Created
August 4, 2011 22:02
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Capture single image V4L2
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| Driver Caps: | |
| Driver: "omap3" | |
| Card: "omap3/mt9v032//" | |
| Bus: "" | |
| Version: 0.0 | |
| Capabilities: 04000001 | |
| Camera Cropping: | |
| Bounds: 752x480+0+0 | |
| Default: 752x480+0+0 | |
| Aspect: 1/1 | |
| FMT : CE Desc | |
| -------------------- | |
| UYVY: UYVY, packed | |
| YUYV: YUYV (YUV 4:2:2), packed | |
| BA10: Bayer10 (GrR/BGb) | |
| Selected Camera Mode: | |
| Width: 752 | |
| Height: 480 | |
| PixFmt: BA10 | |
| Field: 1 | |
| Length: 724992 | |
| Address: 0x40156000 | |
| Image Length: 0 | |
| omap-iommu omap-iommu.0: omap2_iommu_fault_isr: da:000c0000 translation fault | |
| omap-iommu omap-iommu.0: iommu_fault_handler: da:000c0000 pgd:dfd10000 *pgd:9f4d1c01 pte:df4d1f00 *pte:00000000 | |
| omap-iommu omap-iommu.0: omap2_iommu_fault_isr: da:000c0000 translation fault | |
| omap-iommu omap-iommu.0: iommu_fault_handler: da:000c0000 pgd:dfd10000 *pgd:9f4d1c01 pte:df4d1f00 *pte:00000000 |
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| #include <errno.h> | |
| #include <fcntl.h> | |
| #include <linux/videodev2.h> | |
| #include <stdint.h> | |
| #include <stdio.h> | |
| #include <string.h> | |
| #include <sys/ioctl.h> | |
| #include <sys/mman.h> | |
| #include <unistd.h> | |
| uint8_t *buffer; | |
| static int xioctl(int fd, int request, void *arg) | |
| { | |
| int r; | |
| do r = ioctl (fd, request, arg); | |
| while (-1 == r && EINTR == errno); | |
| return r; | |
| } | |
| int print_caps(int fd) | |
| { | |
| struct v4l2_capability caps = {}; | |
| if (-1 == xioctl(fd, VIDIOC_QUERYCAP, &caps)) | |
| { | |
| perror("Querying Capabilities"); | |
| return 1; | |
| } | |
| printf( "Driver Caps:\n" | |
| " Driver: \"%s\"\n" | |
| " Card: \"%s\"\n" | |
| " Bus: \"%s\"\n" | |
| " Version: %d.%d\n" | |
| " Capabilities: %08x\n", | |
| caps.driver, | |
| caps.card, | |
| caps.bus_info, | |
| (caps.version>>16)&&0xff, | |
| (caps.version>>24)&&0xff, | |
| caps.capabilities); | |
| struct v4l2_cropcap cropcap = {0}; | |
| cropcap.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; | |
| if (-1 == xioctl (fd, VIDIOC_CROPCAP, &cropcap)) | |
| { | |
| perror("Querying Cropping Capabilities"); | |
| return 1; | |
| } | |
| printf( "Camera Cropping:\n" | |
| " Bounds: %dx%d+%d+%d\n" | |
| " Default: %dx%d+%d+%d\n" | |
| " Aspect: %d/%d\n", | |
| cropcap.bounds.width, cropcap.bounds.height, cropcap.bounds.left, cropcap.bounds.top, | |
| cropcap.defrect.width, cropcap.defrect.height, cropcap.defrect.left, cropcap.defrect.top, | |
| cropcap.pixelaspect.numerator, cropcap.pixelaspect.denominator); | |
| int support_grbg10 = 0; | |
| struct v4l2_fmtdesc fmtdesc = {0}; | |
| fmtdesc.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; | |
| char fourcc[5] = {0}; | |
| char c, e; | |
| printf(" FMT : CE Desc\n--------------------\n"); | |
| while (0 == xioctl(fd, VIDIOC_ENUM_FMT, &fmtdesc)) | |
| { | |
| strncpy(fourcc, (char *)&fmtdesc.pixelformat, 4); | |
| if (fmtdesc.pixelformat == V4L2_PIX_FMT_SGRBG10) | |
| support_grbg10 = 1; | |
| c = fmtdesc.flags & 1? 'C' : ' '; | |
| e = fmtdesc.flags & 2? 'E' : ' '; | |
| printf(" %s: %c%c %s\n", fourcc, c, e, fmtdesc.description); | |
| fmtdesc.index++; | |
| } | |
| if (!support_grbg10) | |
