我正在Android上使用java试用agora sdk sample。当我在手机和远程设备上运行该应用程序时，音频实际上运行良好，但视频显示黑屏。我如何解决这个问题。
我试过agora docs上说的，但是对我不起作用。
1.我已检查权限，它们工作正常
1.我的前置摄像头工作正常
1.我在代码上启用了视频。
我的代码

public class VideoChatViewActivity extends AppCompatActivity {
private static final String TAG = VideoChatViewActivity.class.getSimpleName();

private static final int PERMISSION_REQ_ID = 22;

private static final String[] REQUESTED_PERMISSIONS = {
        Manifest.permission.RECORD_AUDIO,
        Manifest.permission.CAMERA,
        Manifest.permission.WRITE_EXTERNAL_STORAGE
};

private RtcEngine mRtcEngine;
private boolean mCallEnd;
private boolean mMuted;

private FrameLayout mLocalContainer;
private RelativeLayout mRemoteContainer;
private SurfaceView mLocalView;
private SurfaceView mRemoteView;

private ImageView mCallBtn;
private ImageView mMuteBtn;
private ImageView mSwitchCameraBtn;

// Customized logger view
private LoggerRecyclerView mLogView;

    @Override
    public void onJoinChannelSuccess(String channel, final int uid, int elapsed) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                mLogView.logI("Join channel success, uid: " + (uid & 0xFFFFFFFFL));
            }
        });
    }

    
    @Override
    public void onFirstRemoteVideoDecoded(final int uid, int width, int height, int elapsed) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                mLogView.logI("First remote video decoded, uid: " + (uid & 0xFFFFFFFFL));
                setupRemoteVideo(uid);
            }
        });
    }

    @Override
    public void onUserOffline(final int uid, int reason) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                mLogView.logI("User offline, uid: " + (uid & 0xFFFFFFFFL));
                onRemoteUserLeft();
            }
        });
    }
};

private void setupRemoteVideo(int uid) {
    int count = mRemoteContainer.getChildCount();
    View view = null;
    for (int i = 0; i < count; i++) {
        View v = mRemoteContainer.getChildAt(i);
        if (v.getTag() instanceof Integer && ((int) v.getTag()) == uid) {
            view = v;
        }
    }

    if (view != null) {
        return;
    }

   
    mRemoteView = RtcEngine.CreateRendererView(getBaseContext());
    mRemoteContainer.addView(mRemoteView);
    // Initializes the video view of a remote user.
    mRtcEngine.setupRemoteVideo(new VideoCanvas(mRemoteView, VideoCanvas.RENDER_MODE_HIDDEN, uid));
    mRemoteView.setTag(uid);
}

private void onRemoteUserLeft() {
    removeRemoteVideo();
}

private void removeRemoteVideo() {
    if (mRemoteView != null) {
        mRemoteContainer.removeView(mRemoteView);
    }
    // Destroys remote view
    mRemoteView = null;
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_video_chat_view);
    initUI();

    // Ask for permissions at runtime.
    // This is just an example set of permissions. Other permissions
    // may be needed, and please refer to our online documents.
    if (checkSelfPermission(REQUESTED_PERMISSIONS[0], PERMISSION_REQ_ID) &&
            checkSelfPermission(REQUESTED_PERMISSIONS[1], PERMISSION_REQ_ID) &&
            checkSelfPermission(REQUESTED_PERMISSIONS[2], PERMISSION_REQ_ID)) {
        initEngineAndJoinChannel();
    }
}

private void initUI() {
    mLocalContainer = findViewById(R.id.local_video_view_container);
    mRemoteContainer = findViewById(R.id.remote_video_view_container);

    mCallBtn = findViewById(R.id.btn_call);
    mMuteBtn = findViewById(R.id.btn_mute);
    mSwitchCameraBtn = findViewById(R.id.btn_switch_camera);

    mLogView = findViewById(R.id.log_recycler_view);

    // Sample logs are optional.
    showSampleLogs();
}

private void showSampleLogs() {
    mLogView.logI("Welcome to Agora 1v1 video call");
    mLogView.logW("You will see custom logs here");
    mLogView.logE("You can also use this to show errors");
}

private boolean checkSelfPermission(String permission, int requestCode) {
    if (ContextCompat.checkSelfPermission(this, permission) !=
            PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, REQUESTED_PERMISSIONS, requestCode);
        return false;
    }
    return true;
}

