FFmpeg —— 读取摄像头数据并保存视频为MP4

逃离我推掉我的手 2021-09-24 07:08 900阅读 0赞

该程序的实现方式与这边文章类似：

[FFmpeg —— RTMP推流到流媒体服务器（编码的方式）—— 读取摄像头数据并推流][FFmpeg _ RTMP_]

只需要将推流地址改为本地文件名的形式即可。

#include <stdio.h>
    
    #define __STDC_CONSTANT_MACROS
    
    extern "C"
    {
    #include "libavcodec/avcodec.h"
    #include "libavformat/avformat.h"
    #include "libswscale/swscale.h"
    #include "libavdevice/avdevice.h"
    #include "libavutil/imgutils.h"
    #include "libavutil/dict.h"
    #include "libavutil/mathematics.h"
    #include "libavutil/time.h"
    };
    
    
    int main()
    {
    	AVFormatContext *ifmtCtx = NULL;
    	AVFormatContext *ofmtCtx = NULL;
    	AVPacket pkt;
    	AVFrame *pFrame, *pFrameYUV;
    	SwsContext *pImgConvertCtx;
    	AVDictionary *params = NULL;
    	AVCodec *pCodec;
    	AVCodecContext *pCodecCtx;
    	unsigned char *outBuffer;
    	AVCodecContext *pH264CodecCtx;
    	AVCodec *pH264Codec;
    	AVDictionary *options = NULL;
    
    	int ret = 0;
    	unsigned int i = 0;
    	int videoIndex = -1;
    	int frameIndex = 0;
    
    	const char *inFilename = "0";//输入URL
    	const char *outFilename = "output.mp4"; //输出URL
    	const char *ofmtName = NULL;
    
    	avdevice_register_all();
    	avformat_network_init();
    
    	AVInputFormat *ifmt = av_find_input_format("vfwcap");
    	if (!ifmt)
    	{
    		printf("can't find input device\n");
    		goto end;
    	}
    
    	// 1. 打开输入
    	// 1.1 打开输入文件，获取封装格式相关信息
    	ifmtCtx = avformat_alloc_context();
    	if (!ifmtCtx)
    	{
    		printf("can't alloc AVFormatContext\n");
    		goto end;
    	}
    	av_dict_set_int(&options, "rtbufsize", 18432000  , 0);
    	if ((ret = avformat_open_input(&ifmtCtx, inFilename, ifmt, &options)) < 0)
    	{
    		printf("can't open input file: %s\n", inFilename);
    		goto end;
    	}
    
    	// 1.2 解码一段数据，获取流相关信息
    	if ((ret = avformat_find_stream_info(ifmtCtx, 0)) < 0)
    	{
    		printf("failed to retrieve input stream information\n");
    		goto end;
    	}
    
    	// 1.3 获取输入ctx
    	for (i=0; i<ifmtCtx->nb_streams; ++i)
    	{
    		if (ifmtCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
    		{
    			videoIndex = i;
    			break;
    		}
    	}
    
    	printf("%s:%d, videoIndex = %d\n", __FUNCTION__, __LINE__, videoIndex);
    
    	av_dump_format(ifmtCtx, 0, inFilename, 0);
    
    	// 1.4 查找输入解码器
    	pCodec = avcodec_find_decoder(ifmtCtx->streams[videoIndex]->codecpar->codec_id);
    	if (!pCodec)
    	{
    		printf("can't find codec\n");
    		goto end;
    	}
    
    	pCodecCtx = avcodec_alloc_context3(pCodec);
    	if (!pCodecCtx)
    	{
    		printf("can't alloc codec context\n");
    		goto end;
    	}
    
    	avcodec_parameters_to_context(pCodecCtx, ifmtCtx->streams[videoIndex]->codecpar);
    
    	//  1.5 打开输入解码器
    	if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
    	{
    		printf("can't open codec\n");
    		goto end;
    	}
    
    
    	// 1.6 查找H264编码器
    	pH264Codec = avcodec_find_encoder(AV_CODEC_ID_H264);
    	if (!pH264Codec)
    	{
    		printf("can't find h264 codec.\n");
    		goto end;
    	}
    
    	// 1.6.1 设置参数
    	pH264CodecCtx = avcodec_alloc_context3(pH264Codec);
    	pH264CodecCtx->codec_id = AV_CODEC_ID_H264;
    	pH264CodecCtx->codec_type = AVMEDIA_TYPE_VIDEO;
    	pH264CodecCtx->pix_fmt = AV_PIX_FMT_YUV420P;
    	pH264CodecCtx->width = pCodecCtx->width;
    	pH264CodecCtx->height = pCodecCtx->height;
    	pH264CodecCtx->time_base.num = 1;
    	pH264CodecCtx->time_base.den = 25;	//帧率（即一秒钟多少张图片）
    	pH264CodecCtx->bit_rate = 400000;	//比特率（调节这个大小可以改变编码后视频的质量）
    	pH264CodecCtx->gop_size = 250;
    	pH264CodecCtx->qmin = 10;
    	pH264CodecCtx->qmax = 51;
    	//some formats want stream headers to be separate
    //	if (pH264CodecCtx->flags & AVFMT_GLOBALHEADER)
    	{
    		pH264CodecCtx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
    	}
    
