基于FFMPEG采集攝像頭圖像編碼MP4視頻+時間水印

1.硬件平臺

操作系統：Ubuntu18.04
ffmpeg版本：ffmpeg4.2.5
攝像頭：電腦自帶或USB免驅攝像頭
水印處理：avfilter
圖像渲染：SDL庫

?攝像頭圖像采集+MP4視頻編碼參考示例：https://blog.csdn.net/weixin_44453694/article/details/123885112
水印添加處理參數示例：https://blog.csdn.net/weixin_44453694/article/details/123909568

2.功能實現

本示例采樣三個線程實現：
?子線程1實現ffmpeg編解碼器注冊，設置圖像格式，攝像頭圖像數據采集。
?子線程2實現MP4視頻格式編碼。
?主線程完成子線程創建，SDL庫初始化，窗口創建，圖像數據渲染。
通過ffmpeg自帶avfilter庫實現時間水印添加。

3.核心代碼

3.1 水印處理函數

//添加水印
int waterMark(AVFrame *frame_in,AVFrame *frame_out,int w,int h,const char *str)
{
	int ret;
	/*根據名字獲取ffmegding定義的filter*/
	const AVFilter *buffersrc=avfilter_get_by_name("buffer");//原始數據
	const AVFilter *buffersink=avfilter_get_by_name("buffersink");//處理后的數據
	/*動態分配AVFilterInOut空間*/
	AVFilterInOut *outputs=avfilter_inout_alloc();
	AVFilterInOut *inputs=avfilter_inout_alloc();	
	/*創建AVFilterGraph,分配空間*/
	AVFilterGraph *filter_graph;//對filters系統的整體管理結構體
	filter_graph = avfilter_graph_alloc();
	enum AVPixelFormat pix_fmts[]={AV_PIX_FMT_YUV420P, AV_PIX_FMT_NONE};//設置格式
	/*過濾器參數：解碼器的解碼幀將被插入這里。*/
	char args[256];
	snprintf(args, sizeof(args),
		"video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
		w,h,AV_PIX_FMT_YUV420P,1,25,1,1);//圖像寬高，格式，幀率，畫面橫縱比
	/*創建過濾器上下文,源數據AVFilterContext*/
	AVFilterContext *buffersrc_ctx;
	ret=avfilter_graph_create_filter(&buffersrc_ctx,buffersrc,"in",args,NULL,filter_graph);
	if(ret<0)
	{
		printf("創建src過濾器上下文失敗AVFilterContextn");
		return -1;
	}		
	/*創建過濾器上下文，處理后數據buffersink_params*/
	AVBufferSinkParams *buffersink_params;
	buffersink_params=av_buffersink_params_alloc();
	buffersink_params->pixel_fmts=pix_fmts;//設置格式
	AVFilterContext *buffersink_ctx;
	ret=avfilter_graph_create_filter(&buffersink_ctx,buffersink,"out",NULL,buffersink_params,filter_graph);
	av_free(buffersink_params);
	if(ret<0)
	{
		printf("創建sink過濾器上下文失敗AVFilterContextn");
		return -2;
	}	
	/*過濾器鏈輸入/輸出鏈接列表*/
	outputs->name       =av_strdup("in");
	outputs->filter_ctx =buffersrc_ctx;
	outputs->pad_idx    =0;
	outputs->next		=NULL;

	inputs->name		=av_strdup("out");
	inputs->filter_ctx	=buffersink_ctx;
	inputs->pad_idx    =0;
	inputs->next		=NULL;
	char filter_desrc[200]={0};//要添加的水印數據
	snprintf(filter_desrc,sizeof(filter_desrc),"drawtext=fontfile=msyhbd.ttc:fontcolor=red:fontsize=25:x=50:y=20:text='%snIT_阿水'",str);
	if(avfilter_graph_parse_ptr(filter_graph,filter_desrc,&inputs,&outputs, NULL)<0)//設置過濾器數據內容
	{
		printf("添加字符串信息失敗n");
		return -3;
	}
	/*檢測配置信息是否正常*/
	if(avfilter_graph_config(filter_graph,NULL)<0)
	{
		printf("配置信息有誤n");
		return -4;
	}	
	#if 0
	/*
		查找要在使用的過濾器，將要觸處理的數據添加到過濾器
		注意：時間若從外面傳入(即144行數據已完整)，則此處不需要查找，直接添加即可，否則需要添加下面代碼
	*/
	AVFilterContext* filter_ctx;//上下文
	int parsed_drawtext_0_index = -1;
	 for(int i=0;inb_filters;i++)//查找使用的過濾器
	 {
		 AVFilterContext *filter_ctxn=filter_graph->filters[i];
		 printf("[%s %d]:filter_ctxn_name=%sn",__FUNCTION__,__LINE__,filter_ctxn->name);
		 if(!strcmp(filter_ctxn->name,"Parsed_drawtext_0"))
		 {
			parsed_drawtext_0_index=i;
		 }
	 }
	 if(parsed_drawtext_0_index==-1)
	 {
		printf("[%s %d]:no Parsed_drawtext_0n",__FUNCTION__,__LINE__);//沒有找到過濾器
	 }
	 filter_ctx=filter_graph->filters[parsed_drawtext_0_index];//保存找到的過濾器
	 
