JPH04322565A - Video signal processor - Google Patents

Abstract

PURPOSE:To configurate circuits after a TCI decoder of a MUSE decoder with analog circuits. CONSTITUTION:A luminance signal and a color difference signal from a TCI decoder is processed by a clamp circuit 1, an inverse matrix circuit. External R, G, B signals are analogically processed by a clamp circuit 5. Each signal is selected by a changeover switch 6 to lead out a signal of one system. A signal of the other system is led out via a level adjustment circuit 7 and a matrix circuit 8.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing device for decoding MUSE signals, and particularly focuses on signal processing after a TCI decoder.

0002

[Prior Art] As a method of transmitting a high-definition television signal with a bandwidth equivalent to one channel of a satellite broadcasting signal, four
MUSE (M
ultipleSub-Nyquist Sample
ng Encoding) method.

FIG. 2 shows a MUSE decoder that returns the MUSE signal to the original broadband high-definition television signal. The MUSE baseband signal introduced into the input terminal 1 is converted into a digital signal by an analog/digital (hereinafter referred to as A/D) converter 11 via a low pass filter (hereinafter referred to as LPF) 10 . A/D converter 1
The output of 1 is synchronous. Control. Audio signal separation circuit 2
3, the signal is input to a de-emphasis circuit 12 and de-emphasized, and further multiplied by gamma characteristics by a reverse transmission gamma correction circuit 13. Synchronization. Control. The audio output separated by the audio signal separation circuit 23 is derived via a time expansion circuit 24 and an audio decoder 25. Synchronization. Control. The control signal separated by the audio signal separation circuit 23 is input to the motion detection circuit 14 and the still image processing section. The output of the reverse transmission gamma correction circuit 13 is connected to the still image processing unit, which is composed of an interframe interpolation circuit 15, an LPF 26 sampling frequency conversion circuit 27, and an interfield interpolation circuit 28, an interfield interpolation circuit 16, and a sampling frequency conversion circuit. The signal is input to a moving image processing section composed of a circuit 29. The outputs of the still image processing section and the moving image processing section are respectively input to the mixing circuit 30. The mixing circuit 30 performs mixed output according to the motion based on the control of the motion detection signal of the motion detection circuit 30.

The output of the mixing circuit 30 is TCI (Time
Compressed Integration)
The signal is input to the decoder 17. The TCI decoder 17 outputs the time-extended luminance signal YM and color difference signal (B-YM).
, (B-YM) (hereinafter referred to as PB, PR). The luminance signal YM is input to the inverse matrix circuit 19, and the color difference signals PB and PR are input to the LPF 18.
a, b to the inverse matrix circuit 19, and R
．． G. The signal is converted into a B signal, and further multiplied by gamma characteristics in the gamma correction circuit 20. The output of the gamma correction circuit 20 is
After being converted into analog signals by digital/analog (hereinafter referred to as A/D) converters 21a, b, and c, the L
It is derived via the PFs 22a, b, and c.

As mentioned above, since the MUSE signal is A/D and D/A converted before and after the decoder, most of the processing can be done digitally, resulting in excellent stability and accuracy. There is an advantage. However, a MUSE decoder with such a configuration has a 10
A dedicated digital IC in a package with 0 or more pins is used, resulting in a very high cost. Also, this digital I
In C, it takes time to check the operation, so testing costs more. These problems are essential, and we have no choice but to wait for IC costs to decrease due to technological advances.
There is no solution. Even if there is such a problem, there is no problem if it is used for business purposes, but it is a problem that cannot be ignored when used for consumer purposes.

Furthermore, when used for consumer use, R. G. B signal and brightness. It is necessary to have input and output sections for both color difference signals. Therefore,
In addition to the above digital IC, an input switching section and an R.
G. Brightness from B signal. A matrix circuit for converting into color difference signals must be provided. These input switching units and matrix circuits may be provided in the digital IC, but in order to perform digital processing, an A/D for external input is required.
A converter is required, further increasing the cost.

