CN201403163Y - A Network Video Server Based on Embedded Platform - Google Patents

Abstract

A network video server based on an embedded platform, the server includes a video data acquisition and codec unit, a video data compression and decompression unit, a video data storage unit, a network unit, a control unit and a power supply unit, and an input interface of a video data encoding module It is connected with the camera, the output interface is connected with the input interface of the video data compression/decompression module, the input interface of the video decoding module is connected with the output of the video compression/decompression unit, the output of the video decoding module is connected with the LCD screen, and the compression/decompression module The output interface is connected with the input of the decoding module; the network unit is connected with the control unit through bus expansion. The system has the advantages of fast processing, anti-interference, easy query and record, clear video image and multi-channel image display on a single machine. Remote, real-time, and centralized requirements of the monitoring system.

Description

A Network Video Server Based on Embedded Platform

technical field

The utility model belongs to the field of remote video monitoring, in particular to a network remote video monitoring system based on an embedded platform.

Background technique

With the rapid development of computer technology, digital technology is more and more used in video surveillance systems, which greatly improves the performance of the system, making surveillance, multi-functional automatic alarm, multimedia data retrieval, and multi-screen high-definition display a reality. It has greatly expanded its scope of application, its functions are constantly increasing, and its cost is constantly decreasing. Therefore, digitalization, networking, and intelligence have become a development trend in the field of video surveillance, and digital video surveillance systems have gradually entered the stage of large-scale commercial applications.

In the process of continuous development of digital technology, new video compression standards are constantly introduced. The MPEG standard is a moving picture encoding method for digital storage and transmission formulated by the Moving Picture Experts Group. Since this compression standard combines a variety of compression technologies, it has the characteristics of strong applicability, high compression rate, and good image quality. , has been widely used in video surveillance systems. MPEG-4 is another ISO/IEC standard formulated after MPEG-1 and MPEG-2, namely ISO/IEC14496. It can obtain a higher audio/video compression rate and has content-based interactive capabilities. Its core idea is to adopt a modern object-based image coding method, use the visual characteristics of the human eye, grasp the essence of image information transmission, start from the outline and texture ideas, and divide the image into objects, backgrounds, etc. and the actual scene information reasonably The corresponding object planes then encode the shape, texture, and motion of each object plane, resulting in a solution with better quality and smaller bitstream than traditional encoding partitions. At present, there are mainly two solutions for digital video compression, one is a software solution, and the other is a hardware solution. The former is generally realized by using a digital signal processor (DSP) or a high-performance embedded processor. This design scheme will reduce the design cost to a certain extent, but due to the rational design of the algorithm and the reasonable application of system resources, the entire The opening period increases. The latter method is to use an MPEG-4 exclusive decoding chip to realize the encoding and decoding of the MPEG-4 video standard, which will effectively shorten the product development cycle, and at the same time, the development of high-performance integrated chips has greatly reduced the system cost. Development costs.

Motion detection is a very valuable technology in video surveillance system, which is of great significance to timely alarm and video recording. The application of digital technology makes it possible to detect motion without ancillary equipment (such as infrared detection). Through the analysis of digital video streams, it is possible to detect whether there is movement of objects in the camera lens and to alarm and record in time. In a digital video surveillance system, a video compression card generally digitizes the analog video signal from the camera and compresses it into an MPEG stream. If the MPEG stream is decompressed into a frame-by-frame image and then motion detection is performed, there will be a large amount of calculation, and the gain outweighs the gain; therefore, in this case, it is necessary to use some particularities of the MPEG coding domain for motion detection, so that Motion detection is fast and efficient.

In recent years, the digital video surveillance system has experienced rapid development. Up to the end of the 1990s, the digital video surveillance system can be divided into two types: one is to use computer multimedia technology to realize digital remote monitoring and storage of video. The system takes a general-purpose computer connected to the Internet as the core, and a video data acquisition card is installed on it. The video data collected by the camera is compressed through the acquisition card, and then stored or sent to a remote monitoring terminal. The other is to use embedded technology to realize digital monitoring and storage of video data. Such a system is called a digital local video monitoring system. It can only realize functions such as video data compression storage and local monitoring, and cannot realize real-time remote monitoring. However, with the development of the times, simple and fast long-distance cross-regional monitoring has become an urgent need for people, and the first method needs to install general-purpose computers and other equipment on the monitoring site, and the wiring is complicated and difficult to maintain, which is very complicated and cumbersome. A new convenient and fast all-digital remote video surveillance system needs to be researched and realized urgently.

