FFmpeg —— 10.示例程序（四）：音视频分离（分离为AAC、H264格式）

你的名字 2021-09-24 04:16 806阅读 0赞

参考：[https://blog.csdn.net/leixiaohua1020/article/details/39802819][https_blog.csdn.net_leixiaohua1020_article_details_39802819]

# 流程图 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2d1b3l1bmZlaTEyMw_size_16_color_FFFFFF_t_70][]

# 程序源码  #

/*
     *
     * 本程序可以将封装格式中的视频码流数据和音频码流数据分离出来
     *
     */
    
    #include <stdio.h>
    
    #define __STDC_CONSTANT_MACROS
    
    extern "C"
    {
    #include "libavdevice/avdevice.h"
    #include "libavformat/avformat.h"
    }
    
    /*
     FIX: H.264 in some container format (FLV, MP4, MKV etc.) need
     "h264_mp4toannexb" bitstream filter (BSF)
     *Add SPS,PPS in front of IDR frame
     *Add start code ("0,0,0,1") in front of NALU
     H.264 in some container (MPEG2TS) don't need this BSF.
     */
    //'1': Use H.264 Bitstream Filter
    #define USE_H264BSF 0
    
    int open_codec_context(int *streamIndex, AVFormatContext *&ofmtCtx, AVFormatContext *ifmtCtx, AVMediaType type)
    {
    	AVStream *outStream = NULL, *inStream = NULL;
    	int ret = -1, index = -1;
    
    	index = av_find_best_stream(ifmtCtx, type, -1, -1, NULL, 0);
    	if (index < 0)
    	{
    		printf("can't find %s stream in input file\n", av_get_media_type_string(type));
    		return ret;
    	}
    
    	inStream = ifmtCtx->streams[index];
    
    	outStream = avformat_new_stream(ofmtCtx, NULL);
    	if (!outStream)
    	{
    		printf("failed to allocate output stream\n");
    		return ret;
    	}
    
    	ret = avcodec_parameters_copy(outStream->codecpar, inStream->codecpar);
    	if (ret < 0)
    	{
    		printf("failed to copy codec parametes\n");
    		return ret;
    	}
    
    	outStream->codecpar->codec_tag = 0;
    
    	if (ofmtCtx->oformat->flags & AVFMT_GLOBALHEADER)
    	{
    		outStream->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
    	}
    
    	*streamIndex = index;
    
    	return 0;
    }
    
    
    int main(int argc, char *argv[])
    {
    	AVFormatContext *ifmtCtx = NULL, *ofmtCtxAudio = NULL, *ofmtCtxVideo = NULL;
    //	AVCodecContext *codecCtxVideo = NULL, *codecCtxAudio = NULL;
    	AVPacket packet;
    
    	int videoIndex = -1, audioIndex = -1;
    	int ret = 0;
    
    	char inFilename[128] = "input.mp4";
    	char outFilenameAudio[128] = "output.aac";
    	char outFilenameVideo[128] = "output.h264";
    
    #if USE_H264BSF
    	AVBitStreamFilterContext *h264bsfc = av_bitstream_filter_init("h264_mp4toannexb");
    #endif
    
    	//注册设备
    	avdevice_register_all();
    
    	//打开输入流
    	ret = avformat_open_input(&ifmtCtx, inFilename, 0, 0);
    	if (ret < 0)
    	{
    		printf("can't open input file\n");
    		goto end;
    	}
    
    	//获取流信息
    	ret = avformat_find_stream_info(ifmtCtx, 0);
    	if (ret < 0)
    	{
    		printf("can't retrieve input stream information\n");
    		goto end;
    	}
    
    	//创建输出上下文:视频
    	avformat_alloc_output_context2(&ofmtCtxVideo, NULL, NULL, outFilenameVideo);
    	if (!ofmtCtxVideo)
    	{
    		printf("can't create video output context");
    		goto end;
    	}
    
    	//创建输出上下文：音频
    	avformat_alloc_output_context2(&ofmtCtxAudio, NULL, NULL, outFilenameAudio);
    	if (!ofmtCtxAudio)
    	{
    		printf("can't create audio output context");
    		goto end;
    	}
    
    #if 1
    	ret = open_codec_context(&videoIndex, ofmtCtxVideo, ifmtCtx, AVMEDIA_TYPE_VIDEO);
    	if (ret < 0)
    	{
    		printf("can't decode video context\n");
    		goto end;
    	}
    
    
    	ret = open_codec_context(&audioIndex, ofmtCtxAudio, ifmtCtx, AVMEDIA_TYPE_AUDIO);
    	if (ret < 0)
    	{
    		printf("can't decode video context\n");
    		goto end;
    	}
    #endif
    
