Android Studio - 获取录制的声级

Question

我正在尝试构建一个具有录音功能的应用程序。我遵循了 Android 开发人员文档中的指南 here，并创建了包含以下代码的 AudioRecordTest Class：

package com.example.ssresilience;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;

import android.os.Bundle;

import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import android.media.MediaPlayer;
import android.media.MediaRecorder;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;

import java.io.IOException;

public class AudioRecordTest extends AppCompatActivity {

    private static final String LOG_TAG = "AudioRecordTest";
    private static final int REQUEST_RECORD_AUDIO_PERMISSION = 200;
    private static String fileName = null;

    private RecordButton recordButton = null;
    private MediaRecorder recorder = null;

    private PlayButton playButton = null;
    private MediaPlayer player = null;

    // Requesting permission to RECORD_AUDIO
    private boolean permissionToRecordAccepted = false;
    private String [] permissions = {Manifest.permission.RECORD_AUDIO};

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode){
            case REQUEST_RECORD_AUDIO_PERMISSION:
                permissionToRecordAccepted  = grantResults[0] == PackageManager.PERMISSION_GRANTED;
                break;
        }
        if (!permissionToRecordAccepted ) finish();

    }

    private void onRecord(boolean start) {
        if (start) {
            startRecording();
        } else {
            stopRecording();
        }
    }

    private void onPlay(boolean start) {
        if (start) {
            startPlaying();
        } else {
            stopPlaying();
        }
    }

    private void startPlaying() {
        player = new MediaPlayer();
        try {
            player.setDataSource(fileName);
            player.prepare();
            player.start();
        } catch (IOException e) {
            Log.e(LOG_TAG, "prepare() failed");
        }
    }

    private void stopPlaying() {
        player.release();
        player = null;
    }

    void startRecording() {
        recorder = new MediaRecorder();
        recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
        recorder.setOutputFile(fileName);
        recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);

        try {
            recorder.prepare();
        } catch (IOException e) {
            Log.e(LOG_TAG, "prepare() failed");
        }

        recorder.start();
    }

    private void stopRecording() {
        recorder.stop();
        recorder.release();
        recorder = null;
    }

    class RecordButton extends androidx.appcompat.widget.AppCompatButton {
        boolean mStartRecording = true;

        OnClickListener clicker = new OnClickListener() {
            public void onClick(View v) {
                onRecord(mStartRecording);
                if (mStartRecording) {
                    setText("Stop recording");
                } else {
                    setText("Start recording");
                }
                mStartRecording = !mStartRecording;
            }
        };

        public RecordButton(Context ctx) {
            super(ctx);
            setText("Start recording");
            setOnClickListener(clicker);
        }
    }

    class PlayButton extends androidx.appcompat.widget.AppCompatButton {
        boolean mStartPlaying = true;

        OnClickListener clicker = new OnClickListener() {
            public void onClick(View v) {
                onPlay(mStartPlaying);
                if (mStartPlaying) {
                    setText("Stop playing");
                } else {
                    setText("Start playing");
                }
                mStartPlaying = !mStartPlaying;
            }
        };

        public PlayButton(Context ctx) {
            super(ctx);
            setText("Start playing");
            setOnClickListener(clicker);
        }
    }

    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);

        // Record to the external cache directory for visibility
        fileName = getExternalCacheDir().getAbsolutePath();
        fileName += "/audiorecordtest.3gp";

        ActivityCompat.requestPermissions(this, permissions, REQUEST_RECORD_AUDIO_PERMISSION);

        LinearLayout ll = new LinearLayout(this);
        recordButton = new RecordButton(this);
        ll.addView(recordButton,
                new LinearLayout.LayoutParams(
                        ViewGroup.LayoutParams.WRAP_CONTENT,
                        ViewGroup.LayoutParams.WRAP_CONTENT,
                        0));
        playButton = new PlayButton(this);
        ll.addView(playButton,
                new LinearLayout.LayoutParams(
                        ViewGroup.LayoutParams.WRAP_CONTENT,
                        ViewGroup.LayoutParams.WRAP_CONTENT,
                        0));
        getAmplitude();
        setContentView(ll);
    }

    @Override
    public void onStop() {
        super.onStop();
        if (recorder != null) {
            recorder.release();
            recorder = null;
        }

        if (player != null) {
            player.release();
            player = null;
        }
    }
}

录制开始/停止过程，以及使用媒体播放器播放音频似乎工作正常，但在我的情况下，这并不是我想要实现的。

我希望在此示例中以某种方式实现一个功能，即 returns 我点击“停止录音”后立即记录录音机音量（可能以分贝为单位？），然后打印出来。我看过许多其他示例，但其中 none 似乎有效，因为一旦调用开始录制的方法，应用程序就会崩溃。考虑到这一点，这就是为什么我要坚持这个例子。

有什么想法吗？

Answer 1

想通了！

我不得不在启动和停止方法上调用方法 getMaxAmplitude()，如下所示：

    void startRecording() {
        recorder = new MediaRecorder();
        recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
        recorder.setOutputFile(fileName);
        recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
        try {
            recorder.prepare();
        } catch (IOException e) {
            Log.e(LOG_TAG, "prepare() failed");
        }
        recorder.start();
        audiolevel = recorder.getMaxAmplitude();
        System.out.println(audiolevel);
    }

    private void stopRecording() {
        audiolevelprocessed = recorder.getMaxAmplitude();
        System.out.println(audiolevelprocessed);
        recorder.stop();
        recorder.release();
        recorder = null;
    }

这两次存储和打印最大振幅，第一个始终为 0。如果这两种方法都不存在，我总是将 0 作为打印值。不完全确定为什么会发生这种情况，但如您所见，我已将这两种情况存储在不同的变量中，现在可以使用第二个。

Android Studio - 获取录制的声级

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audio

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