buildroot+qt+qcamrea+opencv打开摄像头进行拍照录像保存功能

1、buildroot添加opencv库

1> 进入PET_RK3288_P01_Linux/buildroot/output/rockchip_rk3288/ 文件夹内，使用 sudo make menuconfig命令进入配置。可以看到一个如下图：

2>选择 Target packages --> Libraries ---> Graphics ---> opencv3 将光标到opencv3（注：最好是选择最新版本的opencv，旧版本的opencv能会出面问题）的库上，点击键盘上的 'y' 键选择。

3>再按下 “Enter” 键进入opencv3里面进行选择，选择样式如下图（注意和红色框选择的一样即可）：

4>将配置好的选项进行保存，选择“Save”进行保存，后退出配置。（注：如果全部选中，再去编译好像会出错，目前未找到原因）

5>最后再将配置保存到默认配置中去：sudo make savedefconfig ，这样配置完后就可以进行编译了。

6>编译完后，会在 PET_RK3288_P01_Linux/buildroot/output/rockchip_rk3288/host/arm-buildroot-linux-gnueabihf/sysroot/usr/ 这个目录下有一个include目录和一个lib目录，编译出的opencv库头文件与库文件就放在这两个目录里。

7> 在include目录里可以找到 opencv 与opencv2 两个目录，在lib目录里可以找到 libopencv_*开头的所有opencv库文件，说明你已将opencv加入到buildroot系统中。

2、在QT中加入opencv库

打开QT项目中的.pro文件，加入下面代码：

INCLUDEPATH += [前面是你个人系统目录]/PET_RK3288_P01_Linux/buildroot/output/rockchip_rk3288/host/arm-buildroot-linux-gnueabihf/sysroot/usr/include[前面是你个人系统目录]/PET_RK3288_P01_Linux/buildroot/output/rockchip_rk3288/host/arm-buildroot-linux-gnueabihf/sysroot/usr/include/opencv[前面是你个人系统目录]/PET_RK3288_P01_Linux/buildroot/output/rockchip_rk3288/host/arm-buildroot-linux-gnueabihf/sysroot/usr/include/opencv2LIBS += [前面是你个人系统目录]/PET_RK3288_P01_Linux/buildroot/output/rockchip_rk3288/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/libopencv_* \

所需要添加的头文件如下：

#include <opencv2/opencv.hpp>
#include <opencv/cv.hpp>using namespace cv;

3、在buildroot中使用opencv出现的一些问题

1>不能使用opencv的以下代码打开摄像头和打开视频文件

cv::VideoCapture capture;
capture.open(0);
或者
cv::VideoCapture capture(0);
不能使用imread()，imwrite()读取和保存图片

2>opencv在保存视频时不支持 H.264编码，目前只测试了MJPG格式的

3>目前测试在保存视频的后缀名也只能使用.avi后缀名进行保存

4、在buildroot中使用QCamrea+opencv进行摄像头处理

1>在.pro文件中需要添加下面代码：

QT       += core gui multimedia multimediawidgets

2>头文件：

#ifndef MAINWIDGET_H
#define MAINWIDGET_H#include <QWidget>
#include <QTimer>
#include <QCameraInfo>
#include <QCamera>
#include <QCameraImageCapture>
#include <QCameraViewfinder>
#include <QVideoProbe>
#include <QVideoFrame>
#include <QCameraViewfinderSettings>
#include <QCameraInfo>
#include <QFileInfo>
#include <QUrl>
//#include <opencv2/opencv.hpp>
#include <opencv/cv.hpp>QT_BEGIN_NAMESPACE
namespace Ui { class MainWidget; }
QT_END_NAMESPACEclass MainWidget : public QWidget
{Q_OBJECTenum RecordStatus{STOP_RECORDED,RECORDING,PAUSE_RECORDING};public:MainWidget(QWidget *parent = nullptr);~MainWidget();void openCamera(void);void savePicture(QString & saveDir);void recordStart(QString & saveDir);void recording(void);void pauseRecord(void);void recodEnd(void);private slots:void updateCameraState(QCamera::State state);void displayCameraError();void onProbeFrameSlot(const QVideoFrame &frame);void imageSaved(int, const QString &);void displayCaptureError(int, QCameraImageCapture::Error, const QString &);void on_pictureBtn_clicked();void on_flashBtn_clicked();void on_videoBtn_clicked();void onTimer1sSlot();private:void initLayout();void setCamera(const QCameraInfo &cameraInfo);void yuyvToRgb(unsigned char *yuv_buffer,unsigned char *rgb_buffer,int iWidth,int iHeight);void nv21ToRgb24(unsigned char *yuyv, unsigned char *rgb, int width, int height);QImage mat2Image(const cv::Mat &mat);cv::Mat imaget2Mat(QImage image);private:Ui::MainWidget *ui;QCamera * m_camera;QCameraViewfinder * m_viewFinder;QVideoProbe * m_videoProbe;cv::VideoWriter outputVideo;cv::Mat matData;QCameraImageCapture * m_imageCapture;enum RecordStatus recordStatus;int imageCnt;int videoCnt;QTimer * time;
};
#endif // MAINWIDGET_H

