CVB

CVBS composite video broadcast signals, a widely used standard, also known as baseband video, transmit data in analog waveforms. The composite video contains color difference (hue and saturation) and Brightness (brightness) information, and synchronizes them in blanking pulses, transmitted with the same signal at a frequency of approximately 6MHz.

PAL standard CVBS signal

1. Pixel clock: at about 13.5MHz, the sampling signal obtained by the sampling theorem is 27MHz. The pixel clock is used to synchronize effective pixel signals.

2. Line synchronization signal: as the name implies, it is a synchronous line scan signal. Each line comes once, and the low level is effective (for positive TV signals).

3. Field synchronization signal: as the name implies, it is the signal of synchronous field scanning. Every time it comes, the low level is effective.

4. Concept of field and frame: Scanning from the top to the bottom of the screen is called a field, but it is not equivalent to a frame. A frame refers to the image data that can constitute a complete picture.

5.About level CVBS waveform analysis: ( assumptions made positive TV signals) a minimum level of 0, the highest level of 1, there is a reasonable boundary between the two values of x, think for pixel values between x to 1, the range is divided into 256 (assuming the accuracy for 8 bits), each value corresponding to a grey value, where x represents the black, 1 white, for all levels of gray level in the middle. X level is not effectively under the pixel value, also can saying is black, in which the synchronization signal fusion, including horizontal synchronization signal and field sync signal, a synchronous signal is much more wide than line sync signal and specific length of time of all have their own definition, so as to maintain the consistency of the sending and receiving period of signal, to restore the original image;

6. Concept of odd and even field; That is, a frame is scanned in two fields. The odd field is scanned first and then the even field is scanned. The two fields constitute a frame.

7, blanking and line of field blanking: with the presence of line synchronization and synchronization, when a row and the right of the screen to the head or a scan to the bottom of the screen, must return to the next line or the next scan, but also can't let people see out, so is the birth of the blanking line and blanking signal, flyback components during this period, although is also the scan but don't see as hidden.