Linux 下 v4l2 和 Qt 连接usb摄像头

#include "imagecamera.h" #include <string.h> #include <unistd.h> #include <fcntl.h> #include <errno.h> #include <sys/ioctl.h> #include <sys/time.h> #include <sys/mman.h> #include <linux/videodev2.h> #include <QDir> #include <dirent.h> #include <unistd.h> #include <asm/types.h> #include <math.h> #include <malloc.h> #include <QImage> #define log_debug qDebug void yuyv_to_rgb888(unsigned char* yuv,unsigned char* rgb, int imgWidth, int imgHeight) { unsigned int i; unsigned char* y0 = yuv + 0; unsigned char* u0 = yuv + 1; unsigned char* y1 = yuv + 2; unsigned char* v0 = yuv + 3; unsigned char* r0 = rgb + 0; unsigned char* g0 = rgb + 1; unsigned char* b0 = rgb + 2; unsigned char* r1 = rgb + 3; unsigned char* g1 = rgb + 4; unsigned char* b1 = rgb + 5; //DBG("yuyv_to_rgb start\n"); float rt0 = 0, gt0 = 0, bt0 = 0, rt1 = 0, gt1 = 0, bt1 = 0; for(i = 0; i <= (imgWidth * imgHeight) / 2 ;i++) { bt0 = 1.164 * (*y0 - 16) + 2.018 * (*u0 - 128); gt0 = 1.164 * (*y0 - 16) - 0.813 * (*v0 - 128) - 0.394 * (*u0 - 128); rt0 = 1.164 * (*y0 - 16) + 1.596 * (*v0 - 128); bt1 = 1.164 * (*y1 - 16) + 2.018 * (*u0 - 128); gt1 = 1.164 * (*y1 - 16) - 0.813 * (*v0 - 128) - 0.394 * (*u0 - 128); rt1 = 1.164 * (*y1 - 16) + 1.596 * (*v0 - 128); if(rt0 > 250) rt0 = 255; if(rt0 < 0) rt0 = 0; if(gt0 > 250) gt0 = 255; if(gt0 < 0) gt0 = 0; if(bt0 > 250) bt0 = 255; if(bt0 < 0) bt0 = 0; if(rt1 > 250) rt1 = 255; if(rt1 < 0) rt1 = 0; if(gt1 > 250) gt1 = 255; if(gt1 < 0) gt1 = 0; if(bt1 > 250) bt1 = 255; if(bt1 < 0) bt1 = 0; *r0 = (unsigned char)bt0; *g0 = (unsigned char)gt0; *b0 = (unsigned char)rt0; *r1 = (unsigned char)bt1; *g1 = (unsigned char)gt1; *b1 = (unsigned char)rt1; yuv = yuv + 4; rgb = rgb + 6; if(yuv == NULL) break; y0 = yuv; u0 = yuv + 1; y1 = yuv + 2; v0 = yuv + 3; r0 = rgb + 0; g0 = rgb + 1; b0 = rgb + 2; r1 = rgb + 3; g1 = rgb + 4; b1 = rgb + 5; } } ImageCamera::ImageCamera(QString c, QObject *parent) : QThread(parent) { camera = c; err.clear(); nWidth = 1280; nHeight = 960; nSize = nWidth * nHeight * 2; bKeep = false; memset(pix_format, 0, sizeof(pix_format)); cam_fd = -1; buffer_count = 5; video_buffer_ptr = new u8*[buffer_count]; } bool ImageCamera::initCamera() { int index = 0; int ret = 0; if(camera.isEmpty()) { err = QString("设备节点位置为空"); return false; } if(cam_fd != -1) { close(cam_fd); } // 打开相机 cam_fd = open(camera.toStdString().c_str(), O_RDWR); if(cam_fd == -1) { err = QString("打开相机节点失败"); return false; } // 设置使用的相机通道，此处为0 if(0 != ioctl(cam_fd, VIDIOC_S_INPUT, &index)) { err = QString("%1").arg(strerror(errno)); return false; } // 查询相机的基本信息 struct v4l2_capability cap; ioctl(cam_fd,VIDIOC_QUERYCAP,&cap); log_debug("Driver Name:%s Card Name:%s Bus info:%s Driver Version:%u.%u.%u", cap.driver,cap.card,cap.bus_info,(cap.version>>16)&0xFF, (cap.version>>8)&0xFF,cap.version&0xFF); // 查询相机支持的采图格式 struct v4l2_fmtdesc fmtdesc; fmtdesc.index=0; fmtdesc.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; log_debug("Support format:"); do{ ret=ioctl(cam_fd, VIDIOC_ENUM_FMT, &fmtdesc); log_debug("index %d, format %s", fmtdesc.index, fmtdesc.description); fmtdesc.index++; }while(0==ret); // 查询相机支持的帧率范围 struct v4l2_streamparm stream_parm; memset(&stream_parm, 0, sizeof(struct v4l2_streamparm)); stream_parm.