ffmpeg 读取摄像头并通过rtmp推流同时在本地显示（新版ffmpeg接口+SDL2）

结合雷博的例子，将ffmpeg换成新版的接口。

看的其他博主的博客，终于勉强能用了。

遇到的坑：推流在本地通过SDL播放正常，推流收到的图片部分是花的，用ffmpeg命令却是正常的

ffmpeg -f dshow -i video="USB2.0 PC CAMERA" -vcodec libx264 -acodec copy -preset:v ultrafast -tune:v zerolatency -f flv rtmp://localhost:1935/live/room

开始是去掉

av_dict_set(&param, "tune", "zerolatency", 0);

虽然解决了，但是这样延时很大

后来对比了下命令输出的信息，发现编码的方式不一样，雷博使用的是YUV420P  而命令采用的是YUV422P。

改正过后，确实解决了问题。

本人新手入门，肯定有写的不够好的地方，恳请各位指正，相互提高。

废话不说上代码

#include <stdio.h>

#define __STDC_CONSTANT_MACROS

#ifdef _WIN32
//Windows
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "libavdevice/avdevice.h"
#include "libavutil/imgutils.h"
#include "libavutil/time.h"
#include "SDL.h"
};
#else
//Linux...
#ifdef __cplusplus
extern "C"
{
#endif
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <libavdevice/avdevice.h>
#include <SDL/SDL.h>
#ifdef __cplusplus
};
#endif
#endif

//Output YUV420P 
#define OUTPUT_YUV420P  0
//'1' Use Dshow 
//'0' Use VFW
#define USE_DSHOW 1

#define USE_SDL 0


//Refresh Event
#define SFM_REFRESH_EVENT  (SDL_USEREVENT + 1)

#define SFM_BREAK_EVENT  (SDL_USEREVENT + 2)

int thread_exit = 0;

int sfp_refresh_thread(void *opaque)
{
	thread_exit = 0;
	while (!thread_exit) {
		SDL_Event event;
		event.type = SFM_REFRESH_EVENT;
		SDL_PushEvent(&event);
		SDL_Delay(40);
	}
	thread_exit = 0;
	//Break
	SDL_Event event;
	event.type = SFM_BREAK_EVENT;
	SDL_PushEvent(&event);

	return 0;
}


//Show Dshow Device
void show_dshow_device() {
	AVFormatContext *ifmt_ctx = avformat_alloc_context();
	AVDictionary* options = NULL;
	av_dict_set(&options, "list_devices", "true", 0);
	AVInputFormat *iformat = av_find_input_format("dshow");
	printf("========Device Info=============\n");
	avformat_open_input(&ifmt_ctx, "video=dummy", iformat, &options);
	printf("================================\n");
}

//Show Dshow Device Option
void show_dshow_device_option() {
	AVFormatContext *ifmt_ctx = avformat_alloc_context();
	AVDictionary* options = NULL;
	av_dict_set(&options, "list_options", "true", 0);
	AVInputFormat *iformat = av_find_input_format("dshow");
	printf("========Device Option Info======\n");
	avformat_open_input(&ifmt_ctx, "video=USB2.0 PC CAMERA", iformat, &options);
	printf("================================\n");
}

//Show VFW Device
void show_vfw_device() {
	AVFormatContext *ifmt_ctx = avformat_alloc_context();
	AVInputFormat *iformat = av_find_input_format("vfwcap");
	printf("========VFW Device Info======\n");
	avformat_open_input(&ifmt_ctx, "list", iformat, NULL);
	printf("=============================\n");
}

