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1 前言

  在某项目中需要在RK3399平台实现USB摄像头画面的实时预览、视频录制、拍照存储等功能。
  先来看需要实现的最终效果。
  

  本项目使用了搭载了RK3399芯片的嵌入式平台，操作系统Debain10，调用ffmpeg-rkmpp库进行H264硬编码。
  本项目需要外接一个支持 2592x1944，1080p，720p，480p的USB摄像头。

2 项目内容详细说明

2.0 功能

  （1）实时预览；
  （2）摄像头分辨率设置，可设置为480p，720p，1080p；
  （3）编码格式设置，可按照H264格式编码，或直接存MJPEG；
  （4）存储文件格式，可设置为.avi或者.mp4格式；
  （5）录制视频时，显示当前录制时间以及“REC”闪烁字样；
  （6）拍照功能，拍摄照片分辨率为2592x1944（500万像素）；
  （7）通过F3、F4键移动光标，通过 ↑ 按键实现“开始、停止”录视频，通过 → 按键实现“确定”，通过 ← 按键实现“拍照”。

2.1 工程文件夹说明

  工程文件夹结构如下：

  在cameraModule文件夹内的是视频相关内容，可单独编译成库，在cameravideowidget.cpp中实现代码的调用。

3 代码

3.1 CameraThread类

  CameraThread类为视频录制、拍照实现的关键类，其接口如下表所示。

成员类型	名称	描述
构造函数	CameraThread()	初始化 CameraThread 对象
析构函数	~CameraThread()	释放 CameraThread 对象的资源。
函数	int CheckUSBCamera()	检查 USB 相机是否正常工作。返回值为 0 表示正常，其他值表示错误代码。
	void setParamter(int, int, int)	设置视频参数（分辨率、编码格式、封装格式）。必须在 OpenCamera() 之前调用。
	int OpenCamera()	开启相机。返回值为 0 表示成功，其他值表示错误代码。
	int CloseCamera()	关闭相机。返回值为 0 表示成功，其他值表示错误代码。
	int TakePhoto(QString name)	拍照接口，调用该函数使用相机拍摄一张照片并保存至指定路径。返回值为 0 表示成功，其他值表示错误代码。
	int DeletPhoto()	删除照片接口，调用该函数删除当前拍摄的照片。返回值为 0 表示成功，其他值表示错误代码。
	int StartTakeVideo(QString name)	开始视频录制并保存到指定路径。返回值为 0 表示成功，其他值表示错误代码。
	int StopTakeVideo()	停止当前视频录制操作，并完成所有未完成任务。返回值为 0 表示成功，其他值表示错误代码。
信号	void sendPhoto(QImage img)	当拍摄照片后发出此信号，传递一个 QImage 类型的图像用于UI绘制。
信号	void sendRealTimePhoto(QImage img)	发送实时图像帧信号，用于传递实时预览图像。
公有变量	bool isOpen	标志相机是否已打开。
公有变量	bool isRecording	标志是否正在录制视频。
公有变量	std::unique_ptr impl	使用 PIMPL 设计模式隐藏实现细节的实现类指针。

  camerathread.cpp实现如下所示。

#include "camerathread.h"
#include "camerathreadimpl.h"CameraThread::CameraThread() :impl(std::make_unique<CameraThreadImpl>())
{connect(impl.get(), &CameraThreadImpl::sendPhoto, this, &CameraThread::sendPhoto);connect(impl.get(), &CameraThreadImpl::sendRealTimePhoto, this, &CameraThread::sendRealTimePhoto);qDebug()<<"libcamerathread.so_version_20250731_";
}CameraThread::~CameraThread()
{}int CameraThread::CheckUSBCamera()
{int ret = 0;qDebug()<<"CheckUSBCamera!";if(isOpen==true){ret = 0;}else{ret = impl->CheckUSBCamera();}return ret;
}void CameraThread::setParamter(int resolution, int encodeformat, int containerformat)
{qDebug()<<"resolution: "<<resolution<<" encodeformat: "<<encodeformat<<"containerformat "<<containerformat;impl->setParamter(resolution, encodeformat, containerformat);
}int CameraThread::OpenCamera()
{int ret = 0;qDebug()<<"Camera Open!";ret=impl->OpenCamera();if(!ret){isOpen = true;}qDebug()<<"OpenCamera isOpen: "<<isOpen;return ret;
}int CameraThread::CloseCamera()
{int ret = 0;qDebug()<<"Camera Close!";qDebug()<<"CloseCamera isOpen: "<<isOpen;if(isOpen == true){ret = impl->CloseCamera();}if(!ret){isOpen = false;}ret = StopTakeVideo();return ret;
}int CameraThread::TakePhoto(QString name)
{int ret = 0;ret=impl->TakePhoto(name);return ret;
}int CameraThread::DeletPhoto()
{int ret = 0;qDebug()<<"Delete Photo";ret=impl->DeletPhoto();return ret;
}int CameraThread::StartTakeVideo(QString name)
{int ret = 0;qDebug()<<"StartTakeVideo: "<<name;ret=impl->StartTakeVideo(name);isRecording = true;return ret;
}int CameraThread::StopTakeVideo()
{int ret = 0;if(isRecording){ret=impl->StopTakeVideo();}isRecording = false;return ret;
}

