With the continuous development of computer technology, computers not only run faster and faster, but also have better performance and richer functions, especially in the application of multimedia, which has reached its peak. Nowadays, personal computers have many functions and a wide range, which was unimaginable before 10. Playing realistic 3D games with computers, watching TV, listening to music, playing DVDs and carving CDs are all familiar to everyone. In fact, the computer can not only become your multimedia broadcasting center, but also become your convenient multimedia production center. Many friends want to make their own multimedia files, especially editing and making their own multimedia videos. With the popularization of VCD and DVD, it is quite practical and interesting to make your own VCD disc, record your favorite TV programs, transcribe the images taken by the camera into MPEG- 1 format, and save MPEG-4 or even MPEG-2 format on the disc. In order to realize this function on your favorite computer, a fully functional video receiving and collecting card (box) is essential. Video capture cards (boxes) are not like ordinary sound cards and graphics cards on the market, and everyone is familiar with them. For users who want to buy capture cards, they may not be familiar with this market. Faced with many products, it is difficult to distinguish the advantages and disadvantages, let alone choose the product that suits you. In order to let everyone know something about the video capture card, it is the purpose of this paper to have a clear mind when purchasing and using it.

Before buying a video capture card (box), first consider whether your computer can be used for video capture, compression and storage. Because the standard video and audio data is very large, it has high requirements for CPU, hard disk and so on. Without compression, the data collected in just one minute may reach hundreds of megabytes. And if your CPU and hard disk can't keep up with the requirements, you can't capture it, or the effect is very poor (such as serious distortion, discontinuity, frame drop, etc.). ), so if you want to make video shooting go smoothly, a CPU above PIII level and a 40G hard disk with at least 7200 rpm are essential.

First, a preliminary understanding of the acquisition card (box)

As the name implies, the acquisition card is the mixed data that imports video data or outputs video and audio from other data sources (such as TV sets, analog video recorders, VCD players, digital video cameras, etc.). ) input into the computer, and convert them into data that the computer can recognize, store them in the computer, and become digital signals that we can edit and process.

Second, the main manufacturers of acquisition cards (boxes)

There are many manufacturers of acquisition cards. At present, the manufacturers that can be seen in the market mainly include: AverMedia, Pinnacle, Hollywood producer, Kangneng Pushi, Snazzi, FlyVideo (sapphire), Broadway, PowerVision and 10Moons, Optibase, T & ampw Tongwei Technology, Taiwan Province Song Li Technology, Gatechnik Technology, etc. They all have their own characteristics, and there is always one that will meet your requirements.

Third, the main product structure of the acquisition card (box) market

According to the current product line, according to their uses, performance and uses, the author thinks that the products on the acquisition card market can be roughly divided into three grades:

1, low grade-the choice of primary users: In fact, the product of this grade is not a real acquisition card, but a product similar to a video converter. The products of this grade are mainly TV boxes (cards) with primary video acquisition function or computer graphics cards with TV input acquisition function. Their function is to convert the analog signals of TV into digital signals that can be recognized by the computer, and then collect videos in the computer with software. The disadvantage is that hardware-level processing, including compression and editing, is impossible. Video shooting can only be regarded as an accessory function of this grade of products. As an accessory function, we can't ask too much. When low-grade products are used as video capture cards, the resolution is low, the types of files saved are few (some can only be saved as AVI video format), and there is no image compression function. Although these products have low cost and relatively simple functions, they are widely used and have the largest number of users. There are several different types of low-end products: (1) AVerMedia TV Genie for TV boxes, (2) AOPEN Mx400a and ATI All-In-Wonder series for multi-function graphics cards, and (3) ATI TV WONDER for TV card reception. (3) Marvel Comics G400- Hybrid TV. The price of low-end products is generally low, ranging from 300-500 yuan, while the price of computer graphics cards with TV input and acquisition functions is around 1,000 yuan. This kind of products are mainly suitable for users who want to watch TV on the computer, do some simple video collection work or take video collection as an entertainment project. This kind of acquisition card has the worst acquisition effect and cannot compress data at the hardware level. It belongs to the product of experiencing entertainment level.

2. Mid-range product-real-time video capture compression card. This kind of product is what we usually call a video capture card. The biggest difference between this grade acquisition card and low-grade products is that it has the hardware compression function of video. It can not only transmit the analog video signal of TV or video recorder to the computer, but more importantly, it has hardware compression function, which can compress video data into MPEG- 1 format video stream in real time and save it as. MPEG file or. DAT file, so that VCD can be made conveniently. At present, there are many kinds of such products. Famous brands include AverMedia, Pinnacle and Snazzi. Mid-range video capture card products are mostly used to edit and make commercial multimedia VCD, and are also welcomed by some users who often make home VCD. Compared with the primary products, the performance of this kind of products has been greatly improved, and the supporting software is more professional, richer in functions and more ideal in use. At present, the price of such products is around 800-2000 yuan. In mid-range products, there are two kinds of video and audio integrated acquisition and video and audio separated acquisition. The video-audio separation acquisition card mainly omits the audio acquisition part in order to save costs, but it requires higher system requirements than the integrated one, especially for sound cards. If the sound card is not good, it may lead to the situation that the sound signal and video signal are not synchronized when collecting. If the user is inexperienced, the probability of this situation will be higher. The integrated acquisition card product, which is more advanced than the video-audio separation acquisition card, has added the audio acquisition component, which has obviously improved the recording effect and is recommended. The mid-range products are Snazzi, Flyvideo EZ-II, 10 MoonEzre-Corderpro, Yinhe Xiaojingang and so on. This kind of products should have many varieties, complete functions and reasonable prices in the market, and belong to popular commercial or household products.

