Events

All events are props on WaveformRecorderView. Payload types are in the API reference.

Event	Payload	When
onStateChange	{ state, durationMs }	On every state change.
onMeter	{ amplitude, peak, db }	meterUpdatesPerSecond times per second while recording.
onComplete	see below	Once the final file is written after stop() or an automatic stop.
onMaxDurationReached	none	When maxDurationMs is reached, right before the automatic stop.
onPermissionDenied	none	When start() cannot get microphone permission.
onError	{ message, code? }	Warnings and failures, see error codes.
onSeek	{ positionMs }	In preview, at the end of a scrub and after seekPreview().
onPlaybackTimeUpdate	{ positionMs, durationMs }	About 30 times per second while preview audio plays.
onSlideProgress	{ cancelProgress, lockProgress }	While the user drags on the view during recording.
onSlideCancel	none	Once per drag, when the cancel threshold is crossed.
onSlideLock	none	Once per drag, when the lock threshold is crossed.
onSilenceDetected	{ durationMs }	Once per quiet stretch, see Silence detection.
onPcmChunk	{ chunk, sampleRate, channels, bytesPerSample, timestampMs }	About every pcmChunkMs while PCM streaming is on, see PCM stream.

onStateChange

state is one of 'idle', 'recording', 'paused', 'preview', 'stopped' or 'error'. durationMs is the recorded time so far, without the time spent paused. See Segments, pause and preview for the transitions.

onMeter

Field	Meaning
amplitude	Current level in [0, 1], the value used for the newest bar.
peak	Highest amplitude so far in this session.
db	Current level in dBFS. 0 is full scale, quieter is more negative.

The two platforms measure the level differently, so the same sound gives different numbers. iOS reports the average power over the last tick and maps it as 10^(db / 20), with anything at or below -60 dB shown as 0. Android reports the peak since the last tick and maps it as the square root of the linear peak. Do not compare raw values across platforms.

onComplete

Field	Type	Meaning
uri	string	file:// URI of the recording.
durationMs	number	Recorded duration, summed over all segments.
format	string	The output.format you asked for.
mimeType	string	MIME type, see Formats.
sizeBytes	number	File size.
sampleRate	number	Sample rate in Hz.
channels	number	Channel count.
samples	number[]	64 values in [0, 1] for a chat bubble, see Export.
peakAmplitude	number	Highest meter amplitude of the session.

onComplete does not fire when nothing was recorded, when cancel() is called, or when minDurationMs discards the recording.

Error codes

onError is used for real failures and for warnings about calls that were ignored. Check code:

Code	Meaning
start	The recorder could not start. The state becomes 'error'.
session	iOS could not configure the audio session. The state becomes 'error'.
resume	Resuming after pause() failed. The state becomes 'error'.
media-recorder	Android: MediaRecorder reported an error while recording.
min-duration	stop() was called below minDurationMs. The recording was discarded.
preview-disabled	enterPreview() was called with enablePreview={false}.
continue-disabled	resume() was called in preview with enableContinueRecording={false}.
preview-snapshot	Preview could not be prepared, for example because nothing was recorded yet.
preview-load	The preview player could not load the audio.
concat	Joining segments failed. onComplete still fires with the first segment so the audio is not lost.
format-unsupported	opus was requested on Android below API 29. The engine records AAC instead.
pcm-stream	iOS: PCM streaming could not open the WAV file.
background-capability	iOS: backgroundRecording is on but audio is missing from UIBackgroundModes. Fires once.

From 'error', calling start() begins a new session.