基于USB摄像头视频数据采集和利用FFMPEG库函数进行视频数据压缩

最新推荐文章于 2024-12-28 11:51:49 发布
Chris_yxp
最新推荐文章于 2024-12-28 11:51:49 发布
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分类专栏：多媒体文章标签： ffmpeg 视频数据压缩摄像头
本文链接：https://blog.youkuaiyun.com/yakimin/article/details/19284467
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/**
** Linux系统中提供的视频设备驱动程序V4L2可以操作视频设备，比如摄像头，来获取视频数据。
** 然后可以通过开源的ffmpeg库中的函数将所采集的视频数据进行压缩编码，生成高效可播放的视频格式。
** 如下的代码是将USB摄像头所采集的视频数据最后压缩封装成FLV格式进行播放，这里所采用的ffmpeg的版本是1.1.2.
**/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <linux/videodev2.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavformat/avio.h>
#include <libavutil/opt.h>
#include <libswscale/swscale.h>
#include <libavutil/mathematics.h>

#define VIDEO_WIDTH 640
#define VIDEO_HEIGHT 480
#define VIDEO_FORMAT V4L2_PIX_FMT_YUYV
#define BUFFER_COUNT 4
#define URL_WRONLY 1

struct fimc_buffer {
	int length;
	void *start;
} framebuf[BUFFER_COUNT];

int fd;
unsigned char yuv4200[1000000] = { 0 };
unsigned char yuv4220[1000000] = { 0 };

AVFormatContext* pFormatCtxEnc;
AVCodecContext* pCodecCtxEnc;
AVFrame* pFrameEnc;

void register_init();
int open_device();
int capability();
int set_v4l2_format();
int request_buffers();
int get_camera_data();
void unregister_all();
void video_encode_init();

int yuv422_2_yuv420(unsigned char* yuv420, unsigned char* yuv422, int width,
		int height);

void register_init() {
	avcodec_register_all();
	av_register_all();

}

int open_device() {
	char camera_device[20];
	struct stat buf;
	int i;
	for (i = 0; i < 10; i++) {
		sprintf(camera_device, "/dev/video%i", i);
		if (stat(camera_device, &buf) == 0) {
			break;
		}

	}
	fd = open(camera_device, O_RDWR, 0); //设备以非阻塞方式打开
	if (fd < 0) {
		printf("Cannot open camera_device\n");
		return -1;
	}

}

int set_v4l2_format() {
	int ret;
	struct v4l2_format fmt; //设置视频制式和帧格式
	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) {
		printf("VIDIOC_S_FMT failed\n");
		return ret;
	}

	ret = ioctl(fd, VIDIOC_G_FMT, &fmt); //获取视频制式和帧格式的实际值，看是否设置正确
	if (ret < 0) {
		printf("VIDIOC_G_FMT failed (%d)/n", ret);
		return ret;
	}

}

int request_buffers() {
	int ret;
	int i;
	struct v4l2_requestbuffers reqbuf; //向驱动申请帧缓冲
	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) {
		printf("VIDIOC_REQBUFS failed \n");
		return ret;
	}

	struct v4l2_buffer buf; //获取帧缓冲地址
	for (i = 0; i < BUFFER_COUNT; i++) {
		buf.index = i;
		buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
		buf.memory = V4L2_MEMORY_MMAP;
		ret = ioctl(fd, VIDIOC_QUERYBUF, &buf);
		if (ret < 0) {
			printf("VIDIOC_QUERYBUF failed\n");
			return ret;
		}
		framebuf[i].length = buf.length;
		framebuf[i].start = (char *) mmap(0, buf.length, PROT_READ | PROT_WRITE,
				MAP_SHARED, fd, buf.m.offset); //将申请到的帧缓冲映射到用户空间，>就能直接操作采集的帧
		if (framebuf[i].start == MAP_FAILED) {
			printf("mmap (%d) failed: %s/n", i, strerror(errno));
			return -1;
		}

		ret = ioctl(fd, VIDIOC_QBUF, &buf); //将申请到的帧缓冲全部入队列，以便存放数据
		if (ret < 0) {
			printf("VIDIOC_QBUF (%d) failed (%d)/n", i, ret);
			return -1;
		}

	}

}

int get_camera_data() {

	int ret;
	int i, k;
	struct v4l2_buffer buf; //获取帧缓冲地址

	enum v4l2_buf_type type = V4L2_BUF_TYPE_VIDEO_CAPTURE; //开始视频采集
	ret = ioctl(fd, VIDIOC_STREAMON, &type);
	if (ret < 0) {
		printf("VIDIOC_STREAMON failed (%d)\n", ret);
		return ret;
	}

	video_encode_init();
	i = 0;
	while (1) {
		static int delayFrame = 0;
		int got_packet = 0;
		printf("-----------seconds = %d----------\n", ++i);
		for (k = 0; k < 25; k++) {
			ret = ioctl(fd, VIDIOC_DQBUF, &buf); //出队列以取得已采集数据的帧缓冲，取得原始数据
			if (ret < 0) {
				printf("VIDIOC_DQBUF failed (%d)/n", ret);
				return ret;
			}
			strncpy(yuv4220, framebuf[buf.index].start,
					framebuf[buf.index].length);
			yuv422_2_yuv420(yuv4200, yuv4220, 640, 480);

