143 lines
3.6 KiB
Go
143 lines
3.6 KiB
Go
package stt
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import (
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"context"
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"encoding/json"
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"fmt"
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"net/http"
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"net/url"
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"strings"
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"time"
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"github.com/gorilla/websocket"
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"go.uber.org/zap"
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)
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// DeepgramService 基于 Deepgram WebSocket API 的语音识别实现。
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type DeepgramService struct {
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apiKey string
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model string
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endpoint string
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timeout time.Duration
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logger *zap.SugaredLogger
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}
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// NewDeepgramService 创建 Deepgram STT 服务。
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// model、endpoint 由 config 层保证非空，timeoutSec 为 0 时默认 5 秒。
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func NewDeepgramService(apiKey, model, endpoint string, timeoutSec int, logger *zap.SugaredLogger) *DeepgramService {
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timeout := time.Duration(timeoutSec) * time.Second
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if timeout <= 0 {
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timeout = 5 * time.Second
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}
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return &DeepgramService{
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apiKey: apiKey,
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model: model,
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endpoint: endpoint,
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timeout: timeout,
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logger: logger,
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}
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}
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// deepgramResponse Deepgram WebSocket 响应。
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type deepgramResponse struct {
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Channel struct {
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Alternatives []struct {
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Transcript string `json:"transcript"`
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Confidence float64 `json:"confidence"`
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} `json:"alternatives"`
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} `json:"channel"`
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IsFinal bool `json:"is_final"`
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}
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// Recognize 实现 stt.Service。通过 WebSocket 发送音频到 Deepgram，返回最终识别文本。
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func (d *DeepgramService) Recognize(ctx context.Context, audio []byte, opts Options) (string, error) {
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if len(audio) == 0 {
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return "", fmt.Errorf("stt: empty audio")
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}
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// 构建 WebSocket URL，附带查询参数
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wsURL := d.buildURL(opts)
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// 总超时
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ctx, cancel := context.WithTimeout(ctx, d.timeout)
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defer cancel()
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// 建立 WebSocket 连接
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conn, _, err := websocket.DefaultDialer.DialContext(ctx, wsURL, http.Header{
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"Authorization": []string{"Token " + d.apiKey},
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})
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if err != nil {
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return "", fmt.Errorf("stt: connect deepgram: %w", err)
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}
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defer conn.Close()
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// 发送音频数据（一次性）
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if err := conn.WriteMessage(websocket.BinaryMessage, audio); err != nil {
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return "", fmt.Errorf("stt: send audio: %w", err)
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}
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// 发送 Close 消息通知服务端音频已发送完毕
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closeMsg := websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")
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_ = conn.WriteMessage(websocket.CloseMessage, closeMsg)
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// 读取识别结果
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var transcript strings.Builder
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for {
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_, message, err := conn.ReadMessage()
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if err != nil {
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// Close 帧是正常的结束信号
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if websocket.IsCloseError(err, websocket.CloseNormalClosure) {
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break
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}
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if websocket.IsUnexpectedCloseError(err, websocket.CloseNormalClosure) {
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break
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}
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return "", fmt.Errorf("stt: read response: %w", err)
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}
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var resp deepgramResponse
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if err := json.Unmarshal(message, &resp); err != nil {
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d.logger.Warnw("stt: unmarshal response failed", "error", err)
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continue
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}
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// 只累积 final 结果，跳过中间结果
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if resp.IsFinal && len(resp.Channel.Alternatives) > 0 {
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text := strings.TrimSpace(resp.Channel.Alternatives[0].Transcript)
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if text != "" {
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transcript.WriteString(text)
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}
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}
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}
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return strings.TrimSpace(transcript.String()), nil
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}
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// buildURL 构建 Deepgram WebSocket URL，包含音频格式参数。
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func (d *DeepgramService) buildURL(opts Options) string {
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u, _ := url.Parse(d.endpoint)
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encoding := opts.Encoding
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if encoding == "" {
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encoding = "pcm_s16le"
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}
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sampleRate := opts.SampleRate
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if sampleRate == 0 {
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sampleRate = 16000
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}
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language := opts.Language
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if language == "" {
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language = "zh-CN"
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}
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q := u.Query()
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q.Set("encoding", encoding)
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q.Set("sample_rate", fmt.Sprintf("%d", sampleRate))
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q.Set("language", language)
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q.Set("model", d.model)
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q.Set("punctuate", "true")
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u.RawQuery = q.Encode()
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return u.String()
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}
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