JP2594182B2 - MUSE decoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a timing signal control circuit for stably deriving a video signal in a still image mode from a MUSE decoder.

[0002]

2. Description of the Related Art A multiplexed sub-Nyquist sampling encoding system (hereinafter referred to as a MUSE system) is used as a system for transmitting a high-definition video signal using a broadcasting satellite after compressing the band. The MUSE system converts a high-definition video signal into a band-compressed video signal having a band of 8.1 MHz (hereinafter referred to as a MUSE signal) by a band-compression encoder for transmission on a single channel of satellite broadcasting (bandwidth of 27 MHz). It is.

[0003] This MUSE signal is obtained by converting a high-quality video signal into a T signal.
Band compression using the CI multiplex sampling method, which is input to a band compression decoder (MUSE decoder) and
By the clock synchronized with the horizontal synchronization signal in the SE signal,
The MUSE signal is subjected to signal processing such as A / D conversion of the MUSE signal, storage / readout of A / D converted data, and synthesis, and is reproduced as a high-definition video signal.

The above-mentioned MUSE decoder stores A / D conversion data for four fields for synthesizing a high-definition video signal, and displays a still image only with the stored data of these four fields. It is possible.

[0005] A conventional MUSE decoder has a configuration shown in FIG. The analog processing unit (1) has an input terminal (2)
It performs analog signal processing such as automatic level control and clamp control of the input analog MUSE signal, and outputs the result to the A / D converter (3).

The timing generator (8) includes a counter reset by a detected frame pulse (reset signal) output from the frame pulse detector (9) and various timing signals required inside the MUSE decoder according to the output of the counter. , And generates a timing signal synchronized with the input MUSE signal.

The clock synchronous reproduction section (13) reproduces a clock in accordance with the horizontal synchronization timing signal synchronized with the horizontal synchronization signal in the input MUSE signal from the timing signal generation section (8) and distributes the clock inside the MUSE decoder.

[0008] The decoder (4) stores and reads out the video data converted by the A / D converter (3) in the memory (5) in a normal state, and according to the sub-sample information and the motion information multiplexed in the MUSE signal. , And performs signal processing such as synthesis to reproduce a high-definition video signal. In the still image display mode, a high-quality still image signal is reproduced by cyclically reading out data stored in the memory (5) in accordance with a mode switching signal input from the terminal (11).

The reproduced high-definition video signal is converted into an analog signal in a D / A converter (6) and output from an output terminal (7).

However, in order to reproduce a high-definition video signal, M
Various timing signals used in the USE decoder are synchronized with the frame pulse in the input MUSE signal.
As shown in the timing chart of FIG. 4, even in the still image display mode, the reproduction is performed in accordance with the timing signal synchronized with the frame pulse of the input MUSE signal regardless of the reproduction image.

Therefore, the conventional MUSE decoder has M
When a reproduction signal of a USE video disk player is input, a search or the like is performed in the still image mode, and when a discontinuous MUSE signal is input, a still image is not displayed correctly.

[0012] Even when a received MUSE signal by satellite broadcasting is input, the MUSE signal is discontinuously input in the still image mode due to the channel switching operation of the receiver, so that the still image image is not displayed correctly.

Therefore, no matter which MUSE signal is input, the still image is not displayed correctly due to the input of the MUSE signal unrelated to the reproduced image in the still image display mode.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in the case where a high-quality still image video signal is synthesized when an input MUSE signal is derived from a video disk player. If the MUSE signal is a broadcast signal and the MUSE signal is a broadcast signal, the video signal generated by the malfunction due to noise during the still image reproduction period or the discontinuity of the horizontal synchronization signal at the time of channel switching of the receiver is generated. It is a technical problem to eliminate unstable operation.

[0015]

According to the present invention, in order to solve the above-mentioned problems, a MUSE signal obtained by band-compressing a high-definition video signal using a TCI multiplex sampling method is input, and the MUSE signal is input.
A / D-converting the MUSE signal in synchronization with the clock while controlling an oscillation circuit that generates a clock by an oscillation control output that follows a synchronization signal in the USE signal;
The A / D converted data is synchronized with the clock by four fields.
While the data is stored in the memory for the flash memory, the data read from the memory and the A / D conversion data that are synchronized with the clock during normal operation are synthesized to derive a high-definition video signal. In a band compression decoder which interrupts and cyclically reads the data in the memory in synchronization with the clock and synthesizes the read data to derive a high quality still picture video signal, the data is always synchronized with the input MUSE signal. A first timing signal generation circuit; and a second timing generation circuit involved in deriving a high-definition video signal, wherein the second timing generation circuit outputs an output signal of the first timing signal generation circuit in a normal state. And in a still image mode, it operates cyclically.

[0016]

According to the MUSE decoder of the present invention, the MUSE decoder
A MUSE signal input during a steady state is provided by providing a timing generator synchronized with a signal and a timing generator for reading field memory, and switching between the still image display mode and the steady mode while maintaining the relationship between these timing generators. A high-definition video signal is reproduced in accordance with the timing synchronized with the M.
A stable high-definition video signal that is not affected by the USE signal can be reproduced.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram showing a configuration of a MUSE decoder according to the present invention.