			av_image_alloc(pFrameEnc->data, pFrameEnc->linesize,
					pCodecCtxEnc->width, pCodecCtxEnc->height,
					pCodecCtxEnc->pix_fmt, 1);
			pFrameEnc->data[0] = yuv4200;
			pFrameEnc->data[1] = pFrameEnc->data[0]
					+ pCodecCtxEnc->width * pCodecCtxEnc->height;
			pFrameEnc->data[2] = pFrameEnc->data[1]
					+ pCodecCtxEnc->width * pCodecCtxEnc->height / 4;
			pFrameEnc->linesize[0] = pCodecCtxEnc->width;
			pFrameEnc->linesize[1] = pCodecCtxEnc->width / 2;
			pFrameEnc->linesize[2] = pCodecCtxEnc->width / 2;
			pFrameEnc->pts = (k + (i - 1) * 25) * 40;
			pFrameEnc->width = 640;
			pFrameEnc->height = 480;

			if (!pFormatCtxEnc->nb_streams) {
				printf("output file does not contain any stream\n");
				exit(0);
			}
			AVPacket pkt;
			av_init_packet(&pkt);
			pkt.data = NULL;
			pkt.size = 0;

			printf("encoding frame %d-------", k);
			ret = avcodec_encode_video2(pCodecCtxEnc, &pkt, pFrameEnc,
					&got_packet);
			if (ret < 0) {
				av_log(NULL, AV_LOG_FATAL, "Video encoding failed\n");
			}
			if (got_packet) {
				printf("output frame %d size = %d\n", k - delayFrame, pkt.size);
				ret = av_interleaved_write_frame(pFormatCtxEnc, &pkt);
				if (ret != 0) {
					fprintf(stderr, "write frame into file is failed\n");
				} else {
					printf("encode and write one frame success\n");
				}
			} else {
				delayFrame++;
				printf("no frame output\n");
			}
			av_free_packet(&pkt);

			ret = ioctl(fd, VIDIOC_QBUF, &buf); //将缓冲重新入对尾，可以循环采集
			if (ret < 0) {
				printf("VIDIOC_QBUF failed (%d)\n", ret);
				return ret;
			}
		}

		/* get the delayed frames */
		for (got_packet = 1; got_packet; k++) {
			fflush(stdout);

			AVPacket pkt;
			av_init_packet(&pkt);
			pkt.data = NULL;
			pkt.size = 0;

			ret = avcodec_encode_video2(pCodecCtxEnc, &pkt, NULL, &got_packet);
			if (ret < 0) {
				fprintf(stderr, "error encoding frame\n");
				exit(1);
			}

			if (got_packet) {
				printf("output delayed frame %3d (size=%5d)\n", k - delayFrame,
						pkt.size);
				av_interleaved_write_frame(pFormatCtxEnc, &pkt);
				av_free_packet(&pkt);
			}
		}
	}

	av_write_trailer(pFormatCtxEnc);
	if (!(pFormatCtxEnc->flags & AVFMT_NOFILE))
		avio_close(pFormatCtxEnc->pb);

	for (i = 0; i < BUFFER_COUNT; i++) {
		munmap(framebuf[i].start, framebuf[i].length); //取消映射，释放内存
	}
	close(fd);
	return 0;
}

int capability() {
	int ret;
	struct v4l2_capability cap;
	ret = ioctl(fd, VIDIOC_QUERYCAP, &cap); //摄像头主要获取功能
	if (ret < 0) {
		printf("VIDIOC_QUERYCAP failed \n");
		return ret;
	}

}

int yuv422_2_yuv420(unsigned char* yuv420, unsigned char* yuv422, int width,
		int height) {
	int imgSize = width * height * 2;
	int widthStep422 = width * 2;

	unsigned char* p422 = yuv422;
	unsigned char* p420y = yuv420;
	unsigned char* p420u = yuv420 + imgSize / 2;
	unsigned char* p420v = p420u + imgSize / 8;
	int i, j;
	for (i = 0; i < height; i += 2) {
		p422 = yuv422 + i * widthStep422;
		for (j = 0; j < widthStep422; j += 4) {
			*(p420y++) = p422[j];
			*(p420u++) = p422[j + 1];
			*(p420y++) = p422[j + 2];
		}
		p422 += widthStep422;
		for (j = 0; j < widthStep422; j += 4) {
			*(p420y++) = p422[j];
			*(p420v++) = p422[j + 3];
			*(p420y++) = p422[j + 2];
		}

	}
	return 0;
}

void unregister_all() {
	int i;
	for (i = 0; i < BUFFER_COUNT; i++) {
		munmap(framebuf[i].start, framebuf[i].length); //取消映射，释放内存
	}
	close(fd);
	printf("Camera test Done.\n");

