Audio

2026-09-02 01:00:09 +03:00
parent 166744fe88
commit eaa46e7494
17 changed files with 1351 additions and 0 deletions
@@ -0,0 +1,61 @@
+package mic
+
+import (
+	"encoding/binary"
+	"errors"
+)
+
+const (
+	SampleRate     = 16000
+	Channels       = 1
+	BitsPerSample  = 16
+	BytesPerSample = BitsPerSample / 8 * Channels
+)
+
+var wavHeaderSize = 44
+
+// EncodeWAV wraps 16-bit mono PCM in a complete WAV file.
+func EncodeWAV(pcm []byte) []byte {
+	if len(pcm) == 0 {
+		return nil
+	}
+	if len(pcm)%BytesPerSample != 0 {
+		pcm = pcm[:len(pcm)-len(pcm)%BytesPerSample]
+	}
+	out := make([]byte, wavHeaderSize+len(pcm))
+	writeWAVHeader(out, len(pcm))
+	copy(out[wavHeaderSize:], pcm)
+	return out
+}
+
+func writeWAVHeader(buf []byte, dataLen int) {
+	if len(buf) < wavHeaderSize {
+		return
+	}
+	copy(buf[0:4], "RIFF")
+	binary.LittleEndian.PutUint32(buf[4:8], uint32(36+dataLen))
+	copy(buf[8:12], "WAVE")
+	copy(buf[12:16], "fmt ")
+	binary.LittleEndian.PutUint32(buf[16:20], 16)
+	binary.LittleEndian.PutUint16(buf[20:22], 1) // PCM
+	binary.LittleEndian.PutUint16(buf[22:24], Channels)
+	binary.LittleEndian.PutUint32(buf[24:28], SampleRate)
+	byteRate := SampleRate * Channels * BytesPerSample
+	binary.LittleEndian.PutUint32(buf[28:32], uint32(byteRate))
+	binary.LittleEndian.PutUint16(buf[32:34], uint16(Channels*BytesPerSample))
+	binary.LittleEndian.PutUint16(buf[34:36], BitsPerSample)
+	copy(buf[36:40], "data")
+	binary.LittleEndian.PutUint32(buf[40:44], uint32(dataLen))
+}
+
+// PCMBytesFromWAV returns PCM payload length implied by a WAV header.
+func PCMBytesFromWAV(hdr []byte) (int, error) {
+	if len(hdr) < wavHeaderSize {
+		return 0, errors.New("wav header too short")
+	}
+	if string(hdr[0:4]) != "RIFF" || string(hdr[8:12]) != "WAVE" {
+		return 0, errors.New("not a wav file")
+	}
+	dataLen := int(binary.LittleEndian.Uint32(hdr[40:44]))
+	return dataLen, nil
+}