3.1 CameraThreadImpl类

  CameraThread类中使用CameraThreadImpl类作为内部实现类，可使得CameraThread接口不暴露具体实现方法。

camerathreadimpl.cpp具体实现如下所示。

#include "camerathreadimpl.h"CameraThreadImpl::CameraThreadImpl()
{initParam();/***************************分配缓冲队列**************************************/video_packet_queue = new AVPacketQueue();video_packet_queue_output = new AVPacketQueue();/***************************分配缓冲队列**************************************/video_frame_queue = new AVFrameQueue();fmtConvert_queue_output = new AVFrameQueue();}CameraThreadImpl::~CameraThreadImpl()
{delete demux_thread;delete decode_thread;delete save_thread;delete video_packet_queue_output;delete video_packet_queue;}void CameraThreadImpl::initParam()
{// 读取INI配置文件QString configFilePath = QCoreApplication::applicationDirPath() + "/config.ini";QSettings settings(configFilePath, QSettings::IniFormat);/************************确认配置文件路径以及是否存在配置文件***************/
//    qDebug()<<"configFilePath: "<<configFilePath;
//    qDebug()<<"File Exists: " << QFile::exists(configFilePath);                         // 确保文件存在
//    qDebug()<<"QSettings file path: " << settings.fileName();/*********************************************************************/// 设置默认值QString defaultCameraUrl;QString defaultSavePath;
#ifdef Q_OS_WIN
//    defaultCameraUrl = "video=Rmoncam FHD 1080P";       // Windows 平台默认相机名称defaultCameraUrl = "video=USB Video Device";       // Windows 平台默认相机名称defaultSavePath = "C:\\Users\\chao8\\Desktop\\";    // Windows 默认保存路径
#else
//    defaultCameraUrl = "/dev/video10";                  // Forlinx 平台默认相机名称
//    defaultSavePath = "/home/forlinx/Desktop/";         // Forlinx 默认保存路径defaultCameraUrl = "/dev/video0";                  // Debain11平台默认相机名称defaultSavePath = "/mnt/ums/data/";                     // Debain11 默认保存路径
#endifdouble defaultRemainingSpace = 0.8;int defaultRecordIntervalMinutes = 1000;QString defaultResolution = "1920x1080";QString defaultBitrate = "40M";// 从INI文件读取配置值，如果没有配置则使用默认值savePath_ = settings.value("Parameters/savePath", defaultSavePath).toString().toStdString();url_ = settings.value("Parameters/url", defaultCameraUrl).toString().toStdString();remainingSpace = settings.value("Parameters/remainingStorageSpace", defaultRemainingSpace).toDouble();recordIntervalMinutes = settings.value("Parameters/recordIntervalMinutes", defaultRecordIntervalMinutes).toInt();Resolution = settings.value("Parameters/resolution", defaultResolution).toString();Bitrate = settings.value("Parameters/bitrate", defaultBitrate).toString();// 设置定时器时间，定时处理视频信息，每隔一段时间自动记录视频timer = new QTimer(this);timer->setInterval(recordIntervalMinutes * 60 * 1000);connect(timer, &QTimer::timeout, this, &CameraThreadImpl::handleVideoData);/*****************************打印各参数配置数值*****************************/
//    qDebug()<<"savePath_: "<<QString::fromStdString(savePath_);
//    qDebug()<<"url_: "<<QString::fromStdString(url_);
//    qDebug()<<"remainingSpace: "<<remainingSpace;
//    qDebug()<<"Resolution: "<<Resolution;
//    qDebug()<<"Bitrate: "<<Bitrate;
//    qDebug()<<"recordIntervalMinutes: "<<recordIntervalMinutes;/**************************************************************************/}int CameraThreadImpl::CheckUSBCamera()