Utility model content

Aiming at the problem that the existing embedded technology can only monitor the local video monitoring system but not remotely, the utility model provides a network video server based on the embedded platform.

The video monitoring system consists of two parts: a network video server installed in the monitored area and a remote monitoring terminal set up in the monitoring center. The remote monitoring terminal includes computers and switches connected to the Internet, and is mainly used to access the video server through its browser, view real-time monitoring information or playback the previous monitoring video, and perform operations such as fast forward and fast rewind as required. And the video files on the remote server can be sent back to the computer of the monitoring terminal for convenient storage.

The network video server includes a video data acquisition and codec unit, a video data compression and decompression unit, a video data storage unit, a network unit, a control unit and a power supply unit. The video data encoding and decoding unit is composed of a CCD camera, a video encoding module and a video decoding module. The input interface of the video data encoding module is connected to the camera, and the output interface is connected to the input interface of the video data compression/decompression module. It is mainly responsible for collecting data from the camera. The input interface of the video decoding module is connected to the output of the video compression/decompression unit, and the output of the video decoding module is connected to the LCD screen. It is mainly responsible for the digital/analog conversion of the decompressed video data. Conversion, thereby realizing local replay; Described video compression and decompression unit mainly comprise video compression/decompression module and its peripheral circuit, the video data input to the video input interface of video compression/decompression module through video data encoding module digitization, compression The output interface of the/decompression module is connected with the input of the decoding module; the network unit is connected with the control unit by bus expansion; the video data storage unit is externally connected with a mobile hard disk, U disk or SD/ The MMC interface expands the SD card to realize; the power supply unit supplies power to several other units; the control unit uses the embedded microprocessor as the core, utilizes the 32-bit bus to expand the FLASH and SDRAM, and compresses/decompresses the video The external host interface of the chip controls the chip and reads the compressed video stream, and uses the I ² C bus interface to control the encoding chip and the decoding chip.

The communication method between the video server and the monitoring center adopts a client/server architecture, the server is a network video server, the client is a monitoring center, and the network video server communicates with the monitoring center through the Internet or a local area network. TCP/IP protocol. The video encoding module performs analog/digital conversion on the analog video signal collected by the camera to obtain a digital video signal, and then compresses the digital video signal through the video/compression decompression module to obtain a video data stream in MPEG format. The user only needs to enter the IP address of the server in the PC browser, log in to the home page of the video server, perform identity verification, download and install the ActiveX control, and then the corresponding operation can be completed. If the user needs to monitor remotely through the network, the compressed video data stream in MPEG format will be sent to the customer through the network in the form of streaming media. If the user needs local storage, the video data stream will be stored in the externally expanded storage unit through the USB interface under the control of the control unit. This system also has the function of local monitoring. If the user needs to play back the locally stored video surveillance video, the control unit will read the video data in the USB external memory, and then decompress and decode it. displayed on the LCD screen.

The video data encoding module of the network video server processes the NTSC/PAL/SECAM format video signal collected by the camera, and generates a digital video signal conforming to the video interface standard of the video compression/decompression unit. Under the control of the external main CPU, the digital video data is compressed and encoded by the compression/decompression chip in hardware, and the generated encoded data stream is output through the integrated Mux FIFO interface inside the chip. Under the control of the control unit, it is processed by USB memory , the processed video data can be stored on physical media for playback by keyboard operation when needed. The decompression encoding of the network video server is the inverse process of compression encoding. The data stream to be decompressed is input through the DemuxFIFO interface integrated in the video compression decompression chip. The decompression encoding process is the inverse process of compression encoding. Several important peripherals in this system are connected with the processor through bus expansion. Among them, the read and write control signals are shared by each peripheral. In order to ensure that they will not interfere with each other, different signals should be mounted on different chip select ports of the processor.

The data encoding and decoding unit of the network video server is an interface circuit between the baseband analog video signal and the video compression/decompression unit. It includes a video encoding chip and a video decoding chip, which is mainly responsible for the analog/digital and digital/analog conversion, and conversion of digital video signal formats.

The video data compression/decompression unit of the network video server is based on the video compression/decompression chip. The chip is connected to the control unit through its host interface. At the same time, the chip also needs to expand the capacity and high-speed SDRAM to cache the video information to be processed. flow.

The video data storage unit of the network video server is realized through a USB external storage device. With the advent of large-capacity USB storage devices, more users are willing to choose this method.