		/*獲取系統時間，將時間加入到過濾器*/
		char sys_time[64];
		time_t sec,sec2;	 
		sec=time(NULL);
		if(sec!=sec2)
		{
			sec2=sec;
			struct tm* today = localtime(&sec2);	
			strftime(sys_time, sizeof(sys_time), "%Y/%m/%d %H:%M:%S", today);       //24小時制
		}
		av_opt_set(filter_ctx->priv, "text", sys_time, 0 );  //設置text到過濾器
	 #endif

	/*往源濾波器buffer中輸入待處理數據*/
	 if(av_buffersrc_add_frame(buffersrc_ctx,frame_in)<0)
	 {
		return -5;
	 }
	 /*從濾波器中輸出處理數據*/
	 if(av_buffersink_get_frame(buffersink_ctx, frame_out)<0)
	 {
		return -6;
	 }
	avfilter_inout_free(&outputs);
    avfilter_inout_free(&inputs);
    avfilter_graph_free(&filter_graph);
	return 0;
}

3.2 讀取一幀數據

??讀取一幀圖像數據，進行圖像解碼，圖像格式轉換，添加時間水印。

static AVFrame *get_video_frame(OutputStream *ost,IntputDev* input, int *got_pic)
{
	
	int ret,got_picture;
	AVCodecContext *c=ost->enc;
	AVFrame *ret_frame=NULL;
	/*在各自的時基中比較兩個時間戳。*/
	if(av_compare_ts(ost->next_pts,c->time_base,STREAM_DURATION, (AVRational){1,1})>=0)
	{
		return  (void*)-1;
	}
	/*確保幀數據可寫，盡可能避免數據復制。*/
	if(av_frame_make_writable(ost->frame)<0)
	{
		exit(1);
	}
	/*此函數返回文件中存儲的內容，并且不驗證是否存在解碼器的有效幀。*/
	if(av_read_frame(input->v_ifmtCtx,input->in_packet)>=0)
	{
		if(input->in_packet->stream_index == input->videoindex)
		{
			/*解碼一幀視頻數據。輸入一個壓縮編碼的結構體AVPacket，輸出一個解碼后的結構體AVFrame*/
			ret=avcodec_decode_video2(input->pcodecCtx, input->pFrame,&got_picture,input->in_packet);
			*got_pic=got_picture;
			if(ret<0)
			{
				printf("Decode Error.n");
				av_packet_unref(input->in_packet);
				return NULL;
			}
			if(got_picture)
			{
				sws_scale(input->img_convert_ctx, (const unsigned char * const *)input->pFrame->data,input->pFrame->linesize,0,input->pcodecCtx->height,input->pFrameYUV->data,input->pFrameYUV->linesize);
				sws_scale(input->img_convert_ctx, (const unsigned char * const *)input->pFrame->data,input->pFrame->linesize,0,input->pcodecCtx->height,ost->frame->data,ost->frame->linesize);

				pthread_mutex_lock(&fastmutex);//互斥鎖上鎖
				memcpy(rgb_buff,input->pFrameYUV->data[0],size);
				pthread_cond_broadcast(&cond);//廣播喚醒所有線程
				pthread_mutex_unlock(&fastmutex);//互斥鎖解鎖
				//ost->frame->pts=ost->next_pts++;

