HOME Delay - Basic Functionality

Inherent Delay (App Latency)

Signals passing through a HOME Delay Inserter are subject to a delay due to the need to process the signals, this is known as latency. Even when there is no delay processing enabled, the signals are subject to a delay, due to the need to receiver and send the signals.

• The inherent delay through the Delay Inserter is 2 fields (interlaced sources) or 2 frames (progressive sources).

Min. and Max. Delay

The inherent delay means that the video stream passing through the app will have a minimum delay of 2 fields (interlaced formats) or 2 frames (progressive formats). An additional delay can then be added of up to 360 fields / frames. Thus, the maximum video delay that can be applied is 362 fields / frames.

By default, when a delay is applied to the video, the audio and meta streams are delayed by the same amount. Audio and/or meta streams can then be offset to the video if required. This offset can be either a positive or negative value.

• If the audio and meta streams have a offset delay of zero (0), they will be delayed by the same duration as the video stream.
• A positive value will add additional delay (stream arrives later) compared to the video stream.
• A negative value will reduce the delay (stream arrives earlier) compared to the video stream.

The table below shows the minimum and maximum delay values. For simplicity, the timings in milliseconds (ms) are rounded to 1 decimal place.

Configuration

To use the Delay Inserter, there are two steps: first, define the maximum additional delay supported by the app; then, once the app is running, set the amount of additional delay (up to the maximum additional delay value).

Initial Configuration

As part of the app configuration, the user is asked to configure a Maximum Additional Delay value, up to 360 Fields / Frames. This sets the maximum additional delay supported by the app which, in turn, defines the amount of App Server memory used to buffer the app's incoming sources (once the app is running).

By setting the maximum additional delay to a lower value, the user can limit the amount of App Server memory reserved by the app. This can be advantageous as, when the user attempts to start the app, the system presents only App Servers with enough available resources and, if a maximum additional delay is specified, then this will include an amount of free memory.

Note that the Maximum Additional Delay control cannot be modified whilst the app is running. If you need to change this value later, then you will need to stop the app and edit the app configuration.