ffmpeg API录制rtsp视频流

这里在录制时，并没有进行转码，只是相当于把rtsp视频直接保存到一个文件中。

#include <stdio.h>

#ifdef __cplusplus
extern "C" {
#endif
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
//#include <libswscale/swscale.h>

#ifdef _MSC_VER
int strcasecmp(const char *s1, const char *s2)
{
	while ((*s1 != '\0')
		&& (tolower(*(unsigned char *) s1) ==
		tolower(*(unsigned char *) s2))) 
	{
		s1++;
		s2++;
	}

	return tolower(*(unsigned char *) s1) - tolower(*(unsigned char *) s2);
}
int strncasecmp(const char *s1, const char *s2, unsigned int n)
{
	if (n == 0)
		return 0;

	while ((n-- != 0)
		&& (tolower(*(unsigned char *) s1) ==
		tolower(*(unsigned char *) s2))) {
			if (n == 0 || *s1 == '\0' || *s2 == '\0')
				return 0;
			s1++;
			s2++;
	}

	return tolower(*(unsigned char *) s1) - tolower(*(unsigned char *) s2);
}
#endif //_MSC_VER

#ifdef __cplusplus
}
#endif

/***********************************************************
'** stream_component_open
*	Description: 
*			 //open the stream component for video/audio
*
*
*	Params:ic-pointer which contains the url and codec details 
:stream_index-index denoting video or audio stream
***********************************************************/
int stream_component_open(AVFormatContext *ic, int stream_index)
{
	AVCodecContext *enc;
	AVCodec *codec;

	if (stream_index < 0 || stream_index >= (int)ic->nb_streams)
		return -1;
	enc = ic->streams[stream_index]->codec;

	/* prepare audio output */
	if (enc->codec_type == CODEC_TYPE_AUDIO)
	{
		if (enc->channels > 0)
			enc->request_channels = FFMIN(2, enc->channels);
		else
			enc->request_channels = 2;

		/*Hardcoding the codec id to PCM_MULAW if the audio
		codec id returned by the lib is CODEC_ID_NONE */

		if(enc->codec_id == CODEC_ID_NONE)
		{
			enc->codec_id = CODEC_ID_PCM_MULAW;
			enc->channels = 1;
			enc->sample_rate = 16000;
			enc->bit_rate = 128;
		}
	}

	codec = avcodec_find_decoder(enc->codec_id);
	enc->idct_algo			= FF_IDCT_AUTO;
	enc->flags2   |= CODEC_FLAG2_FAST;
	enc->skip_frame			= AVDISCARD_DEFAULT;
	enc->skip_idct			= AVDISCARD_DEFAULT;
	enc->skip_loop_filter	= AVDISCARD_DEFAULT;
	enc->error_concealment	= 3;

	if (!codec || avcodec_open(enc, codec) < 0)
		return -1;
	avcodec_thread_init(enc, 1);
	enc->thread_count= 1;
	ic->streams[stream_index]->discard = AVDISCARD_DEFAULT;

	return 0;
}
//声明函数
int enable_local_record(AVFormatContext *ic/*已经打开的视频文件上下文*/,
						int videostream,int audiostream,
						AVFormatContext **out_oc,const char * ofile,const char * ofileformat);

int exit_onerr(const char * err_desc/*错误描述*/,int err_code/*错误码*/)
{
	printf("%s\n",err_desc);
	system("pause");//暂停，查看错误描述
	return err_code;
}
int main(int argc, char* argv[])
{
	//初始化ffmpeg链表结构
	avcodec_register_all();						// Register all formats and codecs
	av_register_all();

	AVPacket  packet;

	//打开文件
	AVFormatContext * ic = NULL;
	const char * rtsp_url = "rtsp://192.168.0.168:8557/PSIA/Streaming/channels/2?videoCodecType=H.264";
	if(av_open_input_file(&ic, rtsp_url, NULL, 0, NULL)!=0)
	{						
		return exit_onerr("can't open file.",-1);
	}
	if(!ic)
	{
		return exit_onerr("unknow error.",-2);
	}
	ic ->max_analyze_duration = 1000;

	//get streams information
	if(av_find_stream_info(ic)<0)
	{
		av_close_input_file(ic);//退出前，记得释放资源
		ic = NULL;
		return exit_onerr("con't init streams information.",-3);
	}


