Switch source on silence

TABLE OF CONTENTS

• Overview
• Switch source on silence main functionality
• Additional notes and scenarios

Overview

Revma contains a loudness analysation mechanism in order to calculate the loudness of a stream. When a stream's loudness is lower than (<) -50 LUFS, we consider it to be streaming silence. When enabled to do so, Revma's silence detection mechanism will force a stream to switch its active source to the one not streaming silence (audible). This article will describe the 'switch source on silence' functionality, introduced to Revma in order to avoid silence for streams that utilise both primary and failover encoders.

Streaming silence is not be confused with stream disconnection.

Switch source on silence main functionality

The main idea of 'switch source on silence' is that a stream will not remain silent if the other encoder/source is streaming what we consider as audible content. In other words, the active source will automatically switch to the one that is audible.

This can be best described in the following basic and most common scenario:

A stream has two sources connected (primary & failover) and primary is active > both sources are streaming audible content > primary begins streaming silence (<-50 LUFS) > the active source will be switched to the failover.

With the same idea, more scenarios follow. For example:

A stream has two sources connected (primary & failover) and failover is active > both sources are streaming audible content > failover begins streaming silence (<-50 LUFS) > the active source will be switched to the primary.

Additional notes and scenarios

Along with the main idea of the 'switch source on silence' functionality, there are some additional things to take under consideration regarding this feature:

1. 'Switch source on silence' applies only for encoder source connections (primary & failover). A failover relay url will not "take over" if at least one encoder is connected, even if it streams silence. The failover relay url will only "take over" if all encoders have been disconnected.

Example scenario: A stream has primary source connected and active and a failover relay url added > primary source begins streaming silence (<-50 LUFS) > the primary source will remain active and no switch to the failover relay url will occur.

2. 'Persistence to failover source' is a functionality expected to affect how the 'Switch source on silence' will be experienced in some occasions. There are a few main facts to keep in mind in regards to this:

a. If there is a 'switch to primary time' set to >0, this will start counting from the time that the source (primary) is connected and not from the time it becomes audible. 

Example scenario: A stream has the failover source connected, audible and active > 'persistence to failover source' has been set to 'switch to primary after 10 minutes' > primary source connects and is streaming silence for 15 minutes b> primary source becomes audible > the primary source will become active without any additional delay, as the 10 minutes from its connection time have been completed.

b. 'Persistence to failover source' set to ≥0 will not force a switch if the active source is the failover and it is audible and the primary source is connected but silent. In other words, the otherwise expected switch to the primary source will not occur if it is streaming silence.

Example scenario: A stream has two sources connected (primary & failover) and failover is active > both sources are streaming audible content > primary begins streaming silence (<-50 LUFS) > 'persistence to failover source' is set to 'switch to primary after 10 minutes' and now these 10 minutes have past > the active source will not switch but remain to failover (which is audible).

c. 'Persistence to failover source' set to ≥0 will not force a switch if both sources are connected and streaming silence. In other words, when both sources are streaming silence the active source will always remain as is.

Example scenario: A stream has two sources connected (primary & failover) and failover is active > 'persistence to failover source' has been set to 'switch to primary after 0 minutes' > both sources begin streaming silence > the failover source will remain the active one.

3. The active source will remain the silent one for some time (approx. 1-2 minutes), before it is switched to the audible one. Therefore, a listener connected at the time that the active source starts streaming silence will audition some silence before being swapped to the audible source. This is expected and necessary for this functionality, as Revma requires this time to analyse and determine that a stream is indeed streaming silence.

By default switch on silence is active.
In case you would like it to be disabled, please contact RCS Revma support.