    
    	// 1.7 打开H.264编码器
    	av_dict_set(&params, "preset", "superfast", 0);
    	av_dict_set(&params, "tune", "zerolatency", 0);	//实现实时编码
    	if (avcodec_open2(pH264CodecCtx, pH264Codec, &params) < 0)
    	{
    		printf("can't open video encoder.\n");
    		goto end;
    	}
    
    	// 2. 打开输出
    	// 2.1 分配输出ctx
    	if (strstr(outFilename, "rtmp://"))
    	{
    		ofmtName = "flv";
    	}
    	else if (strstr(outFilename, "udp://"))
    	{
    		ofmtName = "mpegts";
    	}
    	else
    	{
    		ofmtName = NULL;
    	}
    
    	avformat_alloc_output_context2(&ofmtCtx, NULL, ofmtName, outFilename);
    	if (!ofmtCtx)
    	{
    		printf("can't create output context\n");
    		goto end;
    	}
    
    	// 2.2 创建输出流
    	for (i=0; i<ifmtCtx->nb_streams; ++i)
    	{
    		AVStream *outStream = avformat_new_stream(ofmtCtx, NULL);
    		if (!outStream)
    		{
    			printf("failed to allocate output stream\n");
    			goto end;
    		}
    
    		avcodec_parameters_from_context(outStream->codecpar, pH264CodecCtx);
    	}
    
    	av_dump_format(ofmtCtx, 0, outFilename, 1);
    
    	if (!(ofmtCtx->oformat->flags & AVFMT_NOFILE))
    	{
    		// 2.3 创建并初始化一个AVIOContext, 用以访问URL（outFilename）指定的资源
    		ret = avio_open(&ofmtCtx->pb, outFilename, AVIO_FLAG_WRITE);
    		if (ret < 0)
    		{
    			printf("can't open output URL: %s\n", outFilename);
    			goto end;
    		}
    	}
    
    	// 3. 数据处理
    	// 3.1 写输出文件
    	ret = avformat_write_header(ofmtCtx, NULL);
    	if (ret < 0)
    	{
    		printf("Error accourred when opening output file\n");
    		goto end;
    	}
    
    
    	pFrame = av_frame_alloc();
    	pFrameYUV = av_frame_alloc();
    
    	outBuffer = (unsigned char*) av_malloc(
    			av_image_get_buffer_size(AV_PIX_FMT_YUV420P, pCodecCtx->width,
    					pCodecCtx->height, 1));
    	av_image_fill_arrays(pFrameYUV->data, pFrameYUV->linesize, outBuffer,
    			AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height, 1);
    
    	pImgConvertCtx = sws_getContext(pCodecCtx->width, pCodecCtx->height,
    			pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height,
    			AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
    
    
    	while (frameIndex < 1000)
    	{
    		// 3.2 从输入流读取一个packet
    		ret = av_read_frame(ifmtCtx, &pkt);
    		if (ret < 0)
    		{
    			break;
    		}
    
    		if (pkt.stream_index == videoIndex)
    		{
    			ret = avcodec_send_packet(pCodecCtx, &pkt);
    			if (ret < 0)
    			{
    				printf("Decode error.\n");
    				goto end;
    			}
    
    			if (avcodec_receive_frame(pCodecCtx, pFrame) >= 0)
    			{
    				sws_scale(pImgConvertCtx,
    						(const unsigned char* const*) pFrame->data,
    						pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data,
    						pFrameYUV->linesize);
    
    
    				pFrameYUV->format = pCodecCtx->pix_fmt;
    				pFrameYUV->width = pCodecCtx->width;
    				pFrameYUV->height = pCodecCtx->height;
    
    				ret = avcodec_send_frame(pH264CodecCtx, pFrameYUV);
    				if (ret < 0)
    				{
    					printf("failed to encode.\n");
    					goto end;
    				}
    
    				if (avcodec_receive_packet(pH264CodecCtx, &pkt) >= 0)
    				{
    					// 设置输出DTS,PTS
    			        pkt.pts = pkt.dts = frameIndex * (ofmtCtx->streams[0]->time_base.den) /ofmtCtx->streams[0]->time_base.num / 25;
    			        frameIndex++;
    
    					ret = av_interleaved_write_frame(ofmtCtx, &pkt);
    					if (ret < 0)
    					{
    						printf("send packet failed: %d\n", ret);
    					}
    					else
    					{
    						printf("send %5d packet successfully!\n", frameIndex);
    					}
    				}
    			}
    		}
    
    		av_packet_unref(&pkt);
    	}
    
        av_write_trailer(ofmtCtx);
    
    end:
        avformat_close_input(&ifmtCtx);
    
        /* close output */
        if (ofmtCtx && !(ofmtCtx->oformat->flags & AVFMT_NOFILE)) {
            avio_closep(&ofmtCtx->pb);
        }
        avformat_free_context(ofmtCtx);
    
        if (ret < 0 && ret != AVERROR_EOF) {
            printf("Error occurred\n");
            return -1;
        }
    
        return 0;
    }

#  参考 #

[https://blog.csdn.net/zhangpengzp/article/details/88632455][https_blog.csdn.net_zhangpengzp_article_details_88632455]

[FFmpeg _ RTMP_]: https://blog.csdn.net/guoyunfei123/article/details/106173880
[https_blog.csdn.net_zhangpengzp_article_details_88632455]: https://blog.csdn.net/zhangpengzp/article/details/88632455