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")
+	return c.doOpenAIAudioTranscription(ctx, provider, audio, filename, in, "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
 }
 
 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 {
+func segmentSpeakerLabeledText(text string) []Segment {
-	if !diarize || len(segments) < 2 || segmentsHaveSpeakers(segments) {
+	matches := speakerLabelPattern.FindAllStringSubmatchIndex(text, -1)
-		return segments
+	if len(matches) == 0 {
+		return nil
 	}
-	out := make([]Segment, len(segments))
+	speakerIDs := map[string]string{}
-	copy(out, segments)
+	var out []Segment
-	for i := range out {
+	var t float64
-		if i%2 == 0 {
+	for i, match := range matches {
-			out[i].Speaker = "SPEAKER_00"
+		label := strings.ToLower(strings.TrimSpace(text[match[2]:match[3]]))
-		} else {
+		speaker, ok := speakerIDs[label]
-			out[i].Speaker = "SPEAKER_01"
+		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 {
+func segmentTranscriptText(text string) []Segment {
-	for _, segment := range segments {
-		if strings.TrimSpace(segment.Speaker) != "" {
-			return true
-		}
-	}
-	return false
-}
-
-func segmentTranscriptText(text string, diarize bool) []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
 	}

internal/transcription/client_test.go

@@ -66,21 +66,21 @@ func TestVoxtralUsesAudioTranscriptionsEndpoint(t *testing.T) {
 	if gotModel != "mistralai/Voxtral-Small-24B-2507" {
 		t.Fatalf("model = %q", gotModel)
 	}
-	if gotResponseFormat != "verbose_json" {
+	if gotResponseFormat != "json" {
-		t.Fatalf("response_format = %q, want verbose_json", gotResponseFormat)
+		t.Fatalf("response_format = %q, want json", gotResponseFormat)
 	}
 	if len(got.Segments) != 2 || got.Segments[0].Text != "Алло, тест." || got.Segments[1].Start != 1.2 {
 		t.Fatalf("segments = %#v", got.Segments)
 	}
 }
 
-func TestSegmentTranscriptTextAddsHeuristicSpeakers(t *testing.T) {
+func TestSegmentTranscriptTextDoesNotInventSpeakers(t *testing.T) {
-	got := segmentTranscriptText("Алло, добрый день. Да, слушаю. Скажите, квартира продается? Да, продается.", true)
+	got := segmentTranscriptText("Алло, добрый день. Да, слушаю. Скажите, квартира продается? Да, продается.")
 	if len(got) < 2 {
 		t.Fatalf("segments = %#v, want multiple", got)
 	}
-	if got[0].Speaker != "SPEAKER_00" || got[1].Speaker != "SPEAKER_01" {
+	if got[0].Speaker != "" || got[1].Speaker != "" {
-		t.Fatalf("speakers = %q/%q", got[0].Speaker, got[1].Speaker)
+		t.Fatalf("speakers = %q/%q, want empty", got[0].Speaker, got[1].Speaker)
 	}
 	if got[1].Start <= got[0].Start {
 		t.Fatalf("segment times did not advance: %#v", got)
@@ -93,12 +93,12 @@ func TestNormalizeAudioLLMSegmentsSplitsSingleLongSegment(t *testing.T) {
 	if len(got) < 2 {
 		t.Fatalf("segments = %#v, want heuristic split", got)
 	}
-	if got[0].Speaker != "SPEAKER_00" || got[1].Speaker != "SPEAKER_01" {
+	if got[0].Speaker != "" || got[1].Speaker != "" {
-		t.Fatalf("speakers = %q/%q", got[0].Speaker, got[1].Speaker)
+		t.Fatalf("speakers = %q/%q, want empty", got[0].Speaker, got[1].Speaker)
 	}
 }
 
-func TestNormalizeAudioLLMSegmentsKeepsSegmentsAndAddsSpeakers(t *testing.T) {
+func TestNormalizeAudioLLMSegmentsKeepsSegmentsWithoutFakeSpeakers(t *testing.T) {
 	got := normalizeAudioLLMSegments([]Segment{
 		{Start: 0, End: 1, Text: "Алло."},
 		{Start: 1, End: 2, Text: "Да, слушаю."},
@@ -106,7 +106,21 @@ func TestNormalizeAudioLLMSegmentsKeepsSegmentsAndAddsSpeakers(t *testing.T) {
 	if len(got) != 2 {
 		t.Fatalf("segments = %#v", got)
 	}
-	if got[0].Speaker != "SPEAKER_00" || got[1].Speaker != "SPEAKER_01" {
+	if got[0].Speaker != "" || got[1].Speaker != "" {
-		t.Fatalf("speakers = %q/%q", got[0].Speaker, got[1].Speaker)
+		t.Fatalf("speakers = %q/%q, want empty", got[0].Speaker, got[1].Speaker)
+	}
+}
+
+func TestNormalizeAudioLLMSegmentsUsesExplicitSpeakerLabels(t *testing.T) {
+	text := "Спикер 1: Алло, добрый день. Спикер 2: Да, слушаю. Спикер 1: Скажите, квартира продается?"
+	got := normalizeAudioLLMSegments(nil, text, true)
+	if len(got) != 3 {
+		t.Fatalf("segments = %#v, want 3", got)
+	}
+	if got[0].Speaker != "SPEAKER_00" || got[1].Speaker != "SPEAKER_01" || got[2].Speaker != "SPEAKER_00" {
+		t.Fatalf("speakers = %q/%q/%q", got[0].Speaker, got[1].Speaker, got[2].Speaker)
+	}
+	if got[0].Text != "Алло, добрый день." || got[1].Text != "Да, слушаю." {
+		t.Fatalf("texts = %#v", got)
 	}
 }