File size: 2,747 Bytes
80fcd93 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 | #!/usr/bin/env python3
"""Global camera motion + cut map for a short vertical clip (NumPy + ffmpeg only).
usage: python3 camera_motion.py clip.mp4 [more.mp4 ...] [--fps 12] [--csv out.csv]
"""
import argparse, csv, subprocess, sys
import numpy as np
W, H = 144, 256 # analysis size (9:16); small is enough for global motion
def frames(path, fps):
cmd = ["ffmpeg", "-v", "error", "-i", path, "-vf",
f"fps={fps},scale={W}:{H}:force_original_aspect_ratio=disable,format=gray",
"-f", "rawvideo", "-"]
raw = subprocess.run(cmd, capture_output=True, check=True).stdout
return np.frombuffer(raw, np.uint8).reshape(-1, H, W).astype(np.float32)
WIN = np.outer(np.hanning(H), np.hanning(W)).astype(np.float32)
def phase_corr(a, b):
"""Return (dx, dy, peak) so that b is roughly a shifted by (dx, dy)."""
A = np.fft.fft2((a - a.mean()) * WIN)
B = np.fft.fft2((b - b.mean()) * WIN)
R = np.conj(A) * B
R /= np.abs(R) + 1e-9
r = np.fft.ifft2(R).real
y, x = np.unravel_index(np.argmax(r), r.shape)
if y > H // 2: y -= H
if x > W // 2: x -= W
return float(x), float(y), float(r.max())
def analyse(path, fps, cut_peak=0.06):
f = frames(path, fps)
rows = []
for i in range(1, len(f)):
dx, dy, peak = phase_corr(f[i - 1], f[i])
rows.append({"t": round(i / fps, 3), "dx": dx, "dy": dy,
"peak": round(peak, 3), "cut": peak < cut_peak})
return rows
def summary(rows):
cuts = [r["t"] for r in rows if r["cut"]]
# merge cut flags closer than 0.25 s (one cut can flag two pairs)
merged = []
for t in cuts:
if not merged or t - merged[-1] > 0.25:
merged.append(t)
still = [r for r in rows if not r["cut"]]
pan = sum(abs(r["dx"]) for r in still)
tilt = sum(abs(r["dy"]) for r in still)
moving = sum(1 for r in still if abs(r["dx"]) + abs(r["dy"]) >= 1) / max(len(still), 1)
return merged, pan, tilt, moving
if __name__ == "__main__":
ap = argparse.ArgumentParser()
ap.add_argument("clips", nargs="+")
ap.add_argument("--fps", type=float, default=12)
ap.add_argument("--csv")
a = ap.parse_args()
out = []
print(f"{'clip':<14}{'cuts (s)':<34}{'pan px':>8}{'tilt px':>8}{'moving':>8}")
for c in a.clips:
rows = analyse(c, a.fps)
cuts, pan, tilt, moving = summary(rows)
name = c.rsplit("/", 1)[-1][:12]
print(f"{name:<14}{', '.join(f'{t:.2f}' for t in cuts):<34}{pan:>8.0f}{tilt:>8.0f}{moving:>8.0%}")
out += [{"clip": name, **r} for r in rows]
if a.csv:
with open(a.csv, "w", newline="") as fh:
w = csv.DictWriter(fh, fieldnames=list(out[0]))
w.writeheader(); w.writerows(out)
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