Warning: this is far complete, and currently some of this text is just copied from the JT-NM RA Glossary, and would benefit from improvement.
In NMOS specs several common terms have specific meanings that you should be aware of. Many of these correspond to the glossary of the JT-NM Reference Architecture.
Several of these are formally defined in NMOS specs, but are described here for convenience.
A Device is a logical block of functionality within a networked media infrastructure. Example of Devices could include:
- SDI to IP adapter
- Chroma keyer
- Audio mixer
A Device may have a permanent presence on its Node (Fixed Device, e.g., a networked camera), or it may be created on demand by its Node (Virtual Device, e.g., a software-based transcoder). Nodes may dynamically create different types of Device (Dynamic Device).
In the IS-04 and IS-05 specifications a Flow refers to a sequence of video, audio or time-related data. This is a relatively high-level usage of the word, and should not be confused with a low-level flow within the physical network.
NMOS specifications use Grain as a convenient way of identifying a unit of video, audio or time-related data. This helps with mapping NMOS’s logical data model onto physical Specifications. For example a frame of video may correspond to a VideoGrain.
A Node is a logical host for Devices. This can be physical, or virtual (and a Node can be within a “cluster” or “cloud”).
A Receiver consumes a Flow from a Sender.
A Sender makes a Flow available on the network
A Source represents the logical primary origin of one or more Flows.
Note that (despite its name) a Source is:
- NOT a Device from which the content originates (for example there might be video, audio and perhaps data Sources associated with a camera, the camera itself is NOT a Source).
- NOT about the physical origin of the Flows (for example: two Flows associated with the same Source might physically originate from different hardware in distinct geographical locations)