Support custom frame output root

scripts/extract_vlac2_release_frames.py

@@ -23,6 +23,7 @@ from vlac2_release_common import (
     infer_main_path_from_row,
     load_json,
     normalize_main_path,
+    PORTABLE_IMAGE_ROOT,
 )
 
 try:
@@ -35,6 +36,11 @@ try:
 except ImportError:
     imageio = None
 
+try:
+    import av  # type: ignore
+except ImportError:
+    av = None
+
 
 @dataclass(frozen=True)
 class EpisodeSpec:
@@ -43,7 +49,7 @@ class EpisodeSpec:
 
 def parse_args() -> argparse.Namespace:
     parser = argparse.ArgumentParser(
-        description="Extract the portable VLAC2 release benchmark episodes into the release-local JPG tree."
+        description="Extract the portable VLAC2 release benchmark episodes into a JPG tree."
     )
     parser.add_argument(
         "--data-root",
@@ -51,6 +57,12 @@ def parse_args() -> argparse.Namespace:
         required=True,
         help="Directory containing the extracted raw benchmark videos.",
     )
+    parser.add_argument(
+        "--frames-root",
+        type=Path,
+        default=PORTABLE_IMAGE_ROOT,
+        help="Directory where extracted benchmark frames will be written. Defaults to _extracted_frames under the release directory.",
+    )
     parser.add_argument("--jobs", type=int, default=max(1, (os.cpu_count() or 8) // 2))
     parser.add_argument(
         "--overwrite-existing",
@@ -64,10 +76,18 @@ def bundled_release_root() -> Path:
     return SCRIPT_DIR.parent.resolve()
 
 
+def resolve_data_root(raw_arg: Path, release_root: Path) -> Path:
+    return raw_arg.resolve() if raw_arg.is_absolute() else (release_root / raw_arg).resolve()
+
+
+def resolve_frames_root(raw_arg: Path, release_root: Path) -> Path:
+    return raw_arg.resolve() if raw_arg.is_absolute() else (release_root / raw_arg).resolve()
+
+
 def require_decoder() -> None:
-    if cv2 is None and imageio is None:
+    if cv2 is None and imageio is None and av is None:
         raise SystemExit(
-            "No video decoder available. Install opencv-python or imageio before running frame extraction."
+            "No video decoder available. Install opencv-python, PyAV, or imageio before running frame extraction."
         )
 
 
@@ -240,6 +260,25 @@ def extract_with_imageio(source_video: Path, output_dir: Path) -> int:
     return frame_idx
 
 
+def extract_with_av(source_video: Path, output_dir: Path) -> int:
+    assert av is not None
+    container = av.open(str(source_video))
+    temp_paths: list[Path] = []
+    frame_idx = 0
+    try:
+        for frame in container.decode(video=0):
+            temp_path = output_dir / f"frame_{frame_idx:06d}.jpg"
+            frame.to_image().save(temp_path, format="JPEG")
+            temp_paths.append(temp_path)
+            frame_idx += 1
+    finally:
+        container.close()
+
+    for idx, temp_path in enumerate(temp_paths):
+        temp_path.rename(output_dir / f"{idx}-{frame_idx}.jpg")
+    return frame_idx
+
+
 def extract_one_video(source_video: Path, output_dir: Path, overwrite_existing: bool) -> dict[str, Any]:
     if not overwrite_existing and is_complete(output_dir, source_video):
         manifest = json.loads(manifest_path_for(output_dir).read_text(encoding="utf-8"))
@@ -254,9 +293,14 @@ def extract_one_video(source_video: Path, output_dir: Path, overwrite_existing:
     clear_output_dir(output_dir)
     if cv2 is not None:
         frame_count = extract_with_cv2(source_video, output_dir)
+        if frame_count == 0 and av is not None:
+            clear_output_dir(output_dir)
+            frame_count = extract_with_av(source_video, output_dir)
         if frame_count == 0 and imageio is not None:
             clear_output_dir(output_dir)
             frame_count = extract_with_imageio(source_video, output_dir)
+    elif av is not None:
+        frame_count = extract_with_av(source_video, output_dir)
     elif imageio is not None:
         frame_count = extract_with_imageio(source_video, output_dir)
     else:
@@ -282,8 +326,8 @@ def main() -> None:
     benchmark_root = (release_root / "benchmark_splits").resolve()
     if not benchmark_root.exists():
         raise SystemExit(f"Missing benchmark_splits under {release_root}")
-    data_root = args.data_root.resolve()
-    output_root = (release_root / "_extracted_frames").resolve()
+    data_root = resolve_data_root(args.data_root, release_root)
+    output_root = resolve_frames_root(args.frames_root, release_root)
     ensure_generated_marker(output_root)
     benchmark_paths = benchmark_files_from_root(benchmark_root)