{avdevice_register_all();std::string url_str = url_;AVFormatContext *ifmt_ctx = avformat_alloc_context();char err2str[256] = {0};AVDictionary *options = nullptr;av_dict_set(&options, "fflags", "nobuffer", 0);av_dict_set(&options, "probesize", "4096", 0);av_dict_set(&options, "framerate", "30", 0);av_dict_set(&options, "video_size", "1920x1080", 0);av_dict_set(&options, "input_format", "mjpeg", 0);#ifdef Q_OS_WINconst AVInputFormat *m_inputFormat = av_find_input_format("dshow");
#elseconst AVInputFormat *m_inputFormat = av_find_input_format("v4l2");
#endifint ret = avformat_open_input(&ifmt_ctx, url_str.c_str(), m_inputFormat, &options);//    qDebug()<<"ret: "<<ret;if (ret < 0) {av_strerror(ret, err2str, sizeof(err2str));qDebug("avformat_open_input failed, ret:%d, err2str:%s", ret, err2str);return ret;}ret = avformat_find_stream_info(ifmt_ctx, nullptr);if (ret < 0) {av_strerror(ret, err2str, sizeof(err2str));qDebug("avformat_find_stream_info failed, ret:%d, err2str:%s", ret, err2str);avformat_close_input(&ifmt_ctx);return ret;}avformat_close_input(&ifmt_ctx);qDebug() << "USB camera check OK!";return ret;
}void CameraThreadImpl::ReleaseQueue()
{video_packet_queue_output->release();video_packet_queue->release();video_frame_queue->release();fmtConvert_queue_output->release();
}void CameraThreadImpl::setParamter(int resolution, int encodeformat, int containerformat)
{if(resolution==0){Resolution = "1920x1080";}else if(resolution==1){Resolution = "1280x720";}else if(resolution==2){Resolution = "640x480";}if(encodeformat==0){EncodeFormat = "MJPEG";}else if(encodeformat==1){EncodeFormat = "H264";}if(containerformat==0){VideoContainerFormat = "avi";}else if(containerformat==1){VideoContainerFormat = "mp4";}
}void CameraThreadImpl::handleVideoData()
{qDebug()<<"handleVideoData! ";demux_thread->start_pts = 0;save_thread->Stop();ReleaseQueue();save_thread->Init();save_thread->Start();}int CameraThreadImpl::OpenCamera()
{int ret = 0;/*************************************************************************************/if(EncodeFormat == "MJPEG"){demux_thread = new DemuxThread(video_packet_queue, &url_);demux_thread->setResolution(Resolution);ret = demux_thread->Start();if(ret<0){isCameraValid = false;}else{isCameraValid = true;}/**************************************************************************************/decode_thread = new DecodeThread(video_packet_queue, video_packet_queue_output, &savePath_);decode_thread->setRemainingSpace(remainingSpace);ret = decode_thread->Init(demux_thread->VideoCodecParameters());ret = decode_thread->Start();}if(EncodeFormat == "H264"){demux_thread = new DemuxThread(video_packet_queue, &url_);demux_thread->setResolution(Resolution);ret = demux_thread->Start();if(ret<0){isCameraValid = false;}else{isCameraValid = true;}/**************************************************************************************/decode_thread = new DecodeThread(video_packet_queue, video_frame_queue, &savePath_);decode_thread->setRemainingSpace(remainingSpace);ret = decode_thread->Init(demux_thread->VideoCodecParameters());ret = decode_thread->Start();}/**************************************************************************************/connect(decode_thread, &DecodeThread::frameReady, this, &CameraThreadImpl::sendPhoto);connect(decode_thread, &DecodeThread::realTimeframeReady, this, &CameraThreadImpl::sendRealTimePhoto);connect(decode_thread, &DecodeThread::frameReady, this, &CameraThreadImpl::CloseCamera);connect(decode_thread, &DecodeThread::frameReady, this, &CameraThreadImpl::setisTakePhoto);return ret;
}int CameraThreadImpl::StartTakeVideo(QString name)
