Bandwidth management is only going to get more crucial due to the continued growth of IP camera deployment, resulting in a greater need for better bandwidth management.
In order to balance the growing demand for crisper image quality in video surveillance and the additional network bandwidth that will be consumed, a number of solutions have been developed to help customers get the best image quality possible. These solutions also conserve network bandwidth by employing features such as cropping, on-camera storage, intelligent video analysis, and adaptive bitrate streaming. Here are tips on how to optimize bandwidth for an IP video surveillance system.
Optimizing Existing Bandwidth
The main challenge of network bandwidth management is the difficulty of distinguishing between constantly changing images and static images. Therefore, it is not possible for the system to automatically adjust bandwidth without relying on certain technologies. Using sophisticated techniques, congestion of network traffic can be avoided, bandwidth can be adjusted flexibly and automatically, and information can be prioritized when an alarm is triggered.
One way to try and address network congestion issues is to directly confront the lack of bandwidth available. For example, operators have attempted to increase the available bandwidth with extra leased lines. Unfortunately, this has an associated recurring cost.
Therefore, optimization of existing bandwidth is seen as the path of choice for most since it can deliver efficient use of current infrastructures and provide capacity expansion while keeping the same pre-optimization bandwidth costs; however, it requires the purchase of multiple appliances.
In order to get the maximum return from a digital investment, optimizing the way video streams from different cameras to their destinations in surveillance networks is important.
To do this, QoS (Quality of Service), used in all network equipment, along with the bandwidth management router and simple network management processor (SNMP) switch are musts. An SNMP switch can ensure enough bandwidth for a certain number of channels. With the appropriate QoS setting, the transmission bitrate can be confined within a certain bitrate per second.
Reducing Bandwidth Consumption BY Settings
As mentioned above, it is not always an affordable option to add more bandwidth or new equipment to a surveillance system. This results in some trade-off between image quality and network bandwidth. Instead, the right configuration settings could help reduce network bandwidth consumption.
According to a white paper by Avigilon, temporal compression technologies rely on scene changes as part of its compression methodology. It can also introduce variability in the size of the compressed data stream that is generated, which depends on the compression being used - if it is configured to use a constant bitrate (CBR) or a variable bitrate (VBR), in a camera. The white paper points out when configuring a system for a constant bitrate, the amount of compression applied increases as more activities occur. As a result, compression artifacts could be added to the image and degrade the image quality. On the other hand, to maintain consistent image quality when variable bitrate compression is used, the size of the compressed stream is allowed to vary. Variability in the size of the compressed stream presents important challenges in system design and network bandwidth consumption.
Along with the CBR/VBR setting, it is also important to set up GOP (group of pictures), which refers to the type of setting in camera firmware. This setting makes it possible to further reduce the bandwidth and storage consumption of video streams up to 10 times while the concept of constant bitrate stands on the principle that the bitrate level will be fixed regardless of other settings. It is important to note that GOP should not be adjusted for scenes with a lot of motion or under poor lighting conditions because it may influence the video quality. Therefore, increasing the GOP value and extending the gap between frames could cause a loss of a certain number of frames under CBR. However, GOP can be used in combination with CBR if the priority is image quality.
A new version of VBR encoding technology has been developed by vendors, giving users the advantages of both CBR and VBR encoding while minimizing the disadvantages. According to VIVOTEK, this new encoding technology functions like VBR with limitations - administrators set a maximum value on allowable bitrates, and the bitrate is able to change in this range according to monitoring scenes. This makes it easier to manage network resources because the bitrate of the encoded video is guaranteed not to exceed the preset limit, and thus the network bandwidth required for transmission.
Certain new products feature a GOP control function supporting adaptive GOP settings as a response to specific events on camera site. This function would help save storage and bandwidth consumption under normal situations and automatically switch to a lower GOP value for better video quality if a moving object appears. Take for example a camera monitoring a site with restricted access. Since restricted areas do not usually have many people moving around inside them, a high GOP value is recommended to save bandwidth and storage space consumption. However, if an intruder enters the site, the motion detection system would immediately detect it and take the necessary actions through the camera, one of which is the possibility to set a lower GOP value to enable the highest video quality of the moving intruder.
Adopting High Efficiency Video Coding/H.265 Compression
The amount of bandwidth a camera consumes is largely dependent on its frame rate, resolution, and compression algorithm. For example, cameras using 1080p resolution, transmitting with H.264 encoding, will use around 4 megabits per second (Mbps) of bandwidth. On the other hand, a 4K camera transmitting using the same encoding, will consume 12 Mbps. Even with the improved compression ratio of High Efficiency Video Coding (HEVC), also known as H.265, this amount is still quite demanding for the existing network environment.
H.265 encoding is a video compression standard designed to improve coding efficiency. Depending on the application requirements, HEVC encoders can trade off computational complexity, compression rate, robustness to errors, and encoding delay time. HEVC can substantially improve coding efficiency to reduce bitrate requirements by half with comparable image quality; it also has the key benefits of inheritance from its previous standards, including B frames that generally result in less bits being coded overall. That’s why SoC providers have combined these two elements and launched new video processing engines supporting HEVC and encoding B frames based on a forward prediction with auto referencing techniques to enhance compression rate without causing system latency.
An increasing number of vendors are working on enhanced H.264 or HEVC/H.265 compression standards and developing their own intelligent video encoding technologies such as Zipstream technology from Axis Communications, Smart Coding technology from Panasonic, and Smart Stream II and Smart H.265 from VIVOTEK. These innovative technologies are optimized for video surveillance and more efficient, lowering bandwidth and storage requirements for many common surveillance use cases. These technologies will help users better manage network bandwidth resources, reducing storage requirements by 30 to 80 percent and lowering the overall total cost of ownership compared to H.264, while still providing crisp, high-resolution images.
Taking Advantages OF Cutting-Edge Features
The rising performance expectations of security technologies and systems are only further fueling the pressure to improve bandwidth management. Take 4K resolution for example. Manufacturers have taken network consumption into consideration when developing 4K surveillance cameras, equipping them with intelligent technologies to improve quality and lower the costs of video surveillance. For example, intelligent video analysis tracks and focuses on relevant situations, and adds sense and structure to videos allowing the quick retrieval of the correct data. Regions of interest (ROI) allow zooming in on certain details of a full image. These close-ups are transmitted in a separate stream, so both overview and detail can be viewed at the same time. ROI also allows automatic tracking of persons or objects of interest in a single frame, so you never lose track of them.
Users are rapidly acclimating to HDTV and full-frame rate Internet video has become the norm. To experience the full benefits of 4K surveillance, a camera platform that can meet the demanding resolution, optical, and low-light performance standards of 4K imaging is required. Even though there are only a few security cameras delivering true 4K resolution, true 4K optics, true 4K wide coverage, and true 4K lenses custom designed to pass the full optical bandwidth needed to produce exemplary 4K images, the bandwidth bottleneck is still there.