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testRTC test score

We’ve introduced a scoring/ranking system for test results. This should make it easier to understand the quality of different test and monitor runs by briefly reviewing the score value provided to them.

The WebRTC score that testRTC takes into account the main quality metrics that affect voice and video quality. That includes bitrate, packet loss, jitter and delay. It looks at their values as well as their variance over time.

What is the testRTC quality score?

The scoring mechanism looks at the various quality metrics collected by testRTC during a test run, giving a composite value to measure the quality of the WebRTC session.

What criteria are considered in giving scores?

Scoring looks at different media-related metrics. It specifically checks the bitrate, resolution, and delay, taking into consideration their values and stability over time. The quality score calculation looks at both audio and video.

What is considered a good score value?

That depends a lot on your scenario. Since there is a large variety of use cases, we decided not to go on a static 1-5 score values. This would give the wrong impression. This is why our scale gives a value of 0-10.
The way to use quality score values is by looking at the values across tests and monitor runs. The higher the score – the better the metrics. If you run a monitor for a long period of time, you can see how its media quality behaves over time by checking the quality score. If you run a stress test, you can see how the quality score is affected as you add more and more probes to the test runs.

What is the optimum bitrate considered for scoring?

For audio (Opus) we consider 40 kbps as optimal and for video 1.5 Mbps as a optimum. That said, there are no optimal values besides the one you consider as optimal.

What is the optimum resolution considered for scoring?

The minimum resolution for an optimal score is 1280×720.

Is bitrate stability considered for scoring?

Yes, variation in bitrate during the course of the test inversely affects the scoring. The more stable the bitrate the better the score will be.

How is score computed for large video group calls?

The scoring algorithm gives a score for each individual channel and in the end averages between the score of all channels. This means that you should expect lower score values for large groups, since each channel individually will probably be scored lower (due to is lower bitrate and resolution values).

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