fix: precise TTS word-boundary timing and remove wasted sync calculations

- ffmpeg-service/main.py: replace ffsubsync path with exact word-boundary timing from edge_tts for TTS subtitles. Karaoke styling preserved.
- server/services/ttsSync.ts: fix word count to match TTS-cleaned text, remove artificial punctuationPause subtraction, strip punctuation tokens from count.
- server/routes/reels.ts: remove redundant ttsSyncService calls in preview/background; word_duration is ignored by Python, these only wasted TTS generations.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

ffmpeg-service/main.py

@@ -291,16 +291,16 @@ async def generate_tts_with_subs(
                 # Use display_text for subtitle content if provided
                 text_to_display = display_text if display_text else text
 
-                print("⚠️ Using ffsubsync for precise synchronization as requested by user.")
-                unsynced_srt_path = audio_path.with_suffix(".unsynced.srt")
-                synced_srt_path = audio_path.with_suffix(".synced.srt")
-                
-                # Subtitle syncing pipeline using ffsubsync for the generated TTS voice
-                generate_unsynced_srt(text_to_display, unsynced_srt_path, total_duration=audio_duration)
-                run_ffsubsync(audio_path, unsynced_srt_path, synced_srt_path)
-                convert_srt_to_ass(synced_srt_path, ass_path, font_size=65, delay=delay)
-                
-                print(f"✅ TTS synchronisation completed with ffsubsync")
+                print("🎯 Using precise word-boundary timing from TTS engine")
+                generate_ass_from_word_boundaries(
+                    word_boundaries,
+                    text_to_display,
+                    ass_path,
+                    font_size=65,
+                    total_duration=audio_duration,
+                    delay=delay,
+                )
+                print(f"✅ TTS synchronisation completed with word-boundary timing")
                 return
             else:
                 print(f"⚠️ Audio file empty or missing with voice: {attempt_voice}")
@@ -322,19 +322,22 @@ def generate_ass_from_word_boundaries(
 ):
     """Generate ASS subtitles using precise word-level timing from TTS engine.
 
-    Groups words into readable chunks (~5 words or at punctuation) and uses
+    Groups words into readable chunks (~3 words or at punctuation) and uses
     the real start/end timestamps from the TTS engine for each chunk.
+    Includes karaoke fill tags for word-level visual highlighting.
     """
     if not word_boundaries:
         return
 
-    # Group word boundaries into chunks of ~5 words, or split at punctuation
+    # Group word boundaries into chunks of ~3 words, or split at punctuation
     chunks = []
     current_words = []
+    current_boundaries = []
     current_start = word_boundaries[0]["offset"]
 
     for i, wb in enumerate(word_boundaries):
         current_words.append(wb["text"])
+        current_boundaries.append(wb)
         is_last = i == len(word_boundaries) - 1
         # Split at punctuation or every 3 words (tighter sync with voice)
         ends_sentence = wb["text"].rstrip().endswith((".", "!", "?", ":", ","))
@@ -345,12 +348,14 @@ def generate_ass_from_word_boundaries(
             chunk_end = wb["offset"] + wb["duration"]
             chunks.append(
                 {
-                    "text": " ".join(current_words),
+                    "words": current_words,
+                    "boundaries": current_boundaries,
                     "start": current_start + delay,
                     "end": chunk_end + delay,
                 }
             )
             current_words = []
+            current_boundaries = []
             # Next chunk starts at the next word's offset
             if not is_last:
                 current_start = word_boundaries[i + 1]["offset"]
@@ -364,7 +369,7 @@ def generate_ass_from_word_boundaries(
     for i in range(len(chunks) - 1):
         chunks[i]["end"] = max(chunks[i]["end"], chunks[i + 1]["start"] + 0.05)
 
-    # ASS Header
+    # ASS Header (same karaoke style as convert_srt_to_ass)
     header = f"""[Script Info]
 ScriptType: v4.00+
 PlayResX: 1080
@@ -373,7 +378,7 @@ ScaledBorderAndShadow: yes
 
 [V4+ Styles]
 Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
-Style: Default,Sans,{font_size},&H00FFFFFF,&H000000FF,&H00000000,&H80000000,-1,0,0,0,100,100,0,0,1,4,2,5,50,50,0,1
+Style: Default,Sans,{font_size},&H0000FFFF,&H00FFFFFF,&H00000000,&H80000000,-1,0,0,0,100,100,0,0,1,4,2,5,50,50,0,1
 
 [Events]
 Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
@@ -383,8 +388,16 @@ Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
     for chunk in chunks:
         start_ts = format_ass_time(chunk["start"])
         end_ts = format_ass_time(chunk["end"])
-        sanitized = chunk["text"].replace("{", "(").replace("}", ")")
-        events += f"Dialogue: 0,{start_ts},{end_ts},Default,,0,0,0,,{sanitized}\n"
+
+        karaoke_parts = []
+        for wb in chunk["boundaries"]:
+            # duration in centiseconds, minimum 10cs to avoid zero
+            w_dur_cs = max(10, int(wb["duration"] * 100))
+            sanitized = wb["text"].replace("{", "(").replace("}", ")")
+            karaoke_parts.append(f"{{\\kf{w_dur_cs}}}{sanitized}")
+
+        karaoke_text = " ".join(karaoke_parts)
+        events += f"Dialogue: 0,{start_ts},{end_ts},Default,,0,0,0,,{karaoke_text}\n"
 
     with open(ass_path, "w", encoding="utf-8") as f:
         f.write(header + events)

server/routes/reels.ts

@@ -350,17 +350,7 @@ reelsRouter.post('/reels/preview', async (req: Request, res: Response) => {
             console.error('Error fetching watermark configuration', e);
         }
 
