fix(rendering): synchronize FPS, implement render locks, respect brand segment duration, and fix local audio path resolving for ffmpeg

src/utils/expressCompiler.ts

@@ -87,8 +87,23 @@ export function getAspectDimensions(aspect: string): { w: number; h: number } {
 export function getTemplateDuration(
   template: ExpressTemplate,
   videoDurations?: Record<string, number>,
+  designMD?: DesignMD,
 ): number {
   return template.scenes.reduce((sum, scene) => {
+    // If it's a brand segment, read duration from designMD instead of template
+    if (scene.segmentSource === 'brand' && designMD) {
+      if (scene.type === 'intro') {
+        if (!designMD.introVideoUrl) return sum; // Skipped
+        const frames = designMD.introDurationFrames || (scene.durationSeconds * 30);
+        return sum + (frames / 30);
+      }
+      if (scene.type === 'outro') {
+        if (!designMD.outroVideoUrl) return sum; // Skipped
+        const frames = designMD.outroDurationFrames || (scene.durationSeconds * 30);
+        return sum + (frames / 30);
+      }
+    }
+
     // If we know the actual video duration for this scene, use it
     if (videoDurations && videoDurations[scene.id]) {
       return sum + videoDurations[scene.id];
@@ -121,10 +136,24 @@ export function compileExpressToTimeline(
 
   // Process each scene sequentially — the template's scenes are the sole source of truth
   for (const scene of template.scenes) {
-    // Use actual video duration if available (from useVideoDurations)
-    const sceneDuration = (videoDurations && videoDurations[scene.id])
-      ? videoDurations[scene.id]
-      : scene.durationSeconds;
+    // Default to template's duration
+    let sceneDuration = scene.durationSeconds;
+    
+    // Override if brand segment
+    if (scene.segmentSource === 'brand' && designMD) {
+      if (scene.type === 'intro') {
+        if (!designMD.introVideoUrl) { sceneDuration = 0; }
+        else { sceneDuration = (designMD.introDurationFrames || (scene.durationSeconds * 30)) / 30; }
+      }
+      if (scene.type === 'outro') {
+        if (!designMD.outroVideoUrl) { sceneDuration = 0; }
+        else { sceneDuration = (designMD.outroDurationFrames || (scene.durationSeconds * 30)) / 30; }
+      }
+    } else if (videoDurations && videoDurations[scene.id]) {
+      // Override if user uploaded video
+      sceneDuration = videoDurations[scene.id];
+    }
+
     const sceneDurFrames = sceneDuration * fps;
     const sceneStart = frameOffset;
     const sceneEnd = frameOffset + sceneDurFrames;