Recording
Recording
Starting recordings, pre- and post-trigger buffers, the ring buffer, recording destinations, and WAV file format.
Overview
Chirps records uncompressed PCM WAV files directly to your device’s storage. Recordings are organised in dated subfolders and sync to iCloud Drive automatically if iCloud is enabled.
Starting and stopping a recording
- Start the audio stream (tap the play button in the control bar).
- Tap the record button (circle with inner dot).
- The recording automaically stops after post-trigger seconds, or if stopped using the stop button.
If the stream is not running, record button is inactive. Start the stream, and let pre-trigger seconds pass. Then the record button becomes active.
Pre-trigger buffer
The pre-trigger buffer captures audio from before you pressed record. Its purpose is to handle the reaction-time gap — if a bat call, bird alarm, or other event happens just before you respond, the call is captured anyway.
Default: 5 seconds.
Range: 0.5 to 9.5 seconds (adjustable in 0.5 s steps).
The pre-trigger is drawn from the ring buffer. The ring buffer holds the most recent N seconds of audio continuously in memory while the stream is running. When you start a recording, Chirps reaches back into the ring buffer by the pre-trigger duration and begins the WAV file from that earlier point.
Record becomes available only when enough buffered audio exists for the chosen pre-trigger value. If you start streaming and the pre-trigger buffer is still filling, wait until the buffer is ready before starting the recording.
Adjust the pre-trigger in Settings → Recording → Pre Trigger. Or, preferraly, the pre-trig bar (orange line) on the plots can be moved. The round knob at the bottom of the bar indicates the current value of pre-trigger.
Post-trigger duration
The post-trigger sets how long Chirps continues recording after you stop (tap the record button again). This is useful when you expect an event to continue for a known duration after you react.
Default: 5 seconds.
Range: 0.5 to 10 seconds.
Post-trigger recording is silent — the button indicator shows the session is still writing. The file closes automatically when the post-trigger expires.
Adjust in Settings → Recording → Post Trigger. Or, from the control panel in the main window.
Ring buffer duration
The ring buffer holds a rolling window of recent audio in memory. It is the source for both the visual display and the pre-trigger audio.
Default: 10 seconds.
Range: 2 to 10 seconds, adjustable in 0.1 second steps.
A longer ring buffer means more audio is available for pre-trigger capture. It also means the spectrogram display can retain more history before columns are overwritten.
Setting a very long ring buffer on older devices may increase memory pressure. If the app is terminated by the OS during long sessions, consider reducing it.
The ring buffer duration setting takes effect when the stream is (re)started. It cannot be changed while the stream is running.
Adjust in Settings → Recording → Ring Buffer. Or, from the control panel in the main window.
Recording destination
Chirps can write recordings to:
App Documents (default) — the app’s private Documents directory on your device. Files here sync to iCloud Drive if iCloud Drive is enabled for Chirps (set in iOS Settings → [Your Name] → iCloud → Chirps). You can access them in the Files app under Chirps.
Custom folder — any folder in the Files app, including iCloud Drive folders, On My iPhone/iPad folders, or folders in other document providers. Tap Choose Folder in Settings → Recording and pick a destination using the system folder picker.
To reset to App Documents, tap App Documents in Settings → Recording.
The recording destination is shown with its full path below the destination name in Settings. If the folder has been moved or deleted, Chirps falls back to App Documents.
Dated subfolders
Recordings are written into subfolders named by date in YYYY-MM-DD format. Each recording session that begins on a new calendar day creates a new subfolder. This keeps long field campaigns organised without manual folder management.
File naming and format
File name format: YYYY-MM-DD_HH-MM-SS.wav
Format: Uncompressed linear PCM WAV.
Sample rate: Matches the active hardware sample rate at time of recording.
Bit depth: Set in Settings → Input → Record File Bit Depth — 16, 24, or 32-bit.
Channels: Mono (one channel captured per recording).
The file’s sample rate and bit depth are written into the WAV header. Any standard audio editor or analysis tool (Audacity, Raven Pro, BatScope, etc.) can open the files without conversion.
iCloud Drive sync
If iCloud Drive is enabled for Chirps, files written to App Documents appear in the Chirps folder in iCloud Drive automatically. No Chirps account is required. Sync is handled entirely by the iOS operating system.
Files recorded to a custom folder that is already inside iCloud Drive also sync normally.
To access your recordings on a Mac: open Finder → iCloud Drive → Chirps, or use the Files app on a connected iPad.
Monitoring during recording
Monitoring (passthrough or heterodyne) can run simultaneously with recording. There is no crosstalk — the monitoring output does not appear in the WAV file. The WAV contains exactly what the microphone captures.