android - Android:Media Recorder无法启动

Question

我有个问题。我目前正在开发一个仅记录我的声音而不记录来自手机的声音的应用程序。我读到“ MediaRecorder.AudioSource.VOICE_UPLINK ”可以完成此任务。
这是我的Java代码。

package com.khagendra.zip_it;

import android.media.MediaRecorder;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

import java.io.IOException;


public class Settings extends Fragment {
    Button start,stop;
   boolean fingerDown = false;
    private Thread thread;
    private int lastLevel;
    public Settings(){

    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.settings_activity,container,false);
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);


        start = (Button) view.findViewById(R.id.bstart);
        stop = (Button) view.findViewById(R.id.bstop);
        stop.setEnabled(false);
        final SoundMeter sm = new SoundMeter();

        start.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.d("level","started");
                sm.start();
                sm.getAmplitude();
            }
        });

        stop.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                v.setSelected(false);
                start.setEnabled(true);
                stop.setEnabled(false);
                Log.d("level","stopped");
                sm.stop();
            }
        });


    }
    public class SoundMeter {

        private MediaRecorder mRecorder = null;

        public void start() {
            if (mRecorder == null) {
                mRecorder = new MediaRecorder();
                mRecorder.setAudioSource(MediaRecorder.AudioSource.VOICE_UPLINK);
                mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
                mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
                mRecorder.setOutputFile("/dev/null");

                try {
                    mRecorder.prepare();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                try {
                       mRecorder.start();
                }catch (Throwable t){
                    t.printStackTrace();
                    Log.d("level_error",""+t);

                }
            }
        }

        public void stop() {
            thread.interrupt();
            thread = null;

            if (mRecorder != null) {
                mRecorder.stop();
                mRecorder.release();
                mRecorder = null;
            }
        }

        public void getAmplitude() {



            thread = new Thread(new Runnable() {
                public void run() {
                    while(thread != null && !thread.isInterrupted()){
                        //Let's make the thread sleep for a the approximate sampling time
                        try{Thread.sleep(75);}catch(InterruptedException ie){ie.printStackTrace();}
                        //readAudioBuffer();//After this call we can get the last value assigned to the lastLevel variable

                        getActivity().runOnUiThread(new Runnable() {

                            @Override
                            public void run() {

                                if (mRecorder != null) {
                                          lastLevel = mRecorder.getMaxAmplitude();
                                    if(lastLevel>2000)
                                    Log.d("level", "medium:" + lastLevel);

                                }

                            }
                        });
                    }
                }
            });
            thread.start();



        }
    }
}

这是我的logcat输出:

06-17 18:52:37.994  12129-12129/com.khagendra.zip_it D/level﹕ started
06-17 18:52:38.034  12129-12129/com.khagendra.zip_it E/MediaRecorder﹕ start failed: -2147483648
06-17 18:52:38.054  12129-12129/com.khagendra.zip_it W/System.err﹕ java.lang.RuntimeException: start failed.
06-17 18:52:38.064  12129-12129/com.khagendra.zip_it W/System.err﹕ at android.media.MediaRecorder.start(Native Method)
06-17 18:52:38.064  12129-12129/com.khagendra.zip_it W/System.err﹕ at com.khagendra.zip_it.Settings$SoundMeter.start(Settings.java:103)
06-17 18:52:38.064  12129-12129/com.khagendra.zip_it W/System.err﹕ at com.khagendra.zip_it.Settings$1.onClick(Settings.java:69)
06-17 18:52:38.064  12129-12129/com.khagendra.zip_it W/System.err﹕ at android.view.View.performClick(View.java:4432)
06-17 18:52:38.064  12129-12129/com.khagendra.zip_it W/System.err﹕ at android.view.View$PerformClick.run(View.java:18338)
06-17 18:52:38.064  12129-12129/com.khagendra.zip_it W/System.err﹕ at android.os.Handler.handleCallback(Handler.java:725)
06-17 18:52:38.064  12129-12129/com.khagendra.zip_it W/System.err﹕ at android.os.Handler.dispatchMessage(Handler.java:92)
06-17 18:52:38.064  12129-12129/com.khagendra.zip_it W/System.err﹕ at android.os.Looper.loop(Looper.java:137)
06-17 18:52:38.064  12129-12129/com.khagendra.zip_it W/System.err﹕ at android.app.ActivityThread.main(ActivityThread.java:5283)
06-17 18:52:38.064  12129-12129/com.khagendra.zip_it W/System.err﹕ at java.lang.reflect.Method.invokeNative(Native Method)
06-17 18:52:38.074  12129-12129/com.khagendra.zip_it W/System.err﹕ at java.lang.reflect.Method.invoke(Method.java:511)
06-17 18:52:38.074  12129-12129/com.khagendra.zip_it W/System.err﹕ at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
06-17 18:52:38.074  12129-12129/com.khagendra.zip_it W/System.err﹕ at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
06-17 18:52:38.074  12129-12129/com.khagendra.zip_it W/System.err﹕ at dalvik.system.NativeStart.main(Native Method)
06-17 18:52:38.074  12129-12129/com.khagendra.zip_it D/level_error﹕ java.lang.RuntimeException: start failed.

我知道有人建议使用“ MediaRecorder.AudioSource.MIC ”。所以，我已经尝试过了。它的工作正常，但我希望“ VOICE_UPLINK ”或“ VOICE_DOWNLINK ”起作用。任何帮助将不胜感激。

附加信息:我正在考虑在通话中实施相同的操作，以便仅录制语音。但是现在我希望这个工作。

Answer 1

此功能需要权限CAPTURE_AUDIO_OUTPUT。但是，此权限仅保留给系统应用程序，不能由第三方应用程序使用。这意味着，只要您的应用不是系统应用，就无法使用它。使您的应用成为系统应用将需要一些复杂的东西，并且需要一个有root用户的设备/仅在有root用户的设备上才能运行。

从文档:

VOICE_DOWNLINK

从VOICE_DOWNLINK来源进行捕获需要CAPTURE_AUDIO_OUTPUT权限。该权限保留供系统组件使用，不适用于第三方应用程序。

VOICE_UPLINK

从VOICE_UPLINK来源进行捕获需要CAPTURE_AUDIO_OUTPUT权限。该权限保留供系统组件使用，不适用于第三方应用程序。