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/*
* Copyright (C) 2006 The Android Open Source Project
*
* Licensed 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.
*/
package com.android.speechrecorder;
import java.io.IOException;
import java.io.InputStream;
import android.media.AudioRecord;
import static android.media.AudioFormat.CHANNEL_IN_MONO;
import static android.media.AudioFormat.ENCODING_PCM_16BIT;
import static android.media.MediaRecorder.AudioSource.VOICE_RECOGNITION;
/**
* Provides an InputStream like API over {@code android.media.AudioRecord}.
*
* <b>Not thread safe.</b>
*/
public final class MicrophoneInputStream extends InputStream {
private final int mSampleRate;
private final int mBufferSize;
private final AudioRecord mAudioRecord;
private boolean mRecording;
public MicrophoneInputStream(int sampleRate) throws IOException {
mSampleRate = sampleRate;
mBufferSize = AudioRecord.getMinBufferSize(sampleRate,
CHANNEL_IN_MONO, ENCODING_PCM_16BIT);
mAudioRecord = createAudioRecord();
mRecording = false;
}
private AudioRecord createAudioRecord() throws IOException {
AudioRecord ar = new AudioRecord(VOICE_RECOGNITION,
mSampleRate, CHANNEL_IN_MONO, ENCODING_PCM_16BIT, mBufferSize);
if (ar.getState() != AudioRecord.STATE_INITIALIZED) {
ar.release();
throw new IOException("Unable to create AudioRecord");
}
return ar;
}
private void maybeStartRecording() throws IOException {
if (mRecording) {
return;
}
mAudioRecord.startRecording();
int recordingState = mAudioRecord.getRecordingState();
if (recordingState != AudioRecord.RECORDSTATE_RECORDING) {
throw new IOException("Unexpected recordingState: " + recordingState);
}
mRecording = true;
}
@Override
public int read() throws IOException {
throw new UnsupportedOperationException("Single byte read.");
}
@Override
public int read(byte[] b, int offset, int length) throws IOException {
maybeStartRecording();
final int ret = mAudioRecord.read(b, offset, length);
if (ret == AudioRecord.ERROR_INVALID_OPERATION ||
ret == AudioRecord.ERROR_BAD_VALUE) {
throw new IOException("AudioRecord.read returned: " + ret);
}
return ret;
}
@Override
public void close() throws IOException {
mAudioRecord.stop();
mAudioRecord.release();
}
}
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