Audio Sampling Package

carp_audio_package adds the phone's microphone to a CARP Mobile Sensing (CAMS) study. It measures the noise level around the participant and records audio to files, for example to study the sound environment or a participant's cough. It also defines data types for videos and images that your app captures.

The package is named after audio for historical reasons, but it is a media package. Its classes are named for media, such as MediaSamplingPackage, and its library is package:carp_audio_package/media.dart. Noise levels come from the noise_meter plugin and recordings from flutter_sound.

Features

Measure types

NOISE is event-based, AUDIO records from when its task starts until the task stops, and VIDEO and IMAGE collect nothing by themselves. For the kinds of measures, see Event-based and one-time measures.

Requirements

How it works

Adding the package to a study takes three steps:

1. Register the package

   Registering MediaSamplingPackage makes the four measure types and their data classes known to CAMS.

2. Add the measures to a protocol

   NOISE starts with an ImmediateTrigger() and schedules its own sampling windows. Each AUDIO recording needs a task that stops, for example after a fixed duration.

3. Deploy the protocol

   CAMS asks the participant for microphone access, samples noise in short windows and adds an audio measurement each time a recording stops.

This example registers the package and samples the noise level for 10 seconds every 5 minutes, the default:

import 'package:carp_core/carp_core.dart' hide Smartphone;
import 'package:carp_mobile_sensing/carp_mobile_sensing.dart';
import 'package:carp_audio_package/media.dart';

void main() {
  CarpMobileSensing.ensureInitialized();
  SamplingPackageRegistry().register(MediaSamplingPackage());

  final protocol = SmartphoneStudyProtocol(
    ownerId: 'owner@example.com',
    name: 'Ambient noise',
    dataEndPoint: SQLiteDataEndPoint(),
  );
  final phone = Smartphone();
  protocol.addPrimaryDevice(phone);

  // An event-based measure starts once and runs until the study pauses
  protocol.addTaskControl(
    ImmediateTrigger(),
    BackgroundTask(measures: [Measure(type: MediaSamplingPackage.NOISE)]),
    phone,
  );

  // ... deploy the protocol and start sampling
}

Next steps