--- title: "How to add a silent film with Claude (tested prompt and script)" description: "The orbit around the bottle hurries by at a jerky, hand-cranked pace in gray-scale that pulses brighter and darker every frame, while white scratches run down the picture and black specks and hairs pop in and out. Install one skill and ask Claude Code, or run the Python script we tested yourself." url: https://www.recharm.com/effects/silent-film --- # How to add a silent film with Claude The orbit around the bottle hurries by at a jerky, hand-cranked pace in gray-scale that pulses brighter and darker every frame, while white scratches run down the picture and black specks and hairs pop in and out. 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 silent film to input.mp4 How many times faster than real time: 1.5 Output frames each picture is held for: 2 ``` ## 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 silent film 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 | | ----------- | ------- | --------------------------------------------------------------------------------------------------------------------- | | `SPEED` | `1.5` | How many times faster than real time. A 6 second clip lasts 6 / SPEED seconds. | | `HOLD` | `2` | Output frames each picture is held for. 2 at 30fps gives a choppy, hand-cranked 15 frames a second; 1 plays smoothly. | | `CONTRAST` | `1.35` | Stretch of the grays around mid-gray. 1 keeps the original contrast; old film stock is punchy. | | `WHITE` | `200` | Brightest the picture gets (0-255), so the scratches stand out above it. | | `FLICKER` | `0.10` | How far the brightness jumps from frame to frame. 0.10 is up to 10% brighter or darker; 0 turns the flicker off. | | `VIGNETTE` | `0.45` | How much darker the corners get than the center (0-1). | | `GRAIN` | `9` | Strength of the random film grain. 0 turns it off. | | `SCRATCHES` | `2` | Bright vertical scratches running down the frame at any moment. | | `DUST` | `6` | Dark specks and hairs scattered over each frame. | | `SEED` | `1927` | Change it for a different pattern of flicker, dust and scratches. | ## Without the skill Don’t want to install the skill? Paste this prompt into Claude Code and Claude writes the script itself. ``` Turn input.mp4 (540x960, 30fps, 6 seconds) into a 1920s silent film. Speed it up 1.5x so it lasts exactly 4 seconds (120 frames at 30fps), and make the motion choppy like a hand-cranked camera: output frames 2k and 2k+1 both show input frame 3k (so input frames 0, 3, 6 ... 177, each held for 2 output frames). Make every frame black and white (no color at all, saturation 0), stretch the contrast by 1.35 around mid-gray ((v - 128) x 1.35 + 128), then on every output frame multiply the brightness by a random factor between 0.90 and 1.10 so it flickers, darken toward the corners with a vignette (multiply by 1 - 0.45 x d^2, where d is the distance from the center divided by the distance to a corner, so the corners end up about 30% darker than the center), add random gray film grain (standard deviation 9) and clip the picture so nothing is brighter than 200. Over that, with Pillow, draw 2 bright vertical scratches (gray level 250, 1-2 pixels wide) running the full height of the frame, starting at random positions between 10% and 90% across and drifting sideways by a few pixels each frame, plus 6 dark dust marks per frame (gray level 10-40) at random positions that change every frame: mostly round specks 3-10 pixels across, some short curled hairs. Speed the input's own audio up 1.5x too (ffmpeg atempo=1.5) so it lasts 4 seconds. Don't add any text (if you ever do, draw it with Pillow, not ffmpeg's drawtext). Keep the size (540x960) and 30fps, encode H.264 yuv420p with the audio and save it as output.mp4. ``` ## Run it without Claude This is the exact script we tested. Save it as `silent-film.py` and run: ``` python3 silent-film.py input.mp4 output.mp4 ``` ``` #!