CN100493172C - A scanning method for TV video signal - Google Patents

Abstract

The present invention relates to a scanning method of television video signal. It is characterized by that the television video input signal with different standard can be undergone the process of line frequency normalization treatment, and converted into unified line frequency to implement line scanning output. Its convertible frequency is 33.75KHz signal, and can be used for making line scanning output, so that it can raise the reliability of various television video signals.

Description

A scanning method for TV video signal

【Technical field】

The invention relates to the field of television, in particular to a method for scanning television video signals.

【Background technique】

At present, the main applications of scanning methods in the TV field are as follows:

1. Traditional 15.625K/15.75K line-frequency interlaced scanning: the advantage is that the scanning method is easy to implement, the bandwidth of the image signal is narrow, the cost is low, and the reliability is good. This scanning method has been used until now. The disadvantage is that there is interline flicker and local parallel phenomenon when the odd and even field grating mosaic is not ideal, and when the object moves along the horizontal direction with a large enough speed, the vertical edge of the image will produce jagged phenomenon. In the interlaced scanning mode, the line structure lines are relatively rough, and there are phenomena such as large-area field flickering and crawling. These phenomena are especially obvious when displaying on a large screen above 29 inches.

2.100HZ scanning: This is a scanning technology represented by Philips since the mid-1990s to eliminate large-area field flicker. This solution uses digital technology to process images, and uses SDRAM (buffer memory) to process images. Buffering and storage, the speed of reading is twice that of writing, scanning is performed at a frequency twice the line frequency of the input signal, and the field frequency is changed from 50HZ to 100HZ while ensuring that the number of signal lines in each field remains unchanged , thus eliminating large-area field flicker, and can support VGA input. However, because it still adopts the interlaced scanning method, although it solves the phenomenon of large-area field flicker, the flicker between lines still exists, the problem of rough line structure has not been solved, and the overall image quality is not ideal.

3. Progressive scanning: This technology started in the late 1990s. This technology is similar to 100HZ scanning technology. It doubles the number of lines per frame. Progressive scanning eliminates the phenomenon of rough line structure lines, making the image more delicate, and can also support VGA input, but the problem of large-area field flickering in the image still exists.

4. Frequency conversion scanning: This is a new technology that has only emerged in the past two years. This technology is to convert the PAL signal with 50HZ field frequency to 60HZ field frequency and perform progressive processing and output at the same time. This technology can simultaneously solve the shortcomings of rough line structure, field flicker, and crawling that cannot be solved by traditional TV scanning methods.

5. High-definition digital TV: Since the standard of high-definition digital TV is different from that of traditional TV signals, the TVs with the above scanning methods cannot watch digital TV signals. There are also several types of high-definition digital TVs: 1080i60HZ, 1080i50HZ, 720P (45K), 480P (31.5K), etc. Japan, the United States, and Europe use 1080i60HZ, and some cities in my country have high-definition digital TVs of 1080i60HZ for trial broadcasting, but my country will use 1080i50HZ as my country's future high-definition digital television standard. At present, TV sets used to watch digital TV in our country mostly use multi-line frequency mode, but this multi-line frequency mode is difficult to realize, high cost, and poor reliability. Therefore, the price of digital TV of various manufacturers remains high, which also affects The promotion of digital TV in our country.

【Content of invention】

The purpose of the present invention is to provide a scanning method for television video signals compatible with various traditional video signals and high-definition format video video signals.

The object of the present invention is achieved like this: the scanning method of this a kind of TV video signal is that the TV video input signal of different standards is processed and converted into the signal that unified line frequency is 33.75KHZ through horizontal frequency normalization processing and carries out scanning output.

For the traditional TV video signal, it is first converted into a digital YUV signal, and the digital signal is deinterlaced, and the signal with a line frequency of 15.625KHZ is converted into a progressive signal with a line frequency of 31.5KHZ, and then each frame signal Carry out line interpolation and complement line, and convert the signal into a signal scanning output with a frequency of 33.75KHZ.

For the DVD signal, it is converted into a digital YUV signal, the signal is interpolated, and the signal with a horizontal frequency of 31.5KHZ is converted into a signal with a horizontal frequency of 33.75KHZ for scanning output.