}

void video_encode_init() {

	char* filename = "./264.flv";
	AVCodec* pCodecEnc;
	AVOutputFormat* pOutputFormat;
	AVStream* video_st;

	int i;
	int ret;

	av_register_all();

	pOutputFormat = av_guess_format(NULL, filename, NULL);
	if (pOutputFormat == NULL) {
		fprintf(stderr, "Could not guess the format from file\n");
		exit(0);
	} else {
		printf("guess the format from file success\n");
	}

	pFormatCtxEnc = avformat_alloc_context();
	if (pFormatCtxEnc == NULL) {
		fprintf(stderr, "could not allocate AVFormatContex\n");
		exit(0);
	} else {
		printf("allocate AVFormatContext success\n");
	}

	pFormatCtxEnc->oformat = pOutputFormat;
	sprintf(pFormatCtxEnc->filename, "%s", filename);
	printf("filename is %s\n", pFormatCtxEnc->filename);

	video_st = avformat_new_stream(pFormatCtxEnc, 0);
	if (!video_st) {
		fprintf(stderr, "could not allocate AVstream\n");
		exit(0);
	} else {
		printf("allocate AVstream success\n");
	}
	pCodecCtxEnc = video_st->codec;
	pCodecCtxEnc->codec_id = pOutputFormat->video_codec;
	pCodecCtxEnc->codec_type = AVMEDIA_TYPE_VIDEO;
	pCodecCtxEnc->bit_rate = 1000000;
	pCodecCtxEnc->bit_rate_tolerance = 300000000; //表示有多少bit的视频流可以偏移出目前的设定.这里的"设定"是指的cbr或者vbr.
	pCodecCtxEnc->width = 640;
	pCodecCtxEnc->height = 480;
	pCodecCtxEnc->time_base = (AVRational) {1,25};
	//pCodecCtxEnc->time_base.num = 1;
	//pCodecCtxEnc->time_base.den = 25;
	pCodecCtxEnc->pix_fmt = PIX_FMT_YUV420P;
	pCodecCtxEnc->gop_size = 10;
	pCodecCtxEnc->max_b_frames = 0;

	av_opt_set(pCodecCtxEnc->priv_data, "preset", "superfast", 0);
	av_opt_set(pCodecCtxEnc->priv_data, "tune", "zerolatency", 0);

	pCodecCtxEnc->pre_me = 2;

	pCodecCtxEnc->lmin = 10;
	pCodecCtxEnc->lmax = 50;

	pCodecCtxEnc->qmin = 20;
	pCodecCtxEnc->qmax = 80;
	pCodecCtxEnc->qblur = 0.0;
	pCodecCtxEnc->spatial_cplx_masking = 0.3;
	pCodecCtxEnc->me_pre_cmp = 2;
	pCodecCtxEnc->rc_qsquish = 1;

	pCodecCtxEnc->b_quant_factor = 4.9;
	pCodecCtxEnc->b_quant_offset = 2;
	pCodecCtxEnc->i_quant_factor = 0.1;
	pCodecCtxEnc->i_quant_offset = 0.0;
	pCodecCtxEnc->rc_strategy = 2;
	pCodecCtxEnc->b_frame_strategy = 0;
	pCodecCtxEnc->dct_algo = 0;
	pCodecCtxEnc->lumi_masking = 0.0;
	pCodecCtxEnc->dark_masking = 0.0;

	if (!strcmp(pFormatCtxEnc->oformat->name, "flv")) {
		pCodecCtxEnc->flags |= CODEC_FLAG_GLOBAL_HEADER;
	} else {
		printf("output format is %s\n", pFormatCtxEnc->oformat->name);
	}

	pCodecEnc = avcodec_find_encoder(pCodecCtxEnc->codec_id);
	if (!pCodecEnc) {
		fprintf(stderr, "could not find suitable video encoder\n");
		exit(0);
	} else {
		printf("find the encoder success\n");
	}

	if (avcodec_open2(pCodecCtxEnc, pCodecEnc, NULL) < 0) {
		fprintf(stderr, "could not open video codec\n");
		exit(0);
	} else {
		printf("open the video codec success\n");
	}

	pFrameEnc = avcodec_alloc_frame();
	if (pFrameEnc == NULL) {
		fprintf(stderr, "could not allocate pFrameEnc\n");
		exit(0);
	} else {
		printf("allocate pFrameEnc success\n");
	}

	ret = avio_open(&pFormatCtxEnc->pb, filename, AVIO_FLAG_WRITE);
	if (ret < 0) {
		fprintf(stderr, "could not open '%s': %s\n", filename, av_err2str(ret));
		exit(0);
	} else {
		printf("open filename = %s success\n", filename);
	}

	ret = avformat_write_header(pFormatCtxEnc, NULL);
	if (ret < 0) {
		fprintf(stderr, "error occurred when opening outputfile: %s\n",
				av_err2str(ret));
		exit(0);
	} else {
		printf("write the header success\n");
	}
}

int main() {
	register_init();
	open_device();
	capability();
	set_v4l2_format();
	request_buffers();
	get_camera_data();
	unregister_all();
	return 0;
}