--- title: "How to add a curtain reveal with Claude (tested prompt and script)" description: "Red velvet stage curtains with a gold-trimmed edge fill the screen, then part down the middle and bunch up into their folds as they sweep off both sides to unveil the shot. Install one skill and ask Claude Code, or run the Python script we tested yourself." url: https://www.recharm.com/effects/curtain-reveal --- # How to add a curtain reveal with Claude Red velvet stage curtains with a gold-trimmed edge fill the screen, then part down the middle and bunch up into their folds as they sweep off both sides to unveil the shot. Made by the script on this page, from our own test clip. ## Get this effect 1. ### Switch to Code in your [Claude Desktop App](https://claude.com/download) 2. ### Install the skill (once) ``` Install the Recharm video effects skill: download https://recharm-growth-staging.s3.us-east-2.amazonaws.com/website/downloads/recharm-video-effects.zip and unzip it into ~/.claude/skills ``` 3. ### Ask for the effect ``` Add a curtain reveal to input.mp4 Second the curtains start to part: 0.4 Seconds they take to clear the frame: 1.5 ``` ## Several videos, several effects, one ask Put your clips in the folder, mention them with @, and ask for everything at once. Claude runs one tested script after another on each clip, then joins them. Add a curtain reveal to **@clip1.mp4**, put a sale badge on **@clip2.mp4**, give **@clip3.mp4** a VHS look, then join all three with crossfades. ## Settings you can change Ask Claude to change any of these, or edit them at the top of the script. | Setting | Default | What it does | | ------- | ---------------- | --------------------------------------------------- | | `START` | `0.4` | Second the curtains start to part. | | `OPEN` | `1.5` | Seconds they take to clear the frame. | | `LAG` | `0.25` | Seconds the hem trails the top, for a slight swing. | | `FOLDS` | `5` | Folds across each curtain. | | `COLOR` | `(170, 20, 35)` | Velvet red on a fold's crest. | | `TRIM` | `(212, 170, 70)` | Gold braid on the curtains' inner edges. | ## Without the skill Don’t want to install the skill? Paste this prompt into Claude Code and Claude writes the script itself. ``` Open input.mp4 with a stage curtain reveal. Two red velvet curtains, each half the frame wide, cover the whole frame at first: draw them with numpy as vertical folds, 5 folds per curtain, red (170, 20, 35) on each fold's crest shading down to about 35% of that in the troughs and a little darker toward the top, with a gold (212, 170, 70) braid 1.2% of the frame width wide down each curtain's inner edge where they meet at the center. At 0.4 seconds they part from the center: over 1.5 seconds, with smoothstep easing, each curtain narrows from half the frame width to nothing, anchored at its outer edge (left curtain on the left, right curtain on the right), squeezing its folds tighter as it goes rather than sliding them off. The hem trails the top by 0.25 seconds (row y starts moving 0.25*y/height seconds later), so the curtains swing slightly and are fully gone by 2.15 seconds. Each curtain casts a soft black shadow on the video, 5% of the frame width wide and 60% dark at the curtain's edge. After that the clip plays untouched. Draw the curtains with Python (numpy or Pillow, not ffmpeg's drawtext) and overlay them with ffmpeg, keep the audio, and save it as output.mp4 at the input's size, 6 seconds, 30fps. ``` ## Run it without Claude This is the exact script we tested. Save it as `curtain-reveal.py` and run: ``` python3 curtain-reveal.py input.mp4 output.mp4 ``` ``` #!/usr/bin/env python3 """Curtain reveal: red velvet stage curtains part from the center and bunch up as they sweep off both sides. Usage: python3 curtain-reveal.py input.mp4 output.mp4 Needs ffmpeg and numpy (pip install numpy). """ import json import math import subprocess import sys import numpy as np START = 0.4 # second the curtains start to part OPEN = 1.5 # seconds they take to clear the frame LAG = 0.25 # seconds the hem trails the top, so the curtains swing a little FOLDS = 5 # folds across each curtain COLOR = (170, 20, 35) # velvet red on a fold's crest TRIM = (212, 170, 70) # gold braid down each curtain's inner edge TRIM_W = 0.012 # braid width as a share of the frame width SHADOW_W = 0.05 # width of the shadow each curtain casts on the video, as a share of the frame width def velvet(): """One curtain (half the frame wide): vertical folds, darker at the top and in each fold's trough.""" half = w // 2 x = np.arange(half) / half folds = 0.5 + 0.5 * np.cos(2 * math.pi * FOLDS * x + 0.6 * np.sin(2 * math.pi * 3 * x)) shade = 0.35 + 0.65 * folds ** 0.7 y = np.arange(h) / h shade = shade[None, :] * (0.78 + 0.22 * np.sin(math.pi * np.clip(y, 0, 0.9) / 0.9))[:, None] tex = shade[:, :, None] * np.array(COLOR, np.float32) tex[:, round(half - TRIM_W * w):] = TRIM # braid on the inner edge return tex.astype(np.float32) def smoothstep(p): p = np.clip(p, 0, 1) return p * p * (3 - 2 * p) def overlay(t): """The curtains at time t as an RGBA frame: the left one drawn from tex, the right one mirrored.""" half = tex.shape[1] y = np.arange(h) / h width = half * (1 - smoothstep((t - START - LAG * y) / OPEN)) # each row's curtain width; the hem lags x = np.arange(w // 2)[None, :] + 0.5 cover = np.clip(width[:, None] - x + 0.5, 0, 1) # 1 inside the curtain, soft at its edge cols = np.minimum((x / np.maximum(width[:, None], 1e-3) * half).astype(int), half - 1) rgb = np.take_along_axis(tex, np.broadcast_to(cols[:, :, None], cols.shape + (3,)), axis=1) gap = np.clip((x - width[:, None]) / (SHADOW_W * w), 0, 1) shadow = 0.6 * (1 - gap) ** 2 * (width[:, None] > 0.5) alpha = cover + shadow * (1 - cover) left = np.dstack([rgb * (cover > 0)[:, :, None], alpha * 255]) img = np.zeros((h, w, 4), np.float32) img[:, :w // 2] = left img[:, w - w // 2:] = left[:, ::-1] return img.astype(np.uint8) 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) for i in range(math.ceil(duration * fps)): ff.stdin.write(overlay(i / fps).tobytes()) ff.stdin.close() if ff.wait(): sys.exit("ffmpeg failed") src, out = sys.argv[1:3] w, h, rate, fps, duration = probe(src) tex = velvet() render(src, out) ``` ## More hook openers - [Blur-to-focus reveal **Blur-to-focus reveal**](https://www.recharm.com/effects/blur-to-focus-reveal) - [Breaking news banner **Breaking news banner**](https://www.recharm.com/effects/breaking-news-banner) - [Camera shake **Camera shake**](https://www.recharm.com/effects/camera-shake) - [Color reveal **Color reveal**](https://www.recharm.com/effects/color-reveal) - [Countdown intro **Countdown intro**](https://www.recharm.com/effects/countdown-intro) ## Find 3x _winning ads_ Recharm cuts your ad footage into tagged, searchable clips: hooks, testimonials, product shots. Find the shots that win, add the effect with Claude, and ship 3x more ad edits. [Start 14-day free trial](https://www.recharm.com/get-started)