--- title: "How to add outlined captions with Claude (tested prompt and script)" description: "Each spoken phrase appears in big white letters wrapped in a thick black outline, with no box behind them. Install one skill and ask Claude Code, or run the Python script we tested yourself." url: https://www.recharm.com/effects/outlined-captions --- # How to add outlined captions with Claude Each spoken phrase appears in big white letters wrapped in a thick black outline, with no box behind them. 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 outlined captions to input.mp4 using the word timings in words.json Fill: white Edge: black ``` ## 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 outlined captions 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 | | --------- | ------- | --------------------------------------------------------- | | `SIZE` | `0.085` | Text height as a share of the frame width. | | `OUTLINE` | `0.14` | Outline thickness as a share of the text height. | | `Y` | `0.72` | Where the text's center sits, from top (0) to bottom (1). | | `CHUNK` | `4` | Words per phrase. | | `FILL` | `white` | Text color. | | `EDGE` | `black` | Outline color. | ## Without the skill Don’t want to install the skill? Paste this prompt into Claude Code and Claude writes the script itself. ``` Add captions to input.mp4 using the word timings in words.json. Show four words at a time in white bold text (Arial Black) with a thick black (0, 0, 0) outline, the text 8.5% of the frame width tall and the outline 14% of the text height thick, with no box behind it. Center each phrase horizontally, 72% of the way down the frame, shrinking the text if needed so the phrase fits in 90% of the width, and show it from the group's first word's start to its last word's end. Use Python with Pillow to draw the text (its stroke_width and stroke_fill options make the outline; don't use ffmpeg's drawtext filter) and ffmpeg to put it on 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 `outlined-captions.py` and run: ``` python3 outlined-captions.py input.mp4 words.json output.mp4 ``` ``` #!/usr/bin/env python3 """Outlined captions: each phrase in white text with a thick black outline, on screen while it is spoken. Usage: python3 outlined-captions.py input.mp4 words.json output.mp4 words.json holds word timings, for example from Whisper: [{"word": "This", "start": 0.30, "end": 0.69}, {"word": "serum", "start": 0.77, "end": 1.13}, ...] Needs ffmpeg and Pillow (pip install pillow). """ import json import math import subprocess import sys from pathlib import Path from PIL import Image, ImageDraw, ImageFont SIZE = 0.085 # text height as a share of the frame width (shrinks to fit long phrases) OUTLINE = 0.14 # outline thickness as a share of the text height Y = 0.72 # where the text's center sits (0 = top, 1 = bottom) CHUNK = 4 # words per phrase FILL = "white" # text color EDGE = "black" # outline color FONTS = ["/System/Library/Fonts/Supplemental/Arial Black.ttf", # macOS "/System/Library/Fonts/Supplemental/Arial Bold.ttf", # macOS "/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf", # Linux "C:/Windows/Fonts/ariblk.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") fonts = {} def fitted_font(text): """The largest font up to SIZE that fits the phrase, outline included, in 90% of the frame width.""" size = round(w * SIZE) while size > 12: font = fonts.get(size) or fonts.setdefault(size, ImageFont.truetype(FONT_FILE, size)) if font.getlength(text) + 2 * size * OUTLINE <= w * 0.9: return font size -= 2 return font def overlay(t): img = Image.new("RGBA", (w, h)) for group in (words[i:i + CHUNK] for i in range(0, len(words), CHUNK)): if group[0]["start"] <= t < group[-1]["end"]: text = " ".join(word["word"].strip() for word in group) font = fitted_font(text) ImageDraw.Draw(img).text((w / 2, h * Y), text, font=font, anchor="mm", fill=FILL, stroke_width=round(font.size * OUTLINE), stroke_fill=EDGE) 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) 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, words_file, out = sys.argv[1:4] words = json.loads(Path(words_file).read_text()) w, h, rate, fps, duration = probe(src) render(src, out) ``` ## More captions and text - [AI chat reply animation **AI chat reply animation**](https://www.recharm.com/effects/ai-chat-typing) - [Animated bar chart **Animated bar chart**](https://www.recharm.com/effects/animated-bar-chart) - [Animated checklist **Animated checklist**](https://www.recharm.com/effects/animated-checklist) - [Animated line graph **Animated line graph**](https://www.recharm.com/effects/animated-line-graph) - [Animated pie chart **Animated pie chart**](https://www.recharm.com/effects/animated-pie-chart) ## Find 3x _winning ads_ Recharm cuts your ad footage into tagged, searchable clips: hooks, testimonials, product shots. 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