[0007]

[Problem to be solved by the invention] As explained above,
Conventional MUSE decoders perform most of the signal processing digitally to obtain stability and accuracy of the device. However, when used for consumer use, the increase in cost due to digital IC is a problem that cannot be ignored, and if this device is to be equipped with an external circuit to support multimedia, the cost will further increase. There was a problem. By the way, when the MUSE decoder is considered for consumer use, high accuracy is not required after the TCI decoder. Generally, analog ICs are much cheaper than digital ICs, so if the processing after the TCI decoder is performed in analog, the cost of the MUSE decoder can be significantly reduced.

[0008] The present invention focuses on the above-mentioned points, and it is possible to reduce the cost of the device, to make it compatible with multimedia without increasing the number of external circuits and increasing the cost, and to make the device suitable for IC. An object of the present invention is to provide a video signal processing device after a TCI decoder configured as follows.

[0009]

[Means for Solving the Problems] This invention provides a MUSE (
Multiple Sub-Nyquist Samp
TC that constitutes the decoder
I (Time Compressed Integra
tion) It has means for performing inverse matrix and gamma correction processing after the decoder by analog signal processing,
The luminance signal and color difference signal of the TCI decoder are subjected to the inverse matrix processing and R. G. a first matrix calculation means for converting into a B signal; a gamma correction means for performing the gamma processing on the output of the first matrix calculation means to restore the gamma characteristic; and an output of the gamma correction means; Another strain of R. G. A selection means for selectively deriving the B signal and dealing with two systems of input, and further comprising a second matrix calculation means for converting the output of the selection means into a luminance signal and a color difference signal to obtain two systems of output. This is how it was done.

0010

According to the above means, the inverse matrix circuit and gamma correction circuit subsequent to the TCI decoder can be constructed from analog circuits, and this portion can be implemented as an analog IC. Furthermore, external R. G. A changeover switch for selectively deriving the B signal and the gamma correction signal, and a R.B signal and a gamma correction signal. G. It can be integrated into an IC including a matrix circuit that generates color difference signals from B signals.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a video signal processing apparatus according to the present invention. The present invention relates to signal processing after the TCI decoder 17 of the circuit shown in FIG. Luminance signal Y based on MUSE transmission signal equation
M and the color difference signals (B-YM), (B-YM) are each input to the clamp circuit 1. These signals are
The output of the TCI decoder 17 is a signal converted into an analog signal. Clamp circuit 1 uses clamp pulse CP1
Use the pedestal clamp or sink tip clamp to regenerate the DC component. Each output of the clamp circuit 1 is input to the inverse matrix circuit 2, and R1'. G1'.
It is converted into a B1' signal. These R1'. G1'. B
The 1' signal is input to the gamma correction circuit 3, and the inverse gamma correction applied on the transmitting side is undone. In the case of an analog circuit, deviation from the regular correction curve is unavoidable, so the gamma correction curve can be finely adjusted. Furthermore, since the gamma correction circuit also has a through function, it can also be used in a MUSE-NTSC converter. The outputs of the gamma correction circuits 3 are input to the level adjustment circuits 4, respectively, and errors occurring in the inverse matrix circuit 2 and the gamma correction circuit 3 are corrected. R1 of level adjustment circuit 4. G1. The B1 signals are each input to the changeover switch 6. Here, for example, R2 . G
2. The B2 signal is input to the clamp circuit 5, subjected to DC regeneration using the clamp pulse CP2, and then input to the changeover switch 6. The changeover switch 6 has two sets of R. G. One set is selected and derived from the B signal. These selected outputs are amplified to appropriate amplitudes if necessary and output. At this time, if the clamp voltages of clamp circuits 1 and 5 are made substantially the same, no change in brightness will occur even when switching at high speed, so it is possible not only to simply switch the video signal, but also to form a sub-screen within the main screen. A so-called picture. in. It can also be used as a picture.

