Initial snapshot: hand motion pipeline (Dyn-HaMR + dex-retargeting + SPIDER)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

visualization/video_io.py

@@ -0,0 +1,60 @@
+"""Video I/O utilities: read frames (cv2.VideoCapture) + encode mp4 (imageio/ffmpeg).
+
+Shared by scripts/demo.py.
+"""
+
+from typing import List, Tuple
+
+import cv2
+import numpy as np
+
+
+def read_video_frames(path: str) -> Tuple[List[np.ndarray], float, Tuple[int, int]]:
+    """Read all video frames (BGR uint8).
+
+    Returns:
+        frames_bgr: list of (H, W, 3) BGR uint8
+        fps:       frame rate (30 if unreadable)
+        (H, W):    frame size
+    """
+    cap = cv2.VideoCapture(path)
+    if not cap.isOpened():
+        raise FileNotFoundError(f"Cannot open video: {path}")
+
+    fps = cap.get(cv2.CAP_PROP_FPS) or 30.0
+    frames: List[np.ndarray] = []
+    while True:
+        ret, frame = cap.read()
+        if not ret:
+            break
+        frames.append(frame)
+    cap.release()
+
+    if not frames:
+        raise RuntimeError(f"Video has no valid frames: {path}")
+
+    H, W = frames[0].shape[:2]
+    return frames, float(fps), (H, W)
+
+
+def write_video_ffmpeg(
+    frames_bgr: List[np.ndarray], path: str, fps: float, quality: int = 8
+) -> None:
+    """Encode a BGR frame sequence as mp4 (imageio + libx264).
+
+    Args:
+        frames_bgr: list of (H, W, 3) BGR uint8
+        path:      output mp4 path
+        fps:       frame rate
+        quality:   imageio quality (0-10, higher is better)
+    """
+    import imageio.v2 as imageio
+
+    writer = imageio.get_writer(path, fps=fps, codec="libx264", quality=quality,
+                                macro_block_size=1)
+    try:
+        for frame in frames_bgr:
+            # BGR -> RGB
+            writer.append_data(frame[:, :, ::-1])
+    finally:
+        writer.close()