				//水印添加處理
				//frame->frame->format=AV_PIX_FMT_YUV420P;
				AVFrame *frame_out=av_frame_alloc();
				unsigned char *frame_buffer_out;
				frame_buffer_out=(unsigned char *)av_malloc(size);
				av_image_fill_arrays(frame_out->data,frame_out->linesize,frame_buffer_out,AV_PIX_FMT_YUV420P,width,height,32);
				//添加水印,調用libavfilter庫實現
				time_t sec;
				sec=time(NULL);
				struct tm* today = localtime(&sec);
				char sys_time[64];
				strftime(sys_time, sizeof(sys_time), "%Y/%m/%d %H:%M:%S", today);  
				waterMark(ost->frame,frame_out,width,height,sys_time);
				//yuv420p，y表示亮度，uv表示像素顏色
				ost->frame=frame_out;
				ost->frame->pts=ost->next_pts++;

				ret_frame=frame_out;
			}
		}
		av_packet_unref(input->in_packet);
	}
	return ret_frame;
}

3.3 SDL庫圖像渲染

int main()
{
	/*創建攝像頭采集線程*/
	pthread_t pthid[2];
    pthread_create(&pthid[0],NULL,Video_CollectImage, NULL);
	pthread_detach(pthid[0]);/*設置分離屬性*/
	sleep(1);
	while(1)
	{
		if(width!=0 && height!=0 && size!=0)break;
		if(video_flag==0)return 0;
	}
	printf("image:%d * %d,%dn",width,height,size);
	unsigned char *rgb_data=malloc(size);
	/*創建mp4視頻編碼線程*/
	pthread_create(&pthid[1],NULL,Video_savemp4, NULL);
	pthread_detach(pthid[1]);/*設置分離屬性*/
 	/*創建窗口 */
	SDL_Window *window=SDL_CreateWindow("SDL_VIDEO", SDL_WINDOWPOS_CENTERED,SDL_WINDOWPOS_CENTERED,800,480,SDL_WINDOW_ALLOW_HIGHDPI|SDL_WINDOW_RESIZABLE);
    /*創建渲染器*/
	SDL_Renderer *render=SDL_CreateRenderer(window,-1,SDL_RENDERER_ACCELERATED);
	/*清空渲染器*/
	SDL_RenderClear(render);
   /*創建紋理*/
	SDL_Texture*sdltext=SDL_CreateTexture(render,SDL_PIXELFORMAT_IYUV,SDL_TEXTUREACCESS_STREAMING,width,height);
	bool quit=true;
	SDL_Event event;
	SDL_Rect rect;
	int count=0;
	while(quit)
	{
		while(SDL_PollEvent(&event))/*事件監測*/
		{
			if(event.type==SDL_QUIT)/*退出事件*/
			{
				quit=false;
				video_flag=0;
				pthread_cancel(pthid[1]);/*殺死指定線程*/
				pthread_cancel(pthid[0]);/*殺死指定線程*/
				continue;
			}
			else if(event.type == SDL_KEYDOWN)
			{
				 if(event.key.keysym.sym==SDLK_q)//按‘q’保存視頻
				 {
					count++;
					snprintf(file_name,sizeof(file_name),"%d.mp4",count);
					mp4_decode_stat=1;
				 }
			}
		}
		if(!video_flag)
		{
			quit=false;
			continue;
		}
		pthread_mutex_lock(&fastmutex);//互斥鎖上鎖
		pthread_cond_wait(&cond,&fastmutex);
		memcpy(rgb_data,rgb_buff,size);
		pthread_mutex_unlock(&fastmutex);//互斥鎖解鎖
		SDL_UpdateTexture(sdltext,NULL,rgb_data,width);
		//SDL_RenderCopy(render, sdltext, NULL,NULL); // 拷貝紋理到渲染器
		SDL_RenderCopyEx(render, sdltext,NULL,NULL,0,NULL,SDL_FLIP_NONE);
		SDL_RenderPresent(render); // 渲染
	}
	SDL_DestroyTexture(sdltext);/*銷毀紋理*/
    SDL_DestroyRenderer(render);/*銷毀渲染器*/
    SDL_DestroyWindow(window);/*銷毀窗口 */
    SDL_Quit();/*關閉SDL*/
    pthread_mutex_destroy(&fastmutex);/*銷毀互斥鎖*/
    pthread_cond_destroy(&cond);/*銷毀條件變量*/
	free(rgb_buff);
	free(rgb_data);
	return 0;
}

4.示例效果

??攝像頭采集圖像實時渲染：

5.完整示例

Gitee源碼鏈接：https://gitee.com/it-a-shui/ffmpeg
CSDN源碼鏈接：https://download.csdn.net/download/weixin_44453694/85084851