Showing posts from September, 2016

Bandwidth usage for USB cameras: ZED tests under Linux

Robotics and Computer Vision applications are taking advance of a range USB3 cameras that are characterised by large resolution, high-frame rate and low-latency. Examples of such cameras we worked with are the StereoLabs ZED that provides a side-by-side low-latency stereo image, or monocular PointGrey cameras.

These cameras belong to the USB Video Class that has, since long time, reduced the need of specific drivers. A typical challenge in the use of this camera is the management of USB bandwidth in particular when multiple cameras have to be integrated over a same computer.

The theoretical bandwidth of USB3 is 5 Gbps but then it is known that the effective bulk transfer bandwidth is 440MB/s. In addition to this there are issues of protocol overhead that affect the use of a given resolution and rate selection.

When using multiple cameras there are also limitations in the chipset used in the motherboard. Some chipset have one single USB3 bus shared among multiple ports, instead, if an…