The network unit of the network video server is based on the network chip, and the control unit controls and communicates with the network chip through address, data, control lines and chip selection signal lines.

The control unit of the network video server is based on an embedded microprocessor, which expands SDRAM and NAND FLASH through the bus, and controls the video encoding and decoding unit through the I ² C bus.

The power supply unit of the network video server adopts a regulated linear power supply. The 12V DC power input from the outside is reduced to 5V, 3.3V and 1.8V respectively through the DC voltage regulator chip, and is supplied to different parts of the circuit.

The working principle of the network video server is as follows: the video encoding module performs analog/digital conversion on the analog video signal collected by the camera to obtain a digital video signal, and then compresses the digital video signal through the video/compression decompression module to obtain a video in MPEG format data flow. The user only needs to enter the IP address of the server in the PC browser, log in to the home page of the video server, perform identity verification, download and install the ActiveX control, and then the corresponding operation can be completed. If the user needs to monitor remotely through the network, the compressed video data stream in MPEG format will be sent to the customer through the network in the form of streaming media, and displayed on the customer's browser page. If the user needs local storage, the video data stream will be stored in the externally expanded storage unit through the USB interface under the control of the control unit, and each video file will be named according to the time. This system also has the function of local monitoring. If the user needs to play back the locally stored video surveillance video, the control unit will read the video data in the USB external memory, and then decompress and decode it. It will be displayed on the LCD screen, and operations such as fast forward and fast rewind can be performed.

The software part of the network video server mainly runs in the embedded microprocessor in the control unit, and is mainly composed of 7 functional modules. The specific introduction is as follows:

(1) The control module of the network video server: the control module of the network video server is responsible for controlling each module of the server: the configuration of the video processing chip, receiving the video stream data and storing it with a USB storage device, and configuring the network interface to establish Perfect network function. Start running from power on, execute each module according to the following steps until it is executed when power off.

Step 1: Turn on the power, run the system initialization module to configure the parameters of each module;

Step 2: Run the local graphical interface module;

Step 3: Check whether the U disk has storage space;

Step 4: If the U disk has no storage space, go to step 9;

Step 5: If the U disk has capacity, enter the local storage module;

Step 6: Detect whether the network client has a connection request;

Step 7: If the remote client has no request, go to step 5;

Step 8: If the remote client has a request, send a data packet to the client for real-time video display;

Step 9: The system automatically deletes the video data of the previous period in the U disk, go to step 3.

(2) Video recording module of the network video server: The video recording module of the network video server is mainly responsible for converting the analog signal collected from the camera into MPEG-4 video mode.

Step 1: Power on and run the system;

Step 2: The system completes the configuration of the audio and video processing chip;

Step 3: The system completes the configuration of the analog-to-digital conversion chip;

Step 4: Execute the detection storage space module of the local storage module;

Step 5: No space is detected, delete the earliest video information, and go to step 4;

Step 6: Detect that there is storage space, process the video signal, and then transmit it to the local storage part for storage through the internal interface of the audio and video processing chip.

(3) Local storage module of the network video server: the local storage module of the network video server is mainly responsible for storing encoded video data in MPEG format for local playback and remote network playback by customers. To run from boot, follow the steps below to execute the command.

Step 1: Detect the storage space of the U disk, and display the information on the display level;

Step 2: If the U disk has storage space, the file name will be stored with the system time, which is convenient for users to find and playback video files in chronological order;

Step 3: If the U disk has no storage space, the system will automatically delete the earliest recorded video file and go to step 2;

Step 4: The remote client or local client has a playback requirement, call the stored file and send it to the client;

Step 5: Detect whether there is an end storage signal;

Step 6: Detect that there is an end signal, stop storing;

Step 7: If no end signal is detected, continue to store and go to step 5.

(4) Capture function module of the network video server: the network video server provides the user with the function of capturing images, which is realized by using the JPEG encoding function carried by the video processing chip. The picture is saved in the form of JPEG encoding, and it is also named after the system time when saving and "P" is added after the file name, so as to distinguish it from the video file during playback. The implementation process of picture capture is basically the same as the video encoding process, the difference is that the encoding mode is configured as JPEG mode. Follow the steps below to execute the command.

Step 1: the remote user and the local user request to capture an image;

Step 2: The system starts the JPEG encoding function of the video encoding chip;

Step 3: Detect whether the system has storage space;

Step 4: The system has space, store or display images;

Step 5: There is no space in the system, call the function to delete the earliest video file, go to step 4;

Step 6; Continue to display real-time video data.

