Calling all tech geeks! We know that some of you are curious about how, exactly, Dahua’s optimized video compression codec, Smart H.265+ works. Here are four innovative things it does to reduce bitrate and storage requirements.
1. Scene-Adaptive Encoding
A typical surveillance scene is not fixed; the scene is constantly in flux even though these changes may be imperceptible to human vision. According to the Just Noticeable Difference model, human vision requires a certain amount of change to an object in order for a difference to be noticeable. Similarly, scene-adaptive encoding implements a differentiated strategy based on smart scene analysis that includes the consideration of light, noise, and motion conditions to improve encoding efficiency.
2. Dynamic Regions of Interest (ROI)
Security operators are more interested in moving objects in the surveillance scene and less interested in the background area. With this background in mind, Smart H.265+ automatically separates the moving objects from the background according to the motion in the video scene.After separation, it varies compression levels according to different regions of interest. For example, it can increase the compression level for a background area and reduce the compression level for moving objects, thereby enhancing compression efficiency.
3. Dynamic Group of Pictures (GOP)
A video bit stream is made up of two kinds of pictures: I-frames (intra coded pictures) and P-frames (predictive coded pictures). An I-frame is an image that is coded independently of all other images; a P-frame contains motion-compensated difference information relative to previously decoded images. The size of an I-frame is inherently larger by several factors of size than a P-frame, and comprises a much larger portion of the bitrate of a scene than a P-frame.Because typical surveillance video is mostly static for a majority of the time, Smart H.265+ inserts an I-frame in the video stream only when a change (such as movement) interrupts the scene. Dynamic GOP reduces the number of I-frames, in turn reducing the bitrate needed to produce the expected quality of video.
4. Noise Suppression
Noise artifacts typically show in surveillance video when the lighting is poor. The noise not only affects the video quality, but increases the encoding bitrate as well. Traditional noise reduction strategy implemented intense noise reduction techniques on the entire video scene, but this technique sometimes deleted vital video details in the process. Smart H.265+ uses advanced video analytic technology to distinguish between the motion region and the background region, then applies a different noise reduction level to each. In this way, it reduces noise while maintaining the efficacy of the ROI video quality and reducing the overall bitrate.