一、操作系统介绍
Linux系统: ubuntu18.04 64位
Android系统: Android 8.1/9.0
windows系统: win10
QT版本: 5.12
二、需求介绍
使用QT本身代码在linux平台、Android平台、windows平台实时获取摄像头每一帧数据，进行处理再进行显示。
比如: 捕获数据之后传递给opencv实现图像识别、传递给ffmpeg实现MP4保存录制、或者实现rtsp实时推流。
如果仅仅是显示，不处理就很简单，这里介绍的方式是截取摄像头的原始数据。比如: YUYV、NV21格式。
三、QT获取摄像头数据需要用到的一些头文件
使用QT读取摄像头数据需要用到以下相关头文件:
#include <QCameraViewfinder>
#include <QCameraImageCapture>
#include <QCameraInfo>
#include <QAbstractVideoSurface>
#include <QVideoProbe>在pro工程文件还需要加上:
QT += multimedia四、QT获取摄像头的几种方式介绍
第一种方式:
子类化QAbstractVideoSurface，重写present函数这种方法获取视频帧。
只要摄像头捕获到数据，就会调用Present函数，在Present函数函数就可以得到摄像头捕获的每一帧数据，非常适合做图像处理等操作。
经过测试这种方法在Android平台上无法使用，在windows和ubuntu平台都可以正常使用。
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QWidget>
#include <QCameraViewfinder>
#include <QCameraImageCapture>
#include <QCameraInfo>
#include <QMessageBox>
#include <QFile>
#include <QFileDialog>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QHttpMultiPart>
#include <QFile>
#include <QUrlQuery>
#include <QJsonParseError>
#include <QJsonDocument>
#include <QJsonObject>
#include <QJsonArray>
#include <QBuffer>
#include <QFileDialog>
#include <QMessageBox>
#include <QMainWindow>
#include <QTimer>
#include <QAbstractVideoSurface>
#include <QVideoProbe>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = nullptr);
~MainWindow();
QCamera * camera;
QTimer *timer;
QCameraViewfinder * view_finder; //取景器
QList<QCameraInfo> cameras; //存放系统支持的摄像头列表
QCameraImageCapture* camera_image_capture;
QImageEncoderSettings iamge_setting;
private slots:
void on_pushButton_open_camera_clicked();
void on_pushButton_Camear_up_clicked();
void Camear_handleFrame(QImage image);
private:
Ui::MainWindow *ui;
};
class CameraFrameGrabber :public QAbstractVideoSurface
{
Q_OBJECT
public:
CameraFrameGrabber(QObject *parent = nullptr);
QList<QVideoFrame::PixelFormat> supportedPixelFormats(QAbstractVideoBuffer::HandleType handleType = QAbstractVideoBuffer::NoHandle) const override;
bool present(const QVideoFrame &frame) override;
signals:
void frameAvailable(QImage frame);
public slots:
};
#endif // MAINWINDOW_H
2.2.2 mainwindow.cpp代码
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
cameras = QCameraInfo::availableCameras();
if(cameras.count())
{
for(int i=0;i<cameras.count();i++)
{
ui->comboBox->addItem(tr("%1").arg(i));
}
}
else
{
QMessageBox::warning(this,tr("提示"),"本机没有可用的摄像头!\n"
"软件作者:DS小龙哥\n"
"BUG反馈:[email protected]");
}
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::Camear_handleFrame(QImage image)
{
QImage image1=image.copy();
ui->label_ImageDisplay->setPixmap(QPixmap::fromImage(image1));
}
void MainWindow::on_pushButton_open_camera_clicked()
{
int i=ui->comboBox->currentText().toInt();
/*创建摄像头对象，根据选择的摄像头打开*/
camera = new QCamera(cameras.at(i));
CameraFrameGrabber *_cameraFrameGrabber = new CameraFrameGrabber(this);
camera->setViewfinder(_cameraFrameGrabber);
connect(_cameraFrameGrabber, SIGNAL(frameAvailable(QImage)), this, SLOT(Camear_handleFrame(QImage)));
camera->start();
}
void MainWindow::on_pushButton_Camear_up_clicked()
{
}
CameraFrameGrabber::CameraFrameGrabber(QObject *parent) :
QAbstractVideoSurface(parent)
{
}
QList<QVideoFrame::PixelFormat> CameraFrameGrabber::supportedPixelFormats(QAbstractVideoBuffer::HandleType handleType) const
{
