MediaRecorder IOException: prepare failed

问题:

I want to use MediaRecorder to record voice, my code is:

 public void record(View v) {        Log.d(TAG, "record");      this.mediaRecorder.setAudioChannels(1);     this.mediaRecorder.setAudioSamplingRate(44100);     this.mediaRecorder.setAudioEncodingBitRate(64000);     this.mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);     this.mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);     this.mediaRecorder.setOutputFile(this.file.getAbsolutePath());     this.mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);     try {         this.mediaRecorder.prepare();         this.mediaRecorder.start();          // update the buttons         this.setButtonsEnabled(false, true, false);     } catch (IOException e) {         Log.e(TAG, "Failed to record()", e);     } } 

Or

   public void record(View v) {     Log.d(TAG, "record");     this.mediaRecorder = new MediaRecorder();     this.mediaRecorder.setAudioChannels(1);     this.mediaRecorder.setAudioSamplingRate(8000);      this.mediaRecorder.setAudioEncodingBitRate(16);     this.mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);     this.mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.RAW_AMR);     this.mediaRecorder.setOutputFile(this.file.getAbsolutePath());      this.mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);      try {         this.mediaRecorder.prepare();         this.mediaRecorder.start();          // update the buttons         this.setButtonsEnabled(false, true, false);     } catch (IOException e) {         Log.e(TAG, "Failed to record()", e);     } } 

On a Samsung all is OK, but on a Dell two methods do not succeed

Here is logcat:

 02-01 13:56:51.094: E/AudioRecorderDemoActivity(1397): Failed to record()  02-01 13:56:51.094: E/AudioRecorderDemoActivity(1397): java.io.IOException: prepare failed.  02-01 13:56:51.094: E/AudioRecorderDemoActivity(1397):     at android.media.MediaRecorder._prepare(Native Method)  02-01 13:56:51.094: E/AudioRecorderDemoActivity(1397):     at android.media.MediaRecorder.prepare(MediaRecorder.java:524)  02-01 13:56:51.094: E/AudioRecorderDemoActivity(1397):     at com.marakana.android.audiorecorderdemo.AudioRecorderDemoActivity.record(AudioRecorderDemoActivity.java:69)  02-01 14:05:20.074: E/AndroidRuntime(1790): FATAL EXCEPTION: main  02-01 14:05:20.074: E/AndroidRuntime(1790): java.lang.IllegalStateException: Could not execute method of the activity 

回答1:

First at all you code looks fine. Have you added the required permissions to your manifest file?

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.RECORD_AUDIO" /> 

If yes, then try replacing:

this.mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4); 

by

this.mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP); 

Don't forget to check if the path of your video file is correct.

回答2:

This is a big problem but has a very small solution

In most cases, the filename that we get from this.file.getAbsolutePath() contains file:/// as a prefix

    ////////////////////////////////////////////////* INCORRECT CODE */     this.mediaRecorder.setOutputFile(this.file.getAbsolutePath());     /*the above line sets a file url beginning with a "file:///"     //however, since this setOutputFile requires us to send a     //string referring to the uri, we will have to get rid of the     //"file:///" and simply write the uri */     ////////////////////////////////////////////////* CORRECTED CODE BELOW */     this.mediaRecorder.setOutputFile(this.file.getAbsolutePath().substring(8));     /*the above line of code extracts the string uri eliminating     // file:/// */ 

Hope you find this answer helpful

回答3:

This Exception will be raised . if any of the following things failed:

file not found: Ensure that output file location that yu have specified is existing, otherwise it will throw you filenotfoundexception

Write Permission: You must specify Write permission in your manifest file.

Record permission : specify Record permission in your manifest file.

you can use this..

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.RECORD_AUDIO"/>

Still you get error.. try display the error. Like this

try{         mRecorder.prepare();      } catch (IOException e) {         Log.e(LOG_TAG, "prepare() failed");        System.out.println(""+e);    //to display the error     } 

mRecorder.start();

回答4:

I deleted

this.mediaRecorder.setAudioEncodingBitRate(16);

at method 2 and now it's working.

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