sync: migrate ai-operator to Gitea (2026-08-10)

internal/audio/g711.go

@@ -0,0 +1,54 @@
+package audio
+
+import "encoding/binary"
+
+const muLawBias = 0x84
+const muLawClip = 32635
+
+func EncodeULaw(pcm []byte) []byte {
+	out := make([]byte, len(pcm)/2)
+	for i := range out {
+		out[i] = LinearToULaw(int16(binary.LittleEndian.Uint16(pcm[i*2:])))
+	}
+	return out
+}
+
+func DecodeULaw(data []byte) []byte {
+	out := make([]byte, len(data)*2)
+	for i, sample := range data {
+		binary.LittleEndian.PutUint16(out[i*2:], uint16(ULawToLinear(sample)))
+	}
+	return out
+}
+
+func LinearToULaw(sample int16) byte {
+	pcm := int(sample)
+	sign := byte(0)
+	if pcm < 0 {
+		pcm = -pcm
+		sign = 0x80
+	}
+	if pcm > muLawClip {
+		pcm = muLawClip
+	}
+	pcm += muLawBias
+	exponent := 7
+	for mask := 0x4000; (pcm&mask) == 0 && exponent > 0; mask >>= 1 {
+		exponent--
+	}
+	mantissa := (pcm >> (exponent + 3)) & 0x0f
+	return ^(sign | byte(exponent<<4) | byte(mantissa))
+}
+
+func ULawToLinear(sample byte) int16 {
+	u := ^sample
+	sign := u & 0x80
+	exponent := (u >> 4) & 0x07
+	mantissa := u & 0x0f
+	pcm := ((int(mantissa) << 3) + muLawBias) << exponent
+	pcm -= muLawBias
+	if sign != 0 {
+		pcm = -pcm
+	}
+	return int16(pcm)
+}