Video Optimization for Web

video-optimization-for-web.md

Video Optimization for Web

Quick Command

Convert a single video to web-optimized MP4:

ffmpeg -i input.mov -vf "scale=-2:1080:flags=lanczos" -c:v libx264 -crf 23 -preset slow -c:a aac -b:a 128k -movflags +faststart output_web.mp4

Batch Conversion

Convert all .mov files in current directory:

for file in *.mov; do
  ffmpeg -i "$file" -vf "scale=-2:1080:flags=lanczos" -c:v libx264 -crf 23 -preset slow -c:a aac -b:a 128k -movflags +faststart "${file%.mov}_web.mp4"
done

Parameter Breakdown

Parameter	Purpose
-i input.mov	Input file
-vf "scale=-2:1080:flags=lanczos"	Scale to 1080p height, maintain aspect ratio, use high-quality Lanczos scaling
-c:v libx264	Use H.264 video codec (universally supported)
-crf 23	Quality level (18-28 range; 23 is good balance, lower = better quality/larger size)
-preset slow	Encoding speed (slower = better compression; options: ultrafast, fast, medium, slow, veryslow)
-c:a aac	Use AAC audio codec
-b:a 128k	Audio bitrate 128kbps
-movflags +faststart	Optimize for web streaming (moves metadata to beginning of file)

Adjusting Quality

• Better quality, larger files: Use -crf 18 to -crf 21
• Smaller files, lower quality: Use -crf 25 to -crf 28
• Faster encoding: Change -preset slow to -preset medium or -preset fast

Different Resolutions

• 720p: Change scale=-2:1080 to scale=-2:720
• 1440p: Change scale=-2:1080 to scale=-2:1440
• Keep original size: Remove the -vf "scale=-2:1080:flags=lanczos" parameter entirely

Requirements

• ffmpeg must be installed
• Install on macOS: brew install ffmpeg

Results from 2025-11-20

Converted 5 ProRes .mov files (1000M total) to web-optimized MP4s (14.1M total) - 98.6% reduction with excellent quality maintained.