Reporting of media statistics and perceived call quality
When using the Administrator interface to look at the current and historic status of calls and of individual participants within a call, various media statistics and guidance as to perceived call quality are displayed.
The current and historic participant status screens provide guidance to the perceived quality of a call by looking at packet loss and jitter over multiple time windows.
For an ongoing call, the system looks at packet loss and jitter over the 3 most recent 20 second time windows. To calculate call quality for a time window, packet loss is assessed first: < 1% packet loss is perceived as Good quality; < 3% is OK; < 10% is Bad; otherwise it is Terrible. Then, if jitter is > 40ms the call quality assessment based on packet loss is adjusted to the next level down (e.g. OK is reduced to Bad).
The system then reports the current call quality as the most frequent call quality in those last 3 windows. If all time windows report a different quality, then any of the three qualities may be indicated.
For completed calls, the system looks at packet loss and jitter over multiple 20 second time windows throughout the call and calculates the call quality per window. It then reports the overall call quality as the average call quality of those windows.
The system also provides a graphical representation of the participant's call quality over the duration of the call.
A blue line at the top of the graph indicates Good, down to a red line at the bottom which indicates Terrible. The percentage number indicates the amount of the call where the quality is perceived as Good or OK (above the line in blue). For example:
Note that a call quality of Unknown is reported for all calls of less than 20 seconds duration, and all calls over RTMP (of more than 20 seconds duration) always report a call quality of 100% Good, as they are placed over TCP.
The Administrator interface uses color coding when reporting media statistics, such as perceived call quality, packet loss and jitter. In general, statistics that are shown in green text represent good quality, orange represents intermediate quality, and red is used for bad quality.
- Perceived call quality is calculated as described above and is shown in green if the quality is Good or OK, or in red if the quality is Bad or Terrible.
- Packet loss is shown in green when it is < 0.2%, in orange when it is between 0.2% and 2%, and in red when it is >= 2%.
- Jitter is shown in green when it is < 10ms, in orange when it is 10–50ms, and in red when it is >= 50ms.