Video background removal & compositing.
AlphaCut uses ONNX segmentation models to isolate subjects from video backgrounds, with built-in compositing, batch processing.
AI & Processing
- 8 AI Models — U2Net, ISNet, BiRefNet — from fast drafts to cinema-quality edges
- 7 Output Formats — ProRes 4444+Alpha, WebM VP9+Alpha, Animated WebP, Animated GIF, PNG sequences, green screen, grayscale matte
- Chroma-Key Fallback — auto-detect green/blue screens; FFmpeg chroma-key for 10x speed boost
- Pipelined I/O — parallel decode/infer/save threads for higher throughput
- Frame Skip — process every Nth frame with mask reuse (up to 10x speedup)
- Benchmark Mode — test 10 samples to estimate total processing time
- Memory Monitoring — live RAM % during processing with warnings
- Resume Interrupted Jobs — progress saved every 50 frames, auto-resumes on restart
Advanced Compositing
- Background Replacement — solid color (6 presets + custom picker) or image file
- Color Spill Suppression — reduce green/blue/red spill along mask edges
- Shadow Preservation — detect and keep ground shadows via luminance analysis
- Mask Inversion — remove subject instead of background
Batch & Workflow
- Batch Queue — drop multiple files or a folder, process sequentially
- Job Table — per-file thumbnails, status, progress %, and output path
- CLI Mode — full argparse interface for headless/scripted operation (with auto chroma-key detection)
- Auto-Naming — configurable output patterns ({name}, {model}, {format}, {date})
- Export Presets — save/load all settings including compositing
- Recent Files — last 20 files quick-access menu
UI/UX
- Before/After Split View with draggable divider
- Smart Model Picker, Toast Notifications, Animated Progress
- System Tray integration, Scrubable Preview
- Menu Bar — File, Tools (Model Manager, Settings Folder), Help (Updates, About)
- About Dialog — version, system info, GitHub links
- Update Checker — checks GitHub releases on startup and on demand
- Model Manager — view/delete cached ONNX models with size info
- Settings Persistence — all preferences saved between sessions
| Requirement | Details |
|---|---|
| Python | 3.9+ |
| FFmpeg | On PATH |
| NVIDIA GPU | Optional — CUDA 12 + cuDNN 9 |
# GUI
python AlphaCut.py
# CLI — basic
python AlphaCut.py -i video.mp4 -f prores -m BiRefNet
# CLI — background replacement
python AlphaCut.py -i video.mp4 -f webm --bg-image beach.jpg
# CLI — green spill + shadow preservation
python AlphaCut.py -i greenscreen.mp4 -f prores --spill 60 --shadow 40
# CLI — batch with frame skip
python AlphaCut.py -i vid1.mp4 vid2.mp4 vid3.mp4 -f webm --frame-skip 3
# CLI — invert mask + custom background
python AlphaCut.py -i video.mp4 -f prores --invert --bg-color 0,0,0| Flag | Default | Description |
|---|---|---|
-i, --input |
— | Input video file(s) |
-o, --output |
Auto-named | Output path |
-m, --model |
u2net_human_seg |
Model name (partial match) |
-f, --format |
mp4 |
mp4, prores, webm, webp_anim, png_seq, greenscreen, matte |
--max-res |
0 (original) | Max resolution |
--edge |
0 | Edge softness (0-100) |
--shift |
0 | Mask shift (-20 to +20) |
--temporal |
0 | Temporal smooth (0-7) |
--frame-skip |
1 | Process every Nth frame |
--invert |
— | Invert mask |
--spill |
0 | Spill suppression (0-100) |
--spill-color |
green | Spill color: green, blue, red |
--shadow |
0 | Shadow preservation (0-100) |
--bg-color |
— | Background R,G,B |
--bg-image |
— | Background image path |
--no-audio |
— | Strip audio |
| Model | Speed | Quality | Best For |
|---|---|---|---|
u2netp |
Fast | Good | Quick previews |
u2net_human_seg |
Fast | Great | People (default) |
silueta |
Fast | Good | People (small) |
u2net |
Medium | Great | General subjects |
isnet-general-use |
Medium | Great | General subjects |
isnet-anime |
Medium | Great | Anime / illustrations |
BiRefNet-portrait |
Slow | Excellent | Portraits, hair detail |
BiRefNet-general |
Slow | Excellent | Best overall |
AlphaCut.py (single file, ~2,650 lines)
├── Crash Handler + Bootstrap (auto-installs all deps)
├── AlphaCutEngine — ONNX inference + mask refinement
│ ├── Edge refinement, temporal smoothing
│ ├── Spill suppression, shadow preservation
│ ├── Mask inversion, background compositing
│ ├── SHA-256 model integrity verification
│ └── Engine cache (singleton)
├── ProcessingWorker — Pipelined frame processing
│ ├── Reader thread → AI inference → Saver thread
│ ├── Frame skip with mask reuse
│ └── Resume from last saved frame
├── BatchWorker — Sequential multi-file processing
├── BenchmarkWorker — 10-frame speed estimation
├── PreviewFrameWorker — Single-frame preview
├── UpdateChecker — GitHub releases API
├── AboutDialog — Version/system info
├── ModelManagerDialog — Download/delete models
├── SplitPreviewWidget — Before/after comparison
├── ToastWidget — Floating notifications
├── CLI — Full argparse headless interface
└── Settings/Presets — JSON persistence