MediaRecorder start error codes

问题

I want to record raw h.264 video without sound and possibly HW accelerated (and stream it later). So I decided to use MediaRecorder (and the socket hack for streaming).

I have the following code:

final MediaRecorder recorder = new MediaRecorder();
final Camera camera = Camera.open();
camera.unlock();
recorder.setCamera(camera);
recorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
recorder.setOutputFormat(MediaRecorder.OutputFormat.DEFAULT);
recorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
final CamcorderProfile profile = CamcorderProfile.get(CamcorderProfile.QUALITY_LOW);
recorder.setVideoSize(profile.videoFrameWidth, profile.videoFrameHeight);
recorder.setVideoFrameRate(profile.videoFrameRate);
recorder.setVideoEncodingBitRate(profile.videoBitRate);
recorder.prepare();
recorder.start();

And bam! This in logcat:

E/MediaRecorder﹕ start failed: -38

I started googling, and found plenty of questions and answers, but none about my error code -38.

So I tried to look at Android source code, and noticed it's native method, and I don't know where to look for that.

So my big question is: Is there some list of those error codes, so I could find what error -38 means?`

Also know tjat I'm targeting API 10 (Gingerbread) and building with latest SDK 21.

回答1:

Alright, I think I have an answer for you. The start function that is failing is defined in a file called mediarecorder.cpp. Found here:

frameworks/av/media/libmedia/mediarecorder.cpp

This start function returns a variable of type status_t, and corresponds to the error that you're seeing thrown.

Now, the type status_t is defined in a file called Errors.h which can be found here:

system/core/include/utils/Errors.h

This defines an enumeration that corresponds to status_t as seen here:

enum {
    OK                = 0,    // Everything's swell.
    NO_ERROR          = 0,    // No errors.

    UNKNOWN_ERROR       = 0x80000000,

    NO_MEMORY           = -ENOMEM,
    INVALID_OPERATION   = -ENOSYS,
    BAD_VALUE           = -EINVAL,
    BAD_TYPE            = 0x80000001,
    NAME_NOT_FOUND      = -ENOENT,
    PERMISSION_DENIED   = -EPERM,
    NO_INIT             = -ENODEV,
    ALREADY_EXISTS      = -EEXIST,
    DEAD_OBJECT         = -EPIPE,
    FAILED_TRANSACTION  = 0x80000002,
    JPARKS_BROKE_IT     = -EPIPE,
#if !defined(HAVE_MS_C_RUNTIME)
    BAD_INDEX           = -EOVERFLOW,
    NOT_ENOUGH_DATA     = -ENODATA,
    WOULD_BLOCK         = -EWOULDBLOCK, 
    TIMED_OUT           = -ETIMEDOUT,
    UNKNOWN_TRANSACTION = -EBADMSG,
#else    
    BAD_INDEX           = -E2BIG,
    NOT_ENOUGH_DATA     = 0x80000003,
    WOULD_BLOCK         = 0x80000004,
    TIMED_OUT           = 0x80000005,
    UNKNOWN_TRANSACTION = 0x80000006,
#endif    
    FDS_NOT_ALLOWED     = 0x80000007,
};

As you can see, some of the values here are taken from errno.h, so we just need to see which one equates to a value of 38.

According to this source, 38 corresponds to ENOSYS. So, if we look back at the status_t enumeration, we can see that in android, ENOSYS corresponds to an invalid operation. Not terribly helpful, but I hope this at least points you in the right direction.

回答2:

I have meet this error code in my call recorder app. this error code will show in logcat when you start media recorder while the Microphone is in use in another app like a Voice Assistant (for example: Ok google, etc) or another call recorder application.

来源：https://stackoverflow.com/questions/28610058/mediarecorder-start-error-codes

标签

android

android-mediarecorder