How to calculate Mean Opinion Score (MOS) to measure the quality of WebRTC calls without knowing the Round Trip Time (RTT) of the inbound RTP stream?

Question

WebRTC inbound RTP stream (inbound-rtp) does not return Round Trip Time (RTT), but it is required to to calculate Mean Opinion Score (MOS). Any suggestions?

Is is safe to assume asymmetric latency and take the RTT for inbound-rtp same as RTT of corresponding outbound-rtp?

Sample inbound RTP stream

Answer 1

inbound-rtp doesn't, but candidate-pair from same report does

    pc.getReceivers()[1].getStats().then(res => {
      res.forEach(report=> {
        if (report.type === 'candidate-pair') {
          rtp = report.currentRoundTripTime;
        }
    });
});