the second is the convenience of connection. Only with high performance and inconvenient use, it is also difficult to enter the household product market, and the integration of home appliances and computers is impossible. It is not easy to connect a video recorder with a TV set now. The complicated connection of input, output, video and audio often confuses users. The new interface must be simpler than the existing interface, so as not to affect its popularization and application.
the third is universality. Only if it is not limited to a specific environment and equipment will it have a wide range of application groups. Finally, the price is cheap. If the price is too expensive, the number of users will be limited. IEEE1394 was born in household appliances, and developed in the digitalization of digital entertainment software such as DSS and audio and video equipment including digital communication technology such as ADSL. It is computer-centered, integrating computing, entertainment, communication and various multimedia applications, linking the microcomputer industry with the household appliance industry, thus creating a new field of information technology application. Its competitiveness is especially reflected in the characteristics of facing home appliances and families. Through IEEE1394, mono in 196s can be turned into fever-level stereo, and household appliances can be developed into multi-party interconnected multimedia devices. The envisaged products based on IEEE1394 include cameras, printers, disk drives, DVDs, VCRs, telephones, TV set-top boxes, compression/decompression devices, and audio and video devices in computers. According to the survey of American market and families, one third of families have microcomputers, 96% have televisions and 98% have telephones. Household appliances for general consumers have a bigger market, because consumers want to watch video
images with simpler products and enjoy entertainment at cheaper prices. IEEE1394 can be applied to various remote systems in home networks, commercial networks and the Internet. Products with the same functions are cheaper than ordinary microcomputer supporting equipment and have better scalability. All these make IEEE1394 products have strong and incomparable competitiveness.
comparison of bus types:
at present, the typical new generation buses are SCSI, FiberChannel, SSA and USB. By comparing them, we can see that SCSI, FiberChannel and SSA mainly focus on computer storage devices such as disks. USB is targeted at low-speed keyboards, mice, etc. And IEEE1394 is of epoch-making significance because it contains all the above characteristics.
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@@73212.JPG; Table 3 Comparison between IEEE1394 and USB @@
By comparing the characteristics of USB and IEEE1394 item by item, we can find that USB is a low-speed interface and supports isochronous transmission as IEEE 1394 does. The difference is that USB is mainly designed for PC, while PC,IEEE1394 is not only used for computers, but also widely used in household appliances. In the field of computer, IEEE1394 is juxtaposed with USB, which plays an important role as the bus and interface of computer. However, IEEE1394 has a higher speed than USB and may be used in all kinds of connections except keyboard and mouse. In this way, the back panel and cable of the computer can be simplified, the universality is enhanced, the use is more convenient, and the cost is reduced.
introduction to 1394 card
IEEE1394 is usually used in external devices such as digital cameras and various network devices. It is often called Firewire(Apple name of Apple) and i.link (the name of Sony). At present, 8MbpsIEEE1394 bus (also called Firewire-8) is gradually replacing 4MbpsIEEE1394 bus. The 6-PIN interface contains four signal lines and two power lines, which need no extra power supply, while the 4-PIN interface only has signal lines. The Firewire-8 interface adds a pin and uses a 9-PIN connection line.
the full name of 1394 card is IEEE1394 Interface Card. This interface technology was first founded by Apple, an old computer manufacturer. Apple called it Firewire, so many people used to call 1394 card as firewire card. Its original intention is to use it as a high-speed data transmission interface. In 1995, the Institute of Electrical and Electronics Engineers (IEEE) adopted it as a formal new standard, numbered 1394, which is the origin of the name IEEE1394. Different companies also have different names for 1394 interface technology, because the registered trademarks of their respective manufacturers are different. For example, Sony calls it i.Link, Texas Instruments calls it Lynx, etc., which are actually the same thing.
to sum up, we can know that IEEE1394 is an external serial bus standard, which can achieve a data transmission rate of 4MB/s and is very suitable for video transmission. As an open technical standard for data transmission, IEEE-1394 has been applied in many fields, including digital cameras, high-speed external hard disks, printers and scanners. The standard 1394 interface can transmit digital video signals and digital audio signals at the same time. Compared with the analog video interface, the 1394 technology has no signal loss in the process of acquisition and recording. It is precisely because of this advantage that the 1394 card is more used as a video acquisition card, but its other functions are ignored. The original 1394 cards cost thousands of dollars at every turn. In recent years, with the decline of production costs, the cheapest card only costs tens of dollars, and 1394 cards are rapidly spreading to more ordinary families.
characteristics of IEEE 1394
The characteristics of IEEE 1394 can be summarized as follows:
(1) High speed
The specified speed in IEEE 1394-1995 is 1Mbit/s to 4 mbit/s. The higher speed in IEEE1394b is 8Mbit/s to 3.2 gbit/s. In fact, 4Mbps can meet almost all the requirements. Now the physical stream LSI speed that is usually possible is 2Mbps. In addition, the actual transmitted data is generally compressed, and the original video data is not directly transmitted. Therefore, it can be said that 2Mbps is already a speed that can meet the actual needs. But for multi-channel digital video signal transmission, the higher the transmission rate, the better, and there is no end.
(2) Real-time
The characteristic of p>IEEE1394 is to use isochronous transmission to ensure real-time. At this point, SSA,FiberChannel and Ultra SCSI also have the same performance as IEEE1394.
(3) Thin cable is adopted, which is convenient for installation
4. The thin cable composed of two signal wires and two power wires makes the installation very simple and the price is relatively cheap. However, the contact spacing is only 4.5 meters, which seems to be slightly insufficient. Therefore, some people are also exploring ways to extend the contact spacing. The published experimental POF can extend the contact spacing to 7 meters.
