android mediarecorder error (MediaRecorder start failed : -1

当我试图使相机录像机在我的程序，我得到这个错误:

E/MediaRecorder: start failed: -19

代码是

try {
    final SurfaceView sv = (SurfaceView) findViewById(R.id.srvView);
    MediaRecorder mrec = new MediaRecorder();
    mrec.setCamera(camera);
    mrec.setAudioSource(MediaRecorder.AudioSource.MIC);
    mrec.setVideoSource(MediaRecorder.VideoSource.CAMERA);
    mrec.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
    mrec.setVideoFrameRate(10);
    mrec.setVideoSize(480, 320);
    mrec.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
    mrec.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP);
    mrec.setPreviewDisplay(mSh.getSurface());
    mrec.setOutputFile("/mnt/sdcard/pro/andsend.avi");
    mrec.prepare();
    mrec.start();
} catch(Exception e)
{
    e.printStackTrace();
}

我试着改变序列，改变设置大小，帧率等…

但是，我找不到问题。

有什么问题吗?