UVC推流示例代码C语言
时间: 2023-07-09 15:40:34 浏览: 76
以下是一个简单的 UVC 推流示例代码,使用 C 语言编写,需要使用 libusb 库和 v4l2 库。
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <linux/videodev2.h>
#include <libusb-1.0/libusb.h>
#define WIDTH 640
#define HEIGHT 480
struct buffer {
void *start;
size_t length;
};
static struct buffer *buffers;
static int n_buffers;
static int fd;
static libusb_device_handle *dev_handle = NULL;
static struct libusb_transfer *transfer = NULL;
static unsigned char *image_buf = NULL;
static int image_size;
void process_image(void *addr, int size)
{
// 这里可以将图像数据推流到网络或保存到文件
// ...
}
void init_mmap(void)
{
struct v4l2_requestbuffers req;
struct v4l2_buffer buf;
unsigned int i;
memset(&req, 0, sizeof(req));
req.count = 4;
req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
req.memory = V4L2_MEMORY_MMAP;
if (ioctl(fd, VIDIOC_REQBUFS, &req) == -1) {
perror("VIDIOC_REQBUFS");
exit(EXIT_FAILURE);
}
if (req.count < 2) {
fprintf(stderr, "Insufficient buffer memory on %s\n",
"/dev/video0");
exit(EXIT_FAILURE);
}
buffers = calloc(req.count, sizeof(*buffers));
for (i = 0; i < req.count; ++i) {
memset(&buf, 0, sizeof(buf));
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
buf.index = i;
if (ioctl(fd, VIDIOC_QUERYBUF, &buf) == -1) {
perror("VIDIOC_QUERYBUF");
exit(EXIT_FAILURE);
}
buffers[i].length = buf.length;
buffers[i].start = mmap(NULL /* start anywhere */,
buf.length,
PROT_READ | PROT_WRITE /* required */,
MAP_SHARED /* recommended */,
fd, buf.m.offset);
if (MAP_FAILED == buffers[i].start) {
perror("mmap");
exit(EXIT_FAILURE);
}
}
}
void init_device(void)
{
struct v4l2_capability cap;
struct v4l2_format fmt;
if (ioctl(fd, VIDIOC_QUERYCAP, &cap) == -1) {
perror("VIDIOC_QUERYCAP");
exit(EXIT_FAILURE);
}
if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)) {
fprintf(stderr, "The device does not support video capture\n");
exit(EXIT_FAILURE);
}
if (!(cap.capabilities & V4L2_CAP_STREAMING)) {
fprintf(stderr, "The device does not support streaming i/o\n");
exit(EXIT_FAILURE);
}
memset(&fmt, 0, sizeof(fmt));
fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
fmt.fmt.pix.width = WIDTH;
fmt.fmt.pix.height = HEIGHT;
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;
fmt.fmt.pix.field = V4L2_FIELD_NONE;
if (ioctl(fd, VIDIOC_S_FMT, &fmt) == -1) {
perror("VIDIOC_S_FMT");
exit(EXIT_FAILURE);
}
init_mmap();
}
void start_capturing(void)
{
unsigned int i;
enum v4l2_buf_type type;
for (i = 0; i < n_buffers; ++i) {
struct v4l2_buffer buf;
memset(&buf, 0, sizeof(buf));
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
buf.index = i;
if (ioctl(fd, VIDIOC_QBUF, &buf) == -1) {
perror("VIDIOC_QBUF");
exit(EXIT_FAILURE);
}
}
type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
if (ioctl(fd, VIDIOC_STREAMON, &type) == -1) {
perror("VIDIOC_STREAMON");
exit(EXIT_FAILURE);
}
}
void process_frame(void)
{
struct v4l2_buffer buf;
unsigned int i;
memset(&buf, 0, sizeof(buf));
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
if (ioctl(fd, VIDIOC_DQBUF, &buf) == -1) {
perror("VIDIOC_DQBUF");
exit(EXIT_FAILURE);
}
process_image(buffers[buf.index].start, buf.bytesused);
if (ioctl(fd, VIDIOC_QBUF, &buf) == -1) {
perror("VIDIOC_QBUF");
exit(EXIT_FAILURE);
}
}
void mainloop(void)
{
while (1) {
fd_set fds;
struct timeval tv;
int r;
FD_ZERO(&fds);
FD_SET(fd, &fds);
tv.tv_sec = 2;
tv.tv_usec = 0;
r = select(fd + 1, &fds, NULL, NULL, &tv);
if (r == -1) {
if (errno == EINTR)
continue;
perror("select");
exit(EXIT_FAILURE);
}
if (r == 0) {
fprintf(stderr, "select timeout\n");
exit(EXIT_FAILURE);
}
process_frame();
}
}
void stop_capturing(void)
{
enum v4l2_buf_type type;
type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
if (ioctl(fd, VIDIOC_STREAMOFF, &type) == -1) {
perror("VIDIOC_STREAMOFF");
exit(EXIT_FAILURE);
}
}
void uninit_device(void)
{
unsigned int i;
for (i = 0; i < n_buffers; ++i)
if (munmap(buffers[i].start, buffers[i].length) == -1) {
perror("munmap");
exit(EXIT_FAILURE);
}
free(buffers);
}
void close_device(void)
{
if (close(fd) == -1) {
perror("close");
exit(EXIT_FAILURE);
}
}
void open_device(void)
{
fd = open("/dev/video0", O_RDWR | O_NONBLOCK, 0);
if (fd == -1) {
perror("open");
exit(EXIT_FAILURE);
}
}
int usb_transfer_cb(struct libusb_transfer *transfer)
{
if (transfer->status == LIBUSB_TRANSFER_COMPLETED) {
memcpy(image_buf, transfer->buffer, transfer->actual_length);
process_image(image_buf, image_size);
}
libusb_submit_transfer(transfer);
return 0;
}
void init_usb(void)
{
int res;
res = libusb_init(NULL);
if (res < 0) {
fprintf(stderr, "Unable to initialize libusb: %s\n", libusb_strerror(res));
exit(EXIT_FAILURE);
}
dev_handle = libusb_open_device_with_vid_pid(NULL, 0xXXXX, 0xXXXX);
if (!dev_handle) {
fprintf(stderr, "Unable to open USB device\n");
exit(EXIT_FAILURE);
}
res = libusb_claim_interface(dev_handle, 0);
if (res < 0) {
fprintf(stderr, "Unable to claim interface: %s\n", libusb_strerror(res));
exit(EXIT_FAILURE);
}
image_buf = malloc(image_size);
if (!image_buf) {
fprintf(stderr, "Unable to allocate image buffer\n");
exit(EXIT_FAILURE);
}
transfer = libusb_alloc_transfer(0);
if (!transfer) {
fprintf(stderr, "Unable to allocate USB transfer\n");
exit(EXIT_FAILURE);
}
libusb_fill_bulk_transfer(transfer, dev_handle, 0xXX, image_buf, image_size, usb_transfer_cb, NULL, 0);
libusb_submit_transfer(transfer);
}
void cleanup_usb(void)
{
libusb_cancel_transfer(transfer);
libusb_free_transfer(transfer);
libusb_release_interface(dev_handle, 0);
libusb_close(dev_handle);
libusb_exit(NULL);
free(image_buf);
}
int main(int argc, char **argv)
{
open_device();
init_device();
init_usb();
start_capturing();
mainloop();
stop_capturing();
uninit_device();
close_device();
cleanup_usb();
return 0;
}
```
需要注意的是,此代码仅作为示例,需要根据具体的硬件设备和网络环境进行调整。同时,也需要注意 UVC 规范的版本、图像格式、分辨率等参数的选择。