(5) Video playback module of network video server: The playback module of network video server is set for remote or local users to watch previous video data and images. In order to achieve better human-computer interaction, under the video decoding playback menu, mainly Complete the following functions, the display of U disk files, the selection of video files, the display of the progress bar during playback, and the display of video file decoding, add pause, fast forward and fast rewind functions. Users can operate by calling the video data stored locally. Do the following steps:

Step 1: The remote user and the local user request video playback;

Step 2: The system enables the decoding function of the audio and video processing chip;

Step 3: Call the video data from the local storage module and send it to the requesting client.

Step 4: Detect whether the user stops playback;

Step 5: If there is no stop signal, continue to step 3;

Step 6: Detect the stop signal, and turn off the decoding function of the audio and video processing chip;

Step 7: Continue to execute the function of displaying real-time video data.

(6) The remote monitoring module of the network video server: the remote monitoring module of the network video server is responsible for executing various requests from remote customers, input the IP address of the network video server in the IE browser of the monitoring terminal, and the embedded network video server will follow the request , to display the login interface. If the user’s identity is confirmed, the server will send the ActiveX control to the user. After the user downloads and installs the control, he performs corresponding operations according to different buttons on the web page, and then submits it to the network video server. Different information submitted by the user completes different operations, such as connection, disconnection, playback, fast forward, fast rewind, etc. The specific steps are as follows:

Step 1: The remote user enters the IP address of the video server and connects to the server;

Step 2: The server responds to the connection access of the remote user and displays the login interface;

Step 3: remote user login;

Step 4: If the identity of the remote user does not match, the access request is denied;

Step 5: If the remote user passes the authentication, the server sends the ActiveX control for the remote user to download and install;

Step 6: The customer downloads and installs the ActiveX control, and starts to perform various remote operations for remote real-time monitoring.

(7) Motion detection module of the network video server: the motion detection module of the network video server controls the storage of video data and alarm action through motion detection. There is no motion alarm signal at the beginning, and the storage module is in a waiting state; when the motion alarm signal arrives, the storage module is started, and if the motion alarm signal is not received within a certain period of time, the storage module automatically stops working. In this way, the storage capacity is much less than continuous storage, and a large number of non-moving videos are cut off, which greatly improves the storage efficiency, effectively saves storage space, and improves the use efficiency of the video surveillance system. The specific implementation steps are as follows:

Step 1: The server first sets the detection area and configures the system parameters;

Step 2: The system compresses the video signal collected from the camera, and outputs the compressed stream to the buffer;

Step 3: The system detects whether there is a moving object entering the pre-set area;

Step 4: The system does not detect a moving object, that is, the on-site movement condition does not meet the conditions for sending an alarm signal, go to step 2;

Step 5: When the system detects that a moving object enters the area, that is, the on-site motion conditions meet the conditions for sending an alarm signal, and the video recording function is automatically turned on.

Network video server in the utility model mainly has following 6 functions:

1. Multi-unit networking function

The video server has a flexible networking mode, which can support wireless network card to connect AP (Aceess Point) or form a local area network through Ethernet, and can also be connected to the Internet to realize cross-regional remote monitoring; after using this video server, the network integrated wiring replaces the traditional complex Analog video wiring, plug-and-play network cameras, greatly simplifying engineering implementation.

2. A variety of video compression formats are available for users to choose

The video server has a variety of video image formats, and users can choose according to different needs. The supported codec protocols include MPEG-1, MPEG-2, MPEG-4, H.263, and M-JPEG;

3. Diversification of local functions

This video server has the function of local decompression and playback, providing users with the choice of local playback video; this video server can be connected to storage devices such as mobile hard disks through USB ports, and provides local mass storage functions. In order to meet certain specific needs, provide Maximum flexibility of choice;

4. Anti-theft alarm function

This video server has the function of monitoring moving images and alarming, which can be configured to alarm when there is image movement in the monitored area; it can be used in places with special requirements for safety, such as banks and museums.

5. Support multi-user access

This video server can support up to 20 users to access the embedded server at the same time, it is easy to use, and can monitor the same place in different places.

6. Diversification of network transmission protocols

This video server can support connection-oriented TCP protocol and connectionless UDP protocol at the network layer at the same time. If the video server is only used in the LAN, the user can choose the reliable connection-oriented TCP protocol; if the video server is used in the Internet In , in order to ensure the transmission speed, the user can choose the connectionless UDP protocol.

