Use Voxtral JSON transcription without fake speakers

internal/transcription/client.go

@@ -9,6 +9,7 @@ import (
 	"mime/multipart"
 	"net/http"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"time"
 )
@@ -20,6 +21,8 @@ type Client struct {
 
 const ProviderVoxtral = "voxtral-small"
 
+var speakerLabelPattern = regexp.MustCompile(`(?i)(?:^|[\n\r ]+)((?:speaker|спикер|говорящий)\s*\d+)\s*[:：-]`)
+
 type Options struct {
 	VoxtralBaseURL string
 	VoxtralAPIKey  string
@@ -230,18 +233,7 @@ func clampTime(v float64) float64 {
 }
 
 func (c *Client) transcribeOpenAIAudio(ctx context.Context, provider ProviderConfig, audio []byte, filename string, in Input) (*audioLLMResponse, time.Duration, error) {
-	resp, duration, err := c.doOpenAIAudioTranscription(ctx, provider, audio, filename, in, "verbose_json")
-	if err == nil {
-		return resp, duration, nil
-	}
-	if !strings.Contains(strings.ToLower(err.Error()), "http 4") {
-		return nil, duration, err
-	}
-	fallback, fallbackDuration, fallbackErr := c.doOpenAIAudioTranscription(ctx, provider, audio, filename, in, "json")
-	if fallbackErr != nil {
-		return nil, duration + fallbackDuration, err
-	}
-	return fallback, duration + fallbackDuration, nil
+	return c.doOpenAIAudioTranscription(ctx, provider, audio, filename, in, "json")
 }
 
 func (c *Client) doOpenAIAudioTranscription(ctx context.Context, provider ProviderConfig, audio []byte, filename string, in Input, responseFormat string) (*audioLLMResponse, time.Duration, error) {
@@ -336,45 +328,61 @@ func convertAudioSegments(in []audioTranscriptionSegment) []Segment {
 
 func normalizeAudioLLMSegments(segments []Segment, text string, diarize bool) []Segment {
 	text = strings.TrimSpace(text)
+	if text != "" {
+		if labeled := segmentSpeakerLabeledText(text); len(labeled) > 0 {
+			return labeled
+		}
+	}
 	if len(segments) <= 1 && text != "" {
-		heuristic := segmentTranscriptText(text, diarize)
+		heuristic := segmentTranscriptText(text)
 		if len(heuristic) > len(segments) {
 			segments = heuristic
 		}
 	}
-	return ensureHeuristicSpeakers(segments, diarize)
+	return segments
 }
 
-func ensureHeuristicSpeakers(segments []Segment, diarize bool) []Segment {
-	if !diarize || len(segments) < 2 || segmentsHaveSpeakers(segments) {
-		return segments
+func segmentSpeakerLabeledText(text string) []Segment {
+	matches := speakerLabelPattern.FindAllStringSubmatchIndex(text, -1)
+	if len(matches) == 0 {
+		return nil
 	}
-	out := make([]Segment, len(segments))
-	copy(out, segments)
-	for i := range out {
-		if i%2 == 0 {
-			out[i].Speaker = "SPEAKER_00"
-		} else {
-			out[i].Speaker = "SPEAKER_01"
+	speakerIDs := map[string]string{}
+	var out []Segment
+	var t float64
+	for i, match := range matches {
+		label := strings.ToLower(strings.TrimSpace(text[match[2]:match[3]]))
+		speaker, ok := speakerIDs[label]
+		if !ok {
+			speaker = fmt.Sprintf("SPEAKER_%02d", len(speakerIDs))
+			speakerIDs[label] = speaker
 		}
+		start := match[1]
+		end := len(text)
+		if i+1 < len(matches) {
+			end = matches[i+1][0]
+		}
+		part := strings.TrimSpace(text[start:end])
+		part = strings.Trim(part, ":-— ")
+		if part == "" {
+			continue
+		}
+		words := len(strings.Fields(part))
+		duration := float64(words) * 0.42
+		if duration < 1.2 {
+			duration = 1.2
+		}
+		out = append(out, Segment{Start: t, End: t + duration, Text: part, Speaker: speaker})
+		t += duration
 	}
 	return out
 }
 
-func segmentsHaveSpeakers(segments []Segment) bool {
-	for _, segment := range segments {
-		if strings.TrimSpace(segment.Speaker) != "" {
-			return true
-		}
-	}
-	return false
-}
-
-func segmentTranscriptText(text string, diarize bool) []Segment {
+func segmentTranscriptText(text string) []Segment {
 	parts := splitTranscriptSentences(text)
 	out := make([]Segment, 0, len(parts))
 	var t float64
-	for i, part := range parts {
+	for _, part := range parts {
 		words := len(strings.Fields(part))
 		if words == 0 {
 			continue
@@ -384,13 +392,6 @@ func segmentTranscriptText(text string, diarize bool) []Segment {
 			duration = 1.2
 		}
 		segment := Segment{Start: t, End: t + duration, Text: part}
-		if diarize && len(parts) > 1 {
-			if i%2 == 0 {
-				segment.Speaker = "SPEAKER_00"
-			} else {
-				segment.Speaker = "SPEAKER_01"
-			}
-		}
 		out = append(out, segment)
 		t = segment.End
 	}