Merit LILIN Explores H.264 Compression for Network Cameras

Merit LILIN is in the process of adopting the new video compression technology, H.264/MPEG-4 AVC (Advanced Video Codec), also known as MPEG-4 Part 10, Main Profile (level 3), SoC for CCTV IP camera and PTZ solutions. The new technology is capable of transmitting digital video at full D1 resolution and real time speed via network.  With H.264 AVC advanced compression algorithms, IP cameras and PTZ solutions can provide superior video quality, bandwidth efficiency, and higher storage utilization for CCTV applications.   

Why Use H.264?
With H.264 AVC, the bandwidth and storage requirement are reduced by 41% compared with MPEG-4 ASP (Advanced Simple Profile) and by 64% compared  with MPEG-2 on average.  In other words, H.264 AVC can deliver better video quality than MPEG-2 or MPEG-4 using same network bandwidth.  Higher compression rate also means higher storage utilization.  For DVR/network video recorder (NVR) applications, H.264 AVC video compression can reduce the cost for the storage.      

The Problem of Digital Video Compression
One important issue of IP camerasˇ and DVRsˇ video compression is lack of standard.  A CCTV product equipped with so called modified JPEG or MPEG-4 compatible video codec gives us limited system scalability.  In system level, the timestamp information might be added into the streaming that it breaks the compression standard.  Incompatible digital video streaming causes the limitation prohibiting IP cameras widely adopted by CCTV industry that includes:

* Time-consuming and error prone for system integration among products by system solution providers
* Limited flexibility and scalability in choosing IP products among existing systems by end users

In order to solve this problem, we are unifying IP cameras and DVRs into one system platform,

Compression Standard
The H.264 AVC is analyzed and verified by a third party H.264 streaming analyzer.  The streaming are also verified by using H.264 software player including KMPlayer and VLC Player on Microsoft Windows and/or Linux platforms.  On mobile device platforms, CorePlayer is used for verifying H.264 AVC streaming. 

Timestamps are crucial information for CCTV applications.  The timestamps information should be encapsulated within video streaming of a CCTV IP camera for an evidence.  These time information can be later interpreted by a software or a hardware NVR for end users.  Merit LILIN utilizes the decode time stamp (DTS) and presentation time stamp (PTS) for time information without affecting the standard of H.264 AVC streaming. 

Communication Standard
The IP or DVR products adopt HTTP and UDP unicast/muticast protocols for transmitting H.264 AVC streaming.  On Internet environment, the advantages of adopting HTTP ServerPush transmission technology include:

* An efficient protocol reducing deviceˇs CPU loading
* No RTSP port settings required by end users
* Backward compatible with Merit LILINˇs JPEG IP camera platform
* Simple protocol for testing and verifying the streaming by system developers

Low Latency PTZ Application
It is not acceptable if a user reacts to a live video 5 seconds after moving the PTZˇs lens at low bandwidth network.  Low latency design for PTZ products using H.264 AVC should be considered for both Internet and LAN environments.  For the PTZ applications, Merit LILIN adopts PTZ absolute position and video-click-n-move techniques for fast PTZ positioning to cope low bandwidth Internet usages.   

HTTP ServerPush technique also reduces computational complexities for both sending and receiving video streams.  Merit LILINˇs IP cameraˇs network latency can be minimized within 300ms at 2Mbps bitrate in Full D1 resolution via TCP protocol.  For a CCTV PTZ application, end users will perceive little video delay while controlling a PTZ.

Standard SDK
For system integrators, the software development kit (SDK) of Merit LILINˇs H.264 AVC platform , known as HTTPAPI, follows the SDK of our JPEG IP camera platform SDK.  The unified SDK allows system developers to integrate H.264 AVC into their software systems easily.  Future H.264 DVR development, we will follow this convention and provide single SDK for both IP camera and DVR products.  This reduces tremendous development time for software developers.

About the Technology
The H.264 IP camera and PTZ device developments adopts a low cost - high performance H.264 AVC system on chip (SoC).  The SoCˇs CPU processing speed can run up to 145Mhz.  Furthermore, H.264 AVC complex algorithms are processed by the hardware encoder leaving the rest of CPU speed for network video transmission.  

H.264 AVC codec SoC integrates advanced H.264 algorithms including inter frame prediction, variable block-size motion compensation, main profile (I-, B-, P-frames), and entropy coding.  These technologies effectively improve video quality at high compression rate.


Product Adopted:
Network Cameras
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