The following article explains incoming bandwidth and online display capabilities of ClareVision NVR's.
Incoming bandwidth is a often overlooked, yet important specification on NVR's. Incoming bandwidth limits dictate the number of cameras you can record simultaneously and may impact the reliability of the real time (Live View) displays if not configured correctly.
- Bandwidth or Incoming Bandwidth: this specification is related to the NVR's ability to process inbound video streams, primarily for storage purposes.
- When considering inbound video streams you must take into account both those channels that are being recorded AND those channels that are being viewed. It is the sum of that traffic that determines incoming bandwidth requirements.
The following note walks you through how bandwidth is calculated, what impacts bandwidth, the capacity of the ClareVision NVR's and tips you can use to quickly configure NVR's without a lot of hassle
The bandwidth of the NVR is related to the NVR's ability to process and record incoming video streams from cameras of varying framerates, resolutions and encoding schemes. The following details the bandwidth for ClareVision NVR's
The following camera settings impact bandwidth:
2. Frame rate
3. Encoding scheme (H.264 vs. H.265)
4. Max bitrate
Let's take these one at a time, then summarize with a quick calculator you can use to predict the bandwidth requirements of your camera system.
The ClareVision Camera line includes cameras from 2MP to 8MP. A 2MP camera has roughly 2 million pixels whereas an 8MP camera has roughly 8.3 million pixels, or four times the pixel density of a 2MP camera. While that is true, because of encoding, the bandwidth will not necessarily track linearly with the pixel density, but it is safe to assume higher resolutions will result in increased bandwidth.
The framerate is the number of frames per second transmitted from the camera to the NVR. The framerate is a video setting and can be set from 1 to 30FPS. ClareVision cameras come defaulted to 15FPS which is more than enough to display fluid motion. We do not recommend increasing the FPS beyond 15 FPS
There are two encoding schemes in ClareVision NVR's: H.264 and H.265. These encoding schemes essentially transmit only changed pixels from frame to frame rather than sending the entire image. After an interval called the I-Frame interval (ClareVision is set to 75 frames), the camera will transmit the entire image and follow with changes only for following frames. As a result, the amount of compression you will realize will depend upon how much movement there is in the field of view of the camera. If you have a lot of movement, the compression economy will be lower than if there is very little activity in the field of view.
H.265 is a more current encoding scheme and is therefore more efficient than H.264. You can generally assume H.265 will use 50% of the bandwidth of H.264.
The max bitrate is a setting that governs, as an override, the maximum bitrate the camera will use irrespective of the settings above. Max bitrates are used with ClareVision cameras with the bitrate mode set to variable. This simply means the bitrate consumed will be the actual bitrate required UP TO the max bitrate setting. Generally, you should leave this setting alone UNLESS you change the encoding scheme (e.g. H.264 to H.265)
The max bitrate is set for H.264 in all cameras. If you change the encoding scheme to H.265, you may want to change the bit rate to match the bit rate requirements for H.265. While leaving the max bit rate at the H.264 bitrate will not impact camera performance, that figure is used to determine bandwidth limits for the NVR and display warnings in the user interface may persist if the ALLOWED bandwidth maximum is exceeded per this setting.
You can use the following calculator to calculate the total bandwidth your system configuration will consume: BANDWIDTH CALCULATOR
You can predict your hard drive utilization (also directly related to bandwidth) using this calculator: STORAGE CALCULATOR
NVR Bandwidth Exception Symptoms
The most obvious symptom you are exceeding the NVR bandwidth is dropped frames in a live view or dropped frames in playback. You may also miss motion event recordings in playback but see the event in the event log.
The most obvious place you will see a bandwidth exceeded error message is in the NVR terminal interface (HDMI port output). If you see a message box appear indicating the bandwidth has exceeded capacity, the settings above must be adjusted.
Camera Defaults and NVR Recording Capacity
NVR@15FPS (default from factory)
|Camera||Bit Rate||4 Channel NVR||8 Channel NVR||16 Channel NVR|
|Camera||Bit Rate||4 Channel NVR||8 Channel NVR||16 Channel NVR|
If you are going to load the 8 or 16 channel NVR to capacity with 8MP cameras, you will need to change the encoding to H.265 and reduce the max bitrate to a maximum of 5MBPS in each camera.
Impact of Display (WEBUI or Terminal) on Bandwidth
It is very common to display stream 2 on the webui and the terminal (HDMI) interface when in grid view. If you are going to leave the NVR's HDMI interface on a monitor for extended periods of time, you will need to take into account the bandwidth that second stream uses for each channel (stream 2) displayed on the grid view on the monitor (or Webui).
The default for stream 2 on all ClareVision cameras is D1 resolution or 0.3MBPS at 15 FPS using H.264. While not terribly significant, if you are running the NVR at its capacity with the recording streams and you have 25 images on a grid view, you are adding 8MPBS to the incoming bandwidth of the NVR with the live view running.
If you are using the terminal interface, and the warning message pops up stating you are exceeding the network bandwidth, it is likely NOT the grid view creating the problem, it is the recording settings on stream one that are creating the problem. Go back and review your encoding settings, framerates and max bitrate settings for stream one on each channel.
Recording settings and camera display both affect incoming NVR bandwidth. Since recording is usually assigned to stream one, recording settings and the configuration of stream one on the cameras is far more impactful on incoming bandwidth than is the online display using stream two. Nonetheless, you are much more likely to see the impact of exceeding incoming bandwidth using one of the online displays (Webui or terminal interface). Do not be misled - go to the stream one settings, do the math, and make sure you are not exceeding the bandwidth of the NVR. If you are:
- Make sure the frame rate is set to 15FPS
- Set the encoder to H.265
- Change the max bit rate as needed (8mp is 5MPBS)