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SD
The so-called standard definition is a video format with a physical resolution below 720p (1280*720). 720p refers to the video's vertical resolution of 720 lines of progressive scanning. Specifically, it refers to standard-definition video formats such as VCD, DVD, and TV programs with a resolution of about 400 lines. The physical resolution of 720p or more is referred to as high-definition (English definition High Definition) referred to as HD. With respect to HD standards, there are two internationally recognized standards: video vertical resolution exceeds 720p or 1080i; video aspect ratio is 16:9.
HD
The division of "HD" and "SD" first comes from the video effects that can be seen. Due to the difference in image quality and the bandwidth occupied by channel transmission, digital television signals are classified into HDTV (High Definition Television), SDTV (Standard Definition Television), and LDTV (Ordinary Definition Television). From the visual effects, HDTV has the highest specification, and its image quality can reach or approach the level of a 35mm widescreen movie. It requires the horizontal resolution of video content and display equipment to reach over 1000 lines with a resolution of up to 1920×1080. Judging from the picture quality, because the definition of high-definition is basically equivalent to 4 times that of the traditional analog TV, the picture definition and color reproduction degree are far better than the traditional TV. The 16:9 widescreen display also brings wider visual enjoyment. From the perspective of audio effects, high-definition television programs will support Dolby 5.1-channel surround sound, and high-definition movie programs will support Dolby 5.1 True HD specifications, which will give us a superb listening experience.
Due to cost constraints, HD has not been effectively applied in the video surveillance industry. With the development of chip technology and compression algorithms, high-definition video surveillance products are gradually emerging. The D1 standard-definition video compression format has now been officially written into the National Digital Video Recording System (DVR) national standard. From the perspective of the entire video surveillance industry, there are commercial H.264-based HD IP Cameras and video server products currently on the market. The resolution can usually reach 720P, but the frame rate is usually less than 15 FPS and cannot reach the market. The purpose of real-time video surveillance. The existing 720P HD megapixel network camera, based on the standard H.264 Main Profile compression algorithm, can achieve clearer image effects at a lower code stream. It supports 30FPS 720P real-time dual-stream video encoding, high-definition, real-time, dual stream, SD card and USB video recording capabilities, support for Wifi wireless, more support for high-definition video analog output, with a higher cost performance. 
FULL HD Full HD
The so-called Full HD (FULL HD) refers to physical resolution up to 1920×1080 display (including 1080i and 1080P), where i (interlace) refers to interlaced scanning; P (Progressive) stands for progressive scan, both of which are in the picture There is a big difference in finesse, 1080P picture quality is better than 1080i. Correspondingly, 720 is called standard HD. Obviously, because the data information is more abundant in the process of transmission, 1080 has more advantages in resolution, especially in the large-screen TV, 1080 can ensure a clearer picture quality. Due to cost and other reasons, Full HD products are still less commonly used in surveillance systems and are usually only used in some high-end applications.
HDTV resolution up to 5 times the standard analog TV resolution. HDTV also has better color fidelity and 16:9 format. The two most important HDTV standards defined by SMPTE (Society of Motion Picture and Television Engineers) are SMPTE 296 M and SMPTE 274 M.
SMPTE 296 M (HDTV 720 P) defines a resolution of 1280x720 pixels, high-fidelity color in 16:9 format, 25/30 Hertz (Hz) sequential scanning frequency, ie 25-30 frames per second, depending on country, Also supports 50/60 Hz scanning frequency (50/60 frames per second).
SMPTE 274 M (HDTV 1080) defines a resolution of 1920x1080 pixels, high-fidelity color in 16:9 format, using 25/30 Hertz (Hz) and 50/60 Hz interleaved or sequential scanning frequencies.
Cameras that comply with the SMPTE standard are said to comply with HDTV quality and should provide all HDTV resolution, color fidelity, and frame rate advantages. HDTVs are based on square pixels and are similar to computer screens, so HDTV video from network video products can be displayed on either an HDTV screen or a standard computer monitor. With sequential scanning of HDTV video, no conversion or de-interlacing techniques are applied when the video will be processed by a computer or displayed on a computer screen.
Standard definition, HD, full HD concept list
In the past few years, with the promotion of the consumer electronics market and the shift of CRT TVs to liquid crystal and plasma TV screens, HDTV has achieved great success. With the video surveillance field now also using HDTV, the definition of SD, HD and Full HD in the surveillance basically follows some of the names of HDTV. Compared with analog CCTV systems, high definition means excellent image quality. At present, everyone is speculating on the concept of high-definition. Before, we usually called D1 (704 * 576) or more resolutions in high resolution. In fact, D1 is only the resolution of standard definition. Let's take a look at what is SD, HD and Full HD. Believe that through the efforts of Zhongxing and many high-definition video surveillance vendors, HD will popularize the entire security monitoring market in the near future.