//Show AVFoundation Device
void show_avfoundation_device() {
	AVFormatContext *ifmt_ctx = avformat_alloc_context();
	AVDictionary* options = NULL;
	av_dict_set(&options, "list_devices", "true", 0);
	AVInputFormat *iformat = av_find_input_format("avfoundation");
	printf("==AVFoundation Device Info===\n");
	avformat_open_input(&ifmt_ctx, "", iformat, &options);
	printf("=============================\n");
}


int main(int argc, char* argv[])
{
	AVOutputFormat *ofmt = NULL;
	AVFormatContext	*ifmt_ctx = NULL;
	AVFormatContext *ofmt_ctx = NULL;

	int				i, videoindex;
	AVCodecContext	*iCodecCtx;
	AVCodecContext	*oCodecCtx;
	AVStream		*video_st;
	AVCodec			*iCodec;
	AVCodec			*oCodec;
	//AVPacket		pkt;
	int				ret = -1;
	int				got_decpicture = -1;
	int				got_encpicture = -1;

	int frame_index = 0;
	const char  *out_filename;

	int64_t start_time = 0;

	//av_register_all();
	avformat_network_init();
	ifmt_ctx = avformat_alloc_context();

	//Open File
	//char filepath[]="src01_480x272_22.h265";
	//avformat_open_input(&ifmt_ctx,filepath,NULL,NULL)

	out_filename = "rtmp://localhost:1935/live/room";
	//Register Device
	avdevice_register_all();
	//Network
	avformat_network_init();
	//Windows
#ifdef _WIN32

	//Show Dshow Device
	show_dshow_device();
	//Show Device Options
	show_dshow_device_option();
	//Show VFW Options
	show_vfw_device();

	//输入部分
#if USE_DSHOW
	AVInputFormat *ifmt = av_find_input_format("dshow");
	//Set own video device's name
	if (avformat_open_input(&ifmt_ctx, "video=USB2.0 PC CAMERA", ifmt, NULL) != 0) {
		printf("Couldn't open input stream.（无法打开输入流）\n");
		return -1;
	}
#else
	AVInputFormat *ifmt = av_find_input_format("vfwcap");
	if (avformat_open_input(&ifmt_ctx, "0", ifmt, NULL) != 0) {
		printf("Couldn't open input stream.\n");
		return -1;
	}
#endif
#elif defined linux
	//Linux
	AVInputFormat *ifmt = av_find_input_format("video4linux2");
	if (avformat_open_input(&ifmt_ctx, "/dev/video0", ifmt, NULL) != 0) {
		printf("Couldn't open input stream.\n");
		return -1;
	}
#else
	show_avfoundation_device();
	//Mac
	AVInputFormat *ifmt = av_find_input_format("avfoundation");
	//Avfoundation
	//[video]:[audio]
	if (avformat_open_input(&ifmt_ctx, "0", ifmt, NULL) != 0) {
		printf("Couldn't open input stream.\n");
		return -1;
	}
#endif

	if (avformat_find_stream_info(ifmt_ctx, NULL)<0)
	{
		printf("Couldn't find stream information.（无法获取流信息）\n");
		return -1;
	}
	videoindex = -1;
	for (i = 0; i<ifmt_ctx->nb_streams; i++)
		if (ifmt_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
		{
			videoindex = i;
			break;
		}
	if (videoindex == -1)
	{
		printf("Couldn't find a video stream.（没有找到视频流）\n");
		return -1;
	}
	//pCodecCtx = ifmt_ctx->streams[videoindex]->codec;
	iCodecCtx = avcodec_alloc_context3(NULL);
	avcodec_parameters_to_context(iCodecCtx, ifmt_ctx->streams[videoindex]->codecpar);

	iCodec = avcodec_find_decoder(ifmt_ctx->streams[i]->codecpar->codec_id);
	if (iCodec == NULL)
	{
		printf("Codec not found.(无法找到解码器编码)\n");
		return -1;
	}
	if (avcodec_open2(iCodecCtx, iCodec, NULL)<0)
	{
		printf("Could not open codec.（无法打开解码器）\n");
		return -1;
	}
	//Dump Format------------------
	av_dump_format(ifmt_ctx, 0, "video=USB2.0 PC CAMERA",0);

