| 4CIF || 4x common intermediate format, a format for color images, 704 × 576 images (for PAL color images) |
| BNC || Full name Bayonet Nut Connector, a connector for coaxial cables |
| CIF || Universal Intermediate Format, a format for color images, 352 × 288 pixels (for PAL color images) |
| DHCP || Dynamic host configuration protocol for dynamically assigning configuration information |
| DNS || Domain Name System, which translates names into IP addresses in a user-friendly way |
| EIA || Electronics Industry Association, a standard body |
| H.264 || A video compression standard, also known as MPEG-4 (PART10) |
| HTTP || Hypertext Transfer Protocol |
| IDE || Interface type of a disk drive |
| IP || Internet Protocol |
| ISO || International Organization for Standardization, a standards body |
| ITU-T || International Telecommunication Union-Telecommunications Standards Department |
| NFS || Network file system |
| NTSC || TV system |
| PTZ || PTZ and lens control |
| PPP || Point-to-point protocol |
| PPPoE || Transmission of PPP protocol over Ethernet |
| QCIF || Quarter Common Intermediate Format |
| RCA || A video and audio interface (commonly known as lotus head) |
| RS-232 || A 25-core interface standard developed by EIA, also became EIA-232 |
| RS-485 || A 25-core interface standard developed by EIA, also became EIA-232 |
| RTP || Real-time transport protocol |
| SDK || Software Development Kit |
| TCP || Transmission Control Protocol |
| UDP || User Datagram Protocol |
| URL || Uniform resource positioning |
| USB || Universal serial bus |
| UTP || Unshielded twisted pair, this book refers generally to Ethernet interfaces |
| VGA || Represents a resolution, 640 × 480 pixels. This article refers to a kind of display, the display resolution can support 800 × 600 / 60HZ, 800 × 600 / 75HZ, 1024 × 768 / 60HZ |
Saturation color image intensity or purity of the alarm volume switch signal alarm signal alarm alarm local display video output directly output and display video trigger alarm output conditional output alarm signal serial port serial port number protocol port address, one Integer, used to identify a process. Contrast screen brightness ratio. Multicast address. Multicast address. Composite stream. Contains video and audio compression. Data stream management. Host IP address. Host IP address track for receiving alarms and exceptions. The route of the camera movement loops through the output. This article refers to the one-to-one output of the input video signal. The monitor displays the warning information on the monitor. This article specifically refers to the display of the alarm screen. The decoder can analyze the control protocol. After setting the recording time, the time will be extended in the future. The client initiates communication with the server. A program. Brightness. Color image. Relative brightness. Types of compressed video data, including video stream and composite stream. Command triggers the execution of a task by command. Directory name refers to the file directory name, including the complete path. Screen saver. This article refers to the automatic shutdown of the screen display. Anomalies and other data Chroma color difference component sound warning When the alarm is used to notify the video of the video loss The video input channel has a video connection, but no video signal is received. The video stream contains only the compressed data stream of the video. Video frame rate Frames per second Image size and size. The unit pixel gateway is used to connect two separate devices using different communication protocols. Bit rate Bit rate type. Maximum bit rate. Physical address. Media access control address. Also called MAC address. The motion path of the cruise camera is abnormal. Handling method when an abnormality occurs.Motion detection and analysis of whether there is a change in the video.Pre-recording time.Pre-recording time before starting recording.The preset point is set in advance. Set the coordinate masking alarm. Alarm masking after a certain area is blocked. Hide a video area in the image
The 2CIF (704 * 288, also called Half D1) we often say, has doubled the resolution in the horizontal direction than CIF (352 * 288), and has not changed in the vertical direction. The display ratio we are used to is 4 : 3. After horizontal and vertical zoom processing, the image will be uneven.
Then we take the odd and even HALF D1 and deinterlace to form a D1. D1 is reduced by 3/4 horizontally and 2/3 vertically, and the number of pixels is 528 * 384.528 * 384 is exactly CIF (352 * 288) twice the number of pixels. In order to distinguish it from the 2CIF often said, we call it DOUBLE CIF, or DCIF for short. Obviously, DCIF is more balanced than HalfD1 in both horizontal and vertical directions, and has improved resolution in both horizontal and vertical directions compared to CIF. After testing a large number of video signals, based on the current video compression algorithm, DCIF (528 * 384) can well solve the problems of insufficient CIF definition and too large D1 code stream. Between 512K-1M bit rates, stable high-quality images can be obtained.
There are two international standardization organizations responsible for video coding. One is the Video Code Expert Group (VCEG) under the International Telecommunication Union (ITUT), which has promoted the development of video and audio coding technology. The other is the International Standardization Organization ( MPEG (Motion Picture Expert Group) under the ISO), which promotes the widespread application of video and audio codecs.
After VCEG released H.263 compression standard in 97, VCEG formulated short-term development plan H.26N and long-term development plan H.26L. After H.26N developed into H.263, it released the MPEG-4Sp version.
In the fourth quarter of 2001, when VCEG H.26L developed to TML9.0, MPEG and VCEG formed a joint video coding expert group JVT to improve and perfect the H.26L algorithm. VCEG released H in May 2003. .264 compression standard; based on the modification of the H.26L compression algorithm by JVT, MPEG incorporates this technical specification into the MPEG-4 standard and releases it as the tenth part of MPEG-4 (PART10) is MPEG-4 AVC version. AVC versions of H.264 and MPEG-4. H.264 and MPEG-4 AVC represent the latest achievements of all human beings in video and audio encoding and decoding.