	//find stream
	int videoStream=-1;	// Didn't find a video stream
	int audioStream=-1;	// Didn't find a audio stream 
	// Find the first video stream
	for(int i=0; i<ic ->nb_streams; i++)
	{
		if( ic ->streams[i]->codec->codec_type==CODEC_TYPE_VIDEO)
		{ 
			videoStream=i;
			break;
		}
	}
	// Find the first audio stream
	for(int i=0; i<ic ->nb_streams; i++)
	{
		if( ic ->streams[i]->codec->codec_type==CODEC_TYPE_AUDIO)
		{
			audioStream=i;
			break;
		}
	}
	//判断视频文件中是否包含音视频流，如果没有，退出
	if(audioStream<0 && videoStream<0)
	{
		av_close_input_file(ic);//退出前，记得释放资源
		ic = NULL;
		return exit_onerr("con't find a audio stream or video stream",-4);
	}

	//open the stream component for video
	int videoComponent = -1;
	if(videoStream >= 0)
	{
		videoComponent = stream_component_open(ic, videoStream); 
		if(videoComponent<0)
		{
			av_close_input_file(ic);//退出前，记得释放资源
			return exit_onerr("not supported video stream",-5);//要求重新编译ffmpeg以支持该种编码格式
		}
	}
	//open the stream component for audio
	int audioComponent = -1;
	if(audioStream >= 0)
	{
		audioComponent = stream_component_open(ic, audioStream); 
		if(audioComponent<0)
		{
			av_close_input_file(ic);//退出前，记得释放资源
			return exit_onerr("not supported audio stream",-6);//要求重新编译ffmpeg以支持该种编码格式
		}
	}


	//////////////////////////////////////////////////////
	int ret = 0;
	//初始化并打开录像
	AVFormatContext * oc = NULL;
	const char * out_file_name = "D:\\test.avi";

	//获取一帧完整的图像用于初始化ffmpeg内部的一些结构体数据(这里使用什么数据尚未清楚，请自行查看)，否则会出现写文件头失败
	int got_picture = 0;
	AVFrame *frame = avcodec_alloc_frame();
	while( 1 )
	{
		if(av_read_frame( ic, &packet)<0)
		{
			av_free_packet(&packet);
			av_close_input_file(ic);//退出前，记得释放资源
			return exit_onerr("read frame error.",-7);//读取视频帧失败
		}
		if(packet.stream_index == videoStream)
		{
			avcodec_decode_video(ic->streams[videoStream]->codec, frame, &got_picture, packet.data, packet.size);
		}
		av_free_packet(&packet);
		if(got_picture)
			break;
	}
	av_free(frame);

	ret = enable_local_record(ic,videoStream,audioStream,&oc,out_file_name,"avi");

	if(ret <0 || !oc)
	{
		//退出前，记得释放资源，现在又多了个oc参数需要释放
		if(oc)
		{
			///cleanup the output contents format
			for(unsigned int i=0;i< oc->nb_streams;i++)
			{
				av_metadata_free(&oc ->streams[i]->metadata);
				av_free(oc ->streams[i]->codec);
				av_free(oc ->streams[i]);
			}
			for(unsigned int i=0;i<oc ->nb_programs;i++) 
			{
				av_metadata_free(&oc ->programs[i]->metadata);
			}
			for(unsigned int i=0;i<oc ->nb_chapters;i++) 
			{
				av_metadata_free(&oc ->chapters[i]->metadata);
			}
			av_metadata_free(&oc ->metadata);
			av_free(oc);
		}
		av_close_input_file(ic);
		return exit_onerr("can't init out file.",-8);
	}

	//开始录像
	int video_dts = 0,audio_dts = 0;//时间戳
	int total_frame = 300;//写300帧文件
	while(total_frame--)
	{
		if( av_read_frame( ic, &packet) <0 )		//read the packet
		{		
			//读取数据出错
			av_free_packet(&packet);
			break;
		}
		if(packet.data && (packet.stream_index == videoStream || packet.stream_index == audioStream) )
		{
			//计算时间视频戳，顺序+1，这里可以多研究几种编码的音视频文件，求其时间戳生成格式，h264编码顺序加1即可
			if(packet.stream_index == videoStream)
			{
				packet.dts = video_dts++;
				packet.pts = video_dts;
			}
			else if(packet.stream_index == audioStream)//计算音频时间戳
			{
				packet.dts = audio_dts++;
				packet.pts = audio_dts * (1000 * packet.size /ic ->streams[packet.stream_index]->codec ->sample_rate);
			}
			packet.flags |= PKT_FLAG_KEY;
			if(av_interleaved_write_frame(oc,&packet)<0)
			{
				printf("st:%d\twrite frame failed.\n",packet.stream_index);
			}
		}
		av_free_packet(&packet);
	}

