Intelligent Roadway Information System

Flow Streams

A flow stream is a video stream which is not provided directly by a camera, but by a streambed server. They can be used to transcode from one video encoding to another, overlay text, or rebroadcast a unicast RTSP stream to a multicast address (with RTP).

Streambed can run on one or more dedicated computers, and is controlled by IRIS through the streambed protocol. A controller and associated comm link must exist for each streambed server. Each flow stream must be assigned to an IO pin on a streambed controller.


Select View ➔ Video ➔ Flow Streams menu item

To configure a flow stream, edit the first eight fields in the table. The source can be a camera or video monitor, but not both.

Field Description
Flow stream Flow stream name
Restricted Flag restricting flow to only published cameras
Location overlay Flag indicating whether camera location should be added
Quality Encoder stream quality
Camera Source Camera name
Monitor num Source Video monitor number
Address Sink address
Port Sink port

Camera Source

A camera can be used as the source of a flow stream. The camera field should be configured, but monitor num must be blank.

The camera’s encoder type must contain a stream with the same quality value, but with flow stream unchecked. That stream defines the source.

Camera Sink

With a camera source, the sink is normally defined by the camera’s encoder type. It must contain a stream with flow stream checked and a quality that matches the flow stream.

If the sink encoding is different than the source encoding, the flow stream will be transcoded. Warning: this requires more CPU time than simply rebroadcasting.

The camera sink uses RTP, sent to the camera’s multicast address with the stream’s multicast port.

Video Monitor Source

A video monitor can be used as a flow stream source — more precisely, what’s being displayed on that monitor. The monitor num field should be configured, but camera must be blank.

The source is defined by the current camera displayed on the specified monitor number. That camera’s encoder type must contain a stream with the same quality value. If multiple streams match, the one with flow stream checked is used.

Static Sink

For either type of source, if address and port are specified, they define a static sink, using RTP.

A static sink encoding is: