| /* |
| * Copyright (C) 2011 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 android.media.audiofx; |
| |
| import android.util.Log; |
| |
| /** |
| * Automatic Gain Control (AGC). |
| * <p>Automatic Gain Control (AGC) is an audio pre-processor which automatically normalizes the |
| * output of the captured signal by boosting or lowering input from the microphone to match a preset |
| * level so that the output signal level is virtually constant. |
| * AGC can be used by applications where the input signal dynamic range is not important but where |
| * a constant strong capture level is desired. |
| * <p>An application creates a AutomaticGainControl object to instantiate and control an AGC |
| * engine in the audio framework. |
| * <p>To attach the AutomaticGainControl to a particular {@link android.media.AudioRecord}, |
| * specify the audio session ID of this AudioRecord when creating the AutomaticGainControl. |
| * The audio session is retrieved by calling |
| * {@link android.media.AudioRecord#getAudioSessionId()} on the AudioRecord instance. |
| * <p>On some devices, an AGC can be inserted by default in the capture path by the platform |
| * according to the {@link android.media.MediaRecorder.AudioSource} used. The application should |
| * call AutomaticGainControl.getEnable() after creating the AGC to check the default AGC activation |
| * state on a particular AudioRecord session. |
| * <p>See {@link android.media.audiofx.AudioEffect} class for more details on |
| * controlling audio effects. |
| */ |
| |
| public class AutomaticGainControl extends AudioEffect { |
| |
| private final static String TAG = "AutomaticGainControl"; |
| |
| /** |
| * Checks if the device implements automatic gain control. |
| * @return true if the device implements automatic gain control, false otherwise. |
| */ |
| public static boolean isAvailable() { |
| return AudioEffect.isEffectTypeAvailable(AudioEffect.EFFECT_TYPE_AGC); |
| } |
| |
| /** |
| * Creates an AutomaticGainControl and attaches it to the AudioRecord on the audio |
| * session specified. |
| * @param audioSession system wide unique audio session identifier. The AutomaticGainControl |
| * will be applied to the AudioRecord with the same audio session. |
| * @return AutomaticGainControl created or null if the device does not implement AGC. |
| */ |
| public static AutomaticGainControl create(int audioSession) { |
| AutomaticGainControl agc = null; |
| try { |
| agc = new AutomaticGainControl(audioSession); |
| } catch (IllegalArgumentException e) { |
| Log.w(TAG, "not implemented on this device "+agc); |
| } catch (UnsupportedOperationException e) { |
| Log.w(TAG, "not enough resources"); |
| } catch (RuntimeException e) { |
| Log.w(TAG, "not enough memory"); |
| } |
| return agc; |
| } |
| |
| /** |
| * Class constructor. |
| * <p> The constructor is not guarantied to succeed and throws the following exceptions: |
| * <ul> |
| * <li>IllegalArgumentException is thrown if the device does not implement an AGC</li> |
| * <li>UnsupportedOperationException is thrown is the resources allocated to audio |
| * pre-procesing are currently exceeded.</li> |
| * <li>RuntimeException is thrown if a memory allocation error occurs.</li> |
| * </ul> |
| * |
| * @param audioSession system wide unique audio session identifier. The AutomaticGainControl |
| * will be applied to the AudioRecord with the same audio session. |
| * |
| * @throws java.lang.IllegalArgumentException |
| * @throws java.lang.UnsupportedOperationException |
| * @throws java.lang.RuntimeException |
| */ |
| private AutomaticGainControl(int audioSession) |
| throws IllegalArgumentException, UnsupportedOperationException, RuntimeException { |
| super(EFFECT_TYPE_AGC, EFFECT_TYPE_NULL, 0, audioSession); |
| } |
| } |