	//关闭录像文件和输入文件

	//写文件尾
	av_write_trailer(oc);

	/* close the output file if need.*/
	if (!(oc ->oformat->flags & AVFMT_NOFILE)) 
	{
		url_fclose(oc->pb);
	}

	//释放资源
	/*cleanup the output contents format*/
	for(unsigned int i=0;i< oc->nb_streams;i++)
	{
		av_metadata_free(&oc ->streams[i]->metadata);
		av_free(oc ->streams[i]->codec);
		av_free(oc ->streams[i]);
	}
	for(unsigned int i=0;i<oc ->nb_programs;i++) 
	{
		av_metadata_free(&oc ->programs[i]->metadata);
	}
	for(unsigned int i=0;i<oc ->nb_chapters;i++) 
	{
		av_metadata_free(&oc ->chapters[i]->metadata);
	}
	av_metadata_free(&oc ->metadata);
	av_free(oc);

	av_close_input_file(ic);

	return 0;
}

//初始化录像文件，代码较长，可写成函数
/*
*return <0  failed, 0 success
*/
int enable_local_record(AVFormatContext *ic/*已经打开的视频文件上下文*/,int videostream,int audiostream,AVFormatContext **out_oc,const char * ofile,const char * ofileformat)
{
	AVFormatContext *oc		= NULL;//
	AVOutputFormat  *fmt	= NULL;

	if( ofileformat )
	{
		fmt = av_guess_format(ofileformat, NULL, NULL);
	}
	if(!fmt)
	{
		printf("out file format \"%s\" invalidate.\n",ofileformat);
		return -1;
	}

	/*******************************************init output contents begin**********************************************************/
	/* allocate the output media context */
	oc = avformat_alloc_context();
	if (!oc) 
	{
		printf("out of memory.\n");
		return -2;//内存分配失败
	}

	*out_oc = oc;

