1. Introduction In today's electronics industry, wireless technology has permeated every aspect, from television remote controls to computer peripherals; even some keyboards and mice utilize wireless technology. Wireless network technology has become a hot technology. Wireless network products are widely used in home networks, small offices, exhibition centers, sports centers, aircraft factories, hospitals, schools, ports, residential communities, hotels, and broadband access. It frees people from the constraints of endless wires and cables in Internet applications, allowing them to enter a truly ubiquitous Internet space. Wireless network technology is expected to become a new economic growth point. In recent years, with the increasing popularity of intelligent buildings in the market, doorbell systems have become an important component of intelligent offices and intelligent residential communities, accepted by businesses and users alike. People have begun to use doorbell systems instead of traditional iron keys to manage various access doors, leading to a leap in the development of doorbell systems. In 2000, global doorbell system sales increased nearly tenfold compared to 1999, accounting for 40% of the entire security market. 2. Introduction to Linux Operating System: Linux is a popular operating system compatible with UNIX systems. It is open-source and originally designed as a desktop system, but is now widely used in the server field. Its greater influence lies in its increasing application in embedded devices. However, it retains the main advantages of desktop Linux operating systems, such as stability, powerful networking capabilities, and excellent file system support. Linux has a complete TCP/IP protocol stack and supports many other network protocols. These network protocols are well implemented on Linux. Linux can be considered an excellent network operating system for embedded systems. With its superior performance and free, open-source code, Linux has won the favor of many embedded developers. Compared to past embedded programming based on simple RTOS or even without any operating system, developing applications based on a mature, efficient, robust, reliable, modular, and easy-to-configure operating system like Linux undoubtedly improves efficiency and offers excellent portability. 3. Wireless Video Doorbell System Block Diagram Figure 1. Block Diagram of the Server Side of the Wireless Video Doorbell System 3.1 Basic Working Principle of the Wireless Video Doorbell Server Side The wireless video doorbell is a system based on a high-performance embedded processor and a hardware real-time encoding/decoding chip, combined with a Linux operating system, consisting of a server side and a client side. It mainly implements high-quality audio and video encoding/decoding and network forwarding functions. The specific functions implemented on the server side are as follows: Input signals from the CCD sensor and audio/video ports are converted to video and audio A/D, then encoded with MPEG4 video and MPEG MP3 audio. The encoded audio and video streams are sent to the network multiplexing module for packaging and then sent to the client via the 802.11x wireless network. Specific functions include: 1) Power-on bootstrap function based on the IDT RC32434 high-performance embedded processor and other hardware systems, with system hardware initialization and detection, and loading and starting functions for the embedded operating system or user program. 2) In the embedded operating system environment, initialize and configure the A/V module based on VW2010 and load the VW2010 driver. 3) Perform A/D conversion on analog audio and video, and compress and encode in MPEG-4 format. 4) Forward the compressed and encoded data stream through the wireless network. 5) Save the compressed and encoded data stream/file, decode the input compressed and encoded audio/video files, and output analog audio and video playback. 3.2 Basic Working Principle of Wireless Video Doorbell Client Figure 2, Block Diagram of Wireless Video Doorbell System Client: The data stream received by the wireless network is demultiplexed by the network demultiplexing module. The resulting video and audio streams are sent to the video decoding module and audio decoding module respectively for MPEG4 video decoding and MPEG MP3 audio decoding. The decoded data is then sent to the video terminal for display after analog video encoding, D/A conversion, and audio D/A conversion. 4. Wireless Video Doorbell System Design 4.1 System Design Principles The system design includes hardware and software. The hardware is mainly divided into three parts: the control system and the input/output data sources. Input/output data sources can be IDE interface devices (such as hard drives) or network ports. The control system monitors and controls each part of the system and completes data stream transmission. The control system mainly consists of a main control chip, Flash memory, and SRAM. The main control chip controls other modules of the system via the PCI bus and is the core of the control system; the Flash memory stores the embedded Linux operating system, application software, and backup data; SDRAM serves as memory for system operation. The MPEG-4 hardware encoding and decoding system uses hardware encoding and decoding to encode and decode the input MPEG-4 data stream into ordinary television signals; its core is the encoding and decoding chip. To solve the problem of unstable data streams, the encoding and decoding chip typically uses SDRAM for data buffering to ensure normal encoding and decoding processes. The software mainly includes embedded Linux porting, encoding and decoding drivers, and application program writing. The embedded Linux is ported to the Flash memory controlled by the main control chip's Flash controller. The operating system program files are divided into five main parts: bootloader, kernel, ramdisk, usr, and boot_param, which are placed in five modules within the Flash memory respectively. Different file systems are used for different modules based on their specific functions: bootloader, kernel, ramdisk, and boot param. These do not require dynamic changes after development and have small capacity, so the space-saving ROMFS read-only file system is used. The usr module contains more content and requires read/write operations, so the JFFS file system, which supports dynamic erasure and write operations, is used. 4.2 System Hardware Design The system hardware design mainly consists of two parts: data source interface design and control system design. Data flow first originates from the data source and is sent to the PCI bus via the data source interface. This system's data source interface is the PCI/IDE bridge chip and network control chip on the PCI bus. The control system allocates system resources, controls various parts of the system, and manages data flow transmission. The main control chip is the IDT RC32434. It is a 64-bit MIPS chip that integrates a NAND Flash controller (FlashC), a 32-bit PCI bus controller (PCIC), a 4-channel DMA controller, a 4-channel SDRAM controller (SDRAMC), an external bus controller (EBUSC), an external bus interface (E-BUSI), and two general-purpose serial ports, which are controlled separately through the internal bus. Its operating frequency is 400MHz, offering fast processing speed, powerful functionality, and high cost-effectiveness, perfectly meeting the needs of embedded Linux systems. MIPS controls external Flash and SDRAM through its internal FlashC and SDRAMC. The SDRAM data address lines are connected to the External Bus Control Interface (EBUSI), while the Flash data address lines are connected to the corresponding FlashC data address ports. MIPS controls other PCI interface devices through the PCI Bus Controller (PCIC). 4.3 System Software Design The system software design mainly consists of embedded Linux operating system kernel porting, encoding and decoding chip development, PCI bridge chip and network port driver development, and decoding application development. Its architecture and relationship with the hardware are shown in Figure 3. The embedded Linux operating system is the hardware platform for the user control system. The system drivers are modular, providing API functions to user-level applications and controlling system hardware through system hardware API functions. The encoding and decoding driver modules use real-time loading. Other drivers, such as those for network ports, I2C, and PCI/IDE interfaces, are highly versatile and directly compiled into the kernel. The encoding and decoding application implements the transmission and encoding/decoding of the system's MPEG-4 data stream. Figures 4 and 5 are the main program flowcharts for the server and client sides of the wireless video doorbell, respectively. Figure 3: System Software Schematic Diagram Figure 4: Main Program Flowchart for Wireless Video Doorbell Server Figure 5 : Main Program Flowchart for Wireless Video Doorbell Client 5. Conclusion This paper introduces an embedded wireless video doorbell system. This system uses hardware encoding and decoding to implement MPEG-4 stream input and output from IDE interface devices or network ports. The system uses a 64-bit MIPS chip IDT RC32434 as the main controller and VW2010 as the MPEG-4 encoding and decoding chip; it uses embedded Linux as the operating system and modular VW2010 drivers. The encoding and decoding applications are simple, practical, and highly scalable. Experiments have shown that this system can be widely used in IPTV, satellite TV, wireless video doorbells, and digital television broadcasting systems based on the MPEG-4 standard, with a very broad application prospect.