@Override
public void onRequestPermissionsResult(int requestCode,
                                       @NonNull String[] permissions, @NonNull int[] grantResults) {

    if (requestCode == PERMISSION_REQ_ID) {
        if (grantResults[0] != PackageManager.PERMISSION_GRANTED ||
                grantResults[1] != PackageManager.PERMISSION_GRANTED ||
                grantResults[2] != PackageManager.PERMISSION_GRANTED) {
            showLongToast("Need permissions " + Manifest.permission.RECORD_AUDIO +
                    "/" + Manifest.permission.CAMERA + "/" + Manifest.permission.WRITE_EXTERNAL_STORAGE);
            finish();
            return;
        }

        // Here we continue only if all permissions are granted.
        // The permissions can also be granted in the system settings manually.
        initEngineAndJoinChannel();
    }
}

private void showLongToast(final String msg) {
    this.runOnUiThread(new Runnable() {
        @Override
        public void run() {
            Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_LONG).show();
        }
    });
}

private void initEngineAndJoinChannel() {
    // This is our usual steps for joining
    // a channel and starting a call.
    initializeEngine();
    setupVideoConfig();
    setupLocalVideo();
    joinChannel();
}

private void initializeEngine() {
    try {
        mRtcEngine = RtcEngine.create(getBaseContext(), getString(R.string.agora_app_id), mRtcEventHandler);
    } catch (Exception e) {
        Log.e(TAG, Log.getStackTraceString(e));
        throw new RuntimeException("NEED TO check rtc sdk init fatal error\n" + Log.getStackTraceString(e));
    }
}

private void setupVideoConfig() {
    // In simple use cases, we only need to enable video capturing
    // and rendering once at the initialization step.
    // Note: audio recording and playing is enabled by default.
    mRtcEngine.enableVideo();

    // Please go to this page for detailed explanation
    // https://docs.agora.io/en/Video/API%20Reference/java/classio_1_1agora_1_1rtc_1_1_rtc_engine.html#af5f4de754e2c1f493096641c5c5c1d8f
    mRtcEngine.setVideoEncoderConfiguration(new VideoEncoderConfiguration(
            VideoEncoderConfiguration.VD_640x360,
            VideoEncoderConfiguration.FRAME_RATE.FRAME_RATE_FPS_15,
            VideoEncoderConfiguration.STANDARD_BITRATE,
            VideoEncoderConfiguration.ORIENTATION_MODE.ORIENTATION_MODE_FIXED_PORTRAIT));
}

private void setupLocalVideo() {
    
    mRtcEngine.setupLocalVideo(new VideoCanvas(mLocalView, VideoCanvas.RENDER_MODE_HIDDEN, 0));
}

private void joinChannel() {
    String token = getString(R.string.agora_access_token);
    if (TextUtils.isEmpty(token) || TextUtils.equals(token, "#YOUR ACCESS TOKEN#")) {
        token = null; // default, no token
    }
    mRtcEngine.joinChannel(token, "demoChannel1", "Extra Optional Data", 0);
}

@Override
protected void onDestroy() {
    super.onDestroy();
    if (!mCallEnd) {
        leaveChannel();
    }
    /*
      Destroys the RtcEngine instance and releases all resources used by the Agora SDK.

      This method is useful for apps that occasionally make voice or video calls,
      to free up resources for other operations when not making calls.
     */
    RtcEngine.destroy();
}

private void leaveChannel() {
    mRtcEngine.leaveChannel();
}

public void onLocalAudioMuteClicked(View view) {
    mMuted = !mMuted;
    // Stops/Resumes sending the local audio stream.
    mRtcEngine.muteLocalAudioStream(mMuted);
    int res = mMuted ? R.drawable.btn_mute : R.drawable.btn_unmute;
    mMuteBtn.setImageResource(res);
}

public void onSwitchCameraClicked(View view) {
    // Switches between front and rear cameras.
    mRtcEngine.switchCamera();
}

public void onCallClicked(View view) {
    if (mCallEnd) {
        startCall();
        mCallEnd = false;
        mCallBtn.setImageResource(R.drawable.btn_endcall);
    } else {
        endCall();
        mCallEnd = true;
        mCallBtn.setImageResource(R.drawable.btn_startcall);
    }

    showButtons(!mCallEnd);
}

private void startCall() {
    setupLocalVideo();
    joinChannel();
}

private void endCall() {
    removeLocalVideo();
    removeRemoteVideo();
    leaveChannel();
}

private void removeLocalVideo() {
    if (mLocalView != null) {
        mLocalContainer.removeView(mLocalView);
    }
    mLocalView = null;
}

private void showButtons(boolean show) {
    int visibility = show ? View.VISIBLE : View.GONE;
    mMuteBtn.setVisibility(visibility);
    mSwitchCameraBtn.setVisibility(visibility);
}

}
我真的不知道是什么问题。有人知道我该怎么解决这个问题吗？