Based on MPEG-4 video capture PCI card design and implementation

  Abstract: A MPEG-4 based video compression card. The board is 4-way encoding PCI card, will be collected analog video images in MPEG4 compression way. PCI2.2 standard specifications, complete with CPU control board PCI card with encoded communication between the CPU control board can be accessed via a bridge chip encoding chip registers, read out the chip compression encoding of video compression MPEG-4 streams audio compression stream. So that the compressed MPEG-4 data transmission to complete a remote or local storage. Another is to complete the video preview. The board for the remote real-time monitoring provides the necessary hardware, his latest MPEG-4 compression to encode the entire video network digital surveillance systems and transmission systems provide the most optimized hardware design, digital video data management more convenient and reliable, but the entire system in the market competition is more dynamic.
Keywords: MPEG-4 codec chip; video coding; MPEG-4; Windows operating system
  In the past a long period of time, traditional analog CCTV systems are monitoring the market place mainstream products. But with the development of information technology and user needs increase, analog CCTV surveillance system exposed some flaws. Main features: not very far distance, can not remotely monitor, wiring large projects, especially suited to the digital information age trends. The advantages of digital control systems just to overcome the limitations of analog CCTV, video streaming, such as network transmission, transmission distance, cabling does not repeat, anti-jamming capability, remote monitoring, query and convenient.
   In the security system growth and development, the monitoring system is mainly reflected the trend: from single to multiple - monitoring equipment, with each passing day; from the simple to the intelligence - computer technology into all areas of security equipment; from single to network - network monitoring system is the inevitable trend; from the local to the full - the intelligent building control systems into a hot spot. Therefore, the digital control system is the inevitable trend of development.
The card is now adapted to the requirements of digital surveillance systems, computer-card form, to facilitate networking, installation, use and maintenance. The main board uses a 4-chip MPEG-4 codec chip, with Host and PCI interface, and small size, processing capability and low power consumption. Thus as a separate processing unit that allows researchers to self-development.

1 MPEG-4PCI functional design board
We MPEG-4PCI board features designed to:
(1) audio A / D
Complete analog video signals to digital video signal conversion.
(2) video A / D
Complete analog audio signals to digital audio signal conversion.
(3) compressed audio and video synchronization
The input video data streams compressed into MPEG-4 data stream and the audio signal through the MPEG-4 codec chip IS interface input.
(4) streaming video preview
Not encoded images can preview the output port directly.
(5) Alarm Input
Complete external interface alarm signal input.

 The modular design of 2 PCI card
 The overall block diagram of the board and interface signals shown in Figure 1.
The system consists of four A / D chip (with Philip's SAA7114), 4 片 A / D chip (with Burr-Brown Corporation PCM1801U), 4 片 MPEG-4 codec chip (Vweb company), a bridge chip ( Hint use the company's HB1), a logical control chip (Xilinx Inc.) composition. A / D chip, MPEG-4 codec chip to complete 4 camera input converter and MPEG-4 compressed video data stream. CPLD controls the preview playback, alarm signal and ID authentication signal. A / D chip and MPEG-4 codec chip work is done based on the Windows operating system.


