frequency spectrum diagram in the signal processing process in FIG. 1, and FIG. FIG. 2 is a waveform diagram showing the signal processing process in FIG. 1; First, the encoding device will be explained. In FIG. 1, input terminal too, 101,1
Luminance signal Y, color signal P8 and PR input from 02
are supplied to LpF1103, LPFI1104 and LPFI1105, respectively, and in LPF1103, the luminance signal Y is approximately 27M H as shown in FIG. 2(a).
It is low-pass filtered to a band of about z and sent to the A/D converter 106.
In the LPFs 104 and 105, the color signals PB and PR are low-pass filtered to a band of approximately 9 MHz, as shown in FIG. 2(b), and then supplied to the A/D converter and 108, respectively. The A/D converter 106107.108”i? is shown in Fig. 4 (
As shown in a) and (b), the brightness signal Y and the color signals PB and P are sampled at the sampling frequency f5, and the 8-bit
The video signals are quantized into delay circuits 112,
It is supplied to the line sequentialization circuit 113. Line sequential circuit 113
After aliasing noise is removed by a vertical low-pass filter, the color signals PB and PR are alternately thinned out line by line to form line-sequential color signals, which are supplied to the amplitude modulation circuit 115. In the amplitude modulation circuit 115, as shown in FIG.
) is multiplied by a carrier wave alternating at a frequency r5/2 as shown in FIG. 4(C), and is amplitude modulated to become a carrier color signal as shown in FIG. 4(d). , are output to the adder circuit 114. In the adder circuit 114, the luminance signal Y, which has been delayed by the delay circuit 112 in order to match the timing with the color signal, and the carrier color signal PB/P,
are added and output from the encoded video signal output terminal 116. As shown in Figure 3(a), the frequency spectrum of this encoded video signal has a luminance signal Y on the low frequency side.
are arranged, and the color signals PB/PR are amplitude-modulated and frequency-multiplexed on the high frequency side with the frequency fs/2 as the center. Further, since the luminance signal Y and the color signals PB/PR are band-limited by the LPF 1103 and the LPF IIs 104 and 105, respectively, there is almost no spectrum overlap.

Next, the encoded video signal, which will be explained about the decoding device, is supplied from the input terminal 117 to the delay circuit 118 and the demodulation circuit 119. The video signal is delayed in the delay circuit 118 to match the timing of the luminance signal Y and the color signals PB/PR, and then converted into an analog signal at the sampling frequency rs in the D/A converter 124. This analog signal has a luminance signal Y in the low range and a color signal PB/in the high range.
Because PR is multiplexed, it has a waveform as shown in Figure 4(e), and its frequency spectrum is as shown in Figure 3(a).
) as shown. By low-pass filtering this signal using an LPF 1127 having frequency characteristics as shown in FIG. 2(a), only the luminance signal Y shown in FIG. 3(a) is output from the separated output terminal 130. . Demodulation circuit 11
9, similarly to the amplitude modulation circuit 115, the color signal P
B/PR demodulates the carrier color signal into a baseband signal by multiplying the frequency-multiplexed video signal by amplitude modulating it in a high frequency range using a carrier wave having a frequency f5/2 by a reproduced carrier wave having a frequency fs/2. At this time, the signal in which the color signals PB/PR shown in Fig. 3(a) are multiplexed in the high frequency range is as shown in Fig. 3(b).
), the color signal Pa/PR is placed in the low range,
The luminance signal is amplitude-modulated from a carrier wave of frequency fS/2 and placed in the high frequency range, and the waveform at this time is the fourth waveform.
In the line interpolation circuit 120 as shown in FIG. The video signal with color signal PB is D/A
The video signal carrying the color signal PR is sent to the conversion circuit 125 as D/
The signal is supplied to the A conversion circuit 126. LPFU128 12
94. :, only the video signal in the band shown in FIG.
B. The color signal PR is output from the output terminal 132.

As described above, according to this embodiment, the luminance signal Y and the color signal P
By band-limiting B and PR using an analog low-pass filter, and performing amplitude modulation and demodulation processing on the line-sequential color signal, which has been digitized at a sampling frequency of 15, at a frequency of 1/2f8. , encoding and decoding are performed. Here, sampling frequency r, = 7
If the frequency is 4.25 MHz and the number of quantization bits is 8 bits, the encoded video code bit rate is 594 Mb.
it/see, which is about the same as when encoding the high-definition television signal of the HLO-PAL system mentioned above,
Also, the bit rate is half that of the studio standard encoding. Luminance signal Y and color signals P8 and PR at this time
The bandwidth of is determined by the characteristics of the low-pass filter, and an ideal filter would have a total bandwidth of 37.125 Msec (1/2 fS) for the luminance signal Y and the chrominance signal PB or PR. Become. For example, an LP with the characteristics shown in Figure 2 above.
When using F, luminance signal Y: 27MH2, color signal P a
/PR: A band of about 9 MHz can be obtained, and a higher quality image can be obtained than when encoding with the conventional HLo-pAL method.