FAT32 is a file allocation table (FAT, full name is File Allocation Table) that is a cluster number byte table of 4 bytes (32 bits). Each cluster in the FAT32 partition format is fixed at 4KB, which greatly reduces disk space waste and improves disk utilization.
English full name: Self-Monitoring, Analysis and Reporting Technology, its Chinese meaning is self-monitoring, analysis and reporting technology, this technology has been officially established in the ATA-3 standard, and all hard disk manufacturers also provide support for it.
SMART technology can monitor magnetic heads, disks, motors, circuits, etc. The monitoring software on the host computer analyzes and compares the monitored software's operating conditions with the historical records and preset safety values. In the event, the user can be warned automatically. SMART technology can effectively predict the potential failure of the hard disk and improve the security of the data.
Dynamic adjustment of encoding parameters <br /> The adjustment of encoding parameters will take effect without starting or stopping recording and network transmission. In the monitoring system, in the still monitoring scene, the method of reducing the resolution, image quality, bit rate and frame rate of the video can be used to keep the video at a low bit rate, and the resolution of the video can be increased when the image changes. , Quality, bit rate and frame rate, to achieve high-quality video, because the above parameters can be dynamically modified, so you can maintain the continuous image without frequent file switching, which meets the requirements for high image quality at critical moments, and saves Hard disk space and network bandwidth.
Resolution <br /> The types of resolution include display resolution, image resolution, and pixel resolution.
Display resolution refers to the largest display area on the screen in a particular display mode, expressed in horizontal and vertical pixels.
If the image resolution is greater than the display resolution, some images cannot be displayed.
Pixel resolution refers to the ratio of the width and length of a pixel. Different pixel aspect ratios will cause graphics distortion.
Common image resolutions in digital surveillance:
PAL system: QCIF (1 7 4 * 1 4 4), CIF (3 5 2 * 2 8 8), 2CIF (704 * 288), DCIF (528 * 384), FULLD1 (704 * 576)
NTSC system: QCIF (174 * 120), CIF (352 * 240), 2CIF (704 * 240), DCIF (528 * 320), FULL D1 (704 * 480)
VGA display commonly used display resolution: 640 * 480, 800 * 600, 1024 * 768, etc.
Face detection <br /> A technique for filtering out faces in an image. Face detection is different from face recognition. The goal of face detection is: whether there is a face in the image, and if so, how many are in which position? The goal of face recognition is: Whose face is it. Therefore, through face detection, a face recognition system can be implemented, which can be applied to access control, time and attendance, security (airports, conferences, large-scale cultural and sports activities), public safety, urban monitoring and other occasions.
Dual stream <br /> refers to a video that outputs two independent streams through the video encoder, as shown in the figure
The output stream resolution, frame rate, code rate and other parameters can be set independently. The two generated streams can meet different application requirements, such as one for hard disk storage and one for network transmission.
Watermarking technology <br /> refers to the use of signal processing methods to embed hidden marks in digitized multimedia data. Such marks are usually invisible and can only be extracted by a specially designed detector to protect them. Definition of watermark: The operation of embedding information in a work without being perceived. The watermark system consists of an embedder and a detector, as shown in the figure:
The embedder has two inputs: one is the information to be encoded as a watermark, and the other is the carrier work to be embedded in the watermark. The output of the watermark embedder is usually transmitted and recorded. The watermark works output by the embedder are input into the watermark detector, and most of the detectors will try to detect whether the watermark exists, and if so, output the information of the watermark spinning code.
Application of watermarking technology in the monitoring field: content certificate, that is, the signature information is embedded in the content to check whether the content has been tampered with in the future. The content here refers to video data. Most applications of watermarking can also be accomplished with other technologies, but real watermarking has three advantages over other technologies:
When the work is displayed, the watermark does not disappear.
Watermarks undergo the same transformation as works embedded in watermarks.
Transparent channel <br /> is a technology that analyzes IP data packets and sends them directly to a serial port. Actually played the role of extending the control distance of the serial device. IP network can be used to control a variety of serial devices, such as control decoders, serial devices, alarm hosts, access control, instrumentation and other serial devices. For users, they only see point-to-point transmission and do not need to care about the network transmission process. It is a serial transparent channel.
File fragmentation <br /> A file is recorded in discrete numbers and cluster numbers. The file contents in these discrete clusters are called file fragments. When the file content on the hard disk is repeatedly deleted and written, file fragments are prone to occur, which will increase the seek delay and rotation delay of the hard disk, thereby affecting the operating efficiency and service life of the hard disk.
If the files are predetermined, and each file is assigned a continuous cluster number in advance, the generation of file fragments can be completely avoided.
Cyclic recording and non-cyclic recording <br /> Cyclic recording refers to the recording method of automatically covering the original video data when the program detects that all hard disk space in the hard disk video recorder is full.
Acyclic recording refers to the recording method of stopping recording when all hard disk space in the hard disk recorder is full. In this way, the hard disk must be replaced or the hard disk must be processed (after the video data is backed up and then formatted) to continue recording.
Motion detection <br /> A technology that determines whether a video scene has changed by analyzing the video image.
Factors such as the movement of entities in the scene, changes in light, etc., are considered to have changed the scene.
I (Intra code frame) frames are intra-frame coded frames, P (Predicted frame) frames are coded frames that are predicted forward based on I or neighboring P, and B (Bi-direction frame) frames use neighboring I, P, or P, Interpolation frame for P-frame calculation.