一、初级版
功能：实现了简易视频播放器的功能，能解码H264后播放
工具：FFmpeg 4.0.2 + SDL2-2.0.8
C++代码：

/*************************************
功能：H264解码为YUV序列,通过SDL播放
FFmpeg：4.0.2
*************************************/
#define SDL_MAIN_HANDLED
#include <iostream>
extern "C"
{
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <libavfilter/avfilter.h>
#include <libavutil/imgutils.h>
#include <SDL.h>
#include <SDL_main.h>
};
using namespace std;
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *pFrame, AVFrame *yuvFrame, struct SwsContext *imgCtx, FILE *outfile)
{
	int ret;
	/* send the packet with the compressed data to the decoder */
	ret = avcodec_send_packet(dec_ctx, pkt);
	if (ret < 0)
	{
		fprintf(stderr, "Error submitting the packet to the decoder\n");
		exit(1);
	}
	/* read all the output frames (in general there may be any number of them */
	while (ret >= 0)
	{
		ret = avcodec_receive_frame(dec_ctx, pFrame);
		if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
			return;
		else if (ret < 0)
		{
			fprintf(stderr, "Error during decoding\n");
			exit(1);
		}
		cout << "decoding the frame " << dec_ctx->frame_number << endl;
		sws_scale(imgCtx, pFrame->data, pFrame->linesize, 0, dec_ctx->height, yuvFrame->data, yuvFrame->linesize);
		int y_size = dec_ctx->width*dec_ctx->height;
		fwrite(yuvFrame->data[0], 1, y_size, outfile);		// Y 
		fwrite(yuvFrame->data[1], 1, y_size / 4, outfile);	// U
		fwrite(yuvFrame->data[2], 1, y_size / 4, outfile);	// V
	}
}
int DecodeH264ToYUV(const char *H264FileName, const char *YUVFileName)
{
	//SDL---------------------------
	int screen_w = 0, screen_h = 0;
	SDL_Window *screen;
	SDL_Renderer* sdlRenderer;
	SDL_Texture* sdlTexture;
	SDL_Rect sdlRect;
	//SDL---------------------------
	
	FILE *fp_yuv = NULL;
	fopen_s(&fp_yuv, YUVFileName, "wb+");
	// 打开h264文件，并把文件信息存入fctx中 
	int iRes = 0;
	AVFormatContext *fctx = avformat_alloc_context();
	if ((iRes = avformat_open_input(&fctx, H264FileName, NULL, NULL)) != 0)
	{
		cout << "File open failed!" << endl;
		return -1;
	}
	// 寻找视频流信息
	if (avformat_find_stream_info(fctx, NULL) < 0)
	{
		cout << "Stream find failed!\n";
		return -1;
	}
	// dump调试信息
	av_dump_format(fctx, -1, H264FileName, NULL);
	// 打开了视频并且获取了视频流 ，设置视频索引值默认值
	int vindex = -1;
	for (int i = 0; i < fctx->nb_streams; i++)
	{
		if (fctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
			vindex = i;
	}
	// 如果没有找到视频的索引，说明并不是一个视频文件
	if (vindex == -1)
	{
		cout << "Codec find failed!" << endl;
		return -1;
	}
	// 分配解码器上下文空间
	AVCodecContext *cctx = avcodec_alloc_context3(NULL);
	// 获取编解码器上下文信息
	if (avcodec_parameters_to_context(cctx, fctx->streams[vindex]->codecpar) < 0)
	{
		cout << "Copy stream failed!" << endl;
		return -1;
	}
	// 查找解码器
	AVCodec *c = avcodec_find_decoder(cctx->codec_id);
	if (!c) {
		cout << "Find Decoder failed!" << endl;
		return -1;
	}
	// 打开解码器
	if (avcodec_open2(cctx, c, NULL) != 0) {
		cout << "Open codec failed!" << endl;
		return -1;
	}
	// 对图形进行宽度上方的裁剪，以便于显示得更好
	struct SwsContext *imgCtx = sws_getContext(cctx->width, cctx->height, cctx->pix_fmt, 
		                                       cctx->width, cctx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
	if (!imgCtx)
	{
		cout << "Get swscale context failed!" << endl;
		return -1;
	}

