Visual Export for fee[dB]ack

Visual Export creates an MP4 of the song currently configured in the fee[dB]ack player without having to play and screen-record it in real time. It exports the normal player or the active Splitscreen arrangement, so a separate video can be made for each guitar, bass, keys, and lyrics layout.

Export a video

1. Load a song and arrange the player exactly as it should appear: highway, camera, overlays, lyrics, and (if used) Splitscreen panels.
2. In the player Plugins rail, select Export video.
3. Choose the output resolution, frame rate, and bitrate, then select Render MP4.

The player is paused while the exporter renders timestamps directly and its previous position is restored afterwards. The generated MP4 downloads when FFmpeg has finished muxing its video and audio.

Player controls are deliberately excluded from the export. Ambient particles and other wall-clock visual effects are not synchronized as part of the deterministic render pass.

How it works

The browser asks each highway to draw an explicit song time, composites the visible player canvases and supported overlays, and encodes H.264 frames using WebCodecs. Hardware encoding is requested first and falls back automatically when the browser cannot provide it. The plugin server uses FFmpeg to mux those frames with the original song audio as AAC in a fast-start MP4.

The browser caches the static portion of the scene once per export: immutable backgrounds, borders, labels, and images are precomposed into offscreen layers, so per-frame work is limited to highway canvases and dynamic text/lyrics. Encoded frames are streamed to the server as they are produced. Export speed is therefore independent of the song's playback duration, but still depends on visualization cost, resolution, and hardware encoding performance.

While rendering, the progress line reports elapsed time and how far the render is from real time, and the finished export reports its render time and the encoder that produced it.

Optional: let the server fetch the song audio

Setting FEEDBACK_PUBLIC_ORIGIN to this host's own origin (for example http://127.0.0.1:5173) lets the plugin server fetch the song mix directly, so the browser skips downloading and re-uploading it. The server reports back whether it can do that, so the browser only skips the upload when it can — with the variable unset (the default), the audio is uploaded once to the export session as before, and nothing changes.

If the server is configured but the fetch fails (a 404, an auth wall, or a redirect, which it refuses), the export is not thrown away: the session is kept alive, the browser uploads the mix, and the mux is retried.

The server only ever contacts that configured origin, and it refuses redirects, so a song URL cannot redirect the fetch to another host.

Requirements

Visual Export needs four independent things. Only the first is a feedBack requirement; the rest are separate and are checked separately.

feedBack host (required for every export)

• window.highway.renderFrameAt(time), which paints one explicit chart time without sampling the playback clock. It arrived in feedBack commit f7c761c (Sep 16 2026); see get-flashbacks/feedBack issue #102.

The exporter also calls window.highway.getSongInfo() and window.highway.getSections(), but both are long-standing feedBack APIs that predate f7c761c by months and are not part of the export's floor.

There is deliberately no minHost version in the manifest. feedBack's VERSION file has read 0.3.0-alpha.2 since 2026-08-10 — before renderFrameAt() existed — and feedBack publishes no releases, so no version string identifies a build that can export. Rather than declare a number that is either too low or does not exist, the plugin checks for the interface itself and, when it is absent, says which build to update to.

Split Screen (required only when exporting a split layout)

When Split Screen is active, the export additionally needs its offline-render bridge: beginOfflineRender(), renderFrameAt(time), and endOfflineRender(). The bridge arrived in Split Screen 1.14.8 (commits 2301dd5 and 87e3622a); 1.14.7 is the last version without it. All three are required together, because Split Screen's renderFrameAt() refuses to paint unless beginOfflineRender() has already run — so a partial bridge could never export in the first place. The exporter checks all three up front and reports the missing ones by name instead of failing mid-render. Without Split Screen installed, single-highway export is unaffected.

WebCodecs (browser)

Chromium-family browser with H.264 VideoEncoder support. Missing WebCodecs is reported on its own, separately from any host or Split Screen problem.

FFmpeg (server)

FFmpeg reachable through PATH or the desktop application's bundled resources/bin folder. It muxes the encoded frames with the song audio and is only needed once rendering succeeds, so its absence surfaces as a muxing failure rather than a host compatibility error.

Limits

• The exporter prefers the song package's complete full_mix_url when available, even if the player is currently using an individual stem or native/JUCE routing. Songs without a complete mix fall back to the browser audio source, which is uploaded once to the export session unless FEEDBACK_PUBLIC_ORIGIN lets the server fetch it directly.
• Supported overlays are composited in the browser; advanced third-party CSS/SVG/filter effects may not reproduce pixel-for-pixel.
• Jumping Tab panes do not provide deterministic frame rendering and are not supported in offline split exports.

The runtime implementation is in screen.js, routes.py, and settings.html.