A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 5 shows the configuration of an encoding device and a decoding device in a second embodiment of the present invention. In Figure 5, 5
00 is high-quality television studio equipment, 501 is a digital LPF [, 502°, 503 is a digital LPF■
, 504 is an encoding device in the first embodiment, 505
506 is the output terminal of the encoded video signal, 506 is the input terminal of the encoded video signal, 507 is the decoding device in the embodiment of FIG. Television studio equipment.

The operation of the encoding device and decoding device configured as described above will be described below.

This embodiment is an example in which a part of the encoding device and decoding device in the first embodiment is used to perform a digital interface between devices compliant with the above-mentioned studio standard. The studio device 511 is the transmitting side of the video signal, and the studio equipment 511 is the receiving side of the video signal. Luminance signal Y and color signal PB output from studio equipment 500
and PR are digital LPFI501. In the digital LPFI [502 and 503, the analog LPF 1103. LPFI1104
．． Similarly to 105, the encoder 504 is low-pass filtered.
digital luminance signal DY, color signals DPB and DP
is supplied to the input terminal of R.

In the encoding device 504, the video signal is encoded as described in the first embodiment and outputted from the output terminal 505. The encoded video signal is supplied from an input terminal 506 to a decoding device 507, where demodulation processing of color signals P8 and PR is performed as explained in the first embodiment, and digital luminance signals DY, color signals DPB and Digital LPFI508. LPFn509
and 510. Digital LPF 150
8. In the LPFUs 509 and 510, the luminance signal Y and color signals P8 and P are low-pass filtered and separated from the video signal, and are supplied to the studio equipment 511 on the receiving side.

As described above, according to this embodiment, since the encoding device operates at the same sampling frequency as the studio standard,
A digital interface between studio equipment can be achieved by simply inserting a digital low-pass filter and supplying a clock of frequency fs, and does not require complicated operations such as sampling frequency conversion.

The embodiment of the present invention shown in FIG. 3 will be described below with reference to the drawings.

FIG. 6 shows the configuration of an encoding device and a decoding device in a third embodiment of the present invention. In the same figure, 60
0, 601, 602 are the luminance signal Y11 signal PB respectively
and P, input terminals, 603 is a switch, 604 is L
PF I, 605 is LPFll, 606 is adder circuit, 6
07 is an amplitude modulation circuit, 608 is a band pass filter 8 or less B
609 is a frequency divider circuit, 610 is an A/D converter, 611 is a phase control circuit, 612 is an output terminal for an encoded video signal, and the above is the configuration of the encoding device. In the figure, 613 is an input terminal for an encoded video signal, 614 is a D/A converter, 615 is a demodulation circuit, and 6
16 is a phase control circuit, 617 is a BPF, 618 is a divide-by-2 circuit, 619 is an LPF I, 620 is an LPF II, 62
1 is a 1-line delay line, 622.623 is a switch, 62
4,625°626 are the luminance signal Y11 signal PB respectively
and PR output terminals, and the decoding device is configured as described above.

The operation of the encoding device and decoding device configured as described above will be described below. This embodiment is realized by performing the processing of the first embodiment almost in an analog manner. The color signals P8 and PR are switched for each line by a switch 603 using a line alternating signal.
It is line-sequentialized and supplied to LPFII. The color signal PB/P, which has been band-limited in the LPF, is obtained by dividing the clock signal of the sampling frequency rS by 2 in the amplitude modulation circuit 607 in the divide-by-2 circuit 609, and only the fundamental wave component is band-filtered in the BPF 608. The resulting frequency r
It is amplitude modulated by a 6/2 carrier wave and is supplied to an adder circuit 606. In the adder circuit 606, the LPFI60
4, the band-limited luminance signal Y and the amplitude-modulated carrier color signal are added and supplied to the A/D converter 610. In the phase control circuit 611, the frequency f5 resampling phase is determined by the addition circuit 60 as shown in FIG.
The phase of the sampling clock is controlled or adjusted so as to be at the peak position of the carrier wave of frequency f5/2 included in 6, and is supplied to the A/D converter 610, and the encoded video signal is output from the output terminal 612. The encoding process has been described above, and the decoding process will now be described. The video signal converted into an analog signal by the D/A converter 614 is amplitude-modulated to a high frequency band by the LPFI 619, the multiplexed color signal is removed, and a luminance signal Y is outputted from the output terminal 624. The sampling clock having the frequency fg is divided by two in the divide-by-two circuit 618, and the frequency is divided by two in the divide-by-two circuit 618.
17, only the fundamental frequency component is band-pass filtered and supplied to the phase control circuit 616.
Then, a reproduced carrier wave having the same phase as the carrier wave signal of frequency f5/2 included in the video signal converted into an analog signal by the D/A conversion circuit is supplied to the demodulation circuit 615, and the demodulation circuit 61
5, the amplitude-modulated carrier color signal in the video signal is demodulated by the carrier wave and supplied to the LPFn 620. LPF6
20, only the color signal components PB/PR are separated by lower-pass filtering than the video signal, and the switches 622 and 62
3 and l line delay line 621. In the switches 621 and 623 and the 1-line delay line 621, the line-sequential color signals PB/PR are converted into line-to-line time signals by performing line replacement, and output to the output terminals 625 and 621.
It is output from 26.

