Network quality & getStats

1type Sample = {
2  at: number;
3  inboundBytes: number;
4  outboundBytes: number;
5  packetsLost: number;
6  packetsReceived: number;
7  jitterMs: number | null;
8  rttMs: number | null;
9  relayed: boolean;
10  bitrateIn: number;
11  bitrateOut: number;
12};
13
14export async function collectSample(pc: RTCPeerConnection, previous: Sample | null): Promise<Sample> {
15  const report = await pc.getStats();
16  const now = performance.now();
17  let inboundBytes = 0, outboundBytes = 0;
18  let packetsLost = 0, packetsReceived = 0, jitterMs: number | null = null;
19  let pairId: string | undefined;
20
21  report.forEach((stat) => {
22    if (stat.type === "inbound-rtp") {
23      inboundBytes += stat.bytesReceived ?? 0;
24      packetsLost += stat.packetsLost ?? 0;
25      packetsReceived += stat.packetsReceived ?? 0;
26      if (typeof stat.jitter === "number") jitterMs = stat.jitter * 1000;
27    }
28    if (stat.type === "outbound-rtp") outboundBytes += stat.bytesSent ?? 0;
29    if (stat.type === "transport") pairId = stat.selectedCandidatePairId;
30  });
31
32  const pair = pairId ? report.get(pairId) : undefined;
33  const local = pair ? report.get(pair.localCandidateId) : undefined;
34  const remote = pair ? report.get(pair.remoteCandidateId) : undefined;
35  const elapsed = previous ? Math.max(0.25, (now - previous.at) / 1000) : 0;
36
37  return {
38    at: now,
39    inboundBytes,
40    outboundBytes,
41    packetsLost,
42    packetsReceived,
43    jitterMs,
44    rttMs: pair?.currentRoundTripTime ? pair.currentRoundTripTime * 1000 : null,
45    relayed: local?.candidateType === "relay" || remote?.candidateType === "relay",
46    bitrateIn: elapsed ? Math.max(0, (inboundBytes - (previous?.inboundBytes ?? inboundBytes)) * 8 / elapsed) : 0,
47    bitrateOut: elapsed ? Math.max(0, (outboundBytes - (previous?.outboundBytes ?? outboundBytes)) * 8 / elapsed) : 0,
48  };
49}
50
51export function qualityState(sample: Sample) {
52  if (sample.rttMs === null) return "connecting";
53  const loss = sample.packetsReceived + sample.packetsLost > 0
54    ? sample.packetsLost / (sample.packetsReceived + sample.packetsLost)
55    : 0;
56  if (sample.rttMs > 400 || loss > 0.08) return "poor";
57  if (sample.rttMs > 200 || loss > 0.02 || (sample.jitterMs ?? 0) > 60) return "degraded";
58  return "good";
59}