For the VGA signal, the signal is processed by line insertion and line extraction, and the signal is uniformly converted into a signal with a line frequency of 33.75KHZ for scanning output.

For 720P signal, it converts 720P signal into 33.75KHZ signal for scanning output.

Compared with the prior art, the present invention has the following advantages: by converting the TV video input signals of different standards into signals of a single line frequency for scanning output, the problems of rough TV line structure, field flicker and crawling are solved, and it supports Various traditional TV video signals and high-definition digital TV signals in various standard formats improve reliability.

【Description of drawings】

FIG. 1 is a schematic diagram of the signal processing flow of the present invention.

Fig. 2 is the schematic diagram of the circuit when the present invention converts the signal into a 33.75KHZ horizontal frequency signal.

【Detailed ways】

Please refer to FIG. 1 to FIG. 2 , the scanning method of the TV video signal is to convert the input signals of different standards into a uniform horizontal frequency for scanning and outputting through horizontal frequency normalization processing. This method can convert input signals of various standard formats into a single horizontal frequency of 33.75KHZ.

When converting input signals of different standards into a single signal with a horizontal frequency of 33.75KHZ:

a) For the traditional TV video signal, after the digital YUV signal decoded by the video decoder (model VPC3230) is sent to the digital video processing chip (model PW1235), the chip first performs deinterlacing processing (Deinterlace) on this signal, Convert the signal with a line frequency of 15.625KHZ to a progressive signal with a line frequency of 31.5KHZ, and then perform interline interpolation for each frame signal to convert the signal into a signal with a frequency of 33.75KHZ.

b) After the DVD signal is sent to the digital video processing chip (model PW1235) after the digital YUV signal decoded by the video decoder (model VPC3230), the chip only performs interline interpolation for this signal, and adopts interpolation and supplementary line technology. Convert the original signal with a horizontal frequency of 31.5KHZ to a signal with a horizontal frequency of 33.75KHZ.

c) For high-definition 1080i 50HZ signals, since the field frequency is 50HZ, there will be a large area of field flickering phenomenon in large-screen and high-brightness display, so the digital video processing chip (model PW 1235) will process the signal Converted from 1080i 50HZ to 1080i 60HZ, the horizontal frequency of the signal is just 33.75KHZ.

d) For the 1080i 60HZ signal, only the picture quality is improved.

e) For 720P signal (the signal line frequency is 45KHZ), this is an uncommon signal format. For large-screen display, the reproduction of the picture in 1080i display mode is the display mode with the best picture quality. Therefore, digital video The processing chip (PW1235) converts the 720P signal into a 33.75KHZ signal for scanning processing.

f) For VGA signals in various formats (VGA: 640 X 480 SVGA: 800 X 600XGA: 1024 X 768), line insertion and line fetching are required, and the signals are uniformly converted to 33.75KHZ for output display.

The above method of converting the field frequency of 50HZ to 60HZ is to store and process the input signal through a digital circuit, and compress it on the time axis; for the input signal of 50HZ/20ms, the time to write one field is about 20ms, Through the software, the time for the signal to read one field under the control of the clock pulse is about 16.7ms, so that the reading of each field is 3.3ms faster than the writing. There will be an extra 3.3 X 5 = 16.5ms for every 5 games, 16.5ms is just enough to insert a signal, that is, the input is 5 signals, and the output is 6 signals, inserting a game every 5 games, 50 games 10 field signals can be inserted, which ensures the conversion of 50HZ to 60HZ.

In the above-mentioned digital video processing chip, different input signals are processed accordingly, and converted into a unified horizontal frequency (33.75KHZ) signal. The digital image signal is processed by color and brightness enhancement, and black level extension processing. , after high-precision digital-to-analog conversion (D/A), together with the horizontal and vertical synchronous signals, it is sent to the pillow correction processing and pre-view processing chip (the chip model is TDA9332), and the pre-view processing chip controls the line , Field scanning and other small signals are processed and then sent to the video amplifier circuit for amplification and output. At the same time, in the digital processing module of digital video processing, advanced graphics processing technologies such as motion compensation technology, small-angle image edge processing technology, and movie mode processing are also used to make the image clearer and smoother.