	//SDL Init----------------------
	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) 
	{
		cout << "Could not initialize SDL - " << SDL_GetError() << endl;
		return -1;
	}
	screen_w = cctx->width;
	screen_h = cctx->height;
	//SDL 2.0 Support for multiple windows
	screen = SDL_CreateWindow("FFmpeg Player", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, screen_w, screen_h, SDL_WINDOW_OPENGL);
	if (!screen) {
		cout << "SDL: could not create window - exiting:" << SDL_GetError() << endl;
		return -1;
	}
	sdlRenderer = SDL_CreateRenderer(screen, -1, 0);
	sdlTexture = SDL_CreateTexture(sdlRenderer, SDL_PIXELFORMAT_IYUV, SDL_TEXTUREACCESS_STREAMING, cctx->width, cctx->height);
	sdlRect.x = 0;
	sdlRect.y = 0;
	sdlRect.w = screen_w;
	sdlRect.h = screen_h;
	//SDL Init End----------------------

	// 初始化已解码帧
	AVPacket *pkt = av_packet_alloc();
	AVFrame *pFrame = av_frame_alloc();
	// 初始化解码得到的yuv帧
	AVFrame *yuvFrame = av_frame_alloc();
	int vsize = av_image_get_buffer_size(AV_PIX_FMT_YUV420P, cctx->width, cctx->height, 1);
	uint8_t *buf = (uint8_t *)av_malloc(vsize);
	av_image_fill_arrays(yuvFrame->data, yuvFrame->linesize, buf, AV_PIX_FMT_YUV420P, cctx->width, cctx->height, 1);
	//char errbuf[256] = { 0 };
	// 循环读取每一帧
	while (av_read_frame(fctx, pkt) >= 0)
	{
		if (pkt->stream_index == vindex)
		{
			/*
			if ((iRes = avcodec_send_packet(cctx, pkt)) != 0)
			{
				cout << "Send video stream packet failed!" << endl;
				av_strerror(iRes, errbuf, 256);
				return -5;
			}
			if ((iRes = avcodec_receive_frame(cctx, pFrame)) != 0)
			{
				cout << "Receive video frame failed!" << endl;
				av_strerror(iRes, errbuf, 256);
				return -6;
			}
			cout << "decoding the frame " << cctx->frame_number << endl;
			sws_scale(imgCtx, pFrame->data, pFrame->linesize, 0, cctx->height, yuvFrame->data, yuvFrame->linesize);
			int y_size = cctx->width*cctx->height;
			fwrite(yuvFrame->data[0], 1, y_size, fp_yuv);		// Y 
			fwrite(yuvFrame->data[1], 1, y_size / 4, fp_yuv);	// U
			fwrite(yuvFrame->data[2], 1, y_size / 4, fp_yuv);	// V
			*/
			decode(cctx, pkt, pFrame, yuvFrame, imgCtx, fp_yuv);
			//SDL-----------------------------------------------------------------------------------------------------
			SDL_UpdateYUVTexture(sdlTexture, &sdlRect, yuvFrame->data[0], yuvFrame->linesize[0], 
								 yuvFrame->data[1], yuvFrame->linesize[1], yuvFrame->data[2], yuvFrame->linesize[2]);
			SDL_RenderClear(sdlRenderer);
			SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, &sdlRect);
			SDL_RenderPresent(sdlRenderer);
			SDL_Delay(40);
			//SDL End--------------------------------------------------------------------------------------------------
		}
	}
	/* flush the decoder */
	pkt->data = NULL;
	pkt->size = 0;
	decode(cctx, pkt, pFrame, yuvFrame, imgCtx, fp_yuv);
	//SDL---------------------------------------------------------------------------------------------------------------
	SDL_UpdateYUVTexture(sdlTexture, &sdlRect, yuvFrame->data[0], yuvFrame->linesize[0], 
		                 yuvFrame->data[1], yuvFrame->linesize[1], yuvFrame->data[2], yuvFrame->linesize[2]);
	SDL_RenderClear(sdlRenderer);
	SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, &sdlRect);
	SDL_RenderPresent(sdlRenderer);
	SDL_Delay(40);
	SDL_Quit();
	//SDL End-----------------------------------------------------------------------------------------------------------
	//释放内存
	av_free(buf);
	av_frame_free(&yuvFrame);
	av_frame_free(&pFrame);
	av_packet_free(&pkt);
	sws_freeContext(imgCtx);
	avcodec_free_context(&cctx);
	avformat_close_input(&fctx);
	avformat_free_context(fctx);
	return 0;
}

