namandClaude Opus 5.5
de7ed62d96
The cohost sounded jittery on the 2026-11-03 show. v1 skipped ahead on an underrun and kept playing from an empty buffer, so after the first hiccup every later wobble was another glitch. It also never corrected a slow guest clock: ~12 glitches/min in simulation at 30 ppm slow. - Underrun: hold the sequence position and refill to a larger target - Drift correction both ways (drop/insert a frame in quiet moments), quiet judged relative to the guest's own noise floor - 80 ms start, 300 ms max, relaxes after 2 calm minutes - Log 'rx 1m:' stats, the selected route, and call totals - Ping the guest websocket every 25 s (the proxy closed it every 90 s) - Simulation kept in test/jb_sim_test.go.txt Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
87 lines
3.6 KiB
Plaintext
87 lines
3.6 KiB
Plaintext
package main
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import (
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"fmt"
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"math"
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"math/rand"
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"sort"
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"testing"
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"github.com/pion/rtp"
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"gopkg.in/hraban/opus.v2"
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)
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// Simulate: sender emits a packet every 20ms*(1+ppm) of its clock; network adds jitter;
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// playout pulls one frame every 20ms of MOTU clock. Count audible damage over 3 hours.
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func sim(t *testing.T, name string, noiseFloor float64, ppm float64, jitterMs func(r *rand.Rand) float64) {
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enc, _ := opus.NewEncoder(rate, channels, opus.AppAudio)
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nr := rand.New(rand.NewSource(7))
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mk := func(i int, talk bool) []byte {
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pcm := make([]int16, frameSamps*channels)
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for k := range pcm {
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n := nr.NormFloat64() * noiseFloor * 32768
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v := n
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if talk { v += 8000 * math.Sin(float64(i*frameSamps+k/2)*2*math.Pi*220/rate) * (0.5 + 0.5*math.Sin(float64(i)*0.9)) }
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pcm[k] = int16(v)
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}
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buf := make([]byte, 4000); n, _ := enc.Encode(pcm, buf); return append([]byte(nil), buf[:n]...)
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}
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var talkP, quietP [][]byte
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for i := 0; i < 50; i++ { talkP = append(talkP, mk(i, true)); quietP = append(quietP, mk(i, false)) }
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payloadFor := func(seq int) []byte { if seq%175 < 125 { return talkP[seq%50] }; return quietP[seq%50] }
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dec, _ := opus.NewDecoder(rate, channels)
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jb := newJitterBuffer(dec)
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r := rand.New(rand.NewSource(1))
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const dur = 3 * 3600 * 1000.0
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type ev struct{ at float64; seq uint16 }
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var arr []ev
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period := 20.0 * (1 + ppm*1e-6)
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for i := 0; float64(i)*period < dur; i++ {
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arr = append(arr, ev{float64(i)*period + 50 + jitterMs(r), uint16(i)})
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}
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sort.Slice(arr, func(a, b int) bool { return arr[a].at < arr[b].at })
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k := 0
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depthSum, frames, nearEmpty := 0, 0, 0
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for tms := 0.0; tms < dur; tms += 20 {
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for k < len(arr) && arr[k].at <= tms { jb.push(&rtp.Packet{Header: rtp.Header{SequenceNumber: arr[k].seq}, Payload: payloadFor(int(arr[k].seq) + 65536*0)}); k++ }
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jb.next()
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d := len(jb.pkts); depthSum += d; frames++
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if d == 0 { nearEmpty++ }
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}
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s := jb.stats()
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bad := s["plc"].(int) + s["fec"].(int) + s["dropped"].(int)
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fmt.Printf("%-34s glitches(PLC+FEC)=%5d (~%.1f/min) underruns=%4d late-discarded=%5d drops=%4d inserted=%4d avg depth=%.0fms empty %.0f%% of time final target=%v\n",
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name, bad, float64(bad)/180, s["underruns"], s["late"], s["dropped"], s["inserted"], float64(depthSum)/float64(frames)*20, 100*float64(nearEmpty)/float64(frames), s["targetMs"])
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}
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func TestSim(t *testing.T) {
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for _, nf := range []float64{0.0005, 0.006} {
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fmt.Printf("--- pauses at %.0f dBFS noise floor\n", 20*math.Log10(nf))
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gauss := func(sd float64) func(*rand.Rand) float64 { return func(r *rand.Rand) float64 { return math.Abs(r.NormFloat64() * sd) } }
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spiky := func(r *rand.Rand) float64 { // typical home Wi-Fi: small jitter + occasional 80-200ms stalls
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j := math.Abs(r.NormFloat64() * 4)
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if r.Float64() < 0.002 { j += 80 + r.Float64()*120 }
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return j
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}
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sim(t, "clean net, no drift", nf, 0, gauss(0.5))
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sim(t, "5ms jitter, no drift", nf, 0, gauss(5))
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sim(t, "5ms jitter, guest clock 30ppm FAST", nf, -30, gauss(5))
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sim(t, "5ms jitter, guest clock 30ppm SLOW", nf, 30, gauss(5))
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sim(t, "Wi-Fi-ish spikes, no drift", nf, 0, spiky)
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sim(t, "Wi-Fi-ish spikes, guest 30ppm SLOW", nf, 30, spiky)
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// correlated stall: every packet in a 150 ms window is held until the window ends
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burst := func() func(*rand.Rand) float64 {
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i, until := 0, -1.0
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return func(r *rand.Rand) float64 {
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now := float64(i) * 20; i++
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if now > until && r.Float64() < 0.0005 { until = now + 150 }
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j := math.Abs(r.NormFloat64() * 3)
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if now <= until { j += until - now }
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return j
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}
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}
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sim(t, "burst stalls 150ms, no drift", nf, 0, burst())
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sim(t, "burst stalls 150ms, guest SLOW", nf, 30, burst())
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}
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}
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