1. Definition of video capture card
A Video Capture Card, also known as a video capture card, is a hardware device that can capture digital video image information and store and play it back. It sends the image video signal of the camera, in the unit of frames, to the memory of the computer and VGA frame storage for computer processing, storage, display and transmission. Many video capture cards can capture video information and obtain sound at the same time, so that the audio part and the video part are saved and played simultaneously when digitized.
HDMI HD video capture card
2. the working principle of video capture card
SONY auto focus camera capture video/image after sampling, quantization after conversion into digital image, input, storage to the frame memory process. Because the transmission of the image signal requires a high transmission speed, the general transmission interface can not meet the requirements, so the video capture card is needed.
The signal obtained from the video source is sent to the video capture card through the video interface, and the signal is first converted to analog to digital, and then sent to the digital decoder for decoding. The ADC is actually a video decoder, it can be seen that it decodes and digitizes the video signal from the video source, in addition, different video input decoder chips can be selected using different color Spaces.
Video capture is the process of converting the analog signal of the video source into digital information through processing, and storing the digital information on the hard disk of the computer. This analog to digital transformation is carried out through the capture chip on the video capture card. Usually in the collection process, the digital information also carries on some form of real-time compression processing.
When the signal input rate of the video capture card is high, the bandwidth between the video capture card and the image processing system should be considered. When using a PC, the theoretical peak bandwidth of the video capture card using the PCI interface is 132MB/S.
1. the field of view (FOV) or scene is a specific part of the real world that the camera and optical system “see”.
2. the CCD chip converts light energy into electricity.
3. the camera will output this information to the video capture card in the format of analog signal.
4. AD – converter converts analog signals into 8-bit (or multi-bit) digital signals. Each pixel independently expresses the light intensity in the form of a Gray level value.
5. these light intensity values from the CCD chip matrix is stored in the memory matrix data structure.
Gray Level – The representation of pixel light intensity information Gray value is the representation method of real world image quantification. Usually grayscale values are 0-255 from blackest to whitest. The light enters the CCD pixel, and if the light intensity reaches the limit of CCD sensing, the pixel is pure white. The gray value of this pixel in memory is 255. If no light enters the CCD pixel at all, the pixel is pure black. Corresponding to the gray value of the pixel in memory is 0.
SDI HD video capture card
3. Features of video capture card
(1) The video capture card on the PC can receive the analog video signal from the video input, collect the signal, quantify it into a digital signal, and then compress and encode it into a digital video.
(2) Most video capture cards have the function of hardware compression, the video signal is first compressed on the card when the video signal is collected, and then the compressed video data is transmitted to the host through the PCI interface.
(3) Therefore, the key to achieve real-time acquisition is the processing time required for each frame. If the processing time of each frame of video image exceeds the interval between two adjacent frames, the data will be lost, that is, the phenomenon of frame dropping.
(4) The video capture card first compresses the acquired video sequence and then stores it into the hard disk, that is to say, the acquisition and compression of the video sequence are completed together, eliminating the inconvenience of again compression processing.
4. Video capture card of Xuan Zhan Technology
The video capture card is specially designed for the automatic focus camera, according to the different collocation of the camera and the control board, the audio and video signal is not the same, can be divided into SDI high-definition video capture card, HDMI HD video capture card and HDMI 4K video capture card, can meet the needs of various high-definition equipment acquisition. Widely used in education recording and broadcasting, network video conferencing, remote training, high-definition medical, stunt booth, multimedia high-definition video capture and other fields.