(4) bus structure
IEEE1394 is a bus, not an I/O .. When transmitting data to devices, I/O is not used to transmit data like the network, but reading and writing are included in the conversion space according to IEEE1212 standard. In a word, from the upper level, IEEE1394 is the same bus as PCI.
(5) hot plug
can be plugged and unplugged with electricity. Add or delete new devices without turning off the power supply, and the operation is very simple.
(6) Plug and Play
Adding a new device can be automatically assigned without setting an ID. SCSI users must set the SCSI address, while IEEE1394 users do not need any relevant knowledge, and the operation is very simple, so they can use it when connected.
application
the application of IEEE 1394 is not limited to a single computer interface field. It has the characteristics of high speed and broadband, especially the ability of isochronous transmission, which can be applied not only to computers, but also to home appliances. At the same time, don't think that IEEE1394 can only be applied to such a small area as home LAN. The research on the bridge connection with ATM is under way, and the long-distance broadband application has also been conceived. The idea of connecting microcomputer and household appliances with IEEE1394 is shown in the following figure. It can be seen from the figure that the application of IEEE1394 can be roughly divided into three parts, one is digital video recorder, camcorder and other household appliances, the other is computer peripherals such as printers and scanners, and the third is internal peripherals such as hard disk and DEV-ROM.
@@73213.JPG ; Figure 1 @ @
The popularization of IEEE 1394 has attracted the attention of home appliance manufacturers at first, because its transmission rate reaches 1Mbit/s to 4Mbit/s, and it can transmit uncompressed digital images in real time, and it can not only establish a connection with a microcomputer, but also directly connect home appliances without a microcomputer. In 1996, the digital camcorder forum composed of more than 5 home appliance manufacturers took IEEE1394 as the standard interface of digital video/audio. That is to say, digital TV receivers corresponding to digital camcorders and digital broadcasting also adopt this standard. Sony has launched two NTSC digital camcorders with digital audio and video interfaces of IEEE1394 standard, which is the first step in the global application of IEEE1394. In November 1997, after the technical standards for preventing illegal copying were determined, camcorders and DVDs with IEEE1394 interface could be listed. The European Digital Television Broadcasting Corporation has decided to adopt the bus of IEEE1393 standard for remote control equipment and other peripherals. Sony has fully adopted IEEE1394 interface in its high definition multimedia products, realizing digitalization and networking. Other home appliance companies have also made progress in using IEEE1394. For example, Kodak Company produced the first digital camera supporting IEEE1394. Seiko-Epson's color printer with IEEE1394 interface can directly connect with a digital camera or camcorder to print color photos without a computer.
it seems that computer manufacturers are late to respond to IEEE1394, but some major manufacturers have already started to take action. At the end of 1997, Intel decided to integrate IEEE1394 circuit in peripheral chip (logic LSI). Microsoft Corporation of the United States has supported IEEE1394 port in Windows 98, and developed device driver software supporting digital camcorders and digital video recorders. Another technology called Device Bay, which is advocated by several companies such as Intel and Microsoft, is also emerging. Device Bay will connect various devices through two standards, USB and IEEE1394. It can be seen that these new standards are expected to be widely used.
in a word, IEEE1394 is both a new generation interface and a new generation bus. It is not only a computer peripheral interface standard, but also a home appliance interface standard; As a user-friendly multimedia connection mode, it can be widely used in home, mobile environment and office. As a low-cost digital interface for audio/video, new audio/video products such as digital TV, multimedia and CD-ROM(MMCD-ROM) home network will be the initial market of IEEE1394. IEEE1394 will gradually improve the existing SCSI scanning devices, CD-ROMs, tape drives, printers, etc., thus fundamentally eliminating the obstacles for families to move towards multimedia.
classification of 1394 cards
At present, 1394 cards on the market can be basically divided into two categories: 1394 cards with hard decoding function and 1394 cards with software compression coding. The former one is more expensive, while the latter one is very cheap. As long as 1 yuan is around, Tiger's 1394 card is only bought in 7 yuan, and it has always been good:) Let me talk about these two kinds of 1394 cards slowly.
the first type is the 1394 card with hard decoding function, such as EZDV acquisition card, which not only can transmit the video signal of TV or video recorder to the computer, but also has the hardware compression function, which can compress the video data into MPEG-1 format video stream in real time and save it as an. MPEG file or a. DAT file, so that video discs can be made conveniently. The famous brands are Pinnacle, Snazzi, etc. The performance of these products is generally good, and the matching software is more professional and functional, and the use effect is also ideal, but the price is relatively expensive, generally ranging from hundreds to more than 1, yuan, and the most expensive is 1, yuan!
Another cheap 1394 card which uses software to realize compression coding, its function is to input video signals into a computer to become digital signals that can be recognized by the computer, and then use software to edit the video in the computer. Generally speaking, the function of the 1394 card is to transfer the video content in the digital video tape to the hard disk. The 1394 card is just a data transmission interface, unlike the video capture card, which requires video compression hardware. AVI files transmitted to the hard disk through the 1394 card are edited and post-processed by software. In fact, even if there is compression coding hardware on the 1394 card, it only works when editing and generating MPEG files, but it doesn't work when transmitting data. The biggest feature of this 1394 card is that it is cheap and suitable for beginners. The disadvantage is that the 1394 card is edited by software, and the amount of data is huge (one hour of video is 13-17GB, which means that a 6-minute DV tape takes up 13-17GB of hard disk space), so the requirements for hard disk and CPU are higher. If your computer is older, you'd better upgrade your computer first, and then edit and make videos:) If you don't want to upgrade your computer, you can choose the first one with hardware coding function.