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Antoine Boucher

GreenScreenVideotoAlphaPNGs: A transparent-frame production pipeline

GreenScreenVideotoAlphaPNGs separates video acquisition, frame extraction and chroma keying from final encoding. RGBA PNG frames are an intermediate output that can feed either the GIF path or an alpha-capable video codec.

Application and tools
  • Updated
  • 1
  • C++ · 57.96%
  • MIT
View source README
Repository languagesC++ 57.96%5

Shares calculated from GitHub Linguist bytes.

Language%Bytes
C++57.96%41,566
Python32.32%23,177
JavaScript7.93%5,687
PowerShell0.94%673
Shell0.85%610

GitHub · README · Language statistics

Overview

Why it exists

OpenCV color-keying pipeline converting chroma-key green videos to RGBA alpha PNG sequences.

Best fit

Asset preparation for augmented reality (Snapchat Lens Studio, Spark AR).

Getting started

These commands come from the repository documentation. They were not run during this review.

README.md · Quick start (uv) 
.\install.ps1
uv run greenscreen --help
README.md · Quick start (uv) 
bash install.sh
uv run greenscreen --help
README.md · APNGLib (optional C++ extension) 
$env:SKIP_APNGLIB='1'; uv sync --extra dev
README.md · APNGLib (optional C++ extension) 
$env:SKIP_APNGLIB='0'; uv sync --extra dev

Repository references

Excerpts from the repository’s guides, in their original language. Links open the inspected source revision.

Prerequisites and first run

Quick start (uv)

README.md

Install dev tools: uv sync –extra dev
Read the full instructions ↗

Prerequisites

README.md

  • Python 3.12+ (repo pins .python-version to 3.12 for uv).
  • ffmpeg on PATH for fast frame extract and for gif –fast-ffmpeg / video. A fallback binary can come from imageio-ffmpeg if PATH has no ffmpeg.
Read the full instructions ↗
Configuration and usage

CLI

README.md

Legacy entry points still work and forward to the same CLI:

  • python GreenVideotoAlphaPNGs.py → greenscreen convert
  • python GIFGenerator.py → greenscreen gif
  • python VideoGenerator.py → greenscreen video
Read the full instructions ↗
Source documentation

1 documents read from 1 candidates.

Features and components 2

Conversion stage
The Typer convert command delegates to run_convert. It accepts a local video or URL and can prefer FFmpeg or force OpenCV extraction. The chroma module handles pixel transparency separately from acquisition.
Encoding choices
gif and video take a directory of PNG frames. The GIF path offers an FFmpeg palette option; video accepts qtrle or prores_4444. Encoding is a new stage, so frame rate and format can change without repeating acquisition.

Architecture

The components and their connections remain available as text. The diagram adds an interactive view.

System context Context
  1. Video file or URL
  2. Frame extraction
  3. Chroma key
  4. RGBA PNG sequence
  5. GIF encoder
  6. Alpha video encoder

Links verified in the repository.

Mermaid Interactive diagram (loads on open)

System overview of the components and connections verified in the repository.

Static architecture view for GreenScreenVideotoAlphaPNGs
Static preview. The interactive diagram replaces it after Mermaid loads.
flowchart LR
  n0["Video file or URL"]
  n1["Frame extraction"]
  n2["Chroma key"]
  n3["RGBA PNG sequence"]
  n4["GIF encoder"]
  n5["Alpha video encoder"]
  n0 --> n1
  n1 --> n2
  n2 --> n3
  n3 --> n4
  n3 --> n5
Text version of the diagram
  • Video file or URL → Frame extraction
  • Frame extraction → Chroma key
  • Chroma key → RGBA PNG sequence
  • RGBA PNG sequence → GIF encoder
  • RGBA PNG sequence → Alpha video encoder
Follow one path through the code

Follow cmd_convert into run_convert, then reuse its PNG output for cmd_video. Preserving the intermediate frames makes it easier to inspect matte edges before compression obscures them.

Types and file structure

2 declared types, with 2 in the base-relationship overview.

Type diagram
classDiagram
direction TB
class t6f7d26235a07["CHUNK"] {
  <<struct>>
}
class t05c53bd05b93["APNGFrame"] {
  <<struct>>
}

Unresolved bases remain labelled; full signatures are not reconstructed.

Type index

Reference

21 / 21 eligible files read (45 in the tree); 0 oversized, 0 failed reads and 0 syntax diagnostics.

What the scan covers

Known dependency/build folders, credential files and binaries are excluded. The scan covers READMEs, recognized manifests and parser-supported source files.

Linguist statistics cover the whole repository and may include other languages.

File map
flowchart TD
  root["GreenScreenVideotoAlphaPNGs"]
  f0["src/greenscreen/chroma.py"]
  root --> f0
  f1["src/greenscreen/cli.py"]
  root --> f1
  f2["src/greenscreen/video_pipeline.py"]
  root --> f2
  f3["GIFGenerator.py"]
  root --> f3
  f4["GreenVideotoAlphaPNGs.py"]
  root --> f4
  f5["README.md"]
  root --> f5
  f6["VideoGenerator.py"]
  root --> f6
  f7["install.sh"]
  root --> f7
  f8["pyproject.toml"]
  root --> f8
  f9["requirements.txt"]
  root --> f9
  f10["setup.py"]
  root --> f10
  f11["tests/test_chroma.py"]
  root --> f11
  f12["tests/test_cli_smoke.py"]
  root --> f12
  f13["lib/APNGLib_fix/setup.py"]
  root --> f13
  f14["src/greenscreen/__init__.py"]
  root --> f14
  f15["src/greenscreen/convert.py"]
  root --> f15

Files to read 3

References