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; ret = ioctl(cam_fd, VIDIOC_G_PARM, &stream_parm); log_debug("befor:framerate: numerator = %d,denominator = %d", stream_parm.parm.capture.timeperframe.numerator,stream_parm.parm.capture.timeperframe.denominator); // 设置相机的输出格式，图片大小等数据 struct v4l2_format format; memset(&format, 0, sizeof(format)); format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; format.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG; //V4L2_PIX_FMT_YUYV 设置相机输出为JPEG，也可设置为yuyv，但具体的输出格式不能依靠此处 format.fmt.pix.width = nWidth; // 设置输出图片宽、高 format.fmt.pix.height = nHeight; //******** // format.fmt.pix.bytesperline = IMAGE_WIDTH * 1; // format.fmt.pix.sizeimage = IMAGE_WIDTH * IMAGE_HEIGHT * 1; // format.fmt.pix.field = V4L2_FIELD_NONE; // 尝试相机是否支持改格式 ret = ioctl(cam_fd, VIDIOC_TRY_FMT, &format); if (ret != 0) { err = QString::asprintf("ioctl(VIDIOC_TRY_FMT) failed %d(%s)", errno, strerror(errno)); log_debug(err.toLatin1().constData()); return false; } // 真正进行设置改格式 format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; ret = ioctl(cam_fd, VIDIOC_S_FMT, &format); if (ret != 0) { err = QString::asprintf("ioctl(VIDIOC_S_FMT) failed %d(%s)", errno, strerror(errno)); log_debug(err.toLatin1().constData()); return false; } // 获取相机输出的图片参数 if(-1 == ioctl(cam_fd, VIDIOC_G_FMT, &format)){//得到图片格式 err = QString("set format failed!"); log_debug(err.toLatin1().constData()); return false; } log_debug("fmt.type:\t\t%d",format.type); /**************************************************************/ // 此处的图片格式，决定着采集到的图片数据要怎么解析，一般分为 MJPG 和 YUYV，上面设置的和此处获取的在某些情况下会不一致，因此需要此处决定解析格式 sprintf(pix_format, "%c%c%c%c", \ format.fmt.pix.pixelformat & 0xFF,\ (format.fmt.pix.pixelformat >> 8) & 0xFF, \ (format.fmt.pix.pixelformat >> 16) & 0xFF,\ (format.fmt.pix.pixelformat >> 24) & 0xFF); log_debug("pix.pixelformat:\t%s", pix_format); log_debug("pix.width:\t\t%d",format.fmt.pix.width); log_debug("pix.height:\t\t%d",format.fmt.pix.height); log_debug("pix.field:\t\t%d",format.fmt.pix.field); // 查询相机需要开辟的内存信息 struct v4l2_requestbuffers req; req.count = buffer_count; req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; req.memory = V4L2_MEMORY_MMAP; ret = ioctl(cam_fd, VIDIOC_REQBUFS, &req); if (ret != 0) { err = QString::asprintf("ioctl(VIDIOC_REQBUFS) failed %d(%s)", errno, strerror(errno)); log_debug(err.toLatin1().constData()); return false; } log_debug("req.count: %d", req.count); if (req.count < buffer_count) { err = QString::asprintf("request buffer failed"); log_debug(err.toLatin1().constData()); return false; } // 逐一将相机开辟的内存进行内存映射 struct v4l2_buffer buffer; memset(&buffer, 0, sizeof(buffer)); buffer.type = req.type; buffer.memory = V4L2_MEMORY_MMAP; for (int i=0; i<req.count; i++) { buffer.index = i; ret = ioctl (cam_fd, VIDIOC_QUERYBUF, &buffer); if (ret != 0) { err = QString::asprintf("ioctl(VIDIOC_QUERYBUF) failed %d(%s)", errno, strerror(errno)); log_debug(err.toLatin1().constData()); return false; } log_debug("buffer.length: %d", buffer.length); log_debug("buffer.m.offset: %d", buffer.m.offset); video_buffer_ptr[i] = (u8*) mmap(NULL, buffer.length, PROT_READ|PROT_WRITE, MAP_SHARED, cam_fd