Q1: How many Compression Formats have been using for the most of DVR in the world?

JPEG and MPEG are the most widely used. The major difference between JPEG and MPEG is in compression techniques. JPEG processes images by compressing one by one still picture but MPEG compresses image sequence by sequence.
JPEG compress method can be divided into JPEG, M-JPEG, and Wavelet…, several formats.
MPEG compress method can be divided into H.263, MPEG, MPEG2, and MPEG4……

Q2: What is the advantage of using MPEG4 compression?

MPEG-4 compression technique provides DVD quality video and lower bit rate to transmit digitized video streams in LAN, and also in WAN, where bandwidth is more critical. M-JPEG's bandwidth requirement is more than MPEG4. Besides, M-JPEG’s resolution and frame rate is not good as MPEG4. MPEG-2 can provide DVD-like video. However, MPEG2s bandwidth requirement is so high that it is impossible to use MPEG2 in a LAN or WAN environment.

Q3 : What's the advantage to use MPEG4 ASIC rather than DSP?

Current most popular DSP cannot provide enough processing power to process MPEG4 full D1/30 fps encoding algorithm. The video quality processed via DSP cannot compete with that processed by ASIC. Current DSP usually supports up to CIF (360x240) right now, while ASIC can support not only CIF, but also full D1 (720x480).

Q4 : Why is MPEG4 ASP Compliant important? Is ASP same as Short header as some other manufacturer claims?

There are MPEG4 ASP (Advanced Simple Profile), MPEG4 SP (Simple Profile), and MPEG4 Short Header in the market. MPEG4 ASP provides all I, B, P frames and therefore provide better compression rate, while both MPEG4 SP and MPEG4 Short Header provide I and P frames only. In current practice, MPEG4 ASP and SP are deployed by ASIC, while Short Header is most commonly deployed by DSP. For the same video quality, the bandwidth required for MPEG4 ASP is smaller than that of MPEG4 SP or Short Header.

Q5: What is Power-over-Ethernet (PoE)?

Power-over-Ethernet (PoE) or "Active Ethernet" eliminates the need to run 110/220 VAC power to Wireless Access Points and other devices on a wired LAN. Using Power-over-Ethernet system installers need to run only a single CAT5 Ethernet cable that carries both power and data to each device. This allows greater flexibility in the locating of AP's and network devices and significantly decreasing installation costs in many cases.