Network cameras (IPC) is a combination of traditional cameras and network technology, a new generation of cameras, it can image transmitted through the network to the other side of the planet, and a remote viewer without using any professional software, as long as the standard network browser (such as "MicrosoftIE or Netscape) to monitor its image. network camera (IPC) built an embedded chip, embedded real-time operating system. efficient compression chip compression through the network cameras transmit video signals are digitized by bus to the Web server on the network users can directly use the browser to view the camera image on a Web server, an authorized user can also control the movement of the lens of the camera pan and tilt or operating system configuration.

• Image compression mode
• For network cameras, image compression:
• JPEG, MJPEGMPEG1, MPEG2
• MPEG4H.264H.264

What is H.264?

H.264 is a high-performance video codec technology. The video codec technology developed international organizations have two, one is the ITU (ITU-T) ", it set the standards H.261, H.263, H.263 +, and the other is" It sets the standards of the International Organization for Standardization (ISO) "MPEG-1, MPEG-2, MPEG-4, etc.. H.264 is a new digital video coding standard developed jointly by the two organizations jointly established by the Joint Video Team (JVT), so it is both the ITU-T H.264 and ISO / IEC MPEG-4 Advanced Video coding (AdvancedVideoCoding, AVC), and it will become the standard of the MPEG-4 Part 10. Therefore, both MPEG-4AVC, MPEG-4Part10, ISO/IEC14496-10, all refer to H.264.

H.264 biggest advantage of having a very high data compression ratio, in the conditions of the same image quality, H.264 compression ratio is more than 2 times the MPEG-2, MPEG-4 is 1.5 to 2 times. For example, the size of the original file to 88GB, using MPEG-2 compression standard compression into a 3.5GB compression ratio of 25:1, while using the H.264 compression standard compression becomes 879MB 879MB to 88GB H.264 compression ratio to a staggering 102:1! H.264 Why so high compression ratio? Low bit rate (LowBitRate) played an important role, and MPEG-2 and MPEG-4ASP compression technology, H.264 compression technology will greatly reduce the download time and data traffic charges. In particular, it is worth mentioning that, H.264 also has a high-quality smooth image with a high compression ratio.

MPEG-4

Compared with MPEG-1 and MPEG-2, MPEG-4 characteristics is more suitable for the interactive AV services, and remote monitoring. MPEG-4 is the first from passive to active (no longer just watch allows you to join them, that is interactive dynamic image standard), it´s another feature is its comprehensiveness. Root causes, MPEG-4 attempted fusion of natural objects and man-made objects (sense of visual effects). The scalability of the design goals of the MPEG-4 and wider adaptability and more flexible.

MJPEG

Full name "Motion Joint Photographic Experts Group", is a video encoding format

The analog video signal of the MotionJPEG technique commonly used with a closed circuit television camera "translated" into a video stream, and stored on the hard disk.

Typical applications such as a digital video recorder or the like. The MJPEG Unlike MPEG, do not use interframe coding, it is easy to edit with a non-linear editor. Compression algorithm and MPEG MJPEG same strain, very powerful, able to send high-quality images, generates fully animated video. Accordingly, MJPEG bandwidth requirements is also very high, the equivalent of the T-1, MJPEG information is stored in digital media behemoth, requires a lot of storage space to meet the needs of Today, most users. Thus, from another point of view that, under certain conditions, MJPEG may be one of the least efficient encoder / decoder.

MJPEG 24-bit "true-color" image the standard MJPEG work will be the RGB format convert images YCrCB format, purpose is to reduce the file size can be reduced by 1/3 to 1/2 generally about.

The MJPEG and MJPG the distinction

MJPG MJPEG the abbreviation, but MJPEG can also represent the extension of the file format.

D1 surveillance industry mainly the use of Qcif (176 × 144), CIF (352 x 288), HALFD1 (704 x 288), D1 (704 × 576), several resolutions.

D1 is a high-definition image format, the corresponding resolution is 720 * 576. In order to save some people simply 4CIF (704 * 288), also known as D1. This has been industry and user default. Therefore, in the industry, a product of the D1 720 * 576 or 704 * 576, this is not important. Only in all the way to the video servers and network cameras can experience the clear effect of D1. D1 has been very clear, there are still a lot of people on the D1 effect is still not satisfied, so as the the D1 family members also is entering the stage of monitoring, the way we introduce several members of the D1 family:

D1: 480i format (525i): 720 x 480 (level 480 lines, interlaced), and NTSC analog TV clarity, the line frequency 15.25kHz, the equivalent of what we call 4CIF (720 × 576)

D2: 480P format (525p): 720 x 480 (level 480 lines, progressive scan), compared with D1 interlace to clear a lot of the same and progressive scan DVD specifications, line frequency of 31.5kHz

D3: 1080i format (1125i): 1920 x 1080 (level of 1080 lines, interlaced), high-definition relax adopted a resolution resolution 1920 × 1080i/60Hz, and line frequency 33.75kHz

D4: 720p format (750p): 1280 x 720 (level 720 lines, progressive scan), although the resolution compared to D3 is lower, but relative to progressive scan, there is more people feeling 1080I (actual successive 540 lines) The visual effect is more clear. Personal feeling, however, the maximum resolution of 1920 × 1080, D3 than D4 feeling clearer, especially text expressive with a resolution of 1280 × 720p/60Hz line frequency to 45kHz

D5: 1080p format (1125p): 1920 x 1080 (horizontal 1080 lines, progressive scan), currently the highest standards of civilian high-definition video resolution the 1920 × 1080P/60Hz, line frequency to 67.5 KHZ.

D1 and D2 standards to the highest standards of our general analog TV, and can not be said of the high-definition on D3 1080i is a high-definition TV standard, it can be compatible with the 720p format, D5, 1080P professional standards is not a civil level, given above 60HZ only under ideal conditions, the field frequency and the line frequency of 67.5 KHZ, there is no such the Takayuki frequency of the advent of television, the actual the 1080P the field frequency only in the professional field 24HZ, 25HZ and 30HZ.

CPU

CPU central processor is one of the core components of network cameras, network cameras brain, most of the data are done it. Its speed directly affects the running speed of the camera. CPU logic unit (ArithmeticLogicUnit; ALU), storage units (MemoryUnit; MU) control unit (ControlUnit; CU), can be divided into three parts, from the application point of view can be divided into three categories X86, embedded and other high-performance . Network cameras for general use are embedded CPU.

FlashMemory

I.e. faster FlashMemory erase-type memory, to maintain the stored data even in case of power failure, but the data deletion is not a single byte as a unit, but in units of a fixed block. Block size is generally from 256KB to 20MB. FLASH word originally by Toshiba because the instant removal capacity of the chip made. Flash from the EPROM, chip price is not high, and large storage capacity. Flash memory is becoming the EPROM alternatives, because they can easily be upgraded. Flash PCMCIA card is used, the PCMCIA flash drives, hard disk other forms embedded controller and SMARTMEDIA. If the flash memory or other derivative technology can be cleared within a certain time one byte, and that will cause the arrival of the permanent (non-volatile) RAM.

DRAM

DRAM (Dynamic Random-Access Memory), dynamic random access memory is the most common system memory. DRAM data can only be maintained for a short time. In order to maintain the data, DRAM must from time to time to refresh (refresh) once. If the storage unit is not refreshed, the data will be lost.