The meaning of the described brightness enhancement processing is as follows: in the brightness channel of the digital processing module, a DC reference voltage is provided by the blanking signal to delay the brightness, and the brightness delay line is composed of a delay line that can delay 45ns, 90ns, 100ns, 180ns, And 450ns filter composition. The delay of the luminance signal is controlled between 20 and 1100 ns with a period of 45 ns through the I ² C bus to ensure that the maximum delay of the luminance signal and the color difference signal is within +22 ns, based on the automatic brightness delay controlled by the internal loop of the deviation component Variation in time (using the line frequency as a reference). In the vertical blanking period, the control voltage is peaked through the internal circuit of the chip. Its main function is to increase the high frequency component of the video signal to improve the clarity of the image.

The significance of the color enhancement processing is as follows: the color enhancement processing is mainly used to improve the instantaneous change of the color difference signal and improve the edge characteristics of the color transition. Clamped by a reference voltage during processing, each color difference signal is sent to a moment detector and an analog signal switch with associated voltage and memory circuits. The analog signal switch is open at a certain moment, and then the maintenance voltage is provided to the outside. When this moment comes, the switch is closed to quickly receive these real-time signal levels, so that these real-time signal levels have a consistent gain.

The significance of the described black level extension processing is as follows: in the luminance signal, detect the light black level of the luminance signal, and compare this level with the blanking level, if it does not reach the blanking level (black level Flat) direction expansion, so that the original light black part is expanded into deep black, but it will not exceed the blanking level, which improves the contrast of the image and makes the screen display the level of the super scene in the dark field background. The fuzzy feeling is eliminated.

The significance of the motion compensation technique is as follows: when converting an interlaced signal to a progressive signal, for a moving picture, one frame cannot be obtained simply by adding the scene, which will cause jagged and blurred images. For a moving picture, the heart needs to make different compensations for the content of the two images according to the motion characteristics of the image, and then construct a new frame. The quality of motion compensation directly affects the quality of motion pictures after the interlaced signal is converted to progressive signal.

The described small-angle image edge processing technology is as follows: since the motion compensation is only a certain degree of compensation, when the image edge is a small angle and is a moving image, it is prone to jagged phenomenon. Therefore, when this situation is detected and recognized, the For moving small-angle image edges, the two-field signals are median-filtered to smooth the image edges.

The movie mode processing is as follows: the program source of the TV may be the interlaced signal taken by the TV, or it may be obtained by interlacing processing of the movie program at 24 frames per second, and the signal transferred from the movie program can be identified Yes, but the interlaced-to-progressive-interlaced-to-progressive-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlaced-to-interlace method for movie programs for movies is not the same as motion compensation and other processing, but directly restores the signal to the image state of the original movie, and then passes through The scan output is displayed.

Claims (2)

1, a kind of scan method of television video frequency signal is characterized in that: the television video input signal of various criterion being handled through the line frequency normalizing and be converted to line frequency is that the signal of 33.75KHZ scans output, comprises the steps:

When importing traditional television video input signal, it is converted to digital YUV signal earlier, go interlacing to handle this digital signal, with line frequency is the progressive signal that the signal of 15.625KHZ is converted into 31.5KHZ, then every frame signal is carried out in the ranks interpolate value and mend row, it is that the signal of 33.75KHZ scans output that signal frequency is converted to line frequency;

When input DVD signal, when being converted into digital YUV signal, this signal is carried out interpolation in the ranks, be that the conversion of signals of 31.5KHZ is that line frequency is that the signal of 33.75KHZ scans output with line frequency;

When input VGA signal, when this signal was taken out row and got row and handle, unified was that line frequency is that the signal of 33.75KHZ scans output with conversion of signals;

When input 720P signal, it is that the conversion of signals with 720P is that line frequency is that the signal of 33.75KHZ scans output.

2, the scan method of television video frequency signal according to claim 1, it is characterized in that: the television video input signal of various criterion being handled through the line frequency normalizing and be converted to line frequency is after the signal of 33.75KHZ scans output, the signal that also will be 33.75KHZ to the line frequency of this output carries out colour and brightness lifting processing, and black level extends processing.

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