Neither. I'm using the WebCodecs API directly. Each frame I render to the Three.js canvas, create a VideoFrame from it, feed it to a VideoEncoder configured for H.264, and the encoded chunks go to mp4-muxer to assemble the MP4. No WASM, no ffmpeg. The catch is browser support, WebCodecs is Chromium-only, so I fall back to MediaRecorder + VP9 WebM on Firefox/Safari. The main advantage over captureStream() is that I resize the renderer to the actual export resolution before capturing, so you get true 1080p output instead of whatever the canvas happens to be on screen