voicehat

Voice Hat driver for Android Things

This driver exposes I2S microphone input and audio output from a VoiceHat to standard Android audio APIs using the Android Things AudioInputDriver and the AudioOutputDriver.

At this moment the driver has only been tested on the Raspberry Pi 3.

NOTE: these drivers are not production-ready. They are offered as sample implementations of Android Things user space drivers for common peripherals as part of the Developer Preview release. There is no guarantee of correctness, completeness or robustness.

How to use the driver

Gradle dependency

To use the voicehat driver, simply add the line below to your project's build.gradle, where <version> matches the last version of the driver available on jcenter.

dependencies {
    compile 'com.google.android.things.contrib:driver-voicehat:<version>'
}

In your AndroidManifest, add the following three permissions:

<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
<uses-permission android:name="com.google.android.things.permission.MANAGE_AUDIO_DRIVERS" />

Sample usage

// import the VoiceHat driver
import com.google.android.things.contrib.driver.voicehat.VoiceHat;

// Start voice hat.
mVoiceHat = new VoiceHat(
    "I2S1",
    "BCM16",
    AUDIO_FORMAT_STEREO
  );
mVoiceHat.registerAudioInputDriver();
mVoiceHat.registerAudioOutputDriver();

// Make sure to call mVoiceHatDriver.close() in the onDestroy() method in your activity

// Start recording audio.
mAudioRecord = new AudioRecord.Builder()
    .setAudioSource(MediaRecorder.AudioSource.MIC)
    .setAudioFormat(AUDIO_FORMAT_IN_MONO)
    .setBufferSizeInBytes(inputBufferSize)
    .build();

ByteBuffer audioData = ByteBuffer.allocateDirect(SAMPLE_BLOCK_SIZE);
int result =
    mAudioRecord.read(audioData, audioData.capacity(), AudioRecord.READ_BLOCKING);
if (result < 0) {
    Log.e(TAG, "error reading from audio stream:" + result);
    return;
}
// Audio data stored in `audioData`.

// Play audio
mAudioTrack = new AudioTrack.Builder()
    .setAudioFormat(AUDIO_FORMAT_OUT_MONO)
    .setBufferSizeInBytes(outputBufferSize)
    .build();
mAudioTrack.play();

ByteBuffer audioData = Example.getSampleAudioData(SAMPLE_BLOCK_SIZE);
mAudioTrack.write(audioData, audioData.remaining(), AudioTrack.WRITE_BLOCKING);

License

Copyright 2016 Google Inc.

Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.