🎵 Local web app · FastAPI + FFmpeg

Choir Video Editor

Drag-and-drop video clip stitching with seamless crossfade transitions and audio sync — purpose-built for choir and orchestra video productions.

▶ Run it locally About the project

🎯 What it does

Drop your video clips, reorder them on a timeline, pick a transition, and render a seamless final video — all from your browser.

🎬

Drag & Drop

Drop MP4, MOV, AVI, MKV, or WebM clips onto the interface. Multiple files at once.

🔄

11 Crossfade Transitions

Fade, dissolve, circle open/close, slide, pixelize, radial, and more — with adjustable duration (0.3–3s).

🎵

Audio Sync

Automatic audio crossfade between clips with optional level normalization.

📐

Output Resolution

Export at original, 1080p, 720p, or 480p with smart letterboxing.

📊

Live Progress

Real-time progress bar via SSE while FFmpeg renders the final video.

⬇️

Preview & Download

Play the assembled video in-browser or download as MP4 (H.264 + AAC).

▶️ Run it locally

Requires Python 3.12+ and FFmpeg. Start in under 30 seconds.

1

Clone or download the project

The source is at C:\Users\HomePC\choir-video-editor\ on the development machine.

2

Install dependencies

pip install fastapi uvicorn jinja2

FFmpeg must be installed and available on your PATH.

3

Start the server

cd choir-video-editor
python -m uvicorn main:app --host 127.0.0.1 --port 5000 --log-level warning
4

Open the editor

Navigate to http://localhost:5000 in your browser. Drag in your clips and render.

✨ Available Transitions

All powered by FFmpeg's xfade filter.

fadefadeblackfadewhite dissolvedistancefadegrays hslmixradialpixelize smoothleftsmoothrightsmoothup smoothdowncircleopencircleclose vertopenvertclosehorzopenhorzclose

🔧 API Endpoints

The FastAPI backend exposes a clean REST API.

EndpointMethodDescription
/GETMain UI
/uploadPOSTUpload a video clip
/clipsGETList uploaded clips
/clips/{filename}DELETERemove a clip
/renderPOSTStart render job
/progress/{job_id}GETSSE progress stream
/transitionsGETList available transitions
/output/{filename}GETDownload rendered video

🧠 How it works

The FFmpeg filter graph chains crossfades across N clips.

# For N clips with transition duration T: # Total duration = sum(clip_durations) - (N-1) × T # xfade offset for transition i = sum(durs[0:i]) - i × T # Video chain with chained xfade filters: [0:v]setpts=PTS-STARTPTS[v0_in]; [1:v]setpts=PTS-STARTPTS[v1_in]; [v0_in][v1_in]xfade=transition=fade:duration=1:offset=4.0[v1_xf] # Audio chain with chained acrossfade: [0:a]asetpts=PTS-STARTPTS[a0_in]; [1:a]asetpts=PTS-STARTPTS[a1_in]; [a0_in][a1_in]acrossfade=d=1.0[a1_xf]