The system sends a start signal to the storage device. Once the storage device receives the start signal, it saves all the compressed code streams in the buffer, and then continuously stores the video compressed output code stream until the storage control instruction stops saving. The system alarms at the same time to achieve the function of warning moving objects.

The physical composition of the monitoring system composed of network video servers includes: one or more video servers, wired or wireless monitoring terminals, switches, routers, and alarms. The connection relationship is: the video server is connected to the monitoring terminal through a network cable or a switch, and the video server is connected to the alarm.

The main functions of the monitoring system are: the network camera can not only be used for regional monitoring based on the computer LAN, such as traditional monitoring of residential quarters, office buildings, banks, shopping malls, etc.; it can also be used for new cross-regional remote monitoring and online monitoring through the Internet Display, remote child and elderly care, unattended communication room monitoring, online broadcasting of tourist attractions, online exhibition of products, etc.

Compared with the prior art, the utility model has the following advantages: the system uses a USB storage device to store video data, and has low cost and large capacity. The system has the advantages of fast processing capability, digital information anti-interference ability, quick query record, clear video image and single-machine display of multiple images, etc., and relying on the network, it really takes advantage of the broadband network. Through the IP network, the monitoring center and The monitoring targets anywhere that the network can reach are combined into a system, which truly meets the current remote, real-time, and centralized needs of the video monitoring system.

Description of drawings

Fig. 1 is the structural block diagram of the network video surveillance system that is made of the utility model,

Fig. 2 is the structural diagram of hardware composition of the utility model video server,

Fig. 3 is the structural diagram of the video server software of the present utility model,

Fig. 4 is the software hierarchical diagram of the utility model video server,

Fig. 5 is a detailed circuit schematic diagram of a power supply module 5V, 3A output of an embodiment of the present invention,

Fig. 6 is a detailed circuit schematic diagram of the power supply module 1.8V, 1A output of an embodiment of the present invention,

Fig. 7 is a detailed circuit schematic diagram of a power module 3.3V, 1.5A output of an embodiment of the present invention,

Fig. 8 is a circuit schematic diagram of a video encoding module of a video server according to an embodiment of the present invention,

Fig. 9 is a circuit schematic diagram of a video decoding module of a video server according to an embodiment of the present invention,

Fig. 10 is a circuit schematic diagram of a network interface module of a video server according to an embodiment of the present invention,

Fig. 11 is a schematic circuit diagram of the main control module of the video server in an embodiment of the present invention,

Fig. 12 is a circuit schematic diagram of the video data compression and decompression module of the video server of an embodiment of the present utility model,

Fig. 13 is a circuit schematic diagram of a reset circuit module of a video server according to an embodiment of the present invention,

Fig. 14 is a crystal oscillator circuit diagram of a video server according to an embodiment of the present invention,

Fig. 15 is a schematic diagram of the system clock circuit of the video server audio and video processing module system according to an embodiment of the present invention,

Fig. 16 is a circuit schematic diagram of the buffer memory module FLASH (1) of the video server of an embodiment of the utility model,

Fig. 17 is a circuit schematic diagram of the buffer memory module FLASH (2) of the video server of an embodiment of the utility model,

Fig. 18 is a circuit schematic diagram of a buffer storage module SDRAM of a video server according to an embodiment of the present invention,

Fig. 19 is a schematic diagram of a USB circuit of a local storage module of a video server according to an embodiment of the present invention,

Fig. 20 is a flow chart of video encoding execution of the video server of the present invention,

Fig. 21 is the video decoding execution flowchart of the video server of the present invention,

Fig. 22 is the bootloader guide flowchart of the utility model video server,

Fig. 23 is the execution flowchart of the image capture encoding of the video server of the present invention,

Fig. 24 is the overall execution flowchart of the local application software of the video server of the present invention,

Fig. 25 is the execution flowchart of the motion monitoring of the video server of the present invention,

Fig. 26 is a detailed execution flowchart of the local control module software of the video server of the present invention,

Fig. 27 is the execution flowchart of the remote monitoring application of the video server of the present invention,

Fig. 28 is a block diagram of the network control module of the video server of the utility model.

Detailed ways

As shown in Figure 1 by the video monitoring system that the network video server of the utility model based on embedded platform constitutes, the communication method of video server and monitoring center has adopted the system structure of client/server, and the server end is a network video server, and the client is The monitoring center includes computers and switches connected to the Internet through a wired or wireless network. The network video server communicates with the monitoring terminal of the monitoring center through the Internet or a local area network. The protocol adopted is the TCP/IP protocol.