	//输出


	avformat_alloc_output_context2(&ofmt_ctx, NULL, "flv", out_filename);
	if (!ofmt_ctx) {
		printf("Could not create output context（不能创建输出上下文）\n");
		return -1;
	}
	//ofmt = ofmt_ctx->oformat;

	oCodec = avcodec_find_encoder(AV_CODEC_ID_H264);
	if (!oCodec) {
		printf("Can not find encoder! (没有找到合适的编码器！)\n");
		return -1;
	}

	oCodecCtx = avcodec_alloc_context3(oCodec);
	oCodecCtx->pix_fmt = AV_PIX_FMT_YUV422P;
	oCodecCtx->width = ifmt_ctx->streams[videoindex]->codecpar->width;
	oCodecCtx->height = ifmt_ctx->streams[videoindex]->codecpar->height;
	oCodecCtx->time_base.num = 1;
	oCodecCtx->time_base.den = 25;
	oCodecCtx->bit_rate = 400000;
	oCodecCtx->gop_size = 250;

	if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
		oCodecCtx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
	//H264 codec param  
	//pCodecCtx->me_range = 16;  
	//pCodecCtx->max_qdiff = 4;  
	//pCodecCtx->qcompress = 0.6;  
	oCodecCtx->qmin = 10;
	oCodecCtx->qmax = 51;
	//Optional Param  
	oCodecCtx->max_b_frames = 3;
	// Set H264 preset and tune  
	
	AVDictionary *param = 0;
	av_dict_set(&param, "preset", "ultrafast", 0);
	//解码时花屏，加上有花屏，去掉有延时
	av_dict_set(&param, "tune", "zerolatency", 0);
	//av_dict_set(&param, "tune", "zerolatency", 0);
	if (avcodec_open2(oCodecCtx, oCodec, &param) < 0) {
		printf("Failed to open encoder! (编码器打开失败！)\n");
		return -1;
	}
	//Add a new stream to output,should be called by the user before avformat_write_header() for muxing  
	video_st = avformat_new_stream(ofmt_ctx, oCodec);
	if (video_st == NULL) {
		return -1;
	}
	video_st->time_base.num = 1;
	video_st->time_base.den = 25;
	//video_st->codec = oCodecCtx;
	avcodec_parameters_from_context(video_st->codecpar,oCodecCtx);
	//Open output URL,set before avformat_write_header() for muxing  
	if (avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_READ_WRITE) < 0) {
		printf("Failed to open output file! (输出文件打开失败！)\n");
		return -1;
	}

	//Dump Format------------------
	av_dump_format(ofmt_ctx, 0, out_filename, 1);

	//写文件头（Write file header）
	ret = avformat_write_header(ofmt_ctx, NULL);
	if (ret < 0) {
		printf("Error occurred when opening output URL\n");
		return -1;
	}

	

	//prepare before decode and encode
	AVPacket *dec_packet = (AVPacket *)av_malloc(sizeof(AVPacket));
	AVPacket enc_packet;
	//
	////AVPacket pkt;
	//int y_size = oCodecCtx->width * oCodecCtx->height;
	//av_new_packet(&enc_packet, y_size * 3);

	//转码上下文
	struct SwsContext *img_convert_ctx;
	img_convert_ctx = sws_getContext(iCodecCtx->width, iCodecCtx->height,
		iCodecCtx->pix_fmt, oCodecCtx->width, oCodecCtx->height, AV_PIX_FMT_YUV422P, SWS_BICUBIC, NULL, NULL, NULL);
	
