Standards: GenDC
@imveurope
www.imveurope.com
Decoupling what to transport fromhow to transport it
Stéphane Maurice, GenICam vice chair and director of soſtware development at Matrox Imaging, describes the benefits of GenDC, the latest member of the GenICam standard family
S
tanding for generic data container, GenDC defines a transport media- independent data description that
allows devices to send or receive almost any form of imaging data to and from a host system, using a uniform and standard data description. GenDC completes the GenICam (generic interface for cameras) family of modules that control and exchange data between imaging de vices. GenDC defines a generic and self-
described imaging data container that is independent of the way it is transported or stored. It also defines standard mechanisms shared by the various transport layer (TL) protocols in camera interface standards – such as GigE Vision, USB3 Vision, CoaXPress, and others – to transport it. As a result, a TL needs only to define how to transport the data container, without needing to know the content or format of the data container. Tis separation allows the addition of data types to the GenDC standard without requiring modifications to individual TL specifications. All TL protocols implemented by common machine vision camera interface standards will support GenDC; each of them already has a proposal on how to handle it. A quick and general adoption of GenDC is therefore expected. Tis can be attributed in good part to the common standardisation efforts in the machine vision industry around the globe.
Why GenDC? Similar to other machine vision standardisation projects, the main objectives of GenDC are to avoid work duplication, simplify common tasks, and establish a common definition between various
GenDC modular model decoupling data encoding or decoding from its transmission
manufacturers. All types of cameras and devices can use GenDC as an opaque and portable data blob – a chunk of binary data – that describes the images or data to transport or process. Tis makes porting an imaging device from one transport medium to another a very simple task, as the data description and encoding is always the same and can be done in a shared section separate from the transmission protocol implementation. Accordingly, on the reception side, the common data description format of GenDC decouples the data reception from the data interpretation, making the design of a receiver modular, simple and uniform. Today, most TLs – which are part of the existing camera interface standards – support
32 Imaging and Machine Vision Europe • Yearbook 2019/2020
only basic 2D images, monochrome and packed colour. However, these TLs are all looking to support new, more complex data payload types such as planar colour images, compressed data, 3D data, multi-spectral images, metadata and processing results. Up until now, for every new payload type, each TL standard technical committee independently had to address the way those new payloads are to be formatted and transmitted. Moreover, these technical committees have had to release new versions of their respective TL specification to accommodate those new payload types. It could take several years to have a particular new payload type supported across all the TLs. Manufacturers of transmitter and
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