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項目符號 Image Compression Technology
Motion JPEG


Image Compression Technology

VisionNet Network DVR compress video prior to record them into "Storage Buffer". The compression purpose is to save space and enhance network transmission. For instance, SW-80 compress each frame into 2.5kb in size.

There are many Digital Compression Standard in the field of computing. And many mores are still in research and development. Until now, remarkably one include Motion JPEG, MPEG-1, MPEG-2 and MPEG-4.

Motion JPEG:
With motion JPEG, each frame within the video is stored as a complete image in the JPEG format. The still images are displayed at a high frame rate to produce very high-quality video, but at the cost of producing comparatively large file sizes.
Applications: Webcam, mobile......

Moving Picture Encoding Group international standard ISO/IEC 11172.
This standards produce "VCR quality", giving performance of up to 352x288 pixel, 30fps, max 1.86Mbit/s. As the available resolution is quite limiting, and the size of video is relatively large, one hour recording takes up to 650-700 MB.
Applications: VCD

Moving Picture Encoding Group international standard ISO/IEC 13818.
Most widely known standard for DVD, that offers high quality video suitable for installations where TV-quality is needed. This standard provide a resolution of 720x480 pixels at 30fps NTSC or 720x576, 25fps PAL. The bit rate is typically 1-10 Mbit/s. Although this format is excellent for image quality, but the recording size takes up to GB level.
Applications: DVD

Moving Picture Encoding Group international standard ISO/IEC 14496.
This standard covers a wide variety of applications ranging from the video displayed in cellular phones, to full feature-length movies shown in a cinema. MPEG 4 is widely used to be the video standard of the future. This format contains many enhancements to any of the early MPEG standards: for example, it offers narrower bandwidth and can mix video with text, graphics and 2-D and 3-D animation layers. High performance hardware and sophisticated techniques are required to produce MPEG-4 video, therefore, many security companies can't adopt this format in their products. In fact, this format provide image quality comparable to MPEG2, depending on frame rate and resolution, the recording size is excellent for security surveillance recording. One hour of video with 25fps takes 150-200MB.
Applications: VisionNet Network DVR, digital movie......


For more information:
Video Camera Selection Guide - White Paper

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