- name
- media-compress
- description
- Compress and convert images and videos using ffmpeg. Use when the user wants to reduce file size, change format, resize, or optimize media files. Handles common formats like JPG, PNG, WebP, MP4, MOV, WebM. Triggers on phrases like "compress image", "compress video", "reduce file size", "convert to webp/mp4", "resize image", "make image smaller", "batch compress", "optimize media".
Media Compression Skill
Compress and convert images and videos with intelligent defaults. Supports single files and batch processing.
Supported Formats
Images: JPG, PNG, WebP, BMP, TIFF, GIF → JPG, PNG, WebP Videos: MP4, MOV, AVI, MKV, WebM, FLV, WMV, M4V → MP4
Prerequisites
ffmpeg must be installed:
- Ubuntu/Debian:
sudo apt update && sudo apt install ffmpeg - macOS:
brew install ffmpeg - Windows: Download from https://ffmpeg.org/download.html and add to PATH
Verify installation: ffmpeg -version
Quick Start
Image Compression
# Compress to target size (auto-adjusts quality)
python scripts/compress_image.py photo.jpg --max-size 200kb
# Resize + compress
python scripts/compress_image.py photo.png --width 800 --output photo_small.jpg
# Convert to WebP (better compression)
python scripts/compress_image.py photo.jpg --format webp
# Batch compress entire folder
python scripts/compress_image.py ./photos --output ./compressed --quality 80
# Preview mode - see what will happen without compressing
python scripts/compress_image.py photo.jpg --max-size 500kb --preview
# Keep backup of original file
python scripts/compress_image.py photo.jpg --max-size 500kb --backupVideo Compression
# Compress with default settings (good balance)
python scripts/compress_video.py video.mp4 --output video_small.mp4
# Resize to 720p
python scripts/compress_video.py video.mp4 --height 720
# Target specific file size (approximate)
python scripts/compress_video.py video.mp4 --target-size 50mb
# Lower quality for smaller file
python scripts/compress_video.py video.mp4 --crf 28
# Batch process all videos in folder
python scripts/compress_video.py ./videos --output ./compressed --height 480
# Preview mode - see what will happen without compressing
python scripts/compress_video.py video.mp4 --height 720 --preview
# Keep backup of original file
python scripts/compress_video.py video.mp4 --height 720 --backupCommon Use Cases
1. Upload to Website (Image)
Most websites need images under 500KB:
python scripts/compress_image.py photo.jpg --max-size 500kb --format webp2. Email Attachment (Image)
Email often has 25MB limit:
python scripts/compress_image.py scan.pdf.jpg --max-size 5mb --quality 903. Social Media Video
Platforms prefer 720p, smaller files:
python scripts/compress_video.py clip.mov --height 720 --crf 23 --preset fast4. Archive Old Videos
Maximum compression for storage:
python scripts/compress_video.py old_video.avi --crf 28 --preset slow --height 4805. Convert Format Only
Keep quality, just change format:
# Image
python scripts/compress_image.py image.png --format jpg --quality 95
# Video
python scripts/compress_video.py video.mov --output video.mp4 --crf 18Parameters Reference
Image (compress_image.py)
| Parameter | Description | Default |
|---|---|---|
input | Input file or directory (required) | - |
--output, -o | Output file or directory | Auto-generated |
--max-size | Target max file size (e.g., 500kb, 2mb) | None |
--quality, -q | JPEG/WebP quality (1-100) | 85 |
--width, -w | Max width in pixels | Original |
--height | Max height in pixels | Original |
--format, -f | Output format: jpg, png, webp | Original format |
--no-strip | Keep metadata (default: remove) | False |
--preview, -p | Preview mode: show settings without compressing | False |
--backup, -b | Keep backup of original file | False |
Video (compress_video.py)
| Parameter | Description | Default |
|---|---|---|
input | Input file or directory (required) | - |
--output, -o | Output file or directory | Auto-generated |
--crf | Quality 0-51 (lower=better). 18=visually lossless, 23=default, 28=smaller | 23 |
--preset | Encoding speed: ultrafast, superfast, veryfast, faster, fast, medium, slow, slower, veryslow | medium |
--height | Max height (480, 720, 1080) | Original |
--target-size | Approximate target size (e.g., 50mb, 1gb) | None |
--fps | Limit frame rate (e.g., 30, 24) | Original |
--audio-bitrate | Audio quality (e.g., 128k, 192k) | 128k |
--preview, -p | Preview mode: show settings without compressing | False |
--backup, -b | Keep backup of original file | False |
Quality Guidelines
Images
- 90-95: High quality, minimal compression artifacts
- 85: Sweet spot (default) - good quality, significant size reduction
- 70-80: Acceptable for web, smaller files
- 50-60: Low quality, visible artifacts
Videos (CRF)
- 17-18: Visually lossless, archival quality
- 20-22: High quality, professional use
- 23: Default, good balance (recommended)
- 28: Smaller files, acceptable quality
- 35+: Low quality, preview/draft only
Presets
- ultrafast: Fastest encoding, largest files
- fast: Quick results, slightly larger
- medium: Default balance
- slow: Better compression, smaller files
- veryslow: Maximum compression, smallest files
Batch Processing
When input is a directory:
- All supported files are processed
- Output directory structure mirrors input
- Progress shown for each file
- Original and compressed sizes displayed
Example:
$ python scripts/compress_image.py ./vacation_photos --output ./compressed --max-size 500kb
找到 24 个图像文件
[1/24] 处理: IMG_001.jpg
✓ 2847.3KB → 456.2KB (84.0% 减少)
[2/24] 处理: IMG_002.png
✓ 1532.1KB → 298.5KB (80.5% 减少)
...Troubleshooting
"ffmpeg not found"
Install ffmpeg first:
# Ubuntu/Debian
sudo apt update && sudo apt install ffmpeg
# macOS
brew install ffmpeg"Permission denied"
Make scripts executable:
chmod +x scripts/*.pyQuality too low
Increase quality setting:
# Image
python scripts/compress_image.py photo.jpg --quality 90
# Video
python scripts/compress_video.py video.mp4 --crf 20File not smaller
- Try lower quality or smaller dimensions
- Some files are already optimally compressed
- Use
--max-sizeto force target size
Batch processing stops
Check that all files in directory are valid images/videos. Corrupt files may cause errors.
Advanced Tips
- Strip metadata for privacy (default behavior)
- Use WebP for best web compression
- 720p height is usually enough for mobile viewing
- CRF 23 + preset slow gives great results for archiving
- Test with one file before batch processing
References
- FFmpeg Guide - Detailed ffmpeg commands and parameters