int main()
{
	const char *H264FileName = "../H264/test.h264";
	const char *YUVFileName = "../YUV/test.yuv";
	const char *YUVFilesName = "../YUV/frame";
	if (DecodeH264ToYUV(H264FileName, YUVFileName) < 0)
		cout << "Decode failed!" << endl;
	cout << "Decode finished!" << endl;
	return getchar();
}

实现效果如图所示：
这里写图片描述
二、升级版

/*************************************
功能：H264解码为YUV序列,通过SDL播放
FFmpeg：4.0.2
新增：新增SDL Event，SDL窗口可以任意拖动
*************************************/
#define SDL_MAIN_HANDLED
#include <iostream>
extern "C"
{
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <libavfilter/avfilter.h>
#include <libavutil/imgutils.h>
#include <SDL.h>
#include <SDL_main.h>
};
using namespace std;

//Refresh Event
#define SFM_REFRESH_EVENT  (SDL_USEREVENT + 1)
#define SFM_BREAK_EVENT  (SDL_USEREVENT + 2)

int thread_exit = 0;
int thread_pause = 0;

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

static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *pFrame, AVFrame *yuvFrame, struct SwsContext *imgCtx, FILE *outfile)
{
	int ret;
	/* send the packet with the compressed data to the decoder */
	ret = avcodec_send_packet(dec_ctx, pkt);
	if (ret < 0)
	{
		fprintf(stderr, "Error submitting the packet to the decoder\n");
		exit(1);
	}
	/* read all the output frames (in general there may be any number of them */
	while (ret >= 0)
	{
		ret = avcodec_receive_frame(dec_ctx, pFrame);
		if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
			return;
		else if (ret < 0)
		{
			fprintf(stderr, "Error during decoding\n");
			exit(1);
		}
		cout << "decoding the frame " << dec_ctx->frame_number << endl;
		sws_scale(imgCtx, pFrame->data, pFrame->linesize, 0, dec_ctx->height, yuvFrame->data, yuvFrame->linesize);
		int y_size = dec_ctx->width*dec_ctx->height;
		fwrite(yuvFrame->data[0], 1, y_size, outfile);		// Y 
		fwrite(yuvFrame->data[1], 1, y_size / 4, outfile);	// U
		fwrite(yuvFrame->data[2], 1, y_size / 4, outfile);	// V
	}
}
int DecodeH264ToYUV(const char *H264FileName, const char *YUVFileName)
{
	//SDL---------------------------------------------------------------
	int screen_w = 0, screen_h = 0;
	SDL_Window *screen;
	SDL_Renderer* sdlRenderer;
	SDL_Texture* sdlTexture;
	SDL_Rect sdlRect;
	SDL_Thread *video_tid;
	SDL_Event event;
	//SDL---------------------------------------------------------------

