Defensive screen + audio recorder

Koder Reel

Record everything. No source lost.

A screen and multi-source audio recorder built on a simple rule: never leave you guessing whether the recording is good. Captures every connected mic, Bluetooth, USB, line-in, and system audio by default. Warns the moment anything goes silent.

Download Reel See the problem we fix

koder-reel — recording

00:12:48 2 displays · 4 audio sources

Built-in mic

Bluetooth — AirPods Pro

System loopback

USB — Røde NT-USB

SILENT

Røde NT-USB silent for 4s — check the cable

Pause

● Stop

Audit

The OBS silent-recording problem

A teammate lost an hour of footage of a public-sector tender because OBS had no audio source selected and signaled nothing during the recording. Reel makes that class of failure structurally impossible.

The status quo

Audio source defaults to None or one source — opt-in model.
No live level meters on the record button — you can't see if it's working.
No warning when a source goes silent mid-recording.
No detection when other apps (browser tab, Discord, Zoom) are playing audio outside the capture set.
No post-record audit — you find out hours later that the file is unusable.

The Reel way

Every connected audio source is captured by default — opt-out, not opt-in.
Pre-flight checklist with live dB meters before the record button activates.
Persistent red banner the moment any source falls silent for 3 seconds.
Yellow banner when active media (browser, Discord, Zoom) is outside the capture set, with one-click "add".
Post-record audit screen + embedded manifest readable by editors.

Defensive UX, end to end

Every rule of engines/media/capture RFC-002 (R1–R12) shipped on day one.

Capture-all-by-default

Mic + Bluetooth + USB + line-in + system loopback all simultaneously, every time. You don't pick — you opt out.

Live dB meters in the HUD

Every source's level is visible while you record. Per-source dB bar plus a single global "is everything alive" indicator.

Anomaly banners that don't lie

Red persistent banner the moment any source goes silent for ≥3 seconds. Can't be dismissed while the anomaly persists.

System media-session aware

Polls OS media APIs. Yellow banner if a browser tab, Discord, Zoom or any active stream is outside the capture set. One click to add.

Post-record audit

Every source, every silent segment by timestamp, every hot-plug event. Plus a .kcap.json sidecar manifest readable by editors.

Multi-track MP4 output

One track per audio source plus a synthetic stereo mixdown for dumb players. Editors get clean separation; quick playback just works.

Webcam picture-in-picture

Optional webcam composite during record. Position, size and corner are persistent across sessions.

Three-button happy path

Record. Pause. Stop. Everything else lives in Settings. You don't need a manual to make a recording.

No editor, no streaming — on purpose

Reel produces clean multi-track files; we leave editing to editors. Live streaming is a separate ticket. Small surface, sharp focus.

Capability matrix

Where Reel runs and what each variant can do at v1.

Variant	Screen	Audio sources	Webcam PiP	Status
Desktop · Linux	Full · Window · Region	Mic + BT + USB + line-in + loopback	✓	v1 must-ship
Desktop · Windows	Full · Window · Region	Mic + BT + USB + line-in + loopback	✓	v1 must-ship
Web · Chrome 130+	Full · Window · Tab	Mic + tab audio	✓	v1 must-ship
Mobile · Android	Full display	Mic + system mix	✓	v1 must-ship
Desktop · macOS	—	Needs virtual audio driver	—	post-v1
CLI · Linux	Headless for CI / scripted	Same as desktop	—	post-v1
iOS	—	Sandbox forbids system audio outside the app's session	—	not planned

Frequently asked questions

Quick answers about what Reel covers and what it doesn't.

How is Reel different from OBS?

OBS is a streaming-and-recording studio with strong scene composition and a fragile audio model: source dropdown defaults to None, no warning when silent. Reel is a recorder with strong audio guarantees: every source captured by default, level meters always on, anomaly banners that can't be dismissed while a source is silent. Different priorities, different products.

Does Reel stream to Twitch / YouTube?

Not at v1. Live streaming is a separate ticket — the recorder path needs to be rock-solid first. Recordings export to standard .mp4 that any uploader handles.

Why is there no macOS desktop variant?

macOS sandboxes system audio behind a virtual driver requirement (BlackHole, Loopback, etc.). Shipping a clean install path needs an extra ticket; we'd rather ship a great Linux/Windows experience first than a half-broken Mac one.

What's the audio file format?

A single .mp4 with one PCM/AAC track per audio source plus a synthetic stereo mixdown for players that can't enumerate tracks. A sidecar .kcap.json describes every source, silent segments, and hot-plug events — readable by editors and by the post-record audit screen.

Does Reel record without warning the people I'm capturing?

Reel respects the OS-level capture indicator (screen + mic camera dot). It does not bypass any privacy permission. You're responsible for telling people they're being recorded — Reel doesn't hide that from anyone.

Where do recordings go?

Local disk, in a Reel folder configurable in Settings. No cloud upload at v1. Opt-in upload to Koder Drive or Koder Hub is a future ticket.