The output of the changeover switch 6 is further input to a level adjustment circuit 7 for amplitude adjustment, and then input to a matrix circuit 8. The matrix circuit 8 has an R. G. Brightness of B signal. Color difference signal Y
M. PB. PR, and if necessary, amplify it to an appropriate amplitude and output it.

R.I. input to the clamp circuit 5. G. The B signal does not necessarily include a synchronization signal, and even if it does contain a synchronization signal, it is not the same as the conventional NTSC signal.
The signal may be a binary synchronization signal, but it does not necessarily include a three-value synchronization (hereinafter referred to as 3S) signal necessary for this device. Therefore, the brightness that requires 3S signal. Color difference signal YM. PB. For PR, a 3S signal supplied from the outside is adjusted to an appropriate level by a level conversion circuit 9, and then input to a matrix circuit 8 and added. On the other hand, R. G. Since the B signal does not require a synchronization signal,
The sync signal portion may be muted using the changeover switch 6. In this way, regardless of the presence or absence of the 3S signal, the R. G. B signal and YM. PB.
PR signal is obtained. Note that if each circuit has high precision, the level adjustment circuits 4 and 7 may be omitted.

As explained above, by providing the D/A converter, which was conventionally placed after the gamma correction circuit, after the TCI decoder, the inverse matrix and gamma correction after the TCI decoder can be processed analogously. Furthermore, if this part is made into an analog IC, the cost can be significantly reduced compared to the conventional case where everything is made up of digital ICs. There is also a selector switch and R for switching between multimedia compatible external input and the above gamma correction.
．． G. The matrix circuit that generates the color difference signal from the B signal can also be realized with an analog circuit, so it can be incorporated into the same IC. In this case, only the number of input/output IC pins and the chip size due to the increase in circuits need to be changed, so the increase in cost is small.

[0016]

As described above, since the inverse matrix circuit and gamma correction circuit after the TCI decoder can be constructed from analog circuits, a significant cost reduction can be realized. Furthermore, since it can easily handle multimedia, it is possible to provide a video signal processing device suitable for consumer use.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a video signal processing device according to the present invention.

FIG. 2 is a configuration diagram showing a conventional MUSE decoder.

[Explanation of symbols]

1, 5...clamp circuit, 2, 19...inverse matrix circuit,
3, 20... Gamma correction circuit, 4, 7... Level adjustment circuit,
6... Selector switch, 8... Matrix circuit, 9... Level conversion circuit, CP1, CP2... Clamp pulse, 10, 1
8, 22, 26...LPF, 11...A/D converter, 12...
De-emphasis circuit, 13... Reverse transmission gamma correction circuit,
14...Moving part detection circuit, 15...Interframe interpolation circuit,
16...Field interpolation circuit, 17...TCI decoder,
21...D/A converter, 23...Synchronization. Control. Audio signal separation circuit, 24... Time expansion circuit, 25... Audio decoder, 27, 29... Sampling frequency conversion circuit, 30...
mixed circuit.

Claims (3)

[Claims] [Claim 1] MUSE (Multiple Sub
-Nyquist Sampling Encodin
g) TCI (Time Comp
essed Integration) A video signal processing device characterized by having means for performing inverse matrix and gamma correction processing after a decoder by analog signal processing. 2. The luminance signal and the color difference signal of the TCI decoder are subjected to the inverse matrix processing and R.I. G. a first matrix calculation means for converting into a B signal; a gamma correction means for performing the gamma processing on the output of the first matrix calculation means to restore the gamma characteristic; and an output of the gamma correction means; Another strain of R. G. Select and derive the B signal, 2
2. The video signal processing device according to claim 1, further comprising selection means for dealing with inputs of the system. 3. The video signal according to claim 2, further comprising a second matrix calculation means for converting the output of the selection means into a luminance signal and a color difference signal to obtain outputs of two systems. Processing equipment.