Documentation

Rendering Pipeline

How your VideoSpec becomes a finished MP4 — from assembly through frame capture to final stitching.

Pipeline Stages

Assembly

The assembly engine reads your VideoSpec, loads each scene's template HTML, fills content slots, injects brand CSS variables, and produces a single HTML composition with a master GSAP timeline that sequences all scenes.

Scene Rendering

Each scene is rendered individually through a headless Chromium instance. The browser captures frames at the target resolution, then FFmpeg encodes them into a per-scene MP4 segment. Progress updates are stored in the database in real time.

Stitching

Once all scene segments are ready, FFmpeg's concat demuxer joins them into a single MP4 without re-encoding. This is lossless and fast.

Audio Mixing

If any scenes have voiceover audio, the pipeline downloads each VO clip, aligns it to the correct timeline position using FFmpeg delay filters, and overlays the mixed audio onto the video as an AAC track. Videos without voiceover pass through unchanged.

Upload & Export

The finished MP4 and individual segments are uploaded to cloud storage. An export record is created with the download URL, file size, dimensions, and duration.

Surgical Re-rendering

Need to tweak one scene? The pipeline supports re-rendering a single scene and re-stitching it into the existing video — no need to re-render every other scene.

1. Edit Scene

Update slot content or duration in the editor

2. Re-render Scene

Only the changed scene is re-captured

3. Re-stitch

New segment replaces the old one in the final MP4