The hardware composition of the network video server is shown in Figure 2. The control unit is the embedded microprocessor S3C2410 with ARM9 core produced by South Korea’s Samsung Company. It uses a 32-bit bus to expand FLASH and SDRAM, and through the video compression/decompression chip. The external host interface controls the chip and reads the compressed video stream, and uses the I ² C bus interface to control the encoding chip and decoding chip. Several important peripherals in this network video server are connected to the processor through bus expansion. connected. Among them, the read and write control signals are shared by each peripheral. In order to ensure that they will not interfere with each other, different signals should be mounted on different chip select ports of the processor. The interface circuit is shown in Figure 11. Figure 8 to Figure 18 show the circuit schematics of the peripheral circuits of the S3C2410 chip. The power supply unit of the network video server plays a vital role in the stable operation of the system. Since this network video server uses an analog-to-digital/digital-to-analog conversion chip, in order to make it work more effectively and avoid high-frequency ripple interference, this network video server uses a linear power supply module, MIC4576-5.0, MIC29150-3.3 , MIC39150-1.8. Considering the power consumption of the AT2042 chip, in order to enable it to work stably for a long time, all power chips are sealed with TO-220, so that a heat sink can be added behind each power chip to ensure its long-term effective work. The video data encoding module of the network video server adopts TI’s ultra-low power consumption image decoding chip TVP5150, as shown in Figure 8, it processes the NTSC/PAL/SECAM format video signal collected by the camera, and generates a conforming video signal. Compression/decompression unit video interface standard digital video signal. The compression and decompression chip used by the network video server is the AT2042 chip produced by Pentamicro in South Korea. The output of the integrated Mux FIFO interface in the chip is processed by USB memory under the control of the control unit, and the processed video data can be stored on the physical medium, so that it can be played back by keyboard operation when needed. The decompression encoding of the network video server is the reverse process of compression encoding. The data stream to be decompressed is input through the Demux FIFO interface integrated in the video compression decompression chip. The basic principle of decompression encoding is similar to compression encoding. The video data decoding module of the network video server uses SAA7121, which is a dedicated TV signal encoding chip, which can convert the input digital signal into an analog TV signal suitable for transmission through the internal D/A. By configuring the corresponding registers, it can The output signal is suitable for S-video interface or multiplexing interface.

The network unit of the network video server takes the network interface chip LAN91C111 as the core, and its interface circuit is shown in Figure 10. The main control chip S3C2410 controls and communicates with the LAN91C11 network chip through address, data, control lines and chip selection signal lines. When the main chip sends a signal, first set the sending enable signal, and the data sending signal terminal TXD0~TXD1 is connected to the TXD0~TXD1 pins of LAN91C11, as the data sending channel, the clock signal TCK of S3C2410 is used to send data. The data receiving end RXD0-RXD1 is correspondingly connected with the RXD0-RXD1 pins of LAN91C11, which is the data receiving channel. LAN91C11 is strobed by S3C2410 strobe signal line AEN, through the setting of a series of registers of LAN91C11, the network transmission of video stream can be realized. INTRQ0 end of LAN91C11 is used to generate interrupt signal. The Ethernet control chip transmits data through the DMA channel. First set the parameters of the transmission control and transmission address registers, read data from the designated data storage area in turn, send them to the internal transmission buffer, use MAC to encapsulate and send the data, and record the number of bytes that have been sent at the same time, Wait until the entire data block has been sent. After a group of data is sent, request DMA interrupt, which will be processed by S3C2410.

Bootloader is the first program executed when the system starts, mainly to complete the initialization of the hardware system. Specifically include: S3C2410 initialization, TVP5150 function configuration, SAA7121 function configuration, loading AT2042 firmware, Ethernet and serial port initialization. Since the boot screen should be displayed when booting, in addition to initializing the corresponding hardware resources in the Bootloader, the picture data of the boot screen should also be transferred to the AT2042 SDRAM. Its working process is shown in Figure 22. The startup screen is displayed, which is mainly realized through the JPEG decoding function of AT2042. First configure the JPEG decoding function of AT2042, add the image to be displayed to the program in the form of a header file, and then send the image data to AT2042 when it needs to be displayed.

The pictures captured by the picture capture function are saved in the form of JPEG encoding, and they are also named after the system time when saving and "P" is added after the file name, which is to distinguish them from video files during playback. As shown in Figure 23, the implementation process of picture capture is basically the same as the video encoding process, the difference is that the encoding mode is configured as JPEG mode.

