一、回憶下v4l2驅動操作流程
1.查詢驅動功能
struct v4l2_capability cap;
ioctl(fd,vidioc_querycap,&cap);
printf("tk---------->>>>>driver name:%s\ncard name:%s\nbus info:%s\n",cap.driver,cap.card,cap.bus_info);
struct v4l2_fmtdesc fmtdesc;
fmtdesc.index = 0; fmtdesc.type = v4l2_buf_type_video_capture;
while(ioctl(fd,vidioc_enum_fmt,&fmtdesc) != -1)
struct v4l2_format fmt;
memset(&fmt,0,sizeof(fmt));
fmt.type = v4l2_buf_type_video_capture;
fmt.fmt.pix.width = 1280;
fmt.fmt.pix.height = 720;
fmt.fmt.pix.pixelformat = v4l2_pix_fmt_mjpeg;
fmt.fmt.pix.field = v4l2_field_none;//v4l2_field_interlaced;
fmt.fmt.pix.colorspace = 8;
int fmtreslt = ioctl(fd,vidioc_s_fmt,&fmt);
printf("tk--------_>>>>fmtreslt is %d\n",fmtreslt);
fmt.type = v4l2_buf_type_video_capture;
//重新獲取，看是否設定成功
ioctl(fd,vidioc_g_fmt,&fmt);
printf("tk----------->>>>>fmt.fmt.width is %d\nfmt.fmt.pix.height is %d\nfmt.fmt.pix.colorspace is %d\n",fmt.fmt.pix.width,fmt.fmt.pix.height,fmt.fmt.pix.colorspace);
struct v4l2_requestbuffers req;
req.count = 4;
req.type = v4l2_buf_type_video_capture;
req.memory = v4l2_memory_mmap;
//分配記憶體
ioctl(fd,vidioc_reqbufs,&req);
struct buffer*buffers;
buffers = (struct buffer*)calloc (req.count, sizeof(*buffers));
unsigned int n_buffers = 0;
for(n_buffers = 0; n_buffers < req.count; ++n_buffers)
buffers[n_buffers].length = buf.length;
//對映到使用者空間
buffers[n_buffers].start = mmap(null,buf.length,prot_read|prot_write,map_shared,fd,buf.m.offset);
if(map_failed == buffers[n_buffers].start)
}
unsigned int i;
enum v4l2_buf_type type;
for(i = 0; i < 4; i++)
type = v4l2_buf_type_video_capture;
ioctl(fd,vidioc_streamon,&type);
unsigned int j;
for(j = 0; j < 4; j++)
ioctl(fd,vidioc_streamoff,&type);原來如下——
ioctl(fd,vidioc_qbuf,&buf);
ioctl(fd,vidioc_streamon,&type);
ioctl(fd,vidioc_dqbuf,&buf);
ioctl(fd,vidioc_streamon,&type);
usleep(800000);
ioctl(fd,vidioc_qbuf,&buf);
ioctl(fd,vidioc_dqbuf,&buf);
三、工程例項
status_t v4lcameraadapter::startpreview()
#endif
ret = ioctl(mcamerahandle, vidioc_qbuf, &mvideoinfo->buf);
if (ret < 0)
camhal_logdb("startpreview --length=%d, index:%d", mvideoinfo->buf.length,mvideoinfo->buf.index);
nqueued++;
}*///end tankai
enum v4l2_buf_type buftype;
if (!mvideoinfo->isstreaming)
mvideoinfo->isstreaming = true;
}if( menablecontifocus &&
(cam_focus_mode_auto != cur_focus_mode_for_conti) &&
(cam_focus_mode_infinity != cur_focus_mode_for_conti))
cur_focus_mode_for_conti = cam_focus_mode_conti_vid;
}//add by tankai
usleep(800000);
nqueued = 0;
for (int i = 0; i < mpreviewbuffercount; i++)
#endif
ret = ioctl(mcamerahandle, vidioc_qbuf, &mvideoinfo->buf);
if (ret < 0)
camhal_logdb("startpreview --length=%d, index:%d", mvideoinfo->buf.length,mvideoinfo->buf.index);
nqueued++;
}//end tankai
......
}
看看preview執行緒：
int v4lcameraadapter::previewthread()
*/} char *fp = this->getframe(index);
/*char * v4lcameraadapter::getframe(int &index)
*/
uint8_t* src = (uint8_t*) fp; //camera原始資料
private_handle_t* gralloc_hnd = (private_handle_t*)ptr;
dest = (uint8_t*)gralloc_hnd->base;
if(default_preview_pixel_format == v4l2_pix_fmt_yuyv)
}
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