void

linux环境使用V4l2实现摄像头捕捉界面流畅播放并可以保存图片到本地。

void

0){qDebug(video设备打开失败\n);return;}else{qDebug(video设备打开成功\n);}//查看设备是否为视频采集设备struct

v4l2_capability

V4L2_BUF_TYPE_VIDEO_CAPTURE;qDebug(Video支持所有格式如下:);while(ioctl(fd,

VIDIOC_ENUM_FMT,

fmtdesc.description);fmtdesc.index;}//

枚举分辨率struct

V4L2_BUF_TYPE_VIDEO_CAPTURE;qDebug(Video支持分辨率如下:);while(ioctl(fd,

frmsize)

frmsize.pixel_format);frmsize.index;}//

pixel_width

V4L2_BUF_TYPE_VIDEO_CAPTURE;frmival.pixel_format

V4L2_PIX_FMT_MJPEG;frmival.width

pixel_height;while(ioctl(fd,VIDIOC_ENUM_FRAMEINTERVALS,

frmival)

frmival.discrete.numerator);frmival.index;}//

设置采集格式struct

V4L2_BUF_TYPE_VIDEO_CAPTURE;vfmt.fmt.pix.width

pixel_width;vfmt.fmt.pix.height

pixel_height;vfmt.fmt.pix.pixelformat

V4L2_PIX_FMT_MJPEG;if(ioctl(fd,

VIDIOC_S_FMT,

0){qDebug(video设置格式失败\n);return;}//

VIDIOC_G_FMT,

0){qDebug(video获取格式失败\n);return;}//

获取帧信息struct

V4L2_BUF_TYPE_VIDEO_CAPTURE;ioctl(fd,

VIDIOC_G_PARM,

streamparm.parm.capture.timeperframe.numerator,

streamparm.parm.capture.timeperframe.denominator);//

streamparm.parm.capture.capability){streamparm.parm.capture.timeperframe.numerator

1;streamparm.parm.capture.timeperframe.denominator

30;

streamparm.parm.capture.timeperframe.numerator,

streamparm.parm.capture.timeperframe.denominator);

}}//

V4L2_BUF_TYPE_VIDEO_CAPTURE;reqbuf.count

VIDIOC_REQBUFS,

0){qDebug(video申请缓冲区失败\n);return;}//

将帧缓冲映射到进程地址空间struct

V4L2_BUF_TYPE_VIDEO_CAPTURE;buf.memory

V4L2_MEMORY_MMAP;//

将每一帧对应的缓冲区的起始地址保存在m_userVideoBuf数组中读取采集数据时只需直接读取映射区即可for(buf.index0;

buf.index){ioctl(fd,

buf.m.offset);m_userVideoBufSize[buf.index]

buf.length;if(m_userVideoBuf[buf.index]

mmap

char[3*1024*1024];while(m_isRun){FD_ZERO(fds);FD_SET(fd,

fds);int

V4L2_BUF_TYPE_VIDEO_CAPTURE;readbuffer.memory

VIDIOC_DQBUF,

QDateTime::currentDateTime().toString(hh:mm:ss:zzz);//重点帧数据处理const

uchar

*)m_userVideoBuf[readbuffer.index];int

length

readbuffer.length;//构造并显示QImage

image

sigUpdateImage(image.copy());//

再次入队if(ioctl(fd,

m_userVideoBufSize[i]);}//关闭文件emit

sigUpdateImage(QImage());close(fd);delete[]

fileBuf;qDebug()