3>源文件

#include "mainwidget.h"
#include "ui_mainwidget.h"#include <QDebug>using namespace cv;#define CAMERA_PIXEL_WIDE       (1920)
#define CAMERA_PIXEL_HIGH       (1080)
#define DISPLA_PIXEL_WIDE       (1280)
#define DISPLA_PIXEL_HIGH       (720)//摄像头的帧速率(每秒15帧)
#define CAMERA_FRAME_RATE       (30.0)MainWidget::MainWidget(QWidget *parent): QWidget(parent), ui(new Ui::MainWidget)
{ui->setupUi(this);m_viewFinder = new QCameraViewfinder(this);m_viewFinder->setWindowFlag(Qt::FramelessWindowHint);m_viewFinder->setFixedSize(DISPLA_PIXEL_WIDE, DISPLA_PIXEL_HIGH);imageCnt = 0;videoCnt = 0;recordStatus = RecordStatus::STOP_RECORDED;time = new QTimer(this);connect(time, &QTimer::timeout, this, &MainWidget::onTimer1sSlot);time->start(1000/CAMERA_FRAME_RATE);initLayout();setCamera(QCameraInfo::defaultCamera());
}MainWidget::~MainWidget()
{delete ui;
}void MainWidget::initLayout()
{QBoxLayout *hlayout = new QHBoxLayout;hlayout->setMargin(0);hlayout->addWidget(m_viewFinder);ui->disWidget->setLayout(hlayout);#if defined(Q_OS_UNIX)this->setWindowState(Qt::WindowFullScreen);
#endif
}void MainWidget::setCamera(const QCameraInfo &cameraInfo)
{//初始化摄像头m_camera = new QCamera(cameraInfo);connect(m_camera, &QCamera::stateChanged, this, &MainWidget::updateCameraState);connect(m_camera, QOverload<QCamera::Error>::of(&QCamera::error), this, &MainWidget::displayCameraError);updateCameraState(m_camera->state());QCameraViewfinderSettings settings;settings.setPixelFormat(QVideoFrame::Format_YUYV); //设置像素格式,Android上只支持NV21格式settings.setResolution(QSize(CAMERA_PIXEL_WIDE,CAMERA_PIXEL_HIGH)); //设置摄像头的分辨率settings.setMaximumFrameRate(CAMERA_FRAME_RATE);settings.setMinimumFrameRate(CAMERA_FRAME_RATE);m_camera->setViewfinderSettings(settings);m_imageCapture = new QCameraImageCapture(m_camera);QImageEncoderSettings m_imageSettings;m_imageSettings.setCodec("jpeg");m_imageSettings.setQuality(QMultimedia::VeryHighQuality);m_imageSettings.setResolution(QSize(CAMERA_PIXEL_WIDE, CAMERA_PIXEL_HIGH));m_imageCapture->setEncodingSettings(m_imageSettings);connect(m_imageCapture, &QCameraImageCapture::imageSaved, this, &MainWidget::imageSaved);connect(m_imageCapture, QOverload<int, QCameraImageCapture::Error, const QString &>::of(&QCameraImageCapture::error),this, &MainWidget::displayCaptureError);m_camera->setViewfinder(m_viewFinder);m_videoProbe = new QVideoProbe(this);m_videoProbe->setSource(m_camera);connect(m_videoProbe, &QVideoProbe::videoFrameProbed, this, &MainWidget::onProbeFrameSlot, Qt::QueuedConnection);openCamera();
}void MainWidget::openCamera()
{m_camera->unload();m_camera->setCaptureMode(QCamera::CaptureStillImage);m_camera->start();
}void MainWidget::updateCameraState(QCamera::State state)
{switch (state) {case QCamera::ActiveState:break;case QCamera::UnloadedState:case QCamera::LoadedState:break;}
}void MainWidget::imageSaved(int id, const QString &fileName)
{Q_UNUSED(id);Q_UNUSED(fileName);qDebug()<<"image saved!";
}void MainWidget::displayCaptureError(int id, const QCameraImageCapture::Error error, const QString &errorString)
