Use of QoS on Windows

Jamulus uses Quality of Service (QoS) to mitigate network jitter delays.

If you want to explore the effect of non-default settings, see RFC4594 pages 16-18. Jamulus sets the DS Field byte to 128 (or 0x80) to select DSCP/CS4 in an IPv4 or IPv6 packet header. Other byte values can be set using the -Q option, e.g. -Q [0..255]. However, most people will have no need to do this.

Jamulus’ QoS settings (including the default) are set to 0 on recent Windows and macOS because of the operating system. To use QoS on Windows, follow these instructions. Note that you may need to repeat this procedure every time Jamulus is updated.

In Search box beside Start menu, Type: Local Group Policy Editor (enter)
In new window, (click) on the menu icon to display the Actions third panel
Looking at the first panel of the Local Group Policy Editor
 Local Computer Policy
  Computer Configuration
   Windows Settings
    Policy-based QoS (click)
Looking at the third panel (Actions) of the Local Group Policy Editor
 Policy-based QoS
  More Actions
   Create new Policy (click)
    Policy Name: Jamulus
    Specify DSCP value: 32
    Next
    This QoS policy applies Only to applications with name Jamulus.exe
    Next
    Next
    UDP
    Finish

(Notice Jamulus policy in center panel may be edited)