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

目的是直接采用android中的(确切的是linux内核中)的v4l2进行一张照片的拍摄。
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 ; }

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