Qt OpenCV Android代碼不會超越capture.grab（）

Question

使用OpenCV和QT創建Android應用程序。 VideoCapture對象的方法「抓取」或「讀取」的調用凍結了代碼的進一步執行。之後沒有任何反應。只是出現黑屏。

注意：考慮包括所有必需的頭文件。代碼工作完全在桌面上（Linux）的

int main(int argc, char *argv[]) { QApplication app(argc,argv); qDebug() << "CP 1"; Ptr<VideoCapture> capture; capture = new VideoCapture(CV_CAP_ANDROID_FRONT); if(capture->isOpened()) qDebug() << "CP 1.11"; Mat img; qDebug() << "CP 1.1";

capture->read(img); // **code doesn't moves ahead of this point** 
qDebug() << "CP 1.3"; 

Mat gray; 
Mat prev; 
Mat diff; 
cvtColor(img, prev, CV_BGR2GRAY); 

}

以下是輸出日誌，代碼不超過捕獲收益閱讀方法

`

Starting remote process.I/Qt  (8391): Network start 
I/Qt  (8391): qt start 
W/art  (8391): Thread[14,tid=8446,Native,Thread*=0x484282a8,peer=0x656ce530,"Thread-17697"] attached without supplying a name 
I/Adreno-EGL(8391): <qeglDrvAPI_eglInitialize:320>: EGL 1.4 QUALCOMM Build: I0404c4692afb8623f95c43aeb6d5e13ed4b30ddbDate: 11/06/13 
W/art  (8391): Thread[14,tid=8446,Native,Thread*=0x484282a8,peer=0x656cffa8,"Thread-17698"] attached without supplying a name 
W/art  (8391): Thread[14,tid=8446,Native,Thread*=0x484282a8,peer=0x656d01e0,"Thread-17699"] attached without supplying a name 
D/Qt  (8391): ../test/main.cpp:62 (int main(int, char**)): CP 1 
D/OpenCV::camera(8391): CvCapture_Android::CvCapture_Android(98) 
D/OpenCV::camera(8391): Library name: libopencv_java.so 
D/OpenCV::camera(8391): Library base address: 0x498f6000 
D/OpenCV::camera(8391): Libraries folder found: /data/app-lib/com.sumit.tracker-1/ 
D/OpenCV::camera(8391): CameraWrapperConnector::connectToLib: folderPath=/data/app-lib/com.sumit.tracker-1/ 
E/OpenCV::camera(8391): ||libnative_camera_r4.4.0.so 
D/OpenCV::camera(8391): try to load library 'libnative_camera_r4.4.0.so' 
D/OpenCV::camera(8391): Loaded library '/data/app-lib/com.sumit.tracker-1/libnative_camera_r4.4.0.so' 
D/OpenCV_NativeCamera(8391): Front camera selected 
D/OpenCV_NativeCamera(8391): CameraHandler::initCameraConnect(0x49fcef99, 1, 0x48431af0, 0x0) 
D/OpenCV_NativeCamera(8391): Current process name for camera init: com.sumit.tracker 
D/OpenGLRenderer(8391): Enabling debug mode 0 
D/OpenCV_NativeCamera(8391): Instantiated new CameraHandler (0x49fcef99, 0x48431af0) 
I/OpenCV_NativeCamera(8391): initCameraConnect: [preview-size=1280x960;video-size=1280x960;preferred-preview-size-for-video=1280x960;preview-size-values=1280x960,1280x768,1280x720,1024x768,800x600,800x480,720x480,640x480,352x288,320x240,176x144;video-size-values=1280x960,1280x768,1280x720,1024x768,800x600,800x480,720x480,640x480,352x288,320x240,176x144;preview-format=yuv420sp;preview-format-values=yuv420p,yuv420sp,;preview-frame-rate=15;preview-fps-range=15000,15000;preview-fps-range-values=(15000,15000),(24000,24000),(7000,30000),(30000,30000);preview-frame-rate-values=15,24,30;picture-size=1280x960;picture-size-values=1280x960,1280x768,1280x720,1024x768,800x600,800x480,720x480,640x480,352x288,320x240,176x144;picture-format=jpeg;picture-format-values=jpeg;jpeg-thumbnail-width=320;jpeg-thumbnail-height=240;jpeg-thumbnail-size-values=512x288,480x288,256x154,432x288,320x240,176x144,0x0;jpeg-thumbnail-quality=90;jpeg-quality=90;rotation=0;whitebalance=auto;whitebalance-values=auto,incandescent,fluorescent,warm-fluorescent,daylight,cloudy-d 
D/OpenCV_NativeCamera(8391): Supported Cameras: (null) 
D/OpenCV_NativeCamera(8391): Supported Picture Sizes: 1280x960,1280x768,1280x720,1024x768,800x600,800x480,720x480,640x480,352x288,320x240,176x144 
D/OpenCV_NativeCamera(8391): Supported Picture Formats: jpeg 
D/OpenCV_NativeCamera(8391): Supported Preview Sizes: 1280x960,1280x768,1280x720,1024x768,800x600,800x480,720x480,640x480,352x288,320x240,176x144 
D/OpenCV_NativeCamera(8391): Supported Preview Formats: yuv420p,yuv420sp, 
D/OpenCV_NativeCamera(8391): Supported Preview Frame Rates: 15,24,30 
D/OpenCV_NativeCamera(8391): Supported Thumbnail Sizes: 512x288,480x288,256x154,432x288,320x240,176x144,0x0 
D/OpenCV_NativeCamera(8391): Supported Whitebalance Modes: auto,incandescent,fluorescent,warm-fluorescent,daylight,cloudy-daylight,twilight,shade 
D/OpenCV_NativeCamera(8391): Supported Effects: none,mono,negative,solarize,sepia,posterize,whiteboard,blackboard,aqua 
D/OpenCV_NativeCamera(8391): Supported Scene Modes: auto,landscape,snow,beach,sunset,night,portrait,sports,steadyphoto,candlelight,fireworks,party,night-portrait,theatre,action 
D/OpenCV_NativeCamera(8391): Supported Focus Modes: fixed 
D/OpenCV_NativeCamera(8391): Supported Antibanding Options: off,60hz,50hz,auto 
D/OpenCV_NativeCamera(8391): Supported Flash Modes: off 
D/OpenCV_NativeCamera(8391): initCameraConnect: preview format is set to yuv420sp 
D/OpenCV_NativeCamera(8391): initCameraConnect: preview format is set to 640x480 
D/OpenCV_NativeCamera(8391): Starting preview 
D/OpenCV_NativeCamera(8391): Preview started successfully 
D/Qt  (8391): ../test/main.cpp:66 (int main(int, char**)): CP 1.11 
D/Qt  (8391): ../test/main.cpp:69 (int main(int, char**)): CP 1.1 

`

Answer 1

端達到發現問題涉及的OpenCV 2.4.9在Nexus 5

http://answers.opencv.org/question/30311/opencv_nativecamera-startpreview-fails-on-nexus-5/