--- title: "How to add a shine sweep with Claude (tested prompt and script)" description: "A thin white streak of light, tilted like a slash, glides once from left to right across the bottle as if it caught a reflection. Install one skill and ask Claude Code, or run the Python script we tested yourself." url: https://www.recharm.com/effects/shine-sweep --- # How to add a shine sweep with Claude A thin white streak of light, tilted like a slash, glides once from left to right across the bottle as if it caught a reflection. 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 shine sweep to input.mp4 Second the glint enters at the left edge: 1.0 Seconds it takes to cross the frame: 0.8 ``` ## 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 shine sweep 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` | `1.0` | Second the glint enters at the left edge. | | `SWEEP` | `0.8` | Seconds it takes to cross the frame. | | `ANGLE` | `25` | Tilt of the streak from vertical, in degrees. | | `CORE, GLOW` | `14, 70` | Half-widths in pixels of the bright streak and the soft glow around it. | | `CORE_STRENGTH, GLOW_STRENGTH` | `0.9, 0.3` | How far the streak and the glow push pixels toward white (0-1). | ## Without the skill Don’t want to install the skill? Paste this prompt into Claude Code and Claude writes the script itself. ``` Add a shine sweep to input.mp4: one bright diagonal glint, tilted 25 degrees from vertical with its top leaning right (like /), that slides once across the whole frame from left to right between 1.0 and 1.8 seconds, starting and ending fully off screen and passing the frame's center at 1.4 seconds. Make it a narrow white streak (each pixel pushed 90% of the way to white at the streak's center, falling off over about 14 pixels either side) inside a soft glow (pushed 30% toward white, falling off over about 70 pixels). Leave every frame before 1.0 seconds and after 1.8 seconds untouched. Use Python with numpy to brighten the frames and ffmpeg to read and write the video, keep the audio, and save it as output.mp4. ``` ## Run it without Claude This is the exact script we tested. Save it as `shine-sweep.py` and run: ``` python3 shine-sweep.py input.mp4 output.mp4 ``` ``` #!/usr/bin/env python3 """Shine sweep: a bright diagonal glint slides once across the frame, left to right, like light catching glass. Usage: python3 shine-sweep.py input.mp4 output.mp4 Needs ffmpeg and numpy (pip install numpy). """ import json import subprocess import sys import numpy as np START = 1.0 # second the glint enters at the left edge SWEEP = 0.8 # seconds it takes to cross the frame ANGLE = 25 # tilt of the streak from vertical, in degrees (top leans right, like /) CORE = 14 # half-width of the bright streak, in pixels GLOW = 70 # half-width of the soft glow around it, in pixels CORE_STRENGTH = 0.9 # how far the streak pushes pixels toward white (0-1) GLOW_STRENGTH = 0.3 # how far the glow does def probe(path): info = json.loads(subprocess.check_output(["ffprobe", "-v", "error", "-select_streams", "v:0", "-show_entries", "stream=width,height,r_frame_rate", "-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) def shine(t): """How much of each pixel to push toward white at time t (0-1), or None when the glint is off screen.""" p = (t - START) / SWEEP if not 0 <= p <= 1: return None center = -GLOW + p * (span + 2 * GLOW) # glint starts and ends fully off screen d = np.abs(along - center) return CORE_STRENGTH * np.exp(-(d / CORE) ** 2) + GLOW_STRENGTH * np.exp(-(d / GLOW) ** 2) src, out = sys.argv[1:3] w, h, rate, fps = probe(src) y, x = np.mgrid[0:h, 0:w].astype(np.float32) slope = np.tan(np.radians(ANGLE)) along = x + y * slope # position along the sweep; each value is one tilted line of the streak span = w + h * slope reader = subprocess.Popen(["ffmpeg", "-v", "error", "-i", src, "-f", "rawvideo", "-pix_fmt", "rgb24", "-"], stdout=subprocess.PIPE) writer = subprocess.Popen(["ffmpeg", "-y", "-v", "error", "-f", "rawvideo", "-pix_fmt", "rgb24", "-s", f"{w}x{h}", "-r", rate, "-i", "-", "-i", src, "-map", "0:v", "-map", "1:a?", "-c:v", "libx264", "-crf", "18", "-pix_fmt", "yuv420p", "-c:a", "copy", "-shortest", out], stdin=subprocess.PIPE) i = 0 while raw := reader.stdout.read(w * h * 3): img = np.frombuffer(raw, np.uint8).reshape(h, w, 3) a = shine(i / fps) if a is not None: a = np.minimum(a, 1)[..., None] img = (img + (255 - img.astype(np.float32)) * a).astype(np.uint8) writer.stdin.write(img.tobytes()) i += 1 writer.stdin.close() if reader.wait() or writer.wait(): sys.exit("ffmpeg failed") ``` ## More product shots - [Animated feature callouts **Animated feature callouts**](https://www.recharm.com/effects/animated-feature-callouts) - [Before/after slider **Before/after slider**](https://www.recharm.com/effects/before-after-slider) - [Best seller badge **Best seller badge**](https://www.recharm.com/effects/best-seller-badge) - [Callout arrows and circles **Callout arrows and circles**](https://www.recharm.com/effects/callout-arrows-and-circles) - [Carousel swipe **Carousel swipe**](https://www.recharm.com/effects/carousel-swipe) ## 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)