{Q_UNUSED(id);Q_UNUSED(error);qDebug()<<"Image Capture Error:"<<errorString;
}void MainWidget::displayCameraError()
{qDebug()<<"Camera error:"<<m_camera->errorString();
}void MainWidget::onProbeFrameSlot(const QVideoFrame &frame)
{QVideoFrame cloneFrame(frame);int w = cloneFrame.width();int h = cloneFrame.height();if (cloneFrame.map(QAbstractVideoBuffer::ReadOnly) == false){qDebug()<<"map error";return ;}matData.release();Mat matTemp = Mat(h, w, CV_8UC2, cloneFrame.bits(), static_cast<size_t>(cloneFrame.bytesPerLine()));cvtColor(matTemp, matData, CV_YUV2RGB_YUYV);cloneFrame.unmap();
}void MainWidget::savePicture(QString & saveDir)
{QString lo = saveDir + "PIC" + QString::number(imageCnt) + ".jpg";QFileInfo fi = QFileInfo(lo);while(fi.isFile()){imageCnt++;lo = saveDir + "PIC" + QString::number(imageCnt) + ".jpg";fi = QFileInfo(lo);}m_imageCapture->capture(lo);//mat2Image(matData).save(lo, "JPG");//imwrite(lo.toStdString(), matData);
}void MainWidget::recordStart(QString & saveDir)
{if (recordStatus != RecordStatus::STOP_RECORDED){return ;}QString lo = saveDir + "VIDEO" + QString::number(videoCnt) + ".avi";QFileInfo fi = QFileInfo(lo);while(fi.isFile()){videoCnt++;lo = saveDir + "VIDEO" + QString::number(videoCnt) + ".avi";fi = QFileInfo(lo);}//VideoWriter::fourcc('X', '2', '6', '4')  ('M', 'J', 'P', 'G')outputVideo.open(lo.toStdString(), VideoWriter::fourcc('M', 'J', 'P', 'G'), CAMERA_FRAME_RATE, Size(CAMERA_PIXEL_WIDE, CAMERA_PIXEL_HIGH), true);if (outputVideo.isOpened() == false){qDebug()<<"output video open error";return ;}qDebug()<<"output video open ok";recordStatus = RecordStatus::RECORDING;
}void MainWidget::recording()
{//判断存储空间是否足够//如果空间不够，可直接调用recodEnd();if (recordStatus != RecordStatus::RECORDING){return ;}if (matData.empty()){return ;}outputVideo.write(matData);
}void MainWidget::pauseRecord()
{switch (recordStatus) {case RECORDING: recordStatus = RecordStatus::PAUSE_RECORDING;break;case PAUSE_RECORDING: recordStatus = RecordStatus::PAUSE_RECORDING;break;default:break;}
}void MainWidget::recodEnd()
{if (recordStatus != RecordStatus::STOP_RECORDED){outputVideo.release();recordStatus = RecordStatus::STOP_RECORDED;}
}void MainWidget::yuyvToRgb(unsigned char *yuv_buffer,unsigned char *rgb_buffer,int iWidth,int iHeight)
{int x;int z=0;unsigned char *ptr = rgb_buffer;unsigned char *yuyv= yuv_buffer;for (x = 0; x < iWidth*iHeight; x++){int r, g, b;int y, u, v;if (!z)y = yuyv[0] << 8;elsey = yuyv[2] << 8;u = yuyv[1] - 128;v = yuyv[3] - 128;r = (y + (359 * v)) >> 8;g = (y - (88 * u) - (183 * v)) >> 8;b = (y + (454 * u)) >> 8;*(ptr++) = (r > 255) ? 255 : ((r < 0) ? 0 : r);*(ptr++) = (g > 255) ? 255 : ((g < 0) ? 0 : g);*(ptr++) = (b > 255) ? 255 : ((b < 0) ? 0 : b);if(z++){z = 0;yuyv += 4;}}
}
/** 初始化代码默认设置输出的图像格式是YUYV，在windows和Linux系统上是支持的，这个可能与摄像头有关，实际需要测试调整；Android系统上只支持NV21格式,如果是Android系统上运行，要记得修改格式*/
void MainWidget::nv21ToRgb24(unsigned char *yuyv, unsigned char *rgb, int width, int height)