    #if 0
    	for (i = 0; i < ifmtCtx->nb_streams; ++i)
    	{
    		AVFormatContext *ofmtCtx;
    		AVStream *inStream = ifmtCtx->streams[i];
    		AVStream *outStream = NULL;
    
    		if (ifmtCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
    		{
    			videoIndex = i;
    			outStream = avformat_new_stream(ofmtCtxVideo, inStream->codec->codec);
    			ofmtCtx = ofmtCtxVideo;
    		}
    		else if (ifmtCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO)
    		{
    			audioIndex = i;
    			outStream = avformat_new_stream(ofmtCtxAudio, inStream->codec->codec);
    			ofmtCtx = ofmtCtxAudio;
    		}
    		else
    		{
    			break;
    		}
    
    		if (!outStream)
    		{
    			printf("failed to allocate output stream\n");
    			goto end;
    		}
    
    		if (avcodec_copy_context(outStream->codec, inStream->codec) < 0)
    		{
    			printf("failed to copy context from input to output stream codec context\n");
    			goto end;
    		}
    
    		outStream->codec->codec_tag = 0;
    
    		if (ofmtCtx->oformat->flags & AVFMT_GLOBALHEADER)
    		{
    			outStream->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
    		}
    	}
    #endif
    
    	//Dump Format------------------
    	printf("\n==============Input Video=============\n");
    	av_dump_format(ifmtCtx, 0, inFilename, 0);
    	printf("\n==============Output Video============\n");
    	av_dump_format(ofmtCtxVideo, 0, outFilenameVideo, 1);
    	printf("\n==============Output Audio============\n");
    	av_dump_format(ofmtCtxAudio, 0, outFilenameAudio, 1);
    	printf("\n======================================\n");
    
    	//打开输出文件:视频
    	if (!(ofmtCtxVideo->oformat->flags & AVFMT_NOFILE))
    	{
    		if (avio_open(&ofmtCtxVideo->pb, outFilenameVideo, AVIO_FLAG_WRITE) < 0)
    		{
    			printf("can't open output file: %s\n", outFilenameVideo);
    			goto end;
    		}
    	}
    
    	//打开输出文件：音频
    	if (!(ofmtCtxAudio->oformat->flags & AVFMT_NOFILE))
    	{
    		if (avio_open(&ofmtCtxAudio->pb, outFilenameAudio, AVIO_FLAG_WRITE) < 0)
    		{
    			printf("can't open output file: %s\n", outFilenameVideo);
    			goto end;
    		}
    	}
    
    	//写文件头
    	if (avformat_write_header(ofmtCtxVideo, NULL) < 0)
    	{
    		printf("Error occurred when opening video output file\n");
    		goto end;
    	}
    
    	if (avformat_write_header(ofmtCtxAudio, NULL) < 0)
    	{
    		printf("Error occurred when opening audio output file\n");
    		goto end;
    	}
    
    
    	while (1)
    	{
    		AVFormatContext *ofmtCtx;
    		AVStream *inStream, *outStream;
    
    		if (av_read_frame(ifmtCtx, &packet) < 0)
    		{
    			break;
    		}
    
    		inStream = ifmtCtx->streams[packet.stream_index];
    
    		if (packet.stream_index == videoIndex)
    		{
    			outStream = ofmtCtxVideo->streams[0];
    			ofmtCtx = ofmtCtxVideo;
    #if USE_H264BSF
    			av_bitstream_filter_filter(h264bsfc, inStream->codec, NULL, &packet.data, &packet.size, packet.data,
    					packet.size, 0);
    #endif
    		}
    		else if (packet.stream_index == audioIndex)
    		{
    			outStream = ofmtCtxAudio->streams[0];
    			ofmtCtx = ofmtCtxAudio;
    		}
    		else
    		{
    			continue;
    		}
    
    		//convert PTS/DTS
    		packet.pts = av_rescale_q_rnd(packet.pts, inStream->time_base, outStream->time_base,
    				(AVRounding) (AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
    		packet.dts = av_rescale_q_rnd(packet.dts, inStream->time_base, outStream->time_base,
    				(AVRounding) (AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
    		packet.duration = av_rescale_q(packet.duration, inStream->time_base, outStream->time_base);
    		packet.pos = -1;
    		packet.stream_index = 0;
    
    		//write
    		if (av_interleaved_write_frame(ofmtCtx, &packet) < 0)
    		{
    			printf("Error muxing packet\n");
    			break;
    		}
    
    		av_packet_unref(&packet);
    
    	}
    
    #if USE_H264BSF
    	av_bitstream_filter_close(h264bsfc);
    #endif
    
    	//write file trailer
    	av_write_trailer(ofmtCtxVideo);
    	av_write_trailer(ofmtCtxAudio);
    
    	end:
    
    	avformat_close_input(&ifmtCtx);
    
    	if (ofmtCtxVideo && !(ofmtCtxVideo->oformat->flags & AVFMT_NOFILE))
    	{
    		avio_close(ofmtCtxVideo->pb);
    	}
    
    	if (ofmtCtxAudio && !(ofmtCtxAudio->oformat->flags & AVFMT_NOFILE))
    	{
    		avio_close(ofmtCtxAudio->pb);
    	}
    
    	avformat_free_context(ofmtCtxVideo);
    	avformat_free_context(ofmtCtxAudio);
    
    	return 0;
    }

[https_blog.csdn.net_leixiaohua1020_article_details_39802819]: https://blog.csdn.net/leixiaohua1020/article/details/39802819
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