	AVFrame	*pFrame, *pFrameYUV;
	pFrameYUV = av_frame_alloc();
	//设置帧的格式、宽度和高度，否则会出现
	//1.AVFrame.format is not set
	//2.AVFrame.width or height is not set
	pFrameYUV->format = oCodecCtx->pix_fmt;
	pFrameYUV->width = oCodecCtx->width;
	pFrameYUV->height = oCodecCtx->height;
	// 存储图像数据
	uint8_t *out_buffer;
	// av_image_get_buffer_size：返回使用给定参数存储图像所需的数据量的字节大小
	out_buffer = (uint8_t *)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_YUV422P, oCodecCtx->width, oCodecCtx->height, 1));
	// 根据指定的图像参数和提供的数组设置数据指针和线条（data pointers and linesizes）
	av_image_fill_arrays(pFrameYUV->data, pFrameYUV->linesize, out_buffer, AV_PIX_FMT_YUV422P, oCodecCtx->width, oCodecCtx->height, 1);
#if USE_SDL
	//SDL----------------------------
	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
		printf("Could not initialize SDL - %s\n", SDL_GetError());
		return -1;
	}
	int screen_w = 0, screen_h = 0;
	SDL_Window *screen;
	screen_w = oCodecCtx->width;
	screen_h = oCodecCtx->height;
	//screen = SDL_SetVideoMode(screen_w, screen_h, 0, 0);
	//SDL 2.0 Support for multiple windows
	screen = SDL_CreateWindow("Simplest FFmpeg Device", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
		screen_w, screen_h, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
	if (!screen) {
		printf("SDL: could not set video mode - exiting:%s\n", SDL_GetError());
		return -1;
	}
	SDL_Texture *sdlTexture;
	//bmp = SDL_CreateYUVOverlay(pCodecCtx->width, pCodecCtx->height, SDL_YV12_OVERLAY, screen);

	SDL_Renderer* sdlRenderer = SDL_CreateRenderer(screen, -1, 0);
	Uint32 pixformat = 0;
	//IYUV: Y + U + V  (3 planes)
	//YV12: Y + V + U  (3 planes)
	pixformat = SDL_PIXELFORMAT_IYUV;
	sdlTexture = SDL_CreateTexture(sdlRenderer, pixformat, SDL_TEXTUREACCESS_STREAMING, oCodecCtx->width, oCodecCtx->height);
	SDL_Rect rect;
	rect.x = 0;
	rect.y = 0;
	rect.w = screen_w;
	rect.h = screen_h;
	//SDL End------------------------
	//------------------------------
	SDL_Thread *video_tid = SDL_CreateThread(sfp_refresh_thread, NULL, NULL);
	//
	//SDL_WM_SetCaption("Simplest FFmpeg Read Camera", NULL);
	//Event Loop
	SDL_Event event;
#endif // USE_SDL


	start_time = av_gettime();
	for (;;) 
	{
#if USE_SDL
		//Wait
		SDL_WaitEvent(&event);

		if (event.type == SFM_REFRESH_EVENT) {
#endif
			//------------------------------
			if (av_read_frame(ifmt_ctx, dec_packet) >= 0) 
			{
				if (dec_packet->stream_index == videoindex)
				{
					pFrame = av_frame_alloc();
					if (!pFrame) {
						printf("alloc pFrame Failed.\n");
						return -1;
					}
					//ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
					ret = avcodec_send_packet(iCodecCtx, dec_packet);
					got_decpicture = avcodec_receive_frame(iCodecCtx, pFrame);
					if (ret < 0) 
					{
						av_frame_free(&pFrame);
						printf("Decode Error.\n");
						return -1;
					}
					if (got_decpicture == 0)
					{
						
						//转码成YUV格式
						sws_scale(img_convert_ctx, (const unsigned char* const*)pFrame->data, pFrame->linesize, 0, iCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);
						
						//初始化封装包
						enc_packet.data = NULL;
						enc_packet.size = 0;
						av_init_packet(&enc_packet);
						
						//编码
						//ret = avcodec_encode_video2(oCodecCtx, &enc_packet, pFrameYUV, &got_encpicture);
						ret = avcodec_send_frame(oCodecCtx, pFrameYUV);
						//FIX : non-strictly-monotonic PTS
						pFrameYUV->pts++;
						if (ret < 0) {
							av_frame_free(&pFrame);
							printf("Encode Error.\n");
							return -1;
						}
						got_encpicture = avcodec_receive_packet(oCodecCtx, &enc_packet);
						