	FILE *fp_yuv = NULL;
	fopen_s(&fp_yuv, YUVFileName, "wb+");
	// 打开h264文件，并把文件信息存入fctx中 
	int iRes = 0;
	AVFormatContext *fctx = avformat_alloc_context();
	if ((iRes = avformat_open_input(&fctx, H264FileName, NULL, NULL)) != 0)
	{
		cout << "File open failed!" << endl;
		return -1;
	}
	// 寻找视频流信息
	if (avformat_find_stream_info(fctx, NULL) < 0)
	{
		cout << "Stream find failed!\n";
		return -1;
	}
	// dump调试信息
	av_dump_format(fctx, -1, H264FileName, NULL);
	// 打开了视频并且获取了视频流 ，设置视频索引值默认值
	int vindex = -1;
	for (int i = 0; i < fctx->nb_streams; i++)
	{
		if (fctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
			vindex = i;
	}
	// 如果没有找到视频的索引，说明并不是一个视频文件
	if (vindex == -1)
	{
		cout << "Codec find failed!" << endl;
		return -1;
	}
	// 分配解码器上下文空间
	AVCodecContext *cctx = avcodec_alloc_context3(NULL);
	// 获取编解码器上下文信息
	if (avcodec_parameters_to_context(cctx, fctx->streams[vindex]->codecpar) < 0)
	{
		cout << "Copy stream failed!" << endl;
		return -1;
	}
	// 查找解码器
	AVCodec *c = avcodec_find_decoder(cctx->codec_id);
	if (!c)
	{
		cout << "Find Decoder failed!" << endl;
		return -1;
	}
	// 打开解码器
	if (avcodec_open2(cctx, c, NULL) != 0) {
		cout << "Open codec failed!" << endl;
		return -1;
	}
	// 对图形进行宽度上方的裁剪，以便于显示得更好
	struct SwsContext *imgCtx = sws_getContext(cctx->width, cctx->height, cctx->pix_fmt,
		cctx->width, cctx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
	if (!imgCtx)
	{
		cout << "Get swscale context failed!" << endl;
		return -1;
	}

	//SDL Init--------------------------------------------------------------------------------------------------------------------------------
	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER))
	{
		cout << "Could not initialize SDL - " << SDL_GetError() << endl;
		return -1;
	}
	screen_w = cctx->width;
	screen_h = cctx->height;
	//SDL 2.0 Support for multiple windows
	screen = SDL_CreateWindow("FFmpeg Player", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, screen_w, screen_h, SDL_WINDOW_OPENGL);
	if (!screen)
	{
		cout << "SDL: could not create window - exiting:" << SDL_GetError() << endl;
		return -1;
	}
	sdlRenderer = SDL_CreateRenderer(screen, -1, 0);
	//IYUV: Y + U + V  (3 planes)
	//YV12: Y + V + U  (3 planes)
	sdlTexture = SDL_CreateTexture(sdlRenderer, SDL_PIXELFORMAT_IYUV, SDL_TEXTUREACCESS_STREAMING, cctx->width, cctx->height);
	sdlRect.x = 0;
	sdlRect.y = 0;
	sdlRect.w = screen_w;
	sdlRect.h = screen_h;
	video_tid = SDL_CreateThread(sfp_refresh_thread, NULL, NULL);//SDL事件响应线程
	//SDL Init End-----------------------------------------------------------------------------------------------------------------------------

