A continuous ambient memory recorder. It holds up to the last 45 minutes of sound in RAM and writes to storage only when you explicitly ask it to.
Audio Blackbox is a free, open-source Android app that continuously keeps the last minutes of ambient sound in RAM, in a rolling buffer of 5 to 45 minutes (5-minute steps), and writes it to local storage only when you explicitly tap Save.
It solves a problem a normal voice recorder cannot: you only realize something mattered after it was already said, once the recorder button is no longer any use. Audio Blackbox is always listening into its own volatile memory, so tapping Save exports whatever was said in the preceding 5 to 45 minutes as a local .m4a or .wav file, no rewind needed.
Unlike a normal recorder or a cloud-backed transcription app, Audio Blackbox has no INTERNET permission in its manifest, no analytics SDK, and no account: nothing is written to disk, and nothing leaves the device, until you decide to save it.
Continuous ambient capture without wearing out your SSD, draining your battery, or uploading a single byte to the cloud.
Captured an unexpected joke, brainstorm breakthrough, or critical instruction? Tap save and Audio Blackbox writes the last 5 to 45 minutes, in 5-minute steps, directly to disk.
INTERNET permission is strictly absent from the application manifest. It cannot send telemetry, ping analytics, or upload sound. Full offline guarantee.
Zero disk I/O and zero IPC allocations on the audio capture thread. Guaranteed single-writer synchronization eliminates dropouts and GC pauses.
When another foreground app takes the microphone, Android silences our stream rather than failing it. The service detects that directly and pauses, then resumes the moment the mic is free. The gap is preserved as true silence, so exported timestamps never drift.
Foreground service with active notification and guided manufacturer battery-optimization bypass keeps recording uninterrupted even with the screen off.
Manage, listen, seek, and share your exported `.m4a` (AAC) or `.wav` recordings directly to messaging apps and clouds via Android Sharesheets.
Test the interactive cockpit simulator: real-time VU meter, Korry annunciator status lights, "REMOVE BEFORE FLIGHT" safety tag, and flight tape memory buffer in your browser.
Audio Blackbox allocates its circular buffer once at startup. Slide to calculate exact RAM consumption.
Built on Jetpack Compose and Material 3, dressed in a fixed cockpit palette — FED-STD-595 International Orange, NVIS green, Korry annunciator amber — so the state of the recorder reads at a glance.
Once installed, the app is a background service you rarely open: it listens, and you tap Save when something is worth keeping.
RECORD_AUDIO permission (and, on Android 13+, POST_NOTIFICATIONS) when prompted..m4a (AAC) or .wav file — nothing needs to be pre-armed or predicted.Join our tester community in 3 simple steps.
The buffer holds 5 to 45 minutes of audio, adjustable in 5-minute steps. At the default Voice preset (16,000 Hz mono), the full 45-minute buffer uses about 82.4 MB of RAM; the two higher-fidelity presets (32,000 Hz mono and 44,100 Hz stereo) use proportionally more, up to roughly 454 MB at 45 minutes of 44,100 Hz stereo. The exact figure for any window and preset is shown live by the calculator in the Memory Architecture section of this page.
No. The INTERNET permission is strictly absent from the app's Android manifest, so it cannot send telemetry, ping analytics, or upload sound. Recorded audio stays on the device: in volatile RAM until you save it, and in local storage after that.
Yes. Audio Blackbox runs as a foreground service with a persistent notification, and it includes a guided flow to bypass manufacturer battery optimization, so capture continues uninterrupted with the screen locked.
Yes. It is free and licensed under the GNU General Public License v3.0, with the full source code published on GitHub.
Android 10 (API level 29) and newer.
The app is currently in open beta on Google Play, gated by a Google Group. Join the group, accept the web test invitation Google Play sends to your account, then install from the Play Store on your device. Links for all three steps are in the Open Beta section of this page.
A normal recorder only captures audio after you press record, so anything said before that moment is lost. Audio Blackbox keeps recording continuously into a rolling RAM buffer and only writes to storage when you tap Save, so you can capture the last 5 to 45 minutes of something that already happened. Nothing is written to disk, and nothing leaves the device, until you decide to save it.