| { | |
| printf("Doesn't support GRBG10.\n"); | |
| return 1; | |
| } | |
| struct v4l2_format fmt = {0}; | |
| fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; | |
| fmt.fmt.pix.width = 752; | |
| fmt.fmt.pix.height = 480; | |
| fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_SGRBG10; | |
| fmt.fmt.pix.field = V4L2_FIELD_NONE; | |
| if (-1 == xioctl(fd, VIDIOC_S_FMT, &fmt)) | |
| { | |
| perror("Setting Pixel Format"); | |
| return 1; | |
| } | |
| strncpy(fourcc, (char *)&fmt.fmt.pix.pixelformat, 4); | |
| printf( "Selected Camera Mode:\n" | |
| " Width: %d\n" | |
| " Height: %d\n" | |
| " PixFmt: %s\n" | |
| " Field: %d\n", | |
| fmt.fmt.pix.width, | |
| fmt.fmt.pix.height, | |
| fourcc, | |
| fmt.fmt.pix.field); | |
| return 0; | |
| } | |
| int init_mmap(int fd) | |
| { | |
| struct v4l2_requestbuffers req = {0}; | |
| req.count = 1; | |
| req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; | |
| req.memory = V4L2_MEMORY_MMAP; | |
| if (-1 == xioctl(fd, VIDIOC_REQBUFS, &req)) | |
| { | |
| perror("Requesting Buffer"); | |
| return 1; | |
| } | |
| struct v4l2_buffer buf = {0}; | |
| buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; | |
| buf.memory = V4L2_MEMORY_MMAP; | |
| buf.index = 0; | |
| if(-1 == xioctl(fd, VIDIOC_QUERYBUF, &buf)) | |
| { | |
| perror("Querying Buffer"); | |
| return 1; | |
| } | |
| buffer = mmap (NULL, buf.length, PROT_READ | PROT_WRITE, MAP_SHARED, fd, buf.m.offset); | |
| printf("Length: %d\nAddress: %p\n", buf.length, buffer); | |
| printf("Image Length: %d\n", buf.bytesused); | |
| return 0; | |
| } | |
| int capture_image(int fd) | |
| { | |
| struct v4l2_buffer buf = {0}; | |
| buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; | |
| buf.memory = V4L2_MEMORY_MMAP; | |
| buf.index = 0; | |
| if(-1 == xioctl(fd, VIDIOC_QBUF, &buf)) | |
| { | |
| perror("Query Buffer"); | |
| return 1; | |
| } | |
| if(-1 == xioctl(fd, VIDIOC_STREAMON, &buf.type)) | |
| { | |
| perror("Start Capture"); | |
| return 1; | |
| } | |
| fd_set fds; | |
| FD_ZERO(&fds); | |
| FD_SET(fd, &fds); | |
| struct timeval tv = {0}; | |
| tv.tv_sec = 2; | |
| int r = select(fd+1, &fds, NULL, NULL, &tv); | |
| if(-1 == r) | |
| { | |
| perror("Waiting for Frame"); | |
| return 1; | |
| } | |
| if(-1 == xioctl(fd, VIDIOC_DQBUF, &buf)) | |
| { | |
| perror("Retrieving Frame"); | |
| return 1; | |
| } | |
| int outfd = open("out.img", O_RDWR); | |
| write(outfd, buffer, buf.bytesused); | |
| close(outfd); | |
| return 0; | |
| } | |
| int main() | |
| { | |
| int fd; | |
| fd = open("/dev/video0", O_RDWR); | |
| if (fd == -1) | |
| { | |
| perror("Opening video device"); | |
| return 1; | |
| } | |
| if(print_caps(fd)) | |
| return 1; | |
| if(init_mmap(fd)) | |
| return 1; | |
| if(capture_image(fd)) | |
| return 1; | |
| close(fd); | |
| return 0; | |
| } |
@lingxd try below
- set
fmt.fmt.pix.pixelformatintoV4L2_PIX_FMT_JPEGorV4L2_PIX_FMT_MJPEG- modify
int outfd = open("out.img", O_RDWR);toint outfd = open("img.jpg", O_WRONLY | O_CREAT | O_EXCL, 0600); if ((outfd == -1) && (EEXIST == errno)) { /* open the existing file with write flag */ outfd = open("img.jpg", O_WRONLY); }
thanks, it's useful.
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@lingxd try below
fmt.fmt.pix.pixelformatintoV4L2_PIX_FMT_JPEGorV4L2_PIX_FMT_MJPEGint outfd = open("out.img", O_RDWR);to