	// 初始化已解码帧
	AVPacket *pkt = av_packet_alloc();
	AVFrame *pFrame = av_frame_alloc();
	// 初始化解码得到的yuv帧
	AVFrame *yuvFrame = av_frame_alloc();
	int vsize = av_image_get_buffer_size(AV_PIX_FMT_YUV420P, cctx->width, cctx->height, 1);
	uint8_t *buf = (uint8_t *)av_malloc(vsize);
	av_image_fill_arrays(yuvFrame->data, yuvFrame->linesize, buf, AV_PIX_FMT_YUV420P, cctx->width, cctx->height, 1);
	// 循环读取每一帧
	while (av_read_frame(fctx, pkt) >= 0)
	{
		if (pkt->stream_index == vindex)
		{
			/*
			if ((iRes = avcodec_send_packet(cctx, pkt)) != 0)
			{
			cout << "Send video stream packet failed!" << endl;
			av_strerror(iRes, errbuf, 256);
			return -5;
			}
			if ((iRes = avcodec_receive_frame(cctx, pFrame)) != 0)
			{
			cout << "Receive video frame failed!" << endl;
			av_strerror(iRes, errbuf, 256);
			return -6;
			}
			cout << "decoding the frame " << cctx->frame_number << endl;
			sws_scale(imgCtx, pFrame->data, pFrame->linesize, 0, cctx->height, yuvFrame->data, yuvFrame->linesize);
			int y_size = cctx->width*cctx->height;
			fwrite(yuvFrame->data[0], 1, y_size, fp_yuv);		// Y
			fwrite(yuvFrame->data[1], 1, y_size / 4, fp_yuv);	// U
			fwrite(yuvFrame->data[2], 1, y_size / 4, fp_yuv);	// V
			*/
			decode(cctx, pkt, pFrame, yuvFrame, imgCtx, fp_yuv);
			//SDL-----------------------------------------------------------------------------------------------------
			SDL_UpdateYUVTexture(sdlTexture, &sdlRect, yuvFrame->data[0], yuvFrame->linesize[0],
				yuvFrame->data[1], yuvFrame->linesize[1], yuvFrame->data[2], yuvFrame->linesize[2]);
			SDL_RenderClear(sdlRenderer);
			SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, &sdlRect);
			SDL_RenderPresent(sdlRenderer);
			SDL_Delay(40);
			//SDL End--------------------------------------------------------------------------------------------------
		}
		// SDL事件	
		SDL_WaitEvent(&event);
		if (event.type == SDL_KEYDOWN) 
		{
			//Pause
			if (event.key.keysym.sym == SDLK_SPACE)
				thread_pause = !thread_pause;
		}
		else if (event.type == SDL_QUIT) 
		{
			thread_exit = 1;
		}
		else if (event.type == SFM_BREAK_EVENT) 
		{
			break;
		}
	}
	/* flush the decoder */
	pkt->data = NULL;
	pkt->size = 0;
	decode(cctx, pkt, pFrame, yuvFrame, imgCtx, fp_yuv);
	//SDL---------------------------------------------------------------------------------------------------------------
	SDL_UpdateYUVTexture(sdlTexture, &sdlRect, yuvFrame->data[0], yuvFrame->linesize[0],
		yuvFrame->data[1], yuvFrame->linesize[1], yuvFrame->data[2], yuvFrame->linesize[2]);
	SDL_RenderClear(sdlRenderer);
	SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, &sdlRect);
	SDL_RenderPresent(sdlRenderer);
	SDL_Delay(40);
	SDL_Quit();
	//SDL End-----------------------------------------------------------------------------------------------------------
	//释放内存
	av_free(buf);
	av_frame_free(&yuvFrame);
	av_frame_free(&pFrame);
	av_packet_free(&pkt);
	sws_freeContext(imgCtx);
	avcodec_free_context(&cctx);
	avformat_close_input(&fctx);
	avformat_free_context(fctx);
	return 0;
}

int main()
{
	const char *H264FileName = "../H264/test.h264";
	const char *YUVFileName = "../YUV/test.yuv";
	if (DecodeH264ToYUV(H264FileName, YUVFileName) < 0)
		cout << "Decode failed!" << endl;
	cout << "Decode finished!" << endl;
	return getchar();
}

*【注】如果你觉得此文不错，可以考虑打赏我哦，您的打赏将是我更新的最大动力，非常感谢。（打赏也是基于自愿原则的哦(￣︶￣)）

在这里插入图片描述

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