-        // Calculer le word_duration synchronisé si TTS activé
-        let finalWordDuration = wordDuration;
-        if (ttsEnabled && overlayText) {
-            try {
-                const sync = await ttsSyncService.calculateSyncTiming(overlayText, ttsVoice);
-                finalWordDuration = sync.wordDuration;
-                console.log(`🎯 TTS Sync (preview): ${sync.wordCount} mots, ${sync.audioDuration.toFixed(2)}s audio, word_duration=${finalWordDuration.toFixed(3)}s`);
-            } catch (syncErr) {
-                console.warn('⚠️ TTS sync failed (preview), using default word_duration:', syncErr);
-            }
-        }
+        const finalWordDuration = wordDuration;
 
         // Traiter la vidéo via FFmpeg
         const result = await ffmpegService.processReelFromUrl(resolveInternalUrl(media.originalUrl), {
@@ -593,17 +583,7 @@ async function processReelBackground(
             console.error('Error fetching watermark configuration', e);
         }
 
-        // Calculer le word_duration synchronisé si TTS activé
-        let finalWordDuration = wordDuration ?? 0.6;
-        if (ttsEnabled && overlayText && ttsVoice) {
-            try {
-                const sync = await ttsSyncService.calculateSyncTiming(overlayText, ttsVoice);
-                finalWordDuration = sync.wordDuration;
-                console.log(`🎯 TTS Sync (background): ${sync.wordCount} mots, ${sync.audioDuration.toFixed(2)}s audio, word_duration=${finalWordDuration.toFixed(3)}s`);
-            } catch (syncErr) {
-                console.warn('⚠️ TTS sync failed (background), using default word_duration:', syncErr);
-            }
-        }
+        const finalWordDuration = wordDuration ?? 0.6;
 
         const ffmpegResult = await ffmpegService.processReelFromUrl(resolveInternalUrl(media.originalUrl), {
             text: overlayText,

server/services/ttsSync.ts

@@ -16,11 +16,10 @@ export class TtsSyncService {
    * avec la durée réelle de la voix TTS générée.
    */
   async calculateSyncTiming(text: string, voice: string): Promise<SyncTiming> {
-    const cleanTtsText = this.cleanForTts(text);
-    const cleanDisplayText = this.cleanForDisplay(text);
+    const cleanText = this.cleanText(text);
 
     // 1. Générer le TTS preview et mesurer sa durée exacte
-    const ttsResult = await ffmpegService.previewTTS(cleanTtsText, voice);
+    const ttsResult = await ffmpegService.previewTTS(cleanText, voice);
     if (!ttsResult.success || !ttsResult.audioBase64) {
       throw new Error('TTS preview failed: ' + (ttsResult.error || 'unknown'));
     }
@@ -29,14 +28,11 @@ export class TtsSyncService {
     const metadata = await musicMetadata.parseBuffer(audioBuffer, 'audio/mpeg');
     const audioDuration = metadata.format.duration || 0;
 
-    // 2. Analyser le texte
-    const words = cleanDisplayText.split(/\s+/).filter(w => w.length > 0);
-    const wordCount = words.length;
-    const punctuationPause = this.calculatePunctuationPauses(cleanDisplayText);
+    // 2. Analyser le texte (compte les mots réellement lus par la voix)
+    const wordCount = this.calculateWordCount(cleanText);
 
-    // 3. Calculer le word_duration ajusté
-    const effectiveDuration = Math.max(audioDuration - punctuationPause, 0.5);
-    const wordDuration = wordCount > 0 ? effectiveDuration / wordCount : 0.6;
+    // 3. Calculer le word_duration
+    const wordDuration = wordCount > 0 ? audioDuration / wordCount : 0.6;
 
     // 4. Validation
     const warnings: string[] = [];
@@ -52,13 +48,13 @@ export class TtsSyncService {
       wordDuration,
       audioDuration,
       wordCount,
-      punctuationPause,
+      punctuationPause: 0,
       isHealthy,
       warnings,
     };
   }
 
-  private cleanForTts(text: string): string {
+  private cleanText(text: string): string {
     return text
       .replace(/#\w+/g, '')
       .replace(/https?:\/\/\S+/g, '')
@@ -66,23 +62,9 @@ export class TtsSyncService {
       .trim();
   }
 
-  private cleanForDisplay(text: string): string {
-    return text.trim();
-  }
-
-  private calculatePunctuationPauses(text: string): number {
-    let pause = 0;
-    const chars = text.split('');
-    for (const c of chars) {
-      if (',;'.includes(c)) pause += 0.3;
-      else if ('.!?'.includes(c)) pause += 0.6;
-      else if (':'.includes(c)) pause += 0.4;
-      else if (c === '\n') pause += 0.3;
-    }
-    // "..." compte comme un seul point mais pause plus longue
-    const ellipsisCount = (text.match(/\.\.\./g) || []).length;
-    pause += ellipsisCount * 0.3; // bonus pour les points de suspension
-    return pause;
+  private calculateWordCount(text: string): number {
+    const tokens = text.split(/\s+/).filter(w => w.length > 0);
+    return tokens.filter(w => /[a-zA-Z0-9À-ſ]/.test(w)).length;
   }
 }