How to add a blur-in text with Claude

Add blur-in text to input.mp4: the words "Skin, renewed" in bold sans-serif, deep plum (50, 20, 80), text height 12% of the frame width, centered horizontally and 11% down the frame. Nothing shows before 0.8 seconds. From 0.8 seconds the text appears with a Gaussian blur of radius 5% of the frame width, fading from transparent to full opacity over the first 0.3 seconds, and the blur eases (smoothstep) down to 0 so the letters are fully sharp at 2.0 seconds; then the text stays sharp to the end. Use Python with Pillow to draw and blur the text (don't use ffmpeg's drawtext filter) and ffmpeg to put it on the video, keep the audio, and save it as output.mp4.

#!/usr/bin/env python3
"""Blur-in text: a deep plum headline appears as a soft smudge and sharpens into crisp letters, then stays.

Usage: python3 blur-in-text.py input.mp4 output.mp4
Needs ffmpeg and Pillow (pip install pillow).
"""
import json
import math
import subprocess
import sys
from pathlib import Path

from PIL import Image, ImageDraw, ImageFilter, ImageFont

TEXT = "Skin, renewed"      # the headline
START = 0.8                 # second the text starts to appear
FOCUS = 1.2                 # seconds it takes to sharpen
MAX_BLUR = 0.05             # starting blur radius as a share of the frame width
Y = 0.11                    # text center, 0-1 down the frame
SIZE = 0.12                 # text height as a share of the frame width
COLOR = (50, 20, 80)        # text color, deep plum
FONTS = ["/System/Library/Fonts/Supplemental/Arial Bold.ttf",     # macOS
         "/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf",  # Linux
         "C:/Windows/Fonts/arialbd.ttf"]                          # Windows
FONT_FILE = next((f for f in FONTS if Path(f).exists()), None) or sys.exit("No bold font found: add one to FONTS")


def letters():
    """The text as a white-on-black mask the size of the frame."""
    mask = Image.new("L", (w, h))
    font = ImageFont.truetype(FONT_FILE, round(w * SIZE))
    ImageDraw.Draw(mask).text((w / 2, h * Y), TEXT, font=font, anchor="mm", fill=255)
    return mask


def overlay(t):
    """The text blurred by a radius that eases from MAX_BLUR to 0, fading up over the first quarter."""
    p = min(max((t - START) / FOCUS, 0), 1)
    if p <= 0:
        return blank
    ease = p * p * (3 - 2 * p)
    radius = MAX_BLUR * w * (1 - ease)
    alpha = mask.filter(ImageFilter.GaussianBlur(radius)) if radius > 0.3 else mask
    opacity = min(p / 0.25, 1)
    img = Image.new("RGBA", (w, h), COLOR)
    img.putalpha(alpha.point(lambda v: round(v * opacity)))
    return img


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


def render(src, out):
    """Draw overlay(t) on every frame of src and save to out, keeping the audio."""
    ff = subprocess.Popen(["ffmpeg", "-y", "-v", "error", "-i", src,
                           "-f", "rawvideo", "-pix_fmt", "rgba", "-s", f"{w}x{h}", "-r", rate, "-i", "-",
                           "-filter_complex", "[0:v][1:v]overlay=shortest=1,format=yuv420p[v]",
                           "-map", "[v]", "-map", "0:a?", "-c:v", "libx264", "-crf", "18", "-c:a", "copy", out],
                          stdin=subprocess.PIPE)
    sharp = overlay(START + FOCUS)
    for i in range(math.ceil(duration * fps)):
        t = i / fps
        ff.stdin.write((sharp if t >= START + FOCUS else overlay(t)).tobytes())
    ff.stdin.close()
    if ff.wait():
        sys.exit("ffmpeg failed")


src, out = sys.argv[1:3]
w, h, rate, fps, duration = probe(src)
mask = letters()
blank = Image.new("RGBA", (w, h))
render(src, out)