99 lines
4.2 KiB
Java
99 lines
4.2 KiB
Java
/*
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* Copyright (C) 2011 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.media.audiofx;
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import android.util.Log;
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/**
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* Noise Suppressor (NS).
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* <p>Noise suppression (NS) is an audio pre-processor which removes background noise from the
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* captured signal. The component of the signal considered as noise can be either stationary
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* (car/airplane engine, AC system) or non-stationary (other peoples conversations, car horn) for
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* more advanced implementations.
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* <p>NS is mostly used by voice communication applications (voice chat, video conferencing,
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* SIP calls).
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* <p>An application creates a NoiseSuppressor object to instantiate and control an NS
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* engine in the audio framework.
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* <p>To attach the NoiseSuppressor to a particular {@link android.media.AudioRecord},
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* specify the audio session ID of this AudioRecord when creating the NoiseSuppressor.
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* The audio session is retrieved by calling
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* {@link android.media.AudioRecord#getAudioSessionId()} on the AudioRecord instance.
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* <p>On some devices, NS can be inserted by default in the capture path by the platform
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* according to the {@link android.media.MediaRecorder.AudioSource} used. The application should
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* call NoiseSuppressor.getEnable() after creating the NS to check the default NS activation
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* state on a particular AudioRecord session.
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* <p>See {@link android.media.audiofx.AudioEffect} class for more details on
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* controlling audio effects.
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*/
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public class NoiseSuppressor extends AudioEffect {
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private final static String TAG = "NoiseSuppressor";
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/**
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* Checks if the device implements noise suppression.
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* @return true if the device implements noise suppression, false otherwise.
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*/
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public static boolean isAvailable() {
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return AudioEffect.isEffectTypeAvailable(AudioEffect.EFFECT_TYPE_NS);
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}
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/**
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* Creates a NoiseSuppressor and attaches it to the AudioRecord on the audio
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* session specified.
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* @param audioSession system wide unique audio session identifier. The NoiseSuppressor
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* will be applied to the AudioRecord with the same audio session.
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* @return NoiseSuppressor created or null if the device does not implement noise
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* suppression.
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*/
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public static NoiseSuppressor create(int audioSession) {
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NoiseSuppressor ns = null;
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try {
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ns = new NoiseSuppressor(audioSession);
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} catch (IllegalArgumentException e) {
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Log.w(TAG, "not implemented on this device "+ns);
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} catch (UnsupportedOperationException e) {
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Log.w(TAG, "not enough resources");
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} catch (RuntimeException e) {
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Log.w(TAG, "not enough memory");
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}
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return ns;
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}
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/**
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* Class constructor.
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* <p> The constructor is not guarantied to succeed and throws the following exceptions:
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* <ul>
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* <li>IllegalArgumentException is thrown if the device does not implement an NS</li>
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* <li>UnsupportedOperationException is thrown is the resources allocated to audio
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* pre-procesing are currently exceeded.</li>
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* <li>RuntimeException is thrown if a memory allocation error occurs.</li>
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* </ul>
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*
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* @param audioSession system wide unique audio session identifier. The NoiseSuppressor
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* will be applied to the AudioRecord with the same audio session.
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*
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* @throws java.lang.IllegalArgumentException
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* @throws java.lang.UnsupportedOperationException
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* @throws java.lang.RuntimeException
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*/
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private NoiseSuppressor(int audioSession)
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throws IllegalArgumentException, UnsupportedOperationException, RuntimeException {
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super(EFFECT_TYPE_NS, EFFECT_TYPE_NULL, 0, audioSession);
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}
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}
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