The video coding function is mainly realized by AT2042. First, configure the corresponding encoding registers, such as encoding mode, encoding pixels, encoding frame rate, and setting encoding stream format (PES, PS, TS), etc. This system uses MPEG-4 mode, 720X576, 25 frames per second and generates PES stream to encode video data. Its flow chart is shown in Figure 20.

The video decoding and playback function is the reverse process of the video encoding and storage function, and it is all realized through AT2042. First, pack the data to be decoded according to a certain packet format, and then send the data to the decoding multiplex (DemuxFIFO) queue through the host, which is to configure the decoding function and start decoding. The specific process of implementation is shown in Figure 21.

The network control module is a module for the interaction between the external extension application program and the video server. The working process of the network control module of this system: input the IP address of the network video server in the IE browser of the monitoring terminal, and the embedded network video server will feed back the corresponding control page, that is, the ActiveX control, to the IE browser according to the request, and the user downloads the control Finally, perform corresponding operations according to the instructions on the control, and then submit them. This module extracts the information of the operations, and communicates with the server through the socket socket according to different information to process corresponding events, such as adjusting MPEG-4 related attributes, camera related operations, etc. The design of the network control module mainly includes three parts: the configuration of the local embedded web server, the writing of the ActiveX control, and the socket socket to realize the communication between the server and the monitoring terminal. Its principle is shown in Figure 28

The control module of the network video server is responsible for controlling the startup and operation of the network video server. It starts to run when it is turned on, and executes each module according to the following steps until it is turned off. The overall execution process is shown in Figure 24, and the steps are as follows:

Step 1: Initialize system resources

Step 2: Turn on the AT2042live function

Step 3: Determine whether there is a key operation

Step 4: If yes, perform corresponding operations

Step 5: If not, continue to wait

Step 6: Determine whether to log out of the system

Step 7: No, keep waiting

Step 6: Yes, exit the system

The execution process of the capture function module of the network video server is shown in Figure 23, and the specific steps are as follows:

Step 1: the remote user and the local user request to capture an image;

Step 2: The system starts the JPEG encoding function of the video encoding chip;

Step 3: Detect whether the system has storage space;

Step 4: The system has storage space to store or display images;

Step 5: If the system has no storage space, it will automatically delete the earliest recorded video file and go to step 4;

Step 6; Continue to display real-time video data;

The execution flow of the remote monitoring module of the network video server is shown in Figure 27, and the specific execution steps are as follows:

Step 1: The remote user enters the IP address of the video server and connects to the server;

Step 2: The server responds to the connection access of the remote user and displays the login interface;

Step 3: remote user login;

Step 4: If the identity of the remote user does not match, the access request is denied;

Step 5: If the remote user passes the authentication, the server sends the ActiveX control for the remote user to download and install;

Step 6: The customer downloads and installs the ActiveX control, and starts to perform various remote operations for remote real-time monitoring.

The execution flow of the motion detection module of the network video server is shown in Figure 25, and the specific implementation steps are as follows:

Step 1: The server first sets the detection area and configures the system parameters;

Step 2: The system compresses the video signal collected from the camera, and outputs the compressed stream to the buffer;

Step 3: The system detects whether there is a moving object entering the pre-set area;

Step 4: The system does not detect a moving object, that is, the on-site movement condition does not meet the conditions for sending an alarm signal, skip to step 2;

Step 5: When the system detects that a moving object enters the area, that is, the on-site motion conditions meet the conditions for sending an alarm signal, and the video recording function is automatically turned on.

Using the network video server system of the utility model, the network video server can be started after first confirming that the lead wires, power supply, SD card, etc. are installed correctly. After turning on the power switch of the machine, until the welcome interface is displayed on the LCD screen, the system starts up. At this time, the network function has been initialized. Remote users can access the server through the network, and enter the IP of the network video server in the IE browser of the monitoring terminal. Address, the embedded network video server will feed back the corresponding control page, that is, the ActiveX control, to the IE browser according to the request. After the user downloads and installs the control, the video playback window and [Connect] and [Disconnect] will be displayed on the user browser. , [Record], [Playback], [Snapshot] five buttons, users can perform corresponding operations according to their needs.

Click the [Connect] button, and the client will send a connection request to the server. After the server and client are connected, the video playback window will display the real-time monitoring screen. In this state, click the [Record] or [Capture] button. The network video server will record or capture, and the obtained video files and picture files will be saved in the local storage medium. Click the [Playback] button, the video file stored in the storage medium of the network video server will be displayed on the video playback window, click the selected file, and the corresponding video file will be played back on the video playback window. Click the [Disconnect] button, and the client will be disconnected from the server.