PCI card from the functional code is divided into six modules:
    (1) front-end video and audio processing by the decoding part of the two blocks
    ① 4 片 SAA7114H video decoder chip provides analog video to digital video (BT656) converter.
    ② 4 片 PCM1801U achieve audio A / D sampling, through the I2S and MPEG-4 codec chips.
    (2) MPEG-4 encoding module
       The four MPEG-4 codec chip and its peripheral circuit, mainly to complete real-time video and audio data compression.
    (3) bridge chip driver module
        Zero reaction time PCI-PCI bridge products HB1, he supported PCI2.2 specification, support 32 b 33 MHz for PCI operation. Through the chip, you can implement the bridge          function, multi-chip set support.
    (4) bus and the driver modules
        Including the PCI bus driver and isolation, providing board power, clock, reset and interrupt.
    (5) Alarm circuit
        Through the CPLD programming control of the alarm signal.
    (6) auxiliary circuit
        Is to provide board MPEG-4 codec chip 1.8 V power supply required and 24.576 MHz and 27 MHz clock circuit.
2.1 Video A / D converter module
   Camera to the analog data collected is sent to the A / D converter chip for video decoding, converting the analog video to digital video (BT656 format), digital video signals    into MPEG-4 compression chip. Analog circuits need to provide A / D converter chip clock frequency required 24.576 MHz, A / D conversion chip will use this frequency to    synchronize MPEG-4 compression chip [1].
2.2 audio A / D converter chip
   Microphone collected the audio signal AD sampling, through the I2S and MPEG-4 compression chip connected to the audio signal into MPEG-4 compression chips, the clock frequency of 32 kHz, 44.1 kHz, 48 kHz [2].
2.3 MEPG-4 compression module
   System startup, MPEG-4 compression chip start-up circuit to start reading the code to activate the appropriate download from the corresponding port to download microcode to run, while other chip via the I2C bus to complete initialization, the system starts the process of MPEG-4 codec . SAA7114H analog video through the A / D conversion, real-time video streaming from the mouth into the VPO chip MPEG-4 compression coding part of the VPO port, and analog audio through PCM1801U the A / D conversion, real-time audio streams from MPEG- 4 compression chip I2S input. MPEG-4 compression chip through the PCI interface chip is connected with the bridge, encoding compressed data through the bridge chip and then transmitted to the PCI bus bridge, providing transport to remote or local storage [3].
2.4 bridge chip driver module
   MPEG-4 compression chip encoded data drive through the bridge chip and arbitration, to complete the bridge task, allowing four with MPEG4 compression chip PCI interface to communicate with the PCI bus, support PCI2.2 specification, support 32 b 33 MHz the PCI operation.
2.5 bus and its driver module
   PCI interface board in compliance with PCI specification V2.2 version of the 33 MHz 32 b PCI bus; includes address and data multiplexed AD [0:31]; control signal: PCICLK; REQ #; C / BE [0:3]; IRDY # ; DEVSEL #; LOCK #; PERR #; SERR #; STOP #; TRDY #; FRAME #; IDSEL; GNT #; RST #. Specifically refer to the PCI specification V2.2 version.
2.6 Power Supply Design
As the board chip requires three kinds of power supply: 1.8 V, 3.3 V, 5 V. One 3.3 V and 5 V supply from the system-board, 1.8 V power supply module from the board by 5 V transform from. The main chip is R9052, through his two 1.8V CMOS tube to achieve the transformation, the supply of four MPEG-4 compression chip, the required current, he can produce 10 A of current.
2.7 Design of alarm circuit
   Analog alarm signal came through the DB9, after optocoupler isolation, into CPLD9572, through CPLD9572 programming to control of the alarm signal.
2.8 I2C design
   Control SAA7114H of I2C, especially leads to MPEG-4 compression chip GPIO pins 49 and 50 pins, the first of four MPEG-4 compression chip I2 C used to do his ID CPLD9572 write this piece as a development chip protection. At the same time as the jumper with 47 pins, high, to allow ID to access, or deny access.
2.9 Interface Design Preview
   MPEG-4 compression chip provides the interface as an analog video signal without compression codec and can play back directly, in which the pin signal CD_VALID he is so designed that:
By such a design can be MPEG-4 compression chip playback [3].
2.10 clock reset signal design
   In the clock design, the application of two crystal, 24.576 MHz crystal clock which provides SAA7114H required external clock, while the 27 MHz crystal oscillator provides Vweb2010 use this encoder chip. The main IC chip on the board reset through the reset signal on the PCI slot through the bridge chip, the resulting secondary bus reset signal is provided.

3 board design difficulty
3.1 Principle design difficulties
(1) hardware modules, in order to achieve the preview, this chip was going to use 7146, but considering the cost to change the original design.
(2) In hardware, the drive capability of the entire board analysis, especially the clock and reset the drive capability and integration with Windows, do the drive.
(3) On the hardware side, CPLD's security, in particular, the CPLD to read and write access protection and ID authentication.
(4) In hardware, the entire board and preview when compressed, should give full consideration to any work environment, stability, such as: lightning, against over-current and the interface can work under high temperature and low temperature .
3.2 PCB traces difficult
(1) due to be placed on the 8-layer high-speed chip (SDRAM), go online to pay special attention to the data and clock lines and the walk, taking into account all of the clock and data lines to wait long, for wiring with to great difficulties.
(2) taking into account the cost of the board to be as small as possible, which also brought difficulties to the overall layout.

 4 boards in the network monitoring application
  The board is based on the Windows operating system's video collection and transmission system, is ideal for network monitoring applications. Can be applied to banking, securities, customs, road monitoring, residential district, supermarkets, hotels and other buildings need real-time monitoring and record keeping of the place. Meet the needs of industry and business management of the safety monitoring requirements, monitoring and recording of digital products is preferred.
With the digital product, monitor network, system integration technology, the future Internet to achieve a remote digital surveillance system truly diversified monitoring, centralized management possible. Internet-based monitoring systems can be integrated, such as network cameras, Gateway and other network-enabled device components, each device is an IP (Internet nodes), with Plug and Play (Plug-play) features. Installation, simply connect the device to the nearest network point through the integration of system software, the user is through the LAN, Internet on-line monitoring.
  This article describes the Windows-based video acquisition and processing system that uses MPEG-4 image compression coding, locally digitized and package sent to the network, making digital video capture system in which all functions are integrated on a small board . As long as he inserted in a PC connected to the network will be able to multi-channel parallel acquisition. These characteristics make this board have broad application prospects.