{const int nv_start = width * height ;int rgb_index = 0; //index = 0,uint8_t y, u, v;int r, g, b, nv_index = 0,i, j;for(i = 0; i < height; i++){for(j = 0; j < width; j ++){//nv_index = (rgb_index / 2 - width / 2 * ((i + 1) / 2)) * 2;nv_index = i / 2  * width + j - j % 2;y = yuyv[rgb_index];u = yuyv[nv_start + nv_index ];v = yuyv[nv_start + nv_index + 1];r = y + (140 * (v-128))/100;  //rg = y - (34 * (u-128))/100 - (71 * (v-128))/100; //gb = y + (177 * (u-128))/100; //bif(r > 255)   r = 255;if(g > 255)   g = 255;if(b > 255)   b = 255;if(r < 0)     r = 0;if(g < 0)     g = 0;if(b < 0)     b = 0;//index = rgb_index % width + (height - i - 1) * width;//rgb[index * 3+0] = b;//rgb[index * 3+1] = g;//rgb[index * 3+2] = r;//颠倒图像//rgb[height * width * 3 - i * width * 3 - 3 * j - 1] = b;//rgb[height * width * 3 - i * width * 3 - 3 * j - 2] = g;//rgb[height * width * 3 - i * width * 3 - 3 * j - 3] = r;//正面图像rgb[i * width * 3 + 3 * j + 0] = b;rgb[i * width * 3 + 3 * j + 1] = g;rgb[i * width * 3 + 3 * j + 2] = r;rgb_index++;}}
}QImage MainWidget::mat2Image(const cv::Mat &mat)
{if (mat.type() == CV_8UC1)                 // 单通道{QImage image(mat.cols, mat.rows, QImage::Format_Indexed8);image.setColorCount(256);              // 灰度级数256for (int i = 0; i < 256; i++){image.setColor(i, qRgb(i, i, i));}uchar *pSrc = mat.data;                // 复制mat数据for (int row = 0; row < mat.rows; row++){uchar *pDest = image.scanLine(row);memcpy(pDest, pSrc, mat.cols);pSrc += mat.step;}return image;}else if (mat.type() == CV_8UC3)            // 3通道{const uchar *pSrc = (const uchar*)mat.data;        // 复制像素QImage image(pSrc, mat.cols, mat.rows, mat.step, QImage::Format_RGB888);   // R, G, B 对应 0,1,2return image.rgbSwapped();             // rgbSwapped是为了显示效果色彩好一些。}else if (mat.type() == CV_8UC4){const uchar *pSrc = (const uchar*)mat.data;        // 复制像素// Create QImage with same dimensions as input MatQImage image(pSrc, mat.cols, mat.rows, mat.step, QImage::Format_ARGB32);       // B,G,R,A 对应 0,1,2,3return image.copy();}else{return QImage();}
}cv::Mat MainWidget::imaget2Mat(QImage image)
{cv::Mat mat;switch (image.format()){case QImage::Format_ARGB32:case QImage::Format_RGB32:case QImage::Format_ARGB32_Premultiplied:mat = cv::Mat(image.height(), image.width(), CV_8UC4, (void*)image.constBits(), image.bytesPerLine());break;case QImage::Format_RGB888:mat = cv::Mat(image.height(), image.width(), CV_8UC3, (void*)image.constBits(), image.bytesPerLine());cv::cvtColor(mat, mat, cv::COLOR_BGR2RGB);break;case QImage::Format_Indexed8:mat = cv::Mat(image.height(), image.width(), CV_8UC1, (void*)image.constBits(), image.bytesPerLine());break;default: break;}return mat;
}void MainWidget::on_pictureBtn_clicked()
{QString path("/usr/app/");savePicture(path);
}void MainWidget::on_flashBtn_clicked()
{openCamera();
}void MainWidget::on_videoBtn_clicked()
{static bool videoFlag = false;if (videoFlag == false){QString path("/usr/app/");recordStart(path);if (outputVideo.isOpened()){videoFlag = true;ui->videoBtn->setText(tr("videoing"));}}else{recodEnd();ui->videoBtn->setText(tr("录像"));videoFlag = false;}
}void MainWidget::onTimer1sSlot()
{recording();
}