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package extra
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"io"
"log/slog"
"mime/multipart"
"net/http"
"regexp"
"strings"
"github.com/gordonklaus/portaudio"
)
var specialRE = regexp.MustCompile(`\[.*?\]`)
type STT interface {
StartRecording() error
StopRecording() (string, error)
IsRecording() bool
}
type StreamCloser interface {
Close() error
}
type WhisperSTT struct {
logger *slog.Logger
ServerURL string
SampleRate int
AudioBuffer *bytes.Buffer
recording bool
}
func NewWhisperSTT(logger *slog.Logger, serverURL string, sampleRate int) *WhisperSTT {
return &WhisperSTT{
logger: logger,
ServerURL: serverURL,
SampleRate: sampleRate,
AudioBuffer: new(bytes.Buffer),
}
}
func (stt *WhisperSTT) StartRecording() error {
if err := stt.microphoneStream(stt.SampleRate); err != nil {
return fmt.Errorf("failed to init microphone: %w", err)
}
stt.recording = true
return nil
}
func (stt *WhisperSTT) StopRecording() (string, error) {
stt.recording = false
// wait loop to finish?
if stt.AudioBuffer == nil {
err := errors.New("unexpected nil AudioBuffer")
stt.logger.Error(err.Error())
return "", err
}
// Create WAV header first
body := &bytes.Buffer{}
writer := multipart.NewWriter(body)
// Add audio file part
part, err := writer.CreateFormFile("file", "recording.wav")
if err != nil {
stt.logger.Error("fn: StopRecording", "error", err)
return "", err
}
// Stream directly to multipart writer: header + raw data
dataSize := stt.AudioBuffer.Len()
stt.writeWavHeader(part, dataSize)
if _, err := io.Copy(part, stt.AudioBuffer); err != nil {
stt.logger.Error("fn: StopRecording", "error", err)
return "", err
}
// Reset buffer for next recording
stt.AudioBuffer.Reset()
// Add response format field
err = writer.WriteField("response_format", "text")
if err != nil {
stt.logger.Error("fn: StopRecording", "error", err)
return "", err
}
if writer.Close() != nil {
stt.logger.Error("fn: StopRecording", "error", err)
return "", err
}
// Send request
resp, err := http.Post(stt.ServerURL, writer.FormDataContentType(), body) //nolint:noctx
if err != nil {
stt.logger.Error("fn: StopRecording", "error", err)
return "", err
}
defer resp.Body.Close()
// Read and print response
responseTextBytes, err := io.ReadAll(resp.Body)
if err != nil {
stt.logger.Error("fn: StopRecording", "error", err)
return "", err
}
resptext := strings.TrimRight(string(responseTextBytes), "\n")
// in case there are special tokens like [_BEG_]
resptext = specialRE.ReplaceAllString(resptext, "")
return strings.TrimSpace(strings.ReplaceAll(resptext, "\n ", "\n")), nil
}
func (stt *WhisperSTT) writeWavHeader(w io.Writer, dataSize int) {
header := make([]byte, 44)
copy(header[0:4], "RIFF")
binary.LittleEndian.PutUint32(header[4:8], uint32(36+dataSize))
copy(header[8:12], "WAVE")
copy(header[12:16], "fmt ")
binary.LittleEndian.PutUint32(header[16:20], 16)
binary.LittleEndian.PutUint16(header[20:22], 1)
binary.LittleEndian.PutUint16(header[22:24], 1)
binary.LittleEndian.PutUint32(header[24:28], uint32(stt.SampleRate))
binary.LittleEndian.PutUint32(header[28:32], uint32(stt.SampleRate)*1*(16/8))
binary.LittleEndian.PutUint16(header[32:34], 1*(16/8))
binary.LittleEndian.PutUint16(header[34:36], 16)
copy(header[36:40], "data")
binary.LittleEndian.PutUint32(header[40:44], uint32(dataSize))
if _, err := w.Write(header); err != nil {
stt.logger.Error("writeWavHeader", "error", err)
}
}
func (stt *WhisperSTT) IsRecording() bool {
return stt.recording
}
func (stt *WhisperSTT) microphoneStream(sampleRate int) error {
if err := portaudio.Initialize(); err != nil {
return fmt.Errorf("portaudio init failed: %w", err)
}
in := make([]int16, 64)
stream, err := portaudio.OpenDefaultStream(1, 0, float64(sampleRate), len(in), in)
if err != nil {
if paErr := portaudio.Terminate(); paErr != nil {
return fmt.Errorf("failed to open microphone: %w; terminate error: %w", err, paErr)
}
return fmt.Errorf("failed to open microphone: %w", err)
}
go func(stream *portaudio.Stream) {
if err := stream.Start(); err != nil {
stt.logger.Error("microphoneStream", "error", err)
return
}
for {
if !stt.IsRecording() {
return
}
if err := stream.Read(); err != nil {
stt.logger.Error("reading stream", "error", err)
return
}
if err := binary.Write(stt.AudioBuffer, binary.LittleEndian, in); err != nil {
stt.logger.Error("writing to buffer", "error", err)
return
}
}
}(stream)
return nil
}
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