In FIG. 1, (1) denotes an analog signal processing unit which performs analog signal processing such as automatic level control and clamp control of an analog MUSE signal input from an input terminal (2). (3) is an A / D converter, which converts analog data output from the analog signal processing unit (1) into digital data.

(4) is a decoder.
The video data converted by the D conversion unit (3) is stored in and read from the memory (5), and signal processing such as synthesis is performed in accordance with the sub-sample information and motion information multiplexed in the MUSE signal, thereby obtaining a high-definition video signal. Reproduce.

In the still image display mode, the memory (5) is operated in accordance with the mode switching signal input from the terminal (11).
The high-quality still image signal is reproduced by cyclically reading out the data stored in the memory.

The reproduced high-definition video signal is converted into an analog signal in a D / A converter (6) and output from an output terminal (7).

The timing generator 1 (8) is a counter which is reset by the detected frame pulse (reset signal) output from the frame pulse detector (9) and various types of signals required inside the MUSE decoder in accordance with the output of the counter. It comprises a timing signal reproducing section for reproducing a timing signal, and generates a timing signal synchronized with the input MUSE signal.

The timing generator 2 (10) cyclically generates a timing signal. In addition, the switch (1
It is connected to the timing generator 1 (8) via 2), and is reset by a frame pulse output from the timing generator 1 (8) when the switch (12) is closed.

The clock synchronous reproducing section (13) reproduces a clock according to the horizontal synchronizing timing signal synchronized with the horizontal synchronizing signal of the input MUSE signal from the timing signal generating section 1 (8) and distributes the clock inside the MUSE decoder.

The switch (12) is opened and closed according to a mode switching signal input from a terminal (11).

In a steady state, the switch (12) is closed and the timing signal generator 2 (10) generates a timing signal synchronized with the input MUSE signal by the reset signal from the timing signal generator 1 (8). For this reason, as in the conventional case, the decoder (4) stores the video data converted into digital information by the A / D converter (3) into the memory (5).
And performs signal processing such as synthesis in accordance with the sample information and motion information multiplexed in the MUSE signal, and reproduces and outputs a high-definition video signal.

In the still picture mode, the mode switching signal input from the terminal (11) is switched to the still picture mode, and at the same time, the data stored in the memory (5) is read cyclically, and the switch (12) is opened. , The timing signal generator 1 (8) and the timing generator 2 (10) are separated. Therefore, the timing generator 2 (10) cyclically generates a timing signal while maintaining the relationship with the data stored in the memory (5).

By performing as described above, the input MUSE signal, the timing generator 1 (8), and the timing generator 2 (10) at the time of the steady state and the still image mode of the MUSE decoder.
3 can obtain the relationship shown in FIG. 3, and always outputs a frame pulse synchronized with the data stored in the memory (5), and continuously derives a high-quality still image video signal stably.

[0030]

According to the MUSE decoder of the present invention, during the still image mode, a high-definition video signal can be stably reproduced even if a MUSE signal unrelated to data stored in the memory is input from the input terminal. Input MUSE
Even if the signal is input discontinuously, it is possible to make a stable device without the reproduced video signal being disturbed.

[Brief description of the drawings]

FIG. 1 is a block diagram of a conventional MUSE decoder.

FIG. 2 is a block diagram of a MUSE decoder according to the present invention.

FIG. 3 is a timing chart of the MUSE decoder of the present invention.

FIG. 4 is a timing chart of a conventional MUSE decoder.

[Explanation of symbols]

 1. Analog processing unit 2. Input terminal 3. A / D conversion unit 4. Decoder 5. Memory 6. D / A converter 7. Output terminal 8. Timing generator 1 9. Frame pulse detector 10. Timing generator 2 11. Terminal 12. Switch 13. Clock synchronous playback unit

Continuation of the front page (72) Inventor Yoshikazu Asano 2-18-18 Keihanhondori Moriguchi City Sanyo Electric Co., Ltd. (72) Inventor Yosuke Mizutani 2-18-18 Keihanhondori Moriguchi City Sanyo Electric Co., Ltd.

Claims (1)

(57) [Claims] 1. An oscillator circuit for inputting a MUSE signal obtained by band-compressing a high-definition video signal using a TCI multiplex sampling method and generating a clock by an oscillation control output following a synchronization signal in the MUSE signal. However, the MUSE signal is A / D-converted in synchronization with the clock, and the A / D-converted data is stored in a memory for four fields in synchronization with the clock, while being synchronized with the clock in a steady state. A high-definition video signal is derived by synthesizing the read data from the memory and the A / D conversion data, and when the still image is reproduced, the storage in the memory is interrupted and the data in the memory is cyclically synchronized with the clock. A frame pulse synchronized with the input MUSE signal is generated in a band compression decoder which synthesizes read data and derives a high-quality still image video signal while reading. A first timing signal generating circuit, a second timing signal generating circuit which oscillates in synchronization with the frame pulse and participates in deriving a high-definition video signal, and a second timing signal generating circuit which performs normal reproduction. A MUSE decoder, comprising: switch means for permitting the input of the frame pulse and prohibiting the input of the frame pulse to the second timing signal generating circuit during reproduction of a still image.