Glossary

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• Device
• Flow
• Grain
• Node
• Receiver
• Sender
• Source

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 RA.

Several of these are formally defined in NMOS specs, but are described here for convenience.

Device

A Device is a logical block of functionality within a networked media infrastructure. Example of Devices could include:

• Camera
• 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).

Flow

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.

Grain

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.

Node

A Node is a logical host for Devices. This can be physical, or virtual (and a Node can be within a "cluster" or "cloud").

Receiver

A Receiver consumes a Flow from a Sender.

Sender

A Sender makes a Flow available on the network

Source

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)