fix: delegate multi-line digit selection to visible overlay (#78)

src/media-generator.ts

@@ -158,11 +158,12 @@ export class MediaGenerator {
     videoPath: string,
     startTime: number,
     endTime: number,
-    padding: number = 0.5,
+    padding: number = 0,
     audioStreamIndex: number | null = null,
   ): Promise<Buffer> {
-    const start = Math.max(0, startTime - padding);
-    const duration = endTime - startTime + 2 * padding;
+    const safePadding = Number.isFinite(padding) ? Math.max(0, padding) : 0;
+    const start = Math.max(0, startTime - safePadding);
+    const duration = endTime - start + safePadding;
 
     return new Promise((resolve, reject) => {
       const outputPath = path.join(this.tempDir, `audio_${Date.now()}.mp3`);
@@ -310,7 +311,7 @@ export class MediaGenerator {
     videoPath: string,
     startTime: number,
     endTime: number,
-    padding: number = 0.5,
+    padding: number = 0,
     options: {
       fps?: number;
       maxWidth?: number;
@@ -319,9 +320,12 @@ export class MediaGenerator {
       leadingStillDuration?: number;
     } = {},
   ): Promise<Buffer> {
-    const start = Math.max(0, startTime - padding);
-    const duration = endTime - startTime + 2 * padding;
     const { fps = 10, maxWidth = 640, maxHeight, crf = 35, leadingStillDuration = 0 } = options;
+    const safePadding = Number.isFinite(padding) ? Math.max(0, padding) : 0;
+    const start = Math.max(0, startTime);
+    const duration = endTime - startTime + safePadding;
+    const effectiveLeadingPadding = Math.min(safePadding, start);
+    const totalLeadingStillDuration = Math.max(0, leadingStillDuration) + effectiveLeadingPadding;
 
     const clampedCrf = Math.max(0, Math.min(63, crf));
 
@@ -359,7 +363,7 @@ export class MediaGenerator {
             fps,
             maxWidth,
             maxHeight,
-            leadingStillDuration,
+            leadingStillDuration: totalLeadingStillDuration,
           }),
           ...encoderArgs,
           '-y',