Video capture card, "Video Capture Card", its function is to capture video signals into the computer and save them on the hard disk in the form of data files. It is an indispensable hardware device for video processing. Through it, we can transfer the video signals captured by the camera from the camera tape to the computer, and use relevant video editing software to post-edit the digital video signals. Processing, such as cutting pictures, adding filters, subtitles and sound effects, setting transition effects, adding various video special effects, etc., and finally converting the edited video signals into standard VCD, DVD and online streaming media formats for convenience spread.
Video capture card classification
1. According to the video signal source, it can be divided into digital capture card (using digital interface) and analog capture card.
2. According to the installation link method, it can be divided into external capture card (box) and built-in board.
3. According to the video compression method, it can be divided into soft compression (consuming CPU resources) and hard compression.
4. According to the video signal input and output interface, it can be divided into 1394 capture card, USB capture card, HDMI capture card, VGA video capture card, PCI video card, and PCI-E video capture card.
5. According to their performance and functions, they can be divided into TV cards, image capture cards, DV capture cards, computer video cards, surveillance capture cards, multi-screen cards, streaming media capture cards, component capture cards, high-definition capture cards, notebook capture cards, DVR card, VCD card, non-linear editing card (non-linear editing card for short).
6. According to their uses, they can be divided into broadcast-level video capture cards, professional-level video capture cards, and civilian-level video capture cards. Their levels are mainly due to the different quality of the captured images. The main difference between them is the different image indicators collected.
There are many methods of video image acquisition, which can be basically divided into two categories: digital signal acquisition and analog signal acquisition. Therefore, common image capture cards also include digital capture cards, analog capture cards, and AV+DV two-in-one capture cards.
The highest capture resolution of broadcast video capture cards is generally 768X576 (root mean square value) PAL system, or 720X576 (CCIR-601 value) PAL system 25 frames per second, or 640X480/720X480 NTSC system 30 frames per second minimum compression ratio Generally within 4:1. The characteristics of this type of product are the high resolution of the images collected and the high signal-to-noise ratio of the video. The disadvantage is that the video file is huge, with the data volume per minute being at least 200MB.
The performance of professional-grade video capture cards is slightly lower than that of broadcast-grade video capture cards. The resolutions are the same, but the compression ratio is slightly larger. The minimum compression ratio is generally within 6:1, and the input and output interface is AV. Composite terminal and S terminal. The dynamic resolution of civilian-grade video capture cards is generally up to 384X288, and the PAL system is 25 frames per second.