为什么我在测试 MediaRecorder 样本时会出现 FATAL EXCEPTION？

Question

我使用 Android Studio 在我的真实设备中测试示例 E:\Android_SDK\samples\android-22\media\MediaRecorder，我收到以下错误，为什么？示例中是否存在一些错误？

顺便说一句，我的安卓版本是 5.1

09-28 16:09:31.683  17233-17233/com.example.android.mediarecorder E/Zygote﹕ v2
09-28 16:09:31.683  17233-17233/com.example.android.mediarecorder E/SELinux﹕ [DEBUG] get_category: variable seinfo: default sensitivity: NULL, cateogry: NULL
09-28 16:10:06.343  17233-17772/com.example.android.mediarecorder E/MediaRecorder﹕ start failed: -19
09-28 16:10:06.343  17233-17772/com.example.android.mediarecorder E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1
    Process: com.example.android.mediarecorder, PID: 17233
    java.lang.RuntimeException: An error occured while executing doInBackground()
            at android.os.AsyncTask$3.done(AsyncTask.java:304)
            at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
            at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
            at java.util.concurrent.FutureTask.run(FutureTask.java:242)
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:818)
     Caused by: java.lang.RuntimeException: start failed.
            at android.media.MediaRecorder.start(Native Method)
            at com.example.android.mediarecorder.MainActivity$MediaPrepareTask.doInBackground(MainActivity.java:208)
            at com.example.android.mediarecorder.MainActivity$MediaPrepareTask.doInBackground(MainActivity.java:200)
            at android.os.AsyncTask$2.call(AsyncTask.java:292)
            at java.util.concurrent.FutureTask.run(FutureTask.java:237)
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:818)

已添加

而且，我在AndroidManifest.xml 中删除android:screenOrientation="landscape" 后效果很好，但我不知道为什么？

Answer 1

MediaRecorder 示例在Landscape 模式下工作，要使其在portrait 模式下工作，您还需要以精确序列添加以下代码！

这里是代码：-

将此用于portrait 支持添加到mCamera

mCamera.setDisplayOrientation(90);

并支持Audio/Video 编码器和OutputFormat 添加此

            mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
            mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP);
            mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);

下面将是你的完整方法prepareVideoRecorder

private boolean prepareVideoRecorder(){

        // BEGIN_INCLUDE (configure_preview)
        mCamera = CameraHelper.getDefaultCameraInstance();
        mCamera.setDisplayOrientation(90);
        // We need to make sure that our preview and recording video size are supported by the
        // camera. Query camera to find all the sizes and choose the optimal size given the


        try {
                // Requires API level 11+, For backward compatibility use {@link setPreviewDisplay}
                // with {@link SurfaceView}
                mCamera.setPreviewTexture(mPreview.getSurfaceTexture());

        } catch (IOException e) {
            Log.e(TAG, "Surface texture is unavailable or unsuitable" + e.getMessage());
            return false;
        }
        // END_INCLUDE (configure_preview)


        // BEGIN_INCLUDE (configure_media_recorder)
        mMediaRecorder = new MediaRecorder();

        // Step 1: Unlock and set camera to MediaRecorder
        mCamera.unlock();
        mMediaRecorder.setCamera(mCamera);

        // Step 2: Set sources
        mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
        mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.DEFAULT);

        mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
        mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP);
        mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);

        mMediaRecorder.setOrientationHint(90);

        // Step 3: Set a CamcorderProfile (requires API Level 8 or higher)

        mMediaRecorder.setOutputFile(CameraHelper.getOutputMediaFile(
                CameraHelper.MEDIA_TYPE_VIDEO).toString());
        //
        //mMediaRecorder.setPreviewDisplay(SufaceView);
        // Step 4: Set output file

        // END_INCLUDE (configure_media_recorder)

        // Step 5: Prepare configured MediaRecorder
        try {
            mMediaRecorder.prepare();
            } catch (IllegalStateException e) {
            Log.d(TAG, "IllegalStateException preparing MediaRecorder: " + e.getMessage());
            releaseMediaRecorder();
            return false;
        } catch (IOException e) {
            Log.d(TAG, "IOException preparing MediaRecorder: " + e.getMessage());
            releaseMediaRecorder();
            return false;
        }
        return true;
    }

最后你可以从清单中删除screenOrientation

android:screenOrientation="landscape"

上面的代码在orientation 中都可以工作，但Camera 显示总是90 degree，所以你需要通过正确处理你的方向来进行更改。

Answer 2

我也遇到了上述 MediaRecorder 示例的问题，但我添加了 "android:theme="@android:style/Theme.NoTitleBar.Fullscreen" 然后示例项目在横向模式下也可以正常工作

<activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:screenOrientation="landscape"
            android:theme="@android:style/Theme.NoTitleBar.Fullscreen" >>

Answer 3

理想情况下，您应该在 Activity 下包含 android:screenOrientation="landscape"，这告诉我您手中有一个过时的示例项目。

请确保您运行的是最新版本的示例项目。

通过以下方式打开项目

文件 > 新建 > 导入样本 > 输入 MediaRecorder

或

git clone https://github.com/googlesamples/android-MediaRecorder.git

刚刚使用 Android 5.1（API 级别 22）测试了示例代码，它在平板电脑和智能手机上都运行良好。

请保留android:theme="@style/AppTheme" 在应用程序下，不要更改它，因为这不是示例代码提供的。模板样式在

下定义

res > 值 > 模板样式.xml

它是为平板电脑和智能手机定义的。

Answer 4

缺少权限

在 MainActivity.java 的 onCreate 中添加此调用

 if (!checkPermissionFromDevice())
        requestPermission();

并将这两个方法插入MainActivity.java中

private boolean checkPermissionFromDevice()
{
    int write_external_storage_result = ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
    int camera_result = ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA);
    int record_audio_result = ContextCompat.checkSelfPermission(this, Manifest.permission.RECORD_AUDIO);
    return write_external_storage_result == PackageManager.PERMISSION_GRANTED
            && camera_result == PackageManager.PERMISSION_GRANTED
            && record_audio_result == PackageManager.PERMISSION_GRANTED;
}

private void requestPermission()
{
    ActivityCompat.requestPermissions(
            this,
            new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.CAMERA, Manifest.permission.RECORD_AUDIO},
            REQUEST_PERMISSION_CODE);
}