if (handleType == QAbstractVideoBuffer::NoHandle)
{
qDebug()<<"无效格式1."<<QList<QVideoFrame::PixelFormat>()<< QVideoFrame::Format_RGB32<< QVideoFrame::Format_ARGB32<< QVideoFrame::Format_ARGB32_Premultiplied<< QVideoFrame::Format_RGB565<< QVideoFrame::Format_RGB555;
return QList<QVideoFrame::PixelFormat>()<< QVideoFrame::Format_RGB32<< QVideoFrame::Format_ARGB32<< QVideoFrame::Format_ARGB32_Premultiplied<< QVideoFrame::Format_RGB565<< QVideoFrame::Format_RGB555;
/*
return QList<QVideoFrame::PixelFormat>()
<<QVideoFrame::Format_RGB32
<<QVideoFrame::Format_YUV420P
<<QVideoFrame::Format_YUYV
<<QVideoFrame::Format_ARGB32
<<QVideoFrame::Format_ARGB32_Premultiplied
<<QVideoFrame::Format_RGB565
<<QVideoFrame::Format_Jpeg
<<QVideoFrame::Format_RGB555;*/
}
else
{
qDebug()<<"无效格式2."<<QList<QVideoFrame::PixelFormat>();
return QList<QVideoFrame::PixelFormat>();
}
}
bool CameraFrameGrabber::present(const QVideoFrame &frame)
{
if (frame.isValid()) {
QVideoFrame cloneFrame(frame);
cloneFrame.map(QAbstractVideoBuffer::ReadOnly);
//qDebug()<<"width="<<cloneFrame.width();
//qDebug()<<"height="<<cloneFrame.height();
// qDebug()<<"pixelFormat="<<cloneFrame.pixelFormat();
const QImage image(cloneFrame.bits(),
cloneFrame.width(),
cloneFrame.height(),
QVideoFrame::imageFormatFromPixelFormat(cloneFrame.pixelFormat()));
emit frameAvailable(image);
cloneFrame.unmap();
return true;
}
return false;
}
第二种方式:
使用QVideoProbe类捕获视频帧
QvideoProbe适合所有平台使用。下面代码在Android、ubuntu、windows系统上测试成功显示。
在window和ubuntu系统代码设置摄像头输出的数据格式是YUYV，在我的Android平板上只能输出NV21格式，下面代码里编写了NV21、YUYUV转RGB24的代码。
mainwindow.cpp代码
#include "mainwindow.h"
#include "ui_mainwindow.h"
//#define ANDROID_DEVICE
#ifdef ANDROID_DEVICE
//设置保存文件的路径
#define SAVE_FILE_PATH "/sdcard/DCIM/Camera/"
#else
//设置保存文件的路径
#define SAVE_FILE_PATH "./"
#endif
/*
* 设置QT界面的样式
*/
void MainWindow::SetStyle(const QString &qssFile) {
QFile file(qssFile);
if (file.open(QFile::ReadOnly)) {
QString qss = QLatin1String(file.readAll());
qApp->setStyleSheet(qss);
QString PaletteColor = qss.mid(20,7);
qApp->setPalette(QPalette(QColor(PaletteColor)));
file.close();
}
else
{
qApp->setStyleSheet("");
}
}
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
this->SetStyle(":/images/blue.css"); //设置样式表
this->setWindowIcon(QIcon(":/log.ico")); //设置图标
this->setWindowTitle("照相机");
//获取本机可用摄像头
cameras = QCameraInfo::availableCameras();
if(cameras.count())
{
for(int i=0;i<cameras.count();i++)
{
ui->comboBox->addItem(tr("%1").arg(i));
}
}
else
{
QMessageBox::warning(this,tr("提示"),"本机没有可用的摄像头!\n"
"软件作者:DS小龙哥\n"
"BUG反馈:[email protected]");
}
ui->pushButton_stop->setEnabled(false); //设置停止按钮不可用
ui->pushButton_Camear_up->setEnabled(false);
//创建工作目录
#ifdef ANDROID_DEVICE
QDir dir;
if(!dir.exists("/sdcard/DCIM/Camera/"))
{
if(dir.mkpath("/sdcard/DCIM/Camera/"))
{
Log_Display("/sdcard/DCIM/Camera/目录创建成功.\n");
}
else
{
Log_Display("/sdcard/DCIM/Camera/目录创建失败.\n");
}
}
#endif
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::Log_Display(QString text)
{
ui->plainTextEdit->insertPlainText(text);
}
void MainWindow::on_pushButton_open_camera_clicked()
{
int i=ui->comboBox->currentText().toInt();
/*创建摄像头对象，根据选择的摄像头打开*/
camera = new QCamera(cameras.at(i));
m_pProbe = new QVideoProbe(this);
if(m_pProbe != nullptr)
{
m_pProbe->setSource(camera); // Returns true, hopefully.
