android直接用v4l2采集图片数据
2013-03-20 22:24:59| 分类： Android | 标签：android_v4l2 |字号 订阅
利用v4l2进行视频数据的采集，有很多教程，参照v4l2的示例也可以。下面就是我的采集一帧数据并保存的代码。
#include
#include
#include
#include
#include
#include
#include
#include
"jpeglib.h"
//移植libjpeg库实现yuv——>jpg图片的转换
//#define ANDROID_ENV
#ifdef ANDROID_ENV
#define LOG LOGV
#else
#define LOG printf
#endif
#define CAMERA_DEVICE "/dev/video0"
#define CAPTURE_FILE "frame.yuv420"
#define VIDEO_WIDTH 720
#define VIDEO_HEIGHT 480
#define VIDEO_FORMAT V4L2_PIX_FMT_YUV420 //这里是输出的数据格式，要是摄像头支持jpeg的，可以直接把数据
//V4L2_PIX_FMT_MJPEG //保存为jpg格式的图片，如果是yuv的则需要转换，转换在下篇介绍。
//V4L2_PIX_FMT_JPEG
//这里主要是把yuv格式保存为文件
//V4L2_PIX_FMT_YUYV
//V4L2_PIX_FMT_YUV420
//V4L2_PIX_FMT_RGB32
#define BUFFER_COUNT 4
struct
fimc_buffer
{
int
length
;
void
*
start
;
}
framebuf
[
BUFFER_COUNT
];
//这个函数是把yuv数据转换为jpg图片的函数。
int write_JPEG_file (const char * filename, unsigned char* yuvData, int quality,int image_width,int image_height);
int
main
()
{
int
i
,
ret
;
// Open Device
int fd;
fd = open(CAMERA_DEVICE, O_RDWR, 0);
if (fd < 0) {
LOG("Open %s failed\n", CAMERA_DEVICE);
return -1;
}
// Query Capability
struct v4l2_capability cap;
ret = ioctl(fd, VIDIOC_QUERYCAP, &cap);
if (ret < 0) {
LOG("VIDIOC_QUERYCAP failed (%d)\n", ret);
return ret;
}
// Print capability infomations
LOG("Capability Informations:\n");
LOG(" driver: %s\n", cap.driver);
LOG(" card: %s\n", cap.card);
LOG(" bus_info: %s\n", cap.bus_info);
LOG(" version: %08X\n", cap.version);
LOG(" capabilities: %08X\n", cap.capabilities);
///////////////////////
struct v4l2_fmtdesc fmtdesc; fmtdesc.index=0; fmtdesc.type=V4L2_BUF_TYPE_VIDEO_CAPTURE; printf("Support format:\n");
while
(
ioctl
(
fd
,
VIDIOC_ENUM_FMT
,
&
fmtdesc
)
!=
-
1
)
{
printf
(
"\t%d.%s\n"
,
fmtdesc
.
index
+
1
,
fmtdesc
.
description
);
fmtdesc
.
index
++;
}
/////////////////////
// Set Stream Format
struct v4l2_format fmt;
memset(&fmt, 0, sizeof(fmt));
fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
fmt.fmt.pix.width = VIDEO_WIDTH;
fmt.fmt.pix.height = VIDEO_HEIGHT;
fmt.fmt.pix.pixelformat = VIDEO_FORMAT;
fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
ret = ioctl(fd, VIDIOC_S_FMT, &fmt);
if (ret < 0) {
LOG("VIDIOC_S_FMT failed (%d)\n", ret);
return ret;
}
// Get Stream Format
ret = ioctl(fd, VIDIOC_G_FMT, &fmt);
if (ret < 0) {
LOG("VIDIOC_G_FMT failed (%d)\n", ret);
return ret;
}
// Print Stream Format
LOG("Stream Format Informations:\n");
LOG(" type: %d\n", fmt.type);
LOG(" width: %d\n", fmt.fmt.pix.width);
LOG(" height: %d\n", fmt.fmt.pix.height);
char fmtstr[8];
memset(fmtstr, 0, 8);
memcpy(fmtstr, &fmt.fmt.pix.pixelformat, 4);
LOG(" pixelformat: %s\n", fmtstr);
LOG(" field: %d\n", fmt.fmt.pix.field);
LOG(" bytesperline: %d\n", fmt.fmt.pix.bytesperline);
LOG(" sizeimage: %d\n", fmt.fmt.pix.sizeimage);
LOG(" colorspace: %d\n", fmt.fmt.pix.colorspace);
LOG(" priv: %d\n", fmt.fmt.pix.priv);
LOG(" raw_date: %s\n", fmt.fmt.raw_data);
// Request buffers
struct v4l2_requestbuffers reqbuf;
reqbuf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
reqbuf.memory = V4L2_MEMORY_MMAP;
reqbuf.count = BUFFER_COUNT;
ret = ioctl(fd , VIDIOC_REQBUFS, &reqbuf);
if(ret < 0) {
LOG("VIDIOC_REQBUFS failed (%d)\n", ret);
return ret;
}
// Queen buffers
struct v4l2_buffer buf;
for(i=0; i
// Query buffer
buf.index = i;
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
ret = ioctl(fd , VIDIOC_QUERYBUF, &buf);
if(ret < 0) {
LOG("VIDIOC_QUERYBUF (%d) failed (%d)\n", i, ret);
return ret;
}
// mmap buffer
framebuf[i].length = buf.length;
framebuf[i].start = (char *) mmap(0, buf.length, PROT_READ|PROT_WRITE, MAP_SHARED, fd, buf.m.offset);
if (framebuf[i].start == MAP_FAILED) {
LOG("mmap (%d) failed: %s\n", i, strerror(errno));
return -1;
}
// Queen buffer
ret = ioctl(fd , VIDIOC_QBUF, &buf);
if (ret < 0) {
LOG("VIDIOC_QBUF (%d) failed (%d)\n", i, ret);
return -1;
}
LOG("Frame buffer %d: address=0x%x, length=%d\n", i, (unsigned int)framebuf[i].start, framebuf[i].length);
}
// Stream On
enum v4l2_buf_type type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
ret = ioctl(fd, VIDIOC_STREAMON, &type);
if (ret < 0) {
LOG("VIDIOC_STREAMON failed (%d)\n", ret);
return ret;
}
// Get frame
ret = ioctl(fd, VIDIOC_DQBUF, &buf);
if (ret < 0) {
LOG("
(%d)\n", ret);
return ret;
}
// Process the frame
FILE *fp = fopen(CAPTURE_FILE, "wb");
if (fp < 0) {
LOG("open frame data file failed\n");
return -1;
}
fwrite(framebuf[buf.index].start, 1, buf.length, fp); //保存yuv数据进文件
fclose(fp);
LOG("Capture one frame saved in %s\n", CAPTURE_FILE);
write_JPEG_file("test.jpg", framebuf[buf.index].start, 100, 720, 625); //生成jpg图片
LOG("Capture one frame saved in test.jpg\n");
// Re-queen buffer
ret = ioctl(fd, VIDIOC_QBUF, &buf);
if (ret < 0) {
LOG("VIDIOC_QBUF failed (%d)\n", ret);
return ret;
}
// Release the resource
for (i=0; i
munmap(framebuf[i].start, framebuf[i].length);
}
close
(
fd
);
LOG
(
"Camera test Done.\n"
);
return
0
;
}