	oc ->oformat = fmt;
	sprintf_s( oc ->filename, sizeof( oc ->filename), "%s", ofile);
	av_metadata_conv(oc, fmt->metadata_conv, NULL);
	if( videostream >=0 )
	{
		//AVCodecContext* pCodecCtx= ->streams[videostream]->codec;;
		//add video stream
		AVStream * st = av_new_stream(oc, videostream);
		if(!st)
		{
			printf("can not add a video stream.\n");
			return -3;
		}
		st->codec->codec_id			=  ic ->streams[videostream] ->codec->codec_id;
		st->codec->codec_type		=  CODEC_TYPE_VIDEO;
		st->codec->bit_rate			=  ic ->streams[videostream] ->codec->bit_rate;
		st->codec->width			=  ic ->streams[videostream] ->codec->width;
		st->codec->height			=  ic ->streams[videostream] ->codec->height;
		st->codec->gop_size			=  ic ->streams[videostream] ->codec->gop_size;
		st->codec->pix_fmt			=  ic ->streams[videostream] ->codec->pix_fmt;
		st->codec->frame_size		=  ic ->streams[videostream] ->codec->frame_size;
		st->codec->has_b_frames		=  ic ->streams[videostream] ->codec->has_b_frames;
		st->codec->extradata		=  ic ->streams[videostream] ->codec->extradata;
		st->codec->extradata_size	=  ic ->streams[videostream] ->codec->extradata_size;
		st->codec->codec_tag		=  ic ->streams[videostream] ->codec->codec_tag;
		st->codec->bits_per_raw_sample		=  ic ->streams[videostream] ->codec->bits_per_raw_sample;
		st->codec->chroma_sample_location	=  ic ->streams[videostream] ->codec->chroma_sample_location;
		st->time_base.den			=  ic ->streams[videostream] ->time_base.den;
		st->time_base.num			=  ic ->streams[videostream] ->time_base.num;
		st->cur_dts					=  ic ->streams[videostream] ->cur_dts;
		st->stream_copy				=  1;
		st->pts.den					=  ic ->streams[videostream] ->time_base.den;
		st->pts.num					=  ic ->streams[videostream] ->time_base.num;
		if( oc ->oformat->flags & AVFMT_GLOBALHEADER)
			st ->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
		if(av_q2d(ic ->streams[videostream] ->codec->time_base)*ic ->streams[videostream] ->codec->ticks_per_frame > av_q2d(ic ->streams[videostream]->time_base) && 
			av_q2d(ic ->streams[videostream]->time_base) < 1.0/1000)
		{
			st->codec->time_base = ic ->streams[videostream] ->codec->time_base;
			st->codec->time_base.num *= ic ->streams[videostream] ->codec->ticks_per_frame;
		}
		else
		{
			st->codec->time_base = ic ->streams[videostream] ->time_base;
		}
		st->disposition				=  ic ->streams[videostream] ->disposition;
	}
	if(audiostream >= 0 )
	{
		AVStream * st = av_new_stream( oc, audiostream);
		if(!st)
		{
			printf("can not add a audio stream.\n");
			return -4;
		}
		st->codec->codec_id			=  ic ->streams[audiostream] ->codec->codec_id;
		st->codec->codec_type		=  CODEC_TYPE_AUDIO;
		st->codec->bit_rate			=  ic ->streams[audiostream] ->codec->bit_rate;
		st->codec->gop_size			=  ic ->streams[audiostream] ->codec->gop_size;
		st->codec->pix_fmt			=  ic ->streams[audiostream] ->codec->pix_fmt;
		st->codec->bit_rate			=  ic ->streams[audiostream] ->codec->bit_rate;
		st->codec->channel_layout	=  ic ->streams[audiostream] ->codec->channel_layout;
		st->codec->frame_size		=  ic ->streams[audiostream] ->codec->frame_size;
		st->codec->sample_rate		=  ic ->streams[audiostream] ->codec->sample_rate;
		st->codec->channels			=  ic ->streams[audiostream] ->codec->channels;	
		st->codec->block_align		=  ic ->streams[audiostream] ->codec->block_align;	
		st->time_base.den			=  ic ->streams[audiostream] ->time_base.den;
		st->time_base.num			=  ic ->streams[audiostream] ->time_base.num;
		st->stream_copy				=  1;
		st->pts.den					=  ic ->streams[audiostream] ->time_base.den;
		st->pts.num					=  ic ->streams[audiostream] ->time_base.num;
		if( oc->oformat->flags & AVFMT_GLOBALHEADER)
			st ->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
		if(av_q2d(ic ->streams[audiostream] ->codec->time_base)*ic ->streams[audiostream] ->codec->ticks_per_frame > av_q2d(ic ->streams[audiostream]->time_base) && 
			av_q2d(ic ->streams[audiostream]->time_base) < 1.0/1000)
		{
			st->codec->time_base = ic ->streams[audiostream] ->codec->time_base;
			st->codec->time_base.num *= ic ->streams[audiostream] ->codec->ticks_per_frame;
		}
		else
		{
			st->codec->time_base = ic ->streams[audiostream] ->time_base;
		}
	}
	/* set the output parameters (must be done even if no parameters). */
	//AVFormatParameters params, *ap = ¶ms;
	//memset(ap, 0, sizeof(*ap));
	if (av_set_parameters(oc, NULL/*ap*/) < 0)
	{
		printf("invalid output format parameters.\n");
		return -5;
	}
	oc ->flags |= AVFMT_FLAG_NONBLOCK;
	/*******************************************init output contents end**********************************************************/

	/* open the output file, if needed */
	if (!(oc ->oformat ->flags & AVFMT_NOFILE)) 
	{
		try
		{
			if (url_fopen(&oc->pb, ofile, URL_WRONLY) < 0) 
			{
				printf("Could not open file.\n");
				return -6;
			}
		}
		catch(...)
		{
			printf("Could not open file.\n");
			return -6;
		}
	}

	/* write the stream header, if any */
	if( 0 != av_write_header(oc))
	{
		printf("write the stream header failed.\n");
		return -7;
	}

	return 0;
}