IPC: "Internet Camera", is the abbreviation of IP Camera. It is a camera integrated with a coding module based on the previous generation of analog cameras. The difference between it and the analog camera is the newly added "encoding module".
Analog cameras, as the name suggests, output analog video signals. Analog signals are more susceptible to interference, so the transmission distance is limited. This newly-added encoding module appears to convert the original analog video into digital video after encoding and compression. In order to facilitate transmission on the network, the digital video is encapsulated into a network format suitable for transmission on Ethernet. We just call this new camera "Internet Camera", or IPC for short.
Common IPC systems constitute
the main functional modules of IPC:
- Video Encoding: Capture and encode compressed video signals.
- Audio function: capture and encode compressed audio signal.
- Network function: The encoded and compressed video and audio signals are transmitted through the network.
- PTZ, lens control function: control various actions of PTZ and lens through the network.
- Cache function: the compressed video and audio data can be temporarily stored in the local storage medium.
- Alarm input and output: can receive and process alarm input/output signals, that is, it has alarm linkage function.
- Motion detection alarm: detect motion in the scene and generate an alarm.
- Video Analysis: Automatically analyze video scenes, compare preset principles and trigger alarms.
- Visual parameter adjustment: adjustment of visual parameters such as saturation, contrast, chroma, brightness, etc.
- Coding parameter adjustment: frame rate, resolution, code stream and other coding parameters can be adjusted.
- System integration: It can be integrated with the video management platform to realize large-scale system monitoring.
IPC classification
Like analog cameras, there are many ways to classify IPC, which can be classified according to appearance, definition, and indoor and outdoor applications.
The usual classification method is to classify according to the intuitive shape features such as fixed cameras, PTZ cameras, dome cameras, and integrated dome cameras.
Exterior
- Fixed conch hemisphere IPC
- Fixed Gun IPC
- dome camera
- gun ball machine
- panoramic stitching
etc.
trigger
conch
multi-hemisphere
spherical
Panorama + Dome
Gun ball linkage
IPC signal processing process
In an analog camera, the analog signal generated by the image sensor (CCD or CMOS) is first converted into a digital signal by an analog/digital (A/D) converter, and then processed by the camera's built-in DSP chip, such as Gain, noise reduction, backlight compensation and other processing. The digital signal processed by the DSP is converted into an analog signal by digital/analog (D/A) conversion, used for transmission on the coaxial cable, and then transmitted to the DVR or DVS for analog/digital (A/D ) conversion to complete the encoding and compression work, such multiple analog/digital and digital/analog conversion processes greatly sacrifice the image quality.
In IPC, after the sensor (CCD/CMOS) completes the optical/electrical conversion process, it only needs to perform an analog/digital conversion, and then encode and compress, package and upload. Obviously, the number of analog/digital conversions is less and the image quality loss is less. .
Therefore, IPC has fewer signal conversion links than analog cameras, which can reduce the loss of image quality as little as possible. In addition, IPC usually uses a progressive scan sensor, which has better image quality than the interlaced scan method of an analog camera. The comparison of IP cameras with analog cameras is shown in the figure.
analog camera
IP camera
IPC hardware composition
The hardware composition of IPC generally includes lens, image sensor, sound sensor, signal processor, analog/digital converter, encoding chip, main control chip, network and control interface and other components. The light enters the sensor through the lens, and then converted into a digital signal, which is preprocessed by the built-in signal processor. The processed digital signal is encoded and compressed by the encoding and compression chip, and finally sent to the network for transmission through the network interface. The hardware composition of the IPC is shown in the figure:
IPC hardware composition
- lens
As the front-end part of the IPC, the lens has various types such as fixed aperture, automatic aperture, automatic zoom, and automatic zoom.
- Image Sensor
CCD and CMOS, the current mainstream IPC is using CMOS. High-end scenes use CCD.
- code compression
The function of the encoding compression part is to encode and compress the digital signal after analog/digital conversion according to a certain standard such as H.264, H.265, etc. The purpose of coding and compression is to reduce the redundancy of video information, and realize network transmission and storage of video with a lower bit rate.
- main control part
The main control part is the core control unit of the entire IPC, responsible for the scheduling of the entire system. The main control part can directly send commands to the encoding and compression chip, read the encoded and compressed audio and video data and send them to the network module for transmission.
Major global IPC chip companies, including:
NXP
Texas Instruments
Hisilicon
Ambarella
Morningstar Semiconductor
Shengmai Technology
Fullhan Microelectronics
Beijing Junzheng
Guokewei
crystal morning
Allwinner Technology
Rockchip
Xingchen Technology
Vimicro
- network module
The network module provides the network function of IPC, receives the control command of the main control chip, sends the encoded and compressed video to the network, or receives the control command from the network, and forwards it to the control module to realize PTZ control. The data transmitted from the main control chip is converted into data that can be received by the Ethernet physical layer through the network module, and transmitted to the network through the standard RJ-45 network interface. Usually IPC adopts RTP/RTCP, UPD, HTTP, TCP/IP and other network protocols, allowing users to remotely access IPC, modify parameters, browse real-time video and control PTZ actions.
The current main control chip also basically integrates this part. So today's cameras are getting smaller and smaller.
IPC software The
software composition of IPC generally includes operating system, application software, coding algorithm, underlying driver, etc. The stability of IPC is very important, and the embedded Linux operating system is usually used, which has low cost, open source code, high security and With good portability and other advantages, it is currently the mainstream operating system for IPC.
- device driver
IPC peripheral drivers include drivers for 802.3 Ethernet MAC controllers, general I/O, I2S, AC97, SD/MMC cards, LCD display controllers, video capture devices, hard disk controllers, and high-speed USB controllers.
- Linux operating system
It is the core of the software, mainly responsible for program management and scheduling, memory management, and peripheral drive and management.
The Linux operating system has the advantages of completely free and open source code, tailorable kernel, easy portability of software, and rich drivers. When the Linux system is used as an IPC OS, the problems to be solved mainly include hardware support, providing an environment for secondary development, and cutting the kernel. Small to fit the chip-level operating environment.
- encoding program
Audio and video encoding and compression reduce network bandwidth requirements. At present, the mainstream encoding method is H.265, which is half of the H.264 bit rate under the same definition.
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