Video Compression with FFmpeg

This guide explains how to compress videos using FFmpeg, with detailed explanations of each parameter.

Understanding the Basic Command

ffmpeg -i input.mp4 -b:v 1M output.mp4

Let's break down each part:

What is bitrate? It's how much data is used per second of video. Higher bitrate = better quality but larger file. Lower bitrate = smaller file but lower quality.

Method 1: CRF (Recommended for Beginners)

CRF (Constant Rate Factor) is the easiest way to compress video. You just pick a quality level:

ffmpeg -i input.mp4 -c:v libx264 -crf 23 output.mp4

CRF Value Guide

Tip: Start with CRF 23. If the file is too big, try 28. If quality is too low, try 20.

Method 2: Target File Size

If you need a specific file size, use bitrate mode:

ffmpeg -i input.mp4 -c:v libx264 -b:v 2M output.mp4

Common bitrate values:

• 500K = 500 Kilobits/second (small file, lower quality)
• 1M = 1 Megabit/second (medium)
• 2M = 2 Megabits/second (good quality)
• 5M = 5 Megabits/second (high quality)

Encoding Speed: Presets

The -preset option controls how fast FFmpeg encodes:

ffmpeg -i input.mp4 -c:v libx264 -crf 23 -preset fast output.mp4

Tip: Use fast for quick results, slow for final delivery.

Reduce Resolution

Smaller resolution = much smaller file:

ffmpeg -i input.mp4 -vf scale=-2:720 -c:v libx264 -crf 23 output.mp4

Common resolutions:

• scale=-2:2160 → 4K
• scale=-2:1080 → 1080p (Full HD)
• scale=-2:720 → 720p (HD)
• scale=-2:480 → 480p (SD)

Compress Audio Too

Add audio compression to reduce file size further:

ffmpeg -i input.mp4 -c:v libx264 -crf 23 -c:a aac -b:a 128k output.mp4

Audio bitrate guide:

• 320k → High quality music
• 192k → Good quality
• 128k → Standard (recommended)
• 96k → OK for speech

Complete Examples

Best Balance (Recommended)

Good quality, reasonable file size:

ffmpeg -i input.mp4 -c:v libx264 -crf 23 -preset medium -c:a aac -b:a 128k output.mp4

Smallest File Size

For sharing online when quality is less important:

ffmpeg -i input.mp4 -vf scale=-2:720 -c:v libx264 -crf 28 -preset slow -c:a aac -b:a 96k output.mp4

Best Quality

For archiving when you want to preserve quality:

ffmpeg -i input.mp4 -c:v libx264 -crf 18 -preset slow -c:a aac -b:a 192k output.mp4

Using FFHub API

Send your command to FFHub to process in the cloud:

curl -X POST https://api.ffhub.io/v1/tasks \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "command": "ffmpeg -i https://your-storage.com/input.mp4 -c:v libx264 -crf 23 -c:a aac -b:a 128k output.mp4"
  }'

Note: Replace the input URL with your actual video URL. FFHub will process it and give you a download link for the result.

Quick Reference