95 lines
2.5 KiB
Go
95 lines
2.5 KiB
Go
package transcriber
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import (
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"bytes"
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"context"
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"encoding/binary"
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"fmt"
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"log"
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"time"
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"github.com/sashabaranov/go-openai"
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)
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// OpenAIAdapter implements TranscriptionAdapter for OpenAI Whisper API
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type OpenAIAdapter struct {
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client *openai.Client
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config Config
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}
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func NewOpenAIAdapter(config Config) *OpenAIAdapter {
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client := openai.NewClient(config.APIKey)
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return &OpenAIAdapter{
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client: client,
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config: config,
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}
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}
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func (a *OpenAIAdapter) Transcribe(ctx context.Context, audioData []byte) (string, error) {
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if len(audioData) == 0 {
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return "", nil
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}
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// Convert raw PCM to WAV format
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wavData, err := a.convertToWAV(audioData)
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if err != nil {
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return "", fmt.Errorf("convert to WAV: %w", err)
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}
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// Create transcription request
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req := openai.AudioRequest{
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Model: a.config.Model,
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Reader: bytes.NewReader(wavData),
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FilePath: "audio.wav",
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Language: a.config.Language,
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}
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start := time.Now()
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resp, err := a.client.CreateTranscription(ctx, req)
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duration := time.Since(start)
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if err != nil {
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log.Printf("openai-adapter: API call failed after %v: %v", duration, err)
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return "", fmt.Errorf("openai transcription: %w", err)
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}
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log.Printf("openai-adapter: transcribed %d bytes in %v: %q", len(audioData), duration, resp.Text)
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return resp.Text, nil
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}
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// convertToWAV converts raw 16-bit PCM audio to WAV format
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func (a *OpenAIAdapter) convertToWAV(rawAudio []byte) ([]byte, error) {
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var buf bytes.Buffer
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const sampleRate = 16000
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const channels = 1
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const bitsPerSample = 16
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const byteRate = sampleRate * channels * bitsPerSample / 8
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const blockAlign = channels * bitsPerSample / 8
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dataSize := len(rawAudio)
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fileSize := 36 + dataSize
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// WAV header
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buf.WriteString("RIFF")
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binary.Write(&buf, binary.LittleEndian, uint32(fileSize))
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buf.WriteString("WAVE")
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// fmt chunk
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buf.WriteString("fmt ")
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binary.Write(&buf, binary.LittleEndian, uint32(16)) // fmt chunk size
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binary.Write(&buf, binary.LittleEndian, uint16(1)) // PCM format
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binary.Write(&buf, binary.LittleEndian, uint16(channels)) // number of channels
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binary.Write(&buf, binary.LittleEndian, uint32(sampleRate)) // sample rate
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binary.Write(&buf, binary.LittleEndian, uint32(byteRate)) // byte rate
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binary.Write(&buf, binary.LittleEndian, uint16(blockAlign)) // block align
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binary.Write(&buf, binary.LittleEndian, uint16(bitsPerSample)) // bits per sample
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// data chunk
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buf.WriteString("data")
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binary.Write(&buf, binary.LittleEndian, uint32(dataSize))
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buf.Write(rawAudio)
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return buf.Bytes(), nil
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}
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