Locally, when the LCD screen is in the welcome interface, press any key, and the LCD screen will enter the selection menu interface. At this time, the interface will display 【Record】【Local Playback】【Snapshot】【Local Monitor】【Shutdown System】 five icons. At this time, press the [Left] key or [Right] key on the keyboard, the selection cursor can move on the icons in the menu, and press the [Enter] key to select the corresponding operation. Its execution flow is shown in Figure 26.

Select the recording function on the network video server selection menu interface, and the video server will enter the recording working state. At this time, the real-time monitoring screen will be displayed on the LCD screen, and the network video server will store the video data stream in MPEG-4 format generated by AT2042 in the SD card. If there is not enough space in the SD card, the system will automatically delete the earliest video file, and then continue to store. In the recording working state, press the [Exit] key to return to the selection menu interface.

Select the picture capture function on the network video server selection menu interface, and the video server will enter the picture capture working state. At this time, the LCD screen will display the real-time video monitoring screen. Press the [Snapshot] button, and the network video server will monitor in time Screen capture operation, the captured picture file will be stored in the SD card, at this time, press the [Exit] key, it will return to the selection menu display interface.

Select the video playback function on the network video server selection menu interface, the network video server will enter the video playback state, and the existing video files will be displayed on the LCD screen, and the user can move by pressing the [Up] key or [Down] key. Use the cursor to select, and when the cursor moves to the selected file, press the [OK] key, and the system will play the video file, which can be seen on the LCD screen. The user can use the [Left] key or [Right] key to adjust the playback progress of the video to achieve fast forward or rewind. Press【Exit】key, the network video server will exit the video playback state and return to the selection menu interface.

Select the local monitoring function on the network video server selection menu interface, and the real-time monitoring video image will be displayed on the LCD screen. This design adds a motion capture function here, which can be used to realize the alarm. If there is movement of objects in the monitoring area, the network video The server will give an alarm signal. If required by the user, the network video server can also add an alarm function in the recording state.

Claims (4)

1, a kind of network video server based on embedded platform, it is characterized in that this server comprises video data acquiring and codec unit, video data compression and decompress(ion) unit, the video data memory cell, network element, control unit and power supply unit, wherein the video data codec unit is made up of CCD camera video coding module and video decode module, the input interface of video data encoding module links to each other with camera, output interface links to each other with the input interface of video data compression/decompression module, main be responsible for to camera collection to analog video data carry out mould/number conversion, the input interface of video decode module is connected with the output of video compression/decompress(ion) unit, the output of video decode module links to each other with liquid crystal display screen, main being responsible for carried out D/A switch to the video data behind the decompress(ion), thereby realizes local playback; Described video compression and decompress(ion) unit mainly comprise video compression/decompression module and its peripheral circuit, through the digitlization of video data encoding module video data be input to the video input interface of video compression/decompression module, the output interface of compression/decompression module is connected with the input of decoder module; Described network element links to each other with control unit by the mode of bus expansion; Described video data memory cell extends out the SD card by the external portable hard drive of usb host interface, USB flash disk or SD/MMC interface and realizes; Described power supply unit is to other plurality of units power supplies; Described control unit is a core with the embedded microprocessor, utilizes 32 bus expansion FLASH, and SDRAM controls and read compressing video frequency flow by the external host interface of video compression/decoder chips to this chip, utilizes I ²C bus interface control coding chip and decoding chip.

2, the network video server based on embedded platform according to claim 1, the data codec unit that it is characterized in that described network video server is an interface circuit between baseband analog video signal and the video compression/decompress(ion) unit, it comprises a video coding chip and a video decoding chip, main mould/number and the D/A switch of being responsible for video data, and the conversion of format digital video signal.

3, the network video server based on embedded platform according to claim 1, video data compression/decompress(ion) the unit that it is characterized in that described network video server is to be core with video compression/decoder chips, this chip is connected with control unit by its host interface, and this chip also needs outer expansion capacity, high speed SDRAM to come the pending video stream of buffer memory simultaneously.

4, the network video server based on embedded platform according to claim 1, the power supply unit that it is characterized in that described network video server has adopted the voltage stabilizing linear power supply, 12V DC power supply by the outside input, through the DC voltage-stabilizing chip, drop to 5V, 3.3V, 1.8V respectively, the different piece of supply circuit is used.

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