handle video tagging

src/lib/thumbnails.ts

@@ -87,22 +87,13 @@ async function getVideoDuration(src: string): Promise<number> {
   })
 }
 
-/** Generate a thumbnail from a video using ffmpeg. */
-async function generateVideoThumbnail(src: string, dest: string): Promise<void> {
+/** Extract a single frame from a video at the given offset (seconds) and write to dest. */
+async function generateVideoFrameAtOffset(src: string, dest: string, offsetSeconds: number): Promise<void> {
   const tmp = dest + '.tmp'
 
-  // Seek to 10% of the video duration for a representative frame
-  let offset = 0
-  try {
-    const duration = await getVideoDuration(src)
-    offset = Math.max(0, duration * 0.1)
-  } catch {
-    // If ffprobe fails, fall back to seeking to 0
-  }
-
   const args = [
     '-y',                        // overwrite output
-    '-ss', String(offset),       // seek before input (fast)
+    '-ss', String(offsetSeconds), // seek before input (fast)
     '-i', src,
     '-frames:v', '1',
     '-q:v', '5',
@@ -115,6 +106,58 @@ async function generateVideoThumbnail(src: string, dest: string): Promise<void>
   fs.renameSync(tmp, dest)
 }
 
+/** Generate a thumbnail from a video using ffmpeg (seeks to 10% of duration). */
+async function generateVideoThumbnail(src: string, dest: string): Promise<void> {
+  let offset = 0
+  try {
+    const duration = await getVideoDuration(src)
+    offset = Math.max(0, duration * 0.1)
+  } catch {
+    // If ffprobe fails, fall back to seeking to 0
+  }
+  await generateVideoFrameAtOffset(src, dest, offset)
+}
+
+/**
+ * Extract frames from a video at each given percentage of its duration.
+ * Returns the absolute paths to the cached frame JPEGs, in the same order as `percentages`.
+ * Uses a per-frame cache key so each frame is cached independently.
+ */
+export async function getVideoFramePaths(
+  absoluteFilePath: string,
+  libraryId: string,
+  percentages: number[]
+): Promise<string[]> {
+  ensureCacheDir()
+
+  let duration = 0
+  try {
+    duration = await getVideoDuration(absoluteFilePath)
+  } catch {
+    // Fall back to 0; all frames will seek to position 0
+  }
+
+  const framePaths: string[] = []
+
+  for (const pct of percentages) {
+    const offset = Math.max(0, duration * pct)
+    const key = crypto
+      .createHash('sha1')
+      .update(libraryId + ':' + absoluteFilePath + ':' + pct)
+      .digest('hex')
+    const cacheFile = path.join(CACHE_DIR, key + '.jpg')
+
+    const cached = getCachedPath(cacheFile, absoluteFilePath)
+    if (!cached) {
+      await generateVideoFrameAtOffset(absoluteFilePath, cacheFile, offset)
+    }
+
+    framePaths.push(cacheFile)
+  }
+
+  return framePaths
+}
+
 /**
  * Returns the absolute path to a cached thumbnail JPEG for the given file.
  * Generates it on first call (or when the source has been modified).