3. High-end products-MPEG capture compression cards with powerful functions and more functions. Users of high-end products are rarely family users, so it is not necessary for family users to spend tens of thousands of dollars on a collection card in order to make several VCD discs. Therefore, only professional business users are suitable for this kind of products. High-end products can not only provide high-quality VCD, that is, pure hardware-level compression of MPEG I, but also provide hardware-level clips of DVD(MPEG II). And comes with a lot of expensive professional multimedia production software. This kind of high-end products can collect video and audio from any video source and compress them into MPEG I or MPEG II quality video and digital audio formats, which are suitable for various digital video applications including making VCD, super VCD, DVD and radio and television. This kind of high-end products are naturally expensive, at least several thousand yuan, and some high-end products cost ten thousand yuan, among which the famous ones are: AV-8, AV-800, Broadway Pro, PowerVision998/AV, Movie Maker 200 Publisher FD1DE, etc. Because high-end products are not suitable for ordinary users, there is no need to introduce too much.

Fourth, the key points that should be paid attention to when purchasing

Like other computer hardware, the basic principle of buying is enough. The key is to use it on yourself and not blindly pursue it. Avoid unnecessary expenses. In addition, when choosing a suitable acquisition card, we should shop around, carefully compare the performance and price of various acquisition cards, and carefully identify and proofread the advertisements made by manufacturers and merchants. Users should compare several main performance parameters,

1, whether it supports hardware-level processing of video data is very important.

2, frame rate, this indicator is more important and specific. The frame rate directly affects whether the video file produced by the acquisition card is smooth or not. Generally, products with low frame rate have low grade and high CPU utilization rate. At present, the average mid-range video capture card can basically reach 352 *288 (PAL system), and the frame rate that can be recorded at this resolution can reach 25 frames per second. High-end products can reach 60 frames per second. For ordinary families, the dynamic resolution of MPEG I compressed by PAL system should reach 25 frames per second (NTSC system) and 30 frames per second when the resolution is 352 * 288.

3, resolution, we know that resolution is the main parameter of video file quality. Generally, the resolution of VCD is 352*288 (PAL system, 320*240 NTSC system), while the resolution of DVD is much higher, usually 704*480 30fps or 704*576 25fps. And the average user can't use such a high resolution. In addition, it should be noted that the resolution can be divided into static picture capture resolution and dynamic resolution. In general, the resolution of still picture capture is much higher than that of dynamic resolution, but it may not be indicated in product advertisements, and consumers may regard the resolution of still picture capture as dynamic resolution. Pay attention to distinguish this when buying.

4. Do not underestimate the audio input function. Without this function, we will only capture images, and audio signals will be transmitted and recorded through the sound card, which will increase the occupancy rate of system resources and easily lead to the synchronization of video and audio signals. Once this happens, there is no room for correction, so we can only re-record. As for VCD production software, the more the better, the higher the VCD production software.

IV. Application Guide of Acquisition Card

1, the connection between acquisition card and digital video recorder. With the increasing popularity of digital video cameras, the requirements of film and television lovers for video production are also constantly improving. However, because video products are not very popular, many users will not only buy digital cameras, but also ask me what digital collection and editing cards I should have. In my opinion, what kind of graphics card to match should consider the following factors:

1) output mode:

If the final product is a DV video tape, you can choose a common 1394 interface card just by using the editing function of the graphics card. After editing by software, you can output it to DV video tape. If the final product is VCD or DVD, it is recommended that you use a video compression card with real-time hardware compression function, such as SuperVCD and SuperDVD. AV-800 and so on. Because a major feature of this card is that the hardware completes the compression process, it not only saves time (the compression time of 1: 1, and the compression time of 1394 card is about 1:5), but also saves space (1 hour takes up 650 MB of hard disk space, 65438).

2) computer configuration:

Editing card is a bridge between digital camera and computer. Because 1394 card is edited by software, the data volume is huge (1 hour 17GB), so the requirements for hard disk and CPU are higher. If the computer configuration can't meet the higher requirements, it is more practical to use the real-time compression card, because the real-time compression card is used to edit compressed files (1 hour 650MB), and the requirements for hard disk and CPU are not very high.

3) Image quality requirements:

Generally speaking, exporting to DV video tape or making DVD will not cause much loss of image quality, but if exporting to VCD, the loss after image compression will be considered. Because the resolution of VCD is 352*288, which is only equivalent to the level of AV interface, there is little difference between the input image quality of DV interface and AV interface when making VCD, so general VCD compression cards do not have DV interface.

So how to choose a digital acquisition editing card for a digital camera? The author thinks that the popular digital editing cards on the market can be divided into two grades.

1)DV 1394 data card

This kind of product only transmits DV data recorded by digital camera to computer hard disk, and other functions such as editing and compression are realized by software. Generally, there is only 1394 data interface, which is a 1394 card suitable for home use. More popular are: peak StudioDV, SuperDV, AverDV and other products.

2) Editing card with 1394 interface

In addition to the functions of the above data cards, these products also have real-time editing functions. Adding subtitles and special effects are all done by hardware, and no generation time is needed, which is a nonlinear editing card in the usual sense. In addition to the 1394 interface, these cards are generally equipped with AV and S-Video interfaces. Products are MV 300, DC 30 PLUS and so on.