Video Editor Skill

Overview

Post-production video editing using FFmpeg automation. Enhance videos from google-flow and grok-video-generation with captions, audio, transitions, and format optimization for different platforms.

When to Use

• Add captions/subtitles to videos
• Trim or cut video clips
• Merge multiple videos
• Add background music
• Convert video formats
• Optimize for platform specs
• Create video thumbnails
• Batch process videos

FFmpeg Commands

1. Add Captions/Subtitles

# Generate SRT file
cat > captions.srt << EOF
1
00:00:00,000 --> 00:00:03,000
Welcome to AI Video Tutorial

2
00:00:03,000 --> 00:00:06,000
Learn how to create amazing content
EOF

# Burn subtitles into video
ffmpeg -i input.mp4 -vf subtitles=captions.srt output.mp4

2. Trim Video

# Trim from 5s to 15s
ffmpeg -i input.mp4 -ss 00:00:05 -to 00:00:15 -c copy trimmed.mp4

3. Merge Videos

# Create file list
cat > filelist.txt << EOF
file 'video1.mp4'
file 'video2.mp4'
file 'video3.mp4'
EOF

# Concatenate
ffmpeg -f concat -safe 0 -i filelist.txt -c copy merged.mp4

4. Add Audio/Music

# Add background music
ffmpeg -i video.mp4 -i music.mp3 -c:v copy -c:a aac -map 0:v:0 -map 1:a:0 -shortest output.mp4

# Adjust audio volume
ffmpeg -i input.mp4 -af "volume=0.5" output.mp4

5. Convert Format

# MP4 to WebM
ffmpeg -i input.mp4 -c:v libvpx-vp9 -c:a libopus output.webm

# Optimize for Instagram (1080x1920, 9:16)
ffmpeg -i input.mp4 -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2" instagram.mp4

# Optimize for TikTok
ffmpeg -i input.mp4 -vf "scale=1080:1920" -c:v libx264 -preset slow -crf 22 tiktok.mp4

6. Create Thumbnail

# Extract frame at 3 seconds
ffmpeg -i video.mp4 -ss 00:00:03 -vframes 1 thumbnail.jpg

7. Add Watermark

# Add logo watermark
ffmpeg -i video.mp4 -i logo.png -filter_complex "overlay=W-w-10:H-h-10" watermarked.mp4

Automation Examples

Auto-Caption Generator

const { exec } = require('child_process');
const util = require('util');
const execPromise = util.promisify(exec);

async function addCaptions(videoPath, captionText) {
  // Generate SRT file
  const srtContent = generateSRT(captionText);
  await fs.writeFile('captions.srt', srtContent);
  
  // Add to video
  await execPromise(
    `ffmpeg -i ${videoPath} -vf subtitles=captions.srt output.mp4`
  );
  
  return 'output.mp4';
}

function generateSRT(text) {
  // Simple SRT generation
  return `1\n00:00:00,000 --> 00:00:05,000\n${text}\n`;
}

Batch Processing

async function batchOptimizeForPlatforms(videoPath) {
  const platforms = {
    instagram: '-vf "scale=1080:1920" -c:v libx264',
    tiktok: '-vf "scale=1080:1920" -c:v libx264 -preset slow',
    youtube: '-vf "scale=1920:1080" -c:v libx264',
    x: '-vf "scale=1280:720" -c:v libx264'
  };
  
  for (const [platform, params] of Object.entries(platforms)) {
    await execPromise(
      `ffmpeg -i ${videoPath} ${params} ${platform}.mp4`
    );
  }
}

Platform Specifications

Platform	Resolution	Aspect Ratio	Max Length	Format
Instagram Feed	1080x1080	1:1	60s	MP4
Instagram Reels	1080x1920	9:16	90s	MP4
TikTok	1080x1920	9:16	10min	MP4
X	1280x720	16:9	2:20	MP4
LinkedIn	1920x1080	16:9	10min	MP4
YouTube	1920x1080	16:9	Unlimited	MP4

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Related Skills: productivity/google-flow, content/grok-video-generation, marketing/social-media-upload