{int ret = 0;std::string savefilename = name.toStdString();ReleaseQueue();CloseCamera();OpenCamera();/**************************************************************************************/if(isCameraValid){if(EncodeFormat == "MJPEG"){save_thread = new SaveThread(video_packet_queue_output, demux_thread->inputStream, &savefilename);save_thread->setRemainingSpace(remainingSpace);save_thread->setVideoContainerFormat(VideoContainerFormat);ret = save_thread->Init();ReleaseQueue();demux_thread->start_pts = 0;decode_thread->isSaveFile = true;ret = save_thread->Start();}if(EncodeFormat == "H264"){/************************************************************************/fmtConvert_thread = new FormatConvertThread(video_frame_queue, fmtConvert_queue_output);/*********************************************************************/encode_thread = new EncodeThread(fmtConvert_queue_output, video_packet_queue_output, demux_thread->inputStream);encode_thread->setBitrate(Bitrate);encode_thread->isFIlter = isFilterOn;encode_thread->EncodeFormat = "H264";ret = encode_thread->Init();ret = fmtConvert_thread->Start();ret = encode_thread->Start();save_thread = new SaveThread(video_packet_queue_output, demux_thread->inputStream, &savefilename, encode_thread->encoderContext);save_thread->setRemainingSpace(remainingSpace);save_thread->setVideoContainerFormat(VideoContainerFormat);ret = save_thread->Init();ReleaseQueue();demux_thread->start_pts = 0;decode_thread->isSaveFile = true;ret = save_thread->Start();}timer->start();}else{qDebug()<<"Camera is not Valid! Cannot video!";}return ret;
}int CameraThreadImpl::StopTakeVideo()
{if(isCameraValid){if(save_thread!=nullptr){save_thread->Stop();save_thread = nullptr;decode_thread->isSaveFile = false;if (fmtConvert_thread) fmtConvert_thread->Stop();if (encode_thread) encode_thread->Stop();ReleaseQueue();timer->stop();qDebug()<<"StopTakeVideo!";}else{qDebug()<<"No save_thread!";}}else{qDebug()<<"Camera is not Valid! Cannot video!";}return 0;
}int CameraThreadImpl::CloseCamera()
{StopTakeVideo();if(isCameraValid){decode_thread->Stop();demux_thread->Stop();isCameraValid = false;}ReleaseQueue();      //清空缓冲队列里的东西，每次关闭相机的时候，必须要有！return 0;
}void CameraThreadImpl::setisTakePhoto()
{isTakePhoto = false;
}int CameraThreadImpl::TakePhoto(QString name)
{qDebug()<<"isTakePhoto: "<<isTakePhoto;if(!isTakePhoto){qDebug()<<"In TakePhoto!!!!!! ";isTakePhoto = true;CloseCamera();int ret = 0;demux_thread = new DemuxThread(video_packet_queue, &url_);demux_thread->setResolution("2592x1944");ret = demux_thread->Start();if(ret<0){isCameraValid = false;}else{isCameraValid = true;}/**************************************************************************************/decode_thread = new DecodeThread(video_packet_queue, video_packet_queue_output, &savePath_);decode_thread->setRemainingSpace(remainingSpace);ret = decode_thread->Init(demux_thread->VideoCodecParameters());ret = decode_thread->Start();connect(decode_thread, &DecodeThread::frameReady, this, &CameraThreadImpl::sendPhoto);connect(decode_thread, &DecodeThread::frameReady, this, &CameraThreadImpl::CloseCamera);connect(decode_thread, &DecodeThread::frameReady, this, &CameraThreadImpl::setisTakePhoto);if (decode_thread){decode_thread->takePhoto(name);}else{return -1;}return ret;}else{return 0;}}int CameraThreadImpl::DeletPhoto()
{decode_thread->DeletPhoto();return 0;
}

4 资源下载

本案例中涉及到的所有代码请到此处下载 https://download.csdn.net/download/wang_chao118/91923444。