Advancements in video surveillance techniques since the launch of IP cameras have seen many technological advances that have delivered increased resolution and improved picture quality through better lenses, sensor and image processing technology. These advancements are capable of bringing much needed improvements in evidential image quality and enable the user to realize the investment made in CCTV through deliverable results in terms of clear identification.
Delivering these advancements requires additional design thinking in terms of total bit rate throughput. Typically higher resolutions FHD & 4K require much greater bandwidths that impact on the design and cost of both the network to stream high definition images across and the recording hard drive capacity needed to store them on. System designers now not only need to think in terms of the angle of view or depth of field that a camera needs to produce but also to think of the content within the camera image in terms of what is useful and what is not. For example streaming and recording scenes in high definition of empty streets devoid of movement, people or cars, or the skyline creates lots of useless image data that requires lots of bandwidth to stream and store.
Panasonic have now developed a cost viable solution to the high definition bandwidth problem by enabling important content to stream as high definition whilst economizing or eliminating on unimportant content in an image. This technology is called Panasonic Smart coding and its employment reduces the total cost of ownership and makes the investment in high definition within the reach of a much wider section of the video surveillance marketplace.
Smart Coding is a license free feature available on *Panasonic i-PRO and i-PRO Extreme cameras. Total bit rate throughput can be reduced by combining the two main technologies that make up the Panasonic Smart Coding innovation;
As we are eliminating the unnecessary streaming or high resolution data even greater results in overall bit rate throughput can be saved by combining Smart Coding with Panasonic high-resolution 4K surveillance cameras.
Panasonic’s Smart Coding Technology is based on the coding of the moving video standard, as such special modules and the like are not needed for display or playback by a client who is employing this technology.
The two technologies that make up the Panasonic Smart Coding innovation are made of several elements that are described as follows;
Bit rate is sufficiently assigned to subject matter that is important, such as people or cars and therefore needs to be streamed and recorded as high definition video. However, so-called background elements such as walls and roads are not so important therefore as content does not really need to be as sharp, so lower or no bit rate is assigned to it. Overall the total bit rate that needs to be streamed and recorded is reduced. This technology uses various techniques to accomplish the overall reduction in throughput as follows;
The video stream is comprised of I-frame data encoded closed in the screen (as still image) and P-frame data where the difference from the previous frame is encoded. If the refresh cycle is set to 1 second (the default setting f or Panasonic cameras) at a frame rate of 30 fps, stream data is generated where 29 P-frames follow after one I-frame the data from this I-frame to the next I-frame is called Group of Picture (GOP).
To play back stream data generated in this way, decoding must be done in order from the I-frame. For that reason, the I-frame is also called the reference frame. If the refresh interval (interval between I-frames) is long, much decoding must be performed until playing back the end frame of that GOP.
I-frames encode the entire screen, so the volume of data is large. P-frames encode the difference from the previous frame, so the volume of data becomes smaller.
Figure 1: The image of video stream
Figure 2: The encoded volume of I-picture and P-picture
The GOP Control function detects motion of subjects and makes the interval between I-frames shorter if there is motion or longer if there is no motion. By making the interval longer in scenes with no motion, the number of I-frames with large data volume can be reduced, greatly reducing the total bit rate. And in scenes with motion, the interval is made shorter to secure accessibility to scenes the user wants to view.
Figure 3: The difference of I-frame insertion interval
Panasonic H .265 cameras have been given an Advanced mode in addition to conventional GOP control described on the previous page. The reference frame structure in Advanced mode is shown in Figure 4
Advanced mode utilizes the concept of long term prediction frames. Its reference frame structure consist of I-frames, P-frames, which reference two frames (an I-frame and the previous P-frame), and key frames (P#30,#60,), which reference the first I-frame(IDR) in the GOP.
Figure 4: shows the reference relationsh ip at 30 fps w ith an I-frame interval of 6 0 sec and key frame interval of 1 sec.
If there are no key frames in the GOP, decoding needs to be done sequentially from the I-frame at the head of the GOP. However, key frame s can be decoded using just the I-frame. For example, if key frames are p resent in the GOP, #61can be displayed by decoding just IDR#0, P#60, and P#6 1. Additionally, by inserting key frames, random accessibility can be secured.
The Advanced mode improves prediction efficiency by using two reference P-frames and reduces the bit rate by expanding the I-frame interval whilst maintaining random accessibility.
Auto-VIQS (Variable Image Quality on Specified area) Control can automatically determine areas with and without motion and therefore reduces the data volume of those without motion. In the example below Auto-VIQS has realized two areas of importance that have a lot of movement (seen in red) and one area of little or no movement (seen in yellow).
Figure 5: Left: Original l image. Right: The image is an example of separate a still area and an area with motion.
Smart Facial Coding reduces bit rate by detecting the face and motion areas an d keeping the face area at high image quality, slightly reducing high-frequency components of the motion areas, and reducing high-frequency components of other still areas.
Figure 6: Smart Facial Coding explanatory diagram
Smart Facial Coding and Auto-VIQS can be selected independent of GOP control on H.265 cameras.
Noise from image sensors at night or in other low -illumination environments cause unnecessary data volume as noise is seen as movement with current compression technologies. The data created rise s in volume with higher resolution cameras like 4K that are often less effective at low light and therefore create more noise.
Panasonic have created two technologies to provide a more effective response to noise generated which when employed can reduce data volume by 20% in comparison with conventional camera noise reduction techniques . These two technologies are explained below;
3D-Multi-process Noise Reduction (3 D-MNR) analyzes differeces in signal level and reduces grainy noise generated in low-illuminance environments to achieve a low bit rate. Noise generation patterns can be estimated and predicted by individual luminance level using Panasonic’s own noise reduction algorithm. Noise generated when increasing gain to secure brightness in video is reduced by individual pixel accurately an d in fine detail.
Figure 7: The image diagrams for the description of 3D- MNR
First, noise detection is performed with high precision by creating statistic s for the difference of the signal level of the surrounding pixels by luminance level, deciding the threshold, and estimating a noise mod el in advance. Pixels with a signal level lower than the threshold are averaged with the surrounding pixel s to reduce noise. A Bayes mathematical estimation is then performed on the estimated noise model and the noise model that shifts in the time axis direction. If the pattern s are similar, they are reduced as noise ; if they differ, the afterimage is minimized as motion. Up to approx. 25% of data can be reduced by this function
Frequency Divided Filter (FDF) analyzes frequency and reduces fine noise that is genera ted at slightly low illuminance to achieve low bit rate. I mages are divided into multiple bands, and an optimum coring filter for each is applied to enable noise to be reduced while leaving edge components. Up to approx. 25% of data can be reduced by this function
Figure 8 : The image diagrams for the description of FDF
Figure 9: The outline flow of FDF processing
Since 1957, Panasonic has over 50 years of experience in the surveillance camera industry and has served a broad range of customers around the world. Based on the Panasonic group’s intellectual properties and technologies, Panasonic, the leading company in the audio and video solution market, continues to develop better video surveillance systems.
Panasonic’s Smart Coding technology is technology to reduce video surveillance system costs. It concentrates data volume into that for important scenes and areas, and it reduces data volumes for scenes and areas without motion as well as reduces noise in low-illuminance situations, enabling data volume to be reduced.