As described above, in this embodiment, the same encoding process as in the first embodiment can be realized by mostly analog circuits, and moreover, only one A/D converter and one D/A converter are used. A cheaper encoding device and decoding device can be expected.

Also, the sampling phase when encoding is set to the 7th phase of the carrier wave.
By setting the peak position as shown in the figure (B), it is possible to reduce the amplitude modulation Δe due to the time variation Δt of the sampling clock, as compared in the same figure (C), resulting in encoding with less noise. Can be decrypted.

In addition, 1. In the second embodiment, the sampling frequency of the PR of the color signal P8 is set to the same frequency fg as that of the luminance signal Y, but it is also possible to obtain sampling at the frequency rS by interpolation after sampling at a frequency of 1/215. It is also possible to configure the low-pass filters for the luminance signal and color signal with digital filters. In addition, in the encoding device, the sampling frequency f5 can be generated in phase synchronization with the horizontal synchronization signal of the video signal, and in the decoding device, when used in the transmission path, it is extracted from the transmission data, etc. Can be played.

Further, in the embodiment shown in FIG. 3, sampling phase control or phase control of a reproduced carrier wave for demodulation can be performed by multiplexing a reference signal of a burst signal or the like onto a video signal. Further, in the decoding device, it is also possible to perform line interpolation reproduction of the line-sequential color signal before demodulating, and then perform demodulation.

Effects of the Invention As described above, the present invention enables frequency multiplexing of line-sequential color signals using a carrier wave having a frequency that is half the sampling frequency when encoding/decoding a high-definition television signal. This makes it possible to encode the video signal at half the bit rate of studio standard encoding while maintaining sufficient definition, and also facilitates digital interface with studio equipment that conforms to the studio standard. . In addition, it is easy to convert into an analog circuit, making it possible to realize an inexpensive device with a small circuit scale.As for applications, it can be used for digital transmission via optical fibers or as an encoding/decoding device for digital VTRs, etc. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the encoding device and decoding device in the first embodiment of the present invention, FIG. 2 is a frequency characteristic diagram of the low-pass filter in FIG. 1, and FIG. 3 is the first embodiment of the present invention. FIG. 4 is a waveform diagram showing the signal processing process in FIG. 1, FIG. Fig. 6 is a block diagram of the encoding device and decoding device in the third embodiment of the present invention, Fig. 7 is a waveform diagram showing the sampling phase in Fig. 6, and Fig. 8 is the frequency allocation of the conventional HLO-PAL system. FIG. 103,127...Low pass filter ■, 10410
5.128,129...Low pass filter ■, 106
゜107.108... Analog-digital converter, 113... Line sequential circuit, 114...
... Addition circuit, 115 ... Amplitude modulation circuit, 1
19...Demodulation circuit, 120...Line interpolation circuit, 124,125°126...Digital-to-analog conversion circuit, 500511...Studio equipment, 501, 508...Digital low-pass filter ■, 502, 503, 509゜510...
...Digital low-pass filter I [,604,619...
...Low pass filter I, 605,620...Low pass filter ■, 603,622,623...Switch, 606...Addition circuit, 607... ......Amplitude modulation circuit, 608.617...Band pass filter, 609°618...2 frequency divider circuit, 611,
616... Phase control circuit, 610...
Analog-digital converter, 614... Digital-analog converter, 615... Demodulation circuit, 621... I-line delay line. Name of agent: Patent attorney Shigetaka Awano, 1 person, 1 person, 4 people

Claims (6)

[Claims] (1) A video signal consisting of a luminance signal and a color signal is input, and the luminance signal and the means for band-limiting the color signal; means for amplitude modulating a carrier wave having a frequency of 1/2 of the sampling frequency with the color signal to obtain a carrier color signal; and multiplexing the carrier color signal on the luminance signal. An encoding device characterized by having means for. (2) A claim characterized in that it has means for line-sequentializing two color signals having different hues for each horizontal scanning line.
1) The encoding device described. (3) The encoding apparatus according to claims (1) and (2), further comprising means for controlling the phase of the sampling clock and the carrier wave so that they have a constant phase relationship. (4) means for obtaining a luminance signal by inputting an encoded video signal and low-pass filtering the video signal;
means for demodulating a color signal by multiplying the video signal by a reproduced carrier wave having a frequency of 1/2 of the sampling frequency;
1. A decoding device comprising means for low-pass filtering a demodulated color signal. (5) The decoding device according to claim (4), further comprising means for reproducing two color signals having different hues for each horizontal scanning line by line interpolation. (6) The decoding device according to claims (4) and (5), further comprising means for controlling the phase so that the carrier color signal included in the video signal and the reproduced carrier wave have a constant phase relationship. An encoding device that does