connect(m_pProbe, SIGNAL(videoFrameProbed(QVideoFrame)), this, SLOT(slotOnProbeFrame(QVideoFrame)), Qt::DirectConnection);
}
/*配置摄像头捕获模式为帧捕获模式*/
//camera->setCaptureMode(QCamera::CaptureStillImage); //如果在Linux系统下运行就这样设置
camera->setCaptureMode(QCamera::CaptureVideo);//如果在android系统下运行就这样设置
/*启动摄像头*/
camera->start();
/*设置摄像头的采集帧率和分辨率*/
QCameraViewfinderSettings settings;
settings.setPixelFormat(QVideoFrame::Format_YUYV); //设置像素格式 Android上只支持NV21格式
settings.setResolution(QSize(640, 480)); //设置摄像头的分辨率
camera->setViewfinderSettings(settings);
//获取摄像头支持的分辨率、帧率等参数
//获取摄像头支持的分辨率、帧率等参数
/*
QList<QCameraViewfinderSettings > ViewSets = camera->supportedViewfinderSettings();
foreach (QCameraViewfinderSettings ViewSet, ViewSets) {
//qDebug() << i++ <<" max rate = " << ViewSet.maximumFrameRate() << "min rate = "<< ViewSet.minimumFrameRate() << "resolution "<<ViewSet.resolution();
Log_Display(tr("Format=%1\n").arg(ViewSet.pixelFormat()));
}*/
ui->pushButton_open_camera->setEnabled(false);
ui->pushButton_stop->setEnabled(true); //设置停止按钮可用
ui->pushButton_Camear_up->setEnabled(true);
}
/*
* 摄像头输出的信息
D libandroid_camera_save.so: 32 max rate = 15 min rate = 15 resolution QSize(640, 480) Format= Format_NV21 QSize(1, 1)
D libandroid_camera_save.so: 33 max rate = 30 min rate = 30 resolution QSize(640, 480) Format= Format_NV21 QSize(1, 1)
D libandroid_camera_save.so: 34 max rate = 15 min rate = 15 resolution QSize(640, 480) Format= Format_YV12 QSize(1, 1)
D libandroid_camera_save.so: 35 max rate = 30 min rate = 30 resolution QSize(640, 480) Format= Format_YV12 QSize(1, 1)
*/
void MainWindow::slotOnProbeFrame(const QVideoFrame &frame)
{
QVideoFrame cloneFrame(frame);
cloneFrame.map(QAbstractVideoBuffer::ReadOnly);
//qDebug()<<"height:"<<cloneFrame.height();
//qDebug()<<"width:"<<cloneFrame.width();
//qDebug()<<"bytesPerLine:"<<cloneFrame.bytesPerLine();
//qDebug()<<"mappedBytes:"<<cloneFrame.mappedBytes();
qDebug()<<"pixelFormat:"<<cloneFrame.pixelFormat();
if(cloneFrame.pixelFormat()==QVideoFrame::Format_NV21)
{
unsigned char rgb_buffer[640*480*3];
NV21_TO_RGB24(cloneFrame.bits(),rgb_buffer,cloneFrame.width(),cloneFrame.height());
const QImage image(rgb_buffer,
cloneFrame.width(),
cloneFrame.height(),
QImage::Format_RGB888);
QPixmap my_pixmap;
my_pixmap.convertFromImage(image);
ui->label_ImageDisplay->setPixmap(my_pixmap);
}
else if(cloneFrame.pixelFormat()==QVideoFrame::Format_YUYV)
{
unsigned char rgb_buffer[640*480*3];
yuyv_to_rgb(cloneFrame.bits(),rgb_buffer,cloneFrame.width(),cloneFrame.height());
const QImage image(rgb_buffer,
cloneFrame.width(),
cloneFrame.height(),
QImage::Format_RGB888);
QPixmap my_pixmap;
my_pixmap.convertFromImage(image);
ui->label_ImageDisplay->setPixmap(my_pixmap);
}
else
{
Log_Display(tr("当前格式编码为%1,暂时不支持转换.\n").arg(cloneFrame.pixelFormat()));
}
cloneFrame.unmap();
}
void MainWindow::on_pushButton_Camear_up_clicked()
{
const QPixmap pix=ui->label_ImageDisplay->pixmap()->copy();
QDateTime dateTime(QDateTime::currentDateTime());
//时间效果: 2020-03-05 16:25::04 周四
QString qStr="";
qStr+=SAVE_FILE_PATH; //Android 手机的照相机文件夹
qStr+=dateTime.toString("yyyy-MM-dd-hh-mm-ss");
qStr+=".jpg";
pix.save(qStr);
Log_Display(tr("照片保存路径:%1\n").arg(qStr));
}
void MainWindow::YUV420P_to_RGB24(unsigned char *data, unsigned char *rgb, int width, int height)
{
int index = 0;
unsigned char *ybase = data;
unsigned char *ubase = &data[width * height];
unsigned char *vbase = &data[width * height * 5 / 4];
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
//YYYYYYYYUUVV