						if (got_encpicture==0)
						{
							frame_index++;
							enc_packet.stream_index = video_st->index;
							//FIX：No PTS (Example: Raw H.264)
							//Simple Write PTS
							AVStream *in_stream, *out_stream;
							if (enc_packet.pts == AV_NOPTS_VALUE) 
							{
								//Write PTS
								AVRational time_base1 = ifmt_ctx->streams[videoindex]->time_base;
								//Duration between 2 frames (us)
								int64_t calc_duration = (double)AV_TIME_BASE / av_q2d(ifmt_ctx->streams[videoindex]->r_frame_rate);
								//Parameters
								enc_packet.pts = (double)(frame_index*calc_duration) / (double)(av_q2d(time_base1)*AV_TIME_BASE);
								enc_packet.dts = enc_packet.pts;
								enc_packet.duration = (double)calc_duration / (double)(av_q2d(time_base1)*AV_TIME_BASE);
							}

							//Write PTS
							AVRational time_base = ofmt_ctx->streams[videoindex]->time_base;//{ 1, 1000 };
							AVRational r_framerate1 = ifmt_ctx->streams[videoindex]->r_frame_rate;// { 50, 2 };
							AVRational time_base_q = { 1, AV_TIME_BASE };
							//Duration between 2 frames (us)
							int64_t calc_duration = (double)(AV_TIME_BASE)*(1 / av_q2d(r_framerate1));	//内部时间戳
																										//Parameters
																										//enc_pkt.pts
							//enc_pkt.pts = (double)(framecnt*calc_duration)*(double)(av_q2d(time_base_q)) / (double)(av_q2d(time_base));
							enc_packet.pts = av_rescale_q(frame_index*calc_duration, time_base_q, time_base);
							enc_packet.dts = enc_packet.pts;
							enc_packet.duration = av_rescale_q(calc_duration, time_base_q, time_base); //(double)(calc_duration)*(double)(av_q2d(time_base_q)) / (double)(av_q2d(time_base));
							enc_packet.pos = -1;
							//Delay
							int64_t pts_time = av_rescale_q(enc_packet.dts, time_base, time_base_q);
							int64_t now_time = av_gettime() - start_time;
							if (pts_time > now_time)
								av_usleep(pts_time - now_time);

							//Print to Screen
							if (enc_packet.stream_index == videoindex) {
								printf("Send %8d video frames to output URL\n", frame_index);
								
							}
							//写到输出上下文
							ret = av_interleaved_write_frame(ofmt_ctx, &enc_packet);
							
						}
						av_packet_unref(&enc_packet);
#if USE_SDL
						//SDL---------------------------
						// 设置纹理数据
						SDL_UpdateTexture(sdlTexture, NULL, pFrameYUV->data[0], pFrameYUV->linesize[0]);
						// 清理渲染器
						SDL_RenderClear(sdlRenderer);

						// 将纹理数据copy到渲染器
						//将sdlRect区域的图像显示到dstsdlRect区域
						//SDL_RenderCopy( sdlRenderer, sdlTexture, &sdlRect, &sdlRect );
						SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, NULL);
						// 显示
						SDL_RenderPresent(sdlRenderer);
						//SDL End-----------------------
#endif
					}
					av_frame_free(&pFrame);
				}
				av_packet_unref(dec_packet);
			}
#if USE_SDL
			else 
			{
				//Exit Thread
				thread_exit = 1;
			}
#endif
#if USE_SDL
		}
		else if (event.type == SDL_QUIT) {
			thread_exit = 1;
		}
		else if (event.type == SFM_BREAK_EVENT) {
			break;
		}
#endif
	}
#if USE_SDL
	SDL_Quit();
#endif
	//写文件尾（Write file trailer）
	av_write_trailer(ofmt_ctx);

	av_free(out_buffer);
end:
	if(video_st)
		avcodec_close(oCodecCtx);

	avformat_close_input(&ifmt_ctx);
	/* close output */
	if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
		avio_close(ofmt_ctx->pb);
	avformat_free_context(ifmt_ctx);
	avformat_free_context(ofmt_ctx);
	if (ret < 0 && ret != AVERROR_EOF) {
		printf("Error occurred.\n");
		return -1;
	}


	return 0;
}

文件退出的部分没有测试，担心会有内存泄漏。