cmd/mavwaked/wakeword.go

@@ -0,0 +1,191 @@
+package main
+
+// The wake word, "Мэйвен" (V-487 stage two).
+//
+// Silero answers "is this frame speech". It does not answer "was this said to
+// her", and until this file existed nothing did: every utterance near the
+// microphone became a turn. What made that safe rather than expensive was
+// SurfaceVoice capping acts at L0, and L0 does not cap reading, so the room
+// could still hear his facts read back.
+//
+// This file owns the 80ms cadence and the three rings of state between the
+// models. wakefeatures.go owns the tensors.
+//
+// Nil is a working value, and it is the CLOSED gate rather than the open one.
+// Feed on a nil receiver reports no keyword; session.go asks separately
+// whether a gate exists at all. That split is deliberate: a nil that answers
+// "yes, keyword" reads as a working wake word in every log line it produces.
+
+import (
+	"log"
+	"sync"
+)
+
+// defaultWakeThreshold — score above which the keyword was said. Picked from
+// the false-accept rate on held-out Russian speech, not from accuracy: a miss
+// costs him a repeat, a false accept costs a turn nobody asked for. See
+// docs/evals for the wakes-per-hour this buys.
+const defaultWakeThreshold = 0.99
+
+// wakeWord is the streaming state around wakeModels. It is fed the same
+// capture frames the VAD sees and answers whether the keyword has just been
+// spoken.
+type wakeWord struct {
+	mu sync.Mutex
+	m  *wakeModels
+
+	threshold float64
+
+	// pending holds captured samples not yet part of a full 80ms chunk, and
+	// history holds the melContext samples before them.
+	pending []float32
+	history []float32
+
+	// mels is the newest embedFrames mel frames, oldest first.
+	mels [][melBins]float32
+	// embeds is the newest headWindow embeddings, oldest first.
+	embeds [][embedDim]float32
+
+	last float64 // most recent score, held between chunks
+}
+
+// newWakeWord loads the models and wraps them in the streaming gate.
+func newWakeWord(melPath, embedPath, headPath, libPath string, threshold float64) (*wakeWord, error) {
+	m, err := newWakeModels(melPath, embedPath, headPath, libPath)
+	if err != nil {
+		return nil, err
+	}
+	if threshold <= 0 {
+		threshold = defaultWakeThreshold
+	}
+	return &wakeWord{m: m, threshold: threshold}, nil
+}
+
+// Close releases the models.
+func (w *wakeWord) Close() {
+	if w == nil {
+		return
+	}
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	w.m.Close()
+	w.m = nil
+}
+
+// Feed takes one capture frame and reports whether the keyword was heard on
+// it. A nil wakeWord hears nothing.
+func (w *wakeWord) Feed(frame []int16) bool {
+	if w == nil {
+		return false
+	}
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	for _, v := range frame {
+		w.pending = append(w.pending, float32(v)/32768.0)
+	}
+	fired := false
+	for len(w.pending) >= chunkSamples {
+		chunk := w.pending[:chunkSamples]
+		if w.step(chunk) {
+			fired = true
+		}
+		w.history = append(w.history[:0], tailFloat32(append(w.history, chunk...), melContext)...)
+		// Slide the remainder to the front rather than reslicing. This runs
+		// every 80ms for as long as the daemon lives.
+		w.pending = append(w.pending[:0], w.pending[chunkSamples:]...)
+	}
+	return fired
+}
+
+// Reset drops the streaming state, so a fresh utterance is not judged on audio
+// from before it. Called after every dispatch and after barge-in, for the same
+// reason silero is: echo-era history must not score the next sentence, and her
+// own voice saying the keyword must not wake her.
+func (w *wakeWord) Reset() {
+	if w == nil {
+		return
+	}
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	w.pending, w.history = w.pending[:0], w.history[:0]
+	w.mels, w.embeds = nil, nil
+	w.last = 0
+}
+
+// Score returns the most recent score, for the operator to read out of the
+// journal when picking a threshold for his room.
+func (w *wakeWord) Score() float64 {
+	if w == nil {
+		return 0
+	}
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	return w.last
+}
+
+// step runs one 80ms chunk through all three models. It returns true when the
+// score crosses the threshold on this chunk.
+func (w *wakeWord) step(chunk []float32) bool {
+	buf := make([]float32, 0, melContext+len(chunk))
+	if pad := melContext - len(w.history); pad > 0 {
+		buf = append(buf, make([]float32, pad)...)
+	}
+	buf = append(buf, tailFloat32(w.history, melContext)...)
+	buf = append(buf, chunk...)
+
+	frames, err := w.m.melFrames(buf)
+	if err != nil {
+		// A failed inference must not silence the microphone. Hold the last
+		// score and let the next chunk try again.
+		log.Printf("mavwaked: wake word: mel: %v", err)
+		return false
+	}
+	w.mels = tailMel(append(w.mels, frames...), embedFrames)
+	if len(w.mels) < embedFrames {
+		return false
+	}
+	e, err := w.m.embedding(w.mels)
+	if err != nil {
+		log.Printf("mavwaked: wake word: embedding: %v", err)
+		return false
+	}
+	w.embeds = tailEmbed(append(w.embeds, e), headWindow)
+	if len(w.embeds) < headWindow {
+		return false
+	}
+	score, err := w.m.score(w.embeds)
+	if err != nil {
+		log.Printf("mavwaked: wake word: head: %v", err)
+		return false
+	}
+	// Report the crossing, not the state. A keyword held above the threshold
+	// for a second is one wake, and firing on every chunk of it would make the
+	// gate look open when it is merely slow to fall.
+	crossed := score >= w.threshold && w.last < w.threshold
+	w.last = score
+	return crossed
+}
+
+// The three rings. Each keeps the newest n entries and nothing older.
+
+func tailFloat32(s []float32, n int) []float32 {
+	if len(s) <= n {
+		return s
+	}
+	return s[len(s)-n:]
+}
+
+func tailMel(s [][melBins]float32, n int) [][melBins]float32 {
+	if len(s) <= n {
+		return s
+	}
+	return append(s[:0], s[len(s)-n:]...)
+}
+
+func tailEmbed(s [][embedDim]float32, n int) [][embedDim]float32 {
+	if len(s) <= n {
+		return s
+	}
+	return append(s[:0], s[len(s)-n:]...)
+}