The Design Of Video Transmission System Based On USB Interface

1. The purpose of the topic researchNowadays ,in the information society,the information technique and the information industry take multimedia as the representative ,the influence and function which are brought by the development and application of them is more and more obvious , more and more important to the mankind.The quick development of multimedia technic not only offers more abundant and more socience method for mankind socience, and more important,it raises the efficiency and quality of the mankind work,study and life greatly, so, many science workers for pushing its development carry on various kinds of the science researches and experiments, obtain multilayers results.In the information exchange of Mankind, the most abundant information stream is the sense of vision medium. Video frequency information shares the most part in the information. Compared with the analogy video, the digital video has the obvious advantage at memory, editing, transmission etc. but the information of the digital video takes much space. The characteristics like vast data, real time of the video information show that the equipments are put forward the higher request towards capture, transmission, memory and display. At present, in the capture video, coding and decoding, the development of them adopts the hardware method mostly, mainly because of using the hardware card to collect and compress the video image takes up the CPU resources less, and it provides the development kit is convenient for customers to fast develop, but the cost is higher, and its packed interface function is not good at using again for customers. As the progress of the technique CPU and the computer capability, it can be realize to use software to apply the greatly parts of video data processing. There are various paths to capture video information. Computer becomes the first choose of video source for its great capacity, and high speed.Current real time video transmits with the bus, such as: the PCI, 1394 and USB (the Universal Serial Bus). The relative characteristic of the three, the protocol of the USB high speed is fast, universal, credible, saving power, hot plug etc. Compare with traditional video transmission system which based on PCI bus or 1394 bus, it is flexible, universal, convenient to install, easily expand, especially in the occasion needing the notebook and other portable equipments for video output. The USB2.0 breaks the bottleneck of the USB1.1, can provide the high speed for collecting and transmitting vast data, and can satisfy the resolution as the need that common VGA video collecting and transmitting. It does not need compress the data, thus that it raises up real time, lower the cost of the system. The video image that the resolution higher than the VGA has been captured and decoded by stream medium, will form many data packages, adopts USB to transmit streaming date to the customer in proper orderly and real-time.To transmit a great deal of information in time and accurately to the others, display technique becomes necessary part. It is a bridge between person and information in modern social. As the development of the display technique, various display equipments are full of each corner of people live in. Big as tens even hundreds of square meters large displays, small as mobile telephone,PDA,MP3,digital camera etc., small electron equipments, they are all enrich people's life by their gorgeous and colorful and moving image, the video effect.According to the above-mentioned present condition, according to the USB2.0 techniques, this text researches and designs AMOLED display, transmit system, actualizes the 640×480 resolution for VGA video date transmission,it is satisfied the development of the topic group and the future of video application.2. System designMake use of USB2.0 to carry on the total design principle figure that the video data transmission as follows: Computer is the control backbone for video transmission and display system, including customer application program, namely a video play software and control play software, the computer is responsible for the play content collections, and displays the content on the computer as the request of the screen and certain format and certain display sequence, the transmit video image is 640×480 in this design. On the other hand, sends the image on the display to the screen by USB2.0 transmission control moduleFigure 1 is the video transmission system. The whole system is divided into three parts: The video capture play control module, USB2.0 transmission module, and OLED part. The video signal sources have various way, such as Internet, collect data card and the video file etc., to satisfy the request of the OLED, this design adopts 640×480 AVI format video file. At the control of customer application program, under, make use of the module that the DirectShow correspond to obtain the video data from the video file and carry on a decoding. On the control of application program, USB data transmission module captures the video data from the playing computer, and by USB sends data continuously to the USB equipments as ISO transmission manner.3. Main ConclusionThis text studied the USB bus technique and its specification first, including a bus characteristic, data transmission types, data stream module and information etc., and analysis and compares USB1.1 and other bus. According to USB2.0 technique, carried out a kind of video image transmission system project. Designed the hardware system that based on USB interface and CPLD video image transmission , write firmware for USB2.0 interface and the chip CY7C68013 and customer application program. For carrying out the correspondence between the customers application software system and the hardware system, write the drive procedure for USB equipments.The main contents:First, this text makes detailed discussion to the structure of USB bus system and its specification, specially, thoroughly analyses and researches the way of the USB date transmission and the USB device driveSecond, make use of configuring endpoints and GPIF interface technology of FX2 series chip of the Cypress Corporation, design the USB firmware which can fit the requirement of transforming video data by high speed based on USB2.0 specification.Third, analyses realize theory of transmission on USB bus and the hierarchical structure of the WDM driver. According to the requirement of video transmission, program USB driver by using Driver Works. Forth, designs simple USB Communication program.Fifth, designs the USB control device periphery application circuit and the circuit for video transmission and store.In this article we go into USB2.0 technology. Also we design the video transmission system of the 640×480 resolution of the AMOLED screen. And we develop the video obtain module and processing module technology, USB driver, USB firmware and USB peripheral circuit that based on USB2.0. We through analyzing and debugging the USB driver, USB firmware and the circuit for video data transmission and store controlled by CPLD, make the design come to an expectant design objective. And we get the desire control signals and video data stream which can satisfy with displaying requirement by the 640×480 resolution of the AMOLED screen.