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

internal/audio/pcm16.go

@@ -0,0 +1,79 @@
+package audio
+
+import (
+	"encoding/base64"
+	"encoding/binary"
+	"errors"
+	"math"
+	"time"
+)
+
+func IsPCM16Aligned(data []byte) bool       { return len(data)%2 == 0 }
+func Base64Encode(data []byte) string       { return base64.StdEncoding.EncodeToString(data) }
+func Base64Decode(s string) ([]byte, error) { return base64.StdEncoding.DecodeString(s) }
+func ChunkBytes(data []byte, max int) [][]byte {
+	if max <= 0 || len(data) == 0 {
+		return nil
+	}
+	out := [][]byte{}
+	for len(data) > 0 {
+		n := max
+		if len(data) < n {
+			n = len(data)
+		}
+		cp := append([]byte(nil), data[:n]...)
+		out = append(out, cp)
+		data = data[n:]
+	}
+	return out
+}
+func ChunkPCM16ByDuration(data []byte, rate int, dur time.Duration) [][]byte {
+	if rate <= 0 || dur <= 0 {
+		return nil
+	}
+	bytes := int(dur.Seconds()*float64(rate)) * 2
+	if bytes < 2 {
+		bytes = 2
+	}
+	return ChunkBytes(data, bytes)
+}
+func ResamplePCM16MonoLinear(data []byte, fromRate, toRate int) ([]byte, error) {
+	if len(data) == 0 {
+		return nil, nil
+	}
+	if len(data)%2 != 0 {
+		return nil, errors.New("pcm16 data is not 2-byte aligned")
+	}
+	if fromRate <= 0 || toRate <= 0 {
+		return nil, errors.New("sample rates must be positive")
+	}
+	if fromRate == toRate {
+		return append([]byte(nil), data...), nil
+	}
+	inN := len(data) / 2
+	outN := int(math.Round(float64(inN) * float64(toRate) / float64(fromRate)))
+	if outN < 1 {
+		outN = 1
+	}
+	out := make([]byte, outN*2)
+	for i := 0; i < outN; i++ {
+		pos := float64(i) * float64(fromRate) / float64(toRate)
+		idx := int(math.Floor(pos))
+		frac := pos - float64(idx)
+		if idx >= inN-1 {
+			binary.LittleEndian.PutUint16(out[i*2:], binary.LittleEndian.Uint16(data[(inN-1)*2:]))
+			continue
+		}
+		a := int16(binary.LittleEndian.Uint16(data[idx*2:]))
+		b := int16(binary.LittleEndian.Uint16(data[(idx+1)*2:]))
+		v := float64(a) + (float64(b)-float64(a))*frac
+		if v > math.MaxInt16 {
+			v = math.MaxInt16
+		}
+		if v < math.MinInt16 {
+			v = math.MinInt16
+		}
+		binary.LittleEndian.PutUint16(out[i*2:], uint16(int16(math.Round(v))))
+	}
+	return out, nil
+}