"""Fast BVH to MP4 renderer using PIL + ffmpeg pipe.""" import sys import subprocess import numpy as np from PIL import Image, ImageDraw WIDTH, HEIGHT = 640, 640 BG_COLOR = (0, 0, 0) BONE_COLOR = (0, 255, 170) JOINT_COLOR = (0, 255, 170) JOINT_RADIUS = 3 BONE_WIDTH = 3 def parse_bvh(filepath): with open(filepath) as f: lines = f.readlines() joints = [] parent_stack = [] joint_offsets = {} joint_channels = {} joint_parents = {} channel_order = [] i = 0 while i < len(lines): line = lines[i].strip() if line.startswith('ROOT') or line.startswith('JOINT'): name = line.split()[-1] joints.append(name) joint_parents[name] = parent_stack[-1] if parent_stack else None elif line.startswith('End Site'): name = parent_stack[-1] + '_End' joints.append(name) joint_parents[name] = parent_stack[-1] elif line.startswith('OFFSET'): vals = list(map(float, line.split()[1:])) joint_offsets[joints[-1]] = np.array(vals) elif line.startswith('CHANNELS'): parts = line.split() n_ch = int(parts[1]) ch_names = parts[2:2+n_ch] joint_channels[joints[-1]] = ch_names for ch in ch_names: channel_order.append((joints[-1], ch)) elif line == '{': if joints: parent_stack.append(joints[-1]) elif line == '}': if parent_stack: parent_stack.pop() elif line.startswith('MOTION'): i += 1 break i += 1 n_frames = int(lines[i].split(':')[1]) i += 1 frame_time = float(lines[i].split(':')[1]) i += 1 frames = [] while i < len(lines): line = lines[i].strip() if line: frames.append(list(map(float, line.split()))) i += 1 return joints, joint_offsets, joint_channels, joint_parents, channel_order, np.array(frames), n_frames, frame_time # Precompute rotation matrices for common angles def rot_x(a): c, s = np.cos(a), np.sin(a) return np.array([[1,0,0],[0,c,-s],[0,s,c]]) def rot_y(a): c, s = np.cos(a), np.sin(a) return np.array([[c,0,s],[0,1,0],[-s,0,c]]) def rot_z(a): c, s = np.cos(a), np.sin(a) return np.array([[c,-s,0],[s,c,0],[0,0,1]]) ROT_FN = {'X': rot_x, 'Y': rot_y, 'Z': rot_z} def compute_all_positions(frames, joints, offsets, channels, parents, ch_order): """Vectorized position computation for all frames.""" n_frames = len(frames) n_joints = len(joints) joint_idx = {j: i for i, j in enumerate(joints)} # Build channel mapping ch_map = {} ci = 0 for joint, ch_name in ch_order: if joint not in ch_map: ch_map[joint] = {} ch_map[joint][ch_name] = ci ci += 1 all_positions = np.zeros((n_frames, n_joints, 3)) for fi in range(n_frames): fd = frames[fi] positions = {} rotations = {} for joint in joints: parent = parents[joint] offset = offsets.get(joint, np.zeros(3)) if parent is None: cm = ch_map.get(joint, {}) tx = fd[cm['Xposition']] if 'Xposition' in cm else 0 ty = fd[cm['Yposition']] if 'Yposition' in cm else 0 tz = fd[cm['Zposition']] if 'Zposition' in cm else 0 p_pos = np.array([tx, ty, tz]) p_rot = np.eye(3) else: p_pos = positions[parent] p_rot = rotations[parent] pos = p_pos + p_rot @ offset local_rot = np.eye(3) if joint in channels and joint in ch_map: for ch in channels[joint]: if 'rotation' in ch.lower(): axis = ch[0] val = np.radians(fd[ch_map[joint][ch]]) local_rot = local_rot @ ROT_FN[axis](val) rotations[joint] = p_rot @ local_rot positions[joint] = pos all_positions[fi, joint_idx[joint]] = pos return all_positions def project(pos_3d, center, scale): """Simple orthographic projection: X right, Y up, looking from front-ish.""" # Rotate slightly for a 3/4 view angle = np.radians(30) c, s = np.cos(angle), np.sin(angle) x = pos_3d[:, 0] * c + pos_3d[:, 2] * s y = pos_3d[:, 1] # Map to screen sx = (x - center[0]) * scale + WIDTH / 2 sy = HEIGHT / 2 - (y - center[1]) * scale return np.column_stack([sx, sy]) def main(): bvh_path = sys.argv[1] if len(sys.argv) > 1 else 'dance/J_Dance3_Woah/J_Dance3_Woah.bvh' out_path = sys.argv[2] if len(sys.argv) > 2 else bvh_path.rsplit('.', 1)[0] + '.mp4' print(f"Parsing {bvh_path}...") joints, offsets, channels, parents, ch_order, frames, n_frames, frame_time = parse_bvh(bvh_path) # Filter joints finger_keywords = ['Index', 'Middle', 'Ring', 'Pinky', 'Thumb'] major_mask = [i for i, j in enumerate(joints) if '_End' not in j and not any(k in j for k in finger_keywords)] major_joints = [joints[i] for i in major_mask] major_set = set(major_mask) bones = [] joint_idx = {j: i for i, j in enumerate(joints)} for j in major_joints: p = parents[j] if p is not None and joint_idx[p] in major_set: bones.append((joint_idx[p], joint_idx[j])) # Subsample for speed step = 2 sampled = frames[::step] fps = 1.0 / (frame_time * step) print(f"Computing positions for {len(sampled)} frames...") all_pos = compute_all_positions(sampled, joints, offsets, channels, parents, ch_order) # Compute projection params from all major joint positions major_pos = all_pos[:, major_mask, :] flat = major_pos.reshape(-1, 3) angle = np.radians(30) c, s = np.cos(angle), np.sin(angle) proj_x = flat[:, 0] * c + flat[:, 2] * s proj_y = flat[:, 1] cx = (proj_x.min() + proj_x.max()) / 2 cy = (proj_y.min() + proj_y.max()) / 2 rx = (proj_x.max() - proj_x.min()) / 2 ry = (proj_y.max() - proj_y.min()) / 2 max_r = max(rx, ry) * 1.3 scale = (min(WIDTH, HEIGHT) / 2) / max_r if max_r > 0 else 1 center = np.array([cx, cy]) print(f"Rendering to {out_path} at {fps:.0f} fps...") proc = subprocess.Popen([ 'ffmpeg', '-y', '-f', 'rawvideo', '-pix_fmt', 'rgb24', '-s', f'{WIDTH}x{HEIGHT}', '-r', str(int(round(fps))), '-i', '-', '-c:v', 'libx264', '-preset', 'fast', '-crf', '23', '-pix_fmt', 'yuv420p', out_path ], stdin=subprocess.PIPE, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL) for fi in range(len(sampled)): pts = project(all_pos[fi], center, scale) img = Image.new('RGB', (WIDTH, HEIGHT), BG_COLOR) draw = ImageDraw.Draw(img) for pi, ci in bones: x1, y1 = pts[pi] x2, y2 = pts[ci] draw.line([(x1, y1), (x2, y2)], fill=BONE_COLOR, width=BONE_WIDTH) for idx in major_mask: x, y = pts[idx] draw.ellipse([x-JOINT_RADIUS, y-JOINT_RADIUS, x+JOINT_RADIUS, y+JOINT_RADIUS], fill=JOINT_COLOR) proc.stdin.write(np.array(img).tobytes()) proc.stdin.close() proc.wait() print(f"Done: {out_path}") if __name__ == '__main__': main()