How to add a neon edge wipe with Claude

Join clipA.mp4 and clipB.mp4 with a 0.8 second neon edge wipe that starts 0.8 seconds before the end of clipA. A straight vertical edge moves from the right side of the frame to the left side at a constant speed, with clipA on the left of the edge and clipB on the right (ffmpeg xfade wipeleft). A neon line rides centered on that edge for the whole 0.8 seconds: a 6 pixel wide, near-white (255, 235, 250) line down the full height, inside a hot-pink (255, 40, 200) glow made by Gaussian-blurring a 24 pixel wide pink bar with a 22 pixel radius in Pillow and stacking the blurred bar twice. No line before or after the transition. Match clipB's size to clipA, output 30fps, crossfade the audio over the same 0.8 seconds, draw the line with Pillow (not ffmpeg's drawtext or drawbox), and save it as output.mp4.

#!/usr/bin/env python3
"""Neon edge wipe: a glowing pink neon line sweeps right to left over 0.8s, swapping clip A for clip B behind it.

Usage: python3 neon-edge-wipe.py clipA.mp4 clipB.mp4 output.mp4  (both clips need an audio track)
Needs ffmpeg and Pillow (pip install pillow).
"""
import json
import subprocess
import sys
import tempfile

from PIL import Image, ImageDraw, ImageFilter

D = 0.8                     # transition length in seconds
NEON = (255, 40, 200)       # glow color
CORE = (255, 235, 250)      # color of the bright line at the center of the glow
CORE_WIDTH = 6              # bright line width in pixels
GLOW = 22                   # glow radius (Gaussian blur, in pixels)


def probe(path):
    info = json.loads(subprocess.check_output(["ffprobe", "-v", "error", "-select_streams", "v:0", "-show_entries",
                                               "stream=width,height:format=duration", "-of", "json", path]))
    s = info["streams"][0]
    return s["width"], s["height"], float(info["format"]["duration"])


def neon_line(h):
    """A vertical strip: a soft pink glow with a near-white line down its middle, on a transparent background."""
    sw = GLOW * 8
    glow = Image.new("RGBA", (sw, h), NEON + (0,))
    ImageDraw.Draw(glow).rectangle([sw / 2 - CORE_WIDTH * 2, 0, sw / 2 + CORE_WIDTH * 2, h], fill=NEON + (255,))
    glow = glow.filter(ImageFilter.GaussianBlur(GLOW))
    # stack the glow twice so it stays strong right next to the line
    strip = Image.alpha_composite(glow, glow)
    ImageDraw.Draw(strip).rectangle([sw / 2 - CORE_WIDTH / 2, 0, sw / 2 + CORE_WIDTH / 2 - 1, h], fill=CORE + (255,))
    return strip


a, b, out = sys.argv[1:4]
w, h, length = probe(a)
offset = length - D
with tempfile.NamedTemporaryFile(suffix=".png") as line:
    neon_line(h).save(line.name)
    # xfade's wipeleft moves the A/B edge from x = w to x = 0 over D seconds; the line is centered on that edge
    edge = f"{w}*(1-(t-{offset})/{D})"
    subprocess.run(["ffmpeg", "-y", "-v", "error", "-i", a, "-i", b, "-loop", "1", "-i", line.name, "-filter_complex",
                    f"[0:v]fps=30,format=yuv420p,setsar=1[a];"
                    f"[1:v]scale={w}:{h}:force_original_aspect_ratio=increase,crop={w}:{h},fps=30,format=yuv420p,setsar=1[b];"
                    f"[a][b]xfade=transition=wipeleft:duration={D}:offset={offset}[wiped];"
                    f"[wiped][2:v]overlay=x='{edge}-w/2':y=0:enable='between(t,{offset},{length})':shortest=1,format=yuv420p[v];"
                    f"[0:a][1:a]acrossfade=d={D}[au]",
                    "-map", "[v]", "-map", "[au]", "-c:v", "libx264", "-crf", "18", "-pix_fmt", "yuv420p", "-c:a", "aac", out],
                   check=True)