/usr/bin/env python3 """Silent film: the clip plays 1.5x faster at a choppy 15 frames a second, in flickering black and white with dust and scratches. Usage: python3 silent-film.py input.mp4 output.mp4 Needs ffmpeg, numpy and Pillow (pip install numpy pillow). """ import json import subprocess import sys import numpy as np from PIL import Image, ImageDraw SPEED = 1.5 # how many times faster than real time (a 6 second clip lasts 4) HOLD = 2 # output frames each picture is held for; 2 at 30fps gives a hand-cranked 15fps CONTRAST = 1.35 # stretch of the grays around mid-gray; old film stock is punchy WHITE = 200 # brightest the picture gets, so the scratches stand out above it FLICKER = 0.10 # how far brightness jumps from frame to frame (0.10 = up to 10% up or down) VIGNETTE = 0.45 # how much darker the corners get than the center (0-1) GRAIN = 9 # strength of the random film grain SCRATCHES = 2 # bright vertical scratches running down the frame at any moment DUST = 6 # dark specks and hairs per frame SEED = 1927 # change for a different pattern of flicker, dust and scratches IN, OUT = sys.argv[1], sys.argv[2] info = json.loads(subprocess.check_output(["ffprobe", "-v", "error", "-select_streams", "v:0", "-show_entries", "stream=width,height", "-of", "json", IN]))["streams"][0] w, h = info["width"], info["height"] raw = subprocess.check_output(["ffmpeg", "-v", "error", "-i", IN, "-r", "30", "-f", "rawvideo", "-pix_fmt", "gray", "-"]) frames = np.frombuffer(raw, np.uint8).reshape(-1, h, w) count = round(len(frames) / SPEED) rng = np.random.default_rng(SEED) yy, xx = np.mgrid[0:h, 0:w] dist = np.hypot((xx - w / 2) / (w / 2), (yy - h / 2) / (h / 2)) / np.sqrt(2) vignette = 1 - VIGNETTE * dist ** 2 scratch_x = rng.uniform(0.1, 0.9, SCRATCHES) * w # each scratch drifts slowly sideways def dust(draw): for _ in range(DUST): x, y = rng.uniform(0, w), rng.uniform(0, h) if rng.random() < 0.7: # a speck r = rng.uniform(1.5, 5) draw.ellipse([x - r, y - r, x + r, y + r], fill=int(rng.integers(10, 40))) else: # a curled hair pts = [(x + 25 * np.sin(a) + 6 * a, y + 30 * a) for a in np.linspace(0, rng.uniform(1, 2.5), 12)] draw.line(pts, fill=int(rng.integers(10, 40)), width=2) encoder = subprocess.Popen(["ffmpeg", "-y", "-v", "error", "-f", "rawvideo", "-pix_fmt", "gray", "-s", f"{w}x{h}", "-r", "30", "-i", "-", "-i", IN, "-map", "0:v", "-map", "1:a", "-af", f"atempo={SPEED}", "-c:v", "libx264", "-crf", "18", "-pix_fmt", "yuv420p", "-c:a", "aac", "-shortest", OUT], stdin=subprocess.PIPE) for k in range(count): src = frames[min(round(k // HOLD * HOLD * SPEED), len(frames) - 1)].astype(np.float32) pic = (src - 128) * CONTRAST + 128 pic = pic * (1 + rng.uniform(-FLICKER, FLICKER)) * vignette + rng.normal(0, GRAIN, (h, w)) img = Image.fromarray(np.clip(pic, 0, WHITE).astype(np.uint8)) draw = ImageDraw.Draw(img) scratch_x += rng.normal(0, 3, SCRATCHES) for x in scratch_x: draw.line([(x, 0), (x + rng.uniform(-4, 4), h)], fill=250, width=int(rng.integers(1, 3))) dust(draw) encoder.stdin.write(img.tobytes()) encoder.stdin.close() sys.exit(encoder.wait()) ``` ## More retro and film - [1950s color film look **1950s color film look**](https://www.recharm.com/effects/1950s-color-film-look) - [35mm film look **35mm film look**](https://www.recharm.com/effects/35mm-film-look) - [70s film look **70s film look**](https://www.recharm.com/effects/70s-film-look) - [Camcorder date stamp **Camcorder date stamp**](https://www.recharm.com/effects/camcorder-date-stamp) - [Camcorder viewfinder **Camcorder viewfinder**](https://www.recharm.com/effects/camcorder-viewfinder) ## 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)