unsigned char Y = ybase[x + y * width];
unsigned char U = ubase[y / 2 * width / 2 + (x / 2)];
unsigned char V = vbase[y / 2 * width / 2 + (x / 2)];
rgb[index++] = Y + 1.402 * (V - 128); //R
rgb[index++] = Y - 0.34413 * (U - 128) - 0.71414 * (V - 128); //G
rgb[index++] = Y + 1.772 * (U - 128); //B
}
}
}
/**
* NV12属于YUV420SP格式,android相机默认格式
* @param data
* @param rgb
* @param width
* @param height
*/
void MainWindow::NV21_TO_RGB24(unsigned char *yuyv, unsigned char *rgb, int width, int height)
{
const int nv_start = width * height ;
int index = 0, rgb_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; //r
g = y - (34 * (u-128))/100 - (71 * (v-128))/100; //g
b = y + (177 * (u-128))/100; //b
if(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++;
}
}
}
void MainWindow::YUV420P_TO_RGB24(unsigned char *yuv420p, unsigned char *rgb24, int width, int height) {
int index = 0;
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
int indexY = y * width + x;
int indexU = width * height + y / 2 * width / 2 + x / 2;
int indexV = width * height + width * height / 4 + y / 2 * width / 2 + x / 2;
unsigned char Y = yuv420p[indexY];
unsigned char U = yuv420p[indexU];
unsigned char V = yuv420p[indexV];
rgb24[index++] = Y + 1.402 * (V - 128); //R
rgb24[index++] = Y - 0.34413 * (U - 128) - 0.71414 * (V - 128); //G
rgb24[index++] = Y + 1.772 * (U - 128); //B
}
}
}
void MainWindow::on_pushButton_stop_clicked()
{
camera->stop();
delete camera;
delete m_pProbe;
ui->pushButton_open_camera->setEnabled(true);
ui->pushButton_stop->setEnabled(false); //设置停止按钮不可用
ui->pushButton_Camear_up->setEnabled(false);
}
/*
函数功能: 将YUV数据转为RGB格式
函数参数:
unsigned char *yuv_buffer: YUV源数据
unsigned char *rgb_buffer: 转换之后的RGB数据
int iWidth,int iHeight : 图像的宽度和高度
*/
void MainWindow::yuyv_to_rgb(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;
else
y = 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;
}
}
}
mainwindow.h代码
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QWidget>
#include <QCameraViewfinder>
#include <QCameraImageCapture>
#include <QCameraInfo>
#include <QMessageBox>
#include <QFile>
#include <QFileDialog>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QHttpMultiPart>
#include <QFile>
#include <QUrlQuery>
#include <QJsonParseError>
#include <QJsonDocument>
#include <QJsonObject>
#include <QJsonArray>
#include <QBuffer>
#include <QFileDialog>
#include <QMessageBox>
#include <QMainWindow>
#include <QTimer>
#include <QAbstractVideoSurface>
#include <QVideoProbe>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
void SetStyle(const QString &qssFile);
MainWindow(QWidget *parent = nullptr);
~MainWindow();
QCamera * camera;
QTimer *timer;
QCameraViewfinder * view_finder; //取景器
QList<QCameraInfo> cameras; //存放系统支持的摄像头列表
QCameraImageCapture* camera_image_capture;
QImageEncoderSettings iamge_setting;
QVideoProbe *m_pProbe;
void Log_Display(QString text);
void YUV420P_to_RGB24(unsigned char *data, unsigned char *rgb, int width, int height);
void NV21_TO_RGB24(unsigned char *data, unsigned char *rgb, int width, int height);
void YUV420P_TO_RGB24(unsigned char *yuv420p, unsigned char *rgb24, int width, int height);
void yuyv_to_rgb(unsigned char *yuv_buffer,unsigned char *rgb_buffer,int iWidth,int iHeight);
private slots:
void slotOnProbeFrame(const QVideoFrame &frame);
void on_pushButton_open_camera_clicked();
void on_pushButton_Camear_up_clicked();
void on_pushButton_stop_clicked();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
UI界面:
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