Network Bandwidth Control#

This topic describes parameters for controlling network bandwidth consumption when the blaze camera streams image and depth data.

Using the Feature#

Controlling network bandwidth consumption is necessary when multiple devices are connected via a common link to the receiving host and must share the network bandwidth available. To ensure stable operation, you may have to limit the amount of bandwidth each camera consumes.

Example: If you connect 2 cameras via a switch to a network port of a Gigabit Ethernet adapter of the receiving computer, the sum of the throughputs of both cameras must not exceed the maximum throughput of 1 GBit/s (125 000 000 byte/s).

Another reason to reduce the bandwidth used by a camera is when the receiving host is unable to keep up with the data transfer and has to discard packets.

Controlling Bandwidth Consumption#

In a first step, determine the maximum possible throughput your cameras can generate with their current settings by reading the BslDeviceLinkCurrentThroughput parameter. This parameter indicates the bandwidth consumption when the camera is in free run mode, i.e., when it isn't triggered externally using software or hardware triggers.

Once you have this information, use the DeviceLinkThroughputLimitMode and DeviceLinkThroughputLimit parameters to specify sensible throughput limits for each camera. The sum of the throughputs of all cameras sharing the same link must not exceed the maximum throughput of the network adapter.

To achieve a specified limit, the camera inserts pauses between individual network packets. The lower the limit, the more numerous and longer the pauses will be. The transfer time for a complete frame and the associated latency, i.e., the time between generating the image and the data reaching the host's memory, increases in line with lowering the limit.

At a certain point, this will affect the frame rate you can achieve. Read the BslResultingAcquisitionFrameRate parameter to find out the maximum possible frame rate with the current camera settings.

Specifying a throughput limit is also referred to as assigning network bandwidth.

To limit the throughput:

1. Set the DeviceLinkThroughputLimitMode parameter to On.
2. Specify the desired DeviceLinkThroughputLimit parameter value.
3. Read the BslResultingAcquisitionFrameRate parameter to find out how the device link throughput limit affects the frame rate.

Bandwidth Reserve#

The streaming protocol is based on the UDP protocol. UDP does not guarantee that packets sent by the camera are received by the host.

Packets can be dropped by the host or by network devices between the camera and the host. The receiving software usually detects lost packets and sends appropriate requests to the camera to resend the data lost. A certain bandwidth reserve is kept available for these packets to be resent and for control traffic. If this reserve is used up, the camera can't resend requested packets anymore.

The bandwidth reserve is controlled by the GevSCBWR and GevSCBWRA parameters, which are described in the table below.

Available Parameters#