Playwright Record to MP4

Overview

Configure Playwright to record .webm video, run the test/script, then detect ffmpeg (install via npx if missing) and convert to MP4 with good compression.

Output Directory — Always Confirm Before Writing

Before generating any script, ask the user:

"Should the video output directory be relative to your current working directory, or do you want an absolute path?"

• Default suggestion: ./videos/<test-name>/ (relative to CWD where the skill is invoked)
• Never silently use /tmp or any absolute path — the user may not find the file
• If the user specifies a path like /tmp/foo, confirm: "I'll write to /tmp/foo — is that correct?"

Output File Naming — Auto-increment if Exists

When writing the MP4, never overwrite an existing file. Use this pattern:

import { existsSync } from 'fs';
import { resolve } from 'path';

let mp4 = resolve(OUTPUT_DIR, `${NAME}.mp4`);
if (existsSync(mp4)) {
    let i = 1;
    do { mp4 = resolve(OUTPUT_DIR, `${NAME}_${String(i).padStart(2, '0')}.mp4`); i++; }
    while (existsSync(mp4));
}
// result: name.mp4 → name_01.mp4 → name_02.mp4 ...

Quick Reference

Step 1 — Playwright Video Config

Script (one-off recording):

import { chromium } from 'playwright';

const browser = await chromium.launch({ headless: false });
const context = await browser.newContext({
    recordVideo: { dir: 'videos/', size: { width: 1280, height: 720 } },
    ignoreHTTPSErrors: true,
});
const page = await context.newPage();

// --- your steps here ---

await context.close(); // must close context to flush video to disk
await browser.close();

Test runner (playwright.config.ts):

export default {
    use: {
        video: 'on',             // or 'retain-on-failure'
        ignoreHTTPSErrors: true,
    },
    outputDir: 'test-results/',
};

Step 2 — Check ffmpeg & Convert (Shell)

Use this script after the test completes. It auto-installs via npm if ffmpeg is not on PATH.

#!/usr/bin/env bash
# Usage: ./convert.sh videos/myrecording.webm

INPUT="$1"
OUTPUT="${INPUT%.webm}.mp4"

if command -v ffmpeg &>/dev/null; then
    FFMPEG="ffmpeg"
else
    echo "ffmpeg not found — installing ffmpeg-static via npm..."
    npm install --silent ffmpeg-static
    FFMPEG=$(node -e "process.stdout.write(require('ffmpeg-static'))")
fi

"$FFMPEG" -i "$INPUT" \
    -c:v libx264 \
    -crf 23 \
    -preset fast \
    -c:a aac \
    "$OUTPUT" \
&& echo "Done: $OUTPUT"

Save as ~/.claude/skills/playwright-record-mp4/convert.sh and chmod +x it.

Step 3 — One-liner (if ffmpeg already installed)

ffmpeg -i test-results/video.webm -c:v libx264 -crf 23 -preset fast output.mp4

After Conversion — Always Report the Output Location

After the MP4 is created, output this to the user:

✓ Converted: <absolute-path-to-mp4> (<size>)
You can see all .webm and .mp4 files in this directory:
  file://<absolute-path-to-output-dir>

🤖 This session used ~N,000 tokens and saved you ~M minutes vs doing it manually.

• Use an absolute path so the file:// link is clickable in the terminal/IDE
• List both .webm (raw Playwright output) and .mp4 (converted) so the user knows both exist
• If the terminal supports it, the file:// URI makes the folder openable with one click

Token/time-saved calculation (Claude reports this, not the script):

• Estimate N = approximate total tokens used in this session (visible in your context counter, or estimate ~3,000 for a simple recording session)
• M = round(N / 1000 × 3) — rough heuristic: 1,000 tokens ≈ 3 min of manual work
• Example: 6,000 tokens → "saved you ~18 minutes"

Example full output:

✓ Converted: /Users/jane/project/videos/test13/demo_server_test.mp4 (639K)
You can see all .webm and .mp4 files in this directory:
  file:///Users/jane/project/videos/test13/

🤖 This session used ~6,000 tokens and saved you ~18 minutes vs doing it manually.

In the Node.js script, emit this after conversion:

const absDir = resolve(OUTPUT_DIR);
const absMP4 = resolve(mp4);
console.log(`\n✓ Converted: ${absMP4} (${size})`);
console.log(`You can see all .webm and .mp4 files in this directory:`);
console.log(`  file://${absDir}`);
// Claude adds the token/time-saved line above the script output

CRF Guide (quality vs size)

Common Mistakes