Linux系统USB摄像头测试程序（三）_视频预览

绝知此事要躬行2023-08-24 19:01

这是在linux上usb摄像头视频预览程序，此程序用到了ffmpeg、sdl2、gtk3组件，程序编译之前应先安装他们。

cpp 复制代码 
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <zconf.h>
#include <linux/videodev2.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <gtk-3.0/gtk/gtk.h>


#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "libavdevice/avdevice.h"
#include "libavutil/imgutils.h"
#include <libavfilter/avfilter.h>
#include <libavfilter/buffersrc.h>
#include <libavfilter/buffersink.h>

#include <SDL2/SDL.h>


//dhl:gtk窗口组件
GtkWidget *window;
GtkWidget *fixed;
GtkWidget *button1,*button2,*button3;
GtkWidget *text,*text1,*text2,*text3;
GtkTextBuffer *buffer,*buffer1,*buffer2,*buffer3;
GtkWidget *label1,*label2,*label3,*label_line;

//dhl:sdl窗口组件
SDL_Window *sdl_window; 
SDL_Renderer *sdl_renderer;
SDL_Texture *sdl_texture;


//dhl:消息缓存
char disp[2048]={0};
char temp[128]={0};

int getWHR(char *device_name,char *win_size,int *win_width,int *win_height, char *frame_rate_t)
{
	GtkTextIter start,end;
	gtk_text_buffer_get_bounds(GTK_TEXT_BUFFER(buffer1),&start,&end);
	GtkTextIter s=start,e=end;
	sprintf(device_name,"%s",gtk_text_buffer_get_text(GTK_TEXT_BUFFER(buffer1),&s,&e,FALSE));
	
	gtk_text_buffer_get_bounds(GTK_TEXT_BUFFER(buffer2),&start,&end);
	s=start,e=end;
	gchar *win_size1 = gtk_text_buffer_get_text(GTK_TEXT_BUFFER(buffer2),&s,&e,FALSE);
	sprintf(win_size,"%s",gtk_text_buffer_get_text(GTK_TEXT_BUFFER(buffer2),&s,&e,FALSE));
    
	gtk_text_buffer_get_bounds(GTK_TEXT_BUFFER(buffer3),&start,&end);
	s=start,e=end;
    sprintf(frame_rate_t,"%s",gtk_text_buffer_get_text(GTK_TEXT_BUFFER(buffer3),&s,&e,FALSE));
    
    
    if (!strcmp(device_name,"")|| !strcmp(win_size,"")||!strcmp(frame_rate_t,"")) {
		GtkWidget * dialog= dialog = gtk_message_dialog_new (NULL,
                                 GTK_DIALOG_DESTROY_WITH_PARENT,
                                 GTK_MESSAGE_INFO,
                                 GTK_BUTTONS_CLOSE,
                                 "请输入摄像头设备名称、窗口尺寸、帧速率");
		gtk_dialog_run (GTK_DIALOG (dialog));
		gtk_widget_destroy (dialog);
		return -1;
		
	}
    
    sscanf(win_size1, "%dx%d", win_width, win_height);
	return 0;
}




//dhl:发现摄像头
void button1_clicked(GtkWidget *widget, gpointer data)
{
	char camera_devices_name[128]={0};
	for (int loop=0;loop<10;loop++) {
		sprintf(camera_devices_name,"/dev/video%d",loop);
		int fd = open(camera_devices_name, O_RDWR);
		if(fd < 0)
		{
			printf("打开设备失败(%s)\n",camera_devices_name);
			close(fd);
			continue;
		}
	    close(fd);
		sprintf(temp,"发现摄像头:%s\n",camera_devices_name);
		strcat(disp,temp);
		gtk_text_buffer_set_text(buffer,disp,-1);
	}
	sprintf(disp,"%s","");
}

//dhl:查询配置信息
void button2_clicked(GtkWidget *widget, gpointer data)
{
	int line_num=0;
	gchar *device_name;
	GtkTextIter start,end;
	gtk_text_buffer_get_bounds(GTK_TEXT_BUFFER(buffer1),&start,&end);
	const GtkTextIter s=start,e=end;
	device_name=gtk_text_buffer_get_text(GTK_TEXT_BUFFER(buffer1),&s,&e,FALSE);
	if (!strcmp(device_name,""))
	{
		sprintf(temp,"请输入摄像头设备文件名\n");
		strcat(disp,temp);
		gtk_text_buffer_set_text(buffer,disp,-1);
		sprintf(disp,"%s","");
		return;
	}
		
		
	//dhl:查询摄像头支持的视频格式
	int fd = open(device_name, O_RDWR);
	if(fd < 0)
	{
		printf("打开设备失败\n");
		return;
	}

	struct v4l2_fmtdesc v4fmt;
	v4fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; //视频捕获设备
	int i=0;

	while(1)
	{
		v4fmt.index = i++;
		int ret = ioctl(fd, VIDIOC_ENUM_FMT, &v4fmt);
		if(ret < 0)
		{
			printf("获取摄像头格式失败");
			break;
		}
		printf("index=%d\n", v4fmt.index);
		printf("flags=%d\n", v4fmt.flags);
		printf("description=%s\n", v4fmt.description);
		unsigned char *p = (unsigned char *)&v4fmt.pixelformat;
		printf("pixelformat=%c%c%c%c\n", p[0],p[1],p[2],p[3]);
		printf("reserved=%d\n", v4fmt.reserved[0]);
		
		sprintf(temp,"摄像头支持的视频格式(%d)\n",i);
		strcat(disp,temp);
		
		sprintf(temp,"index=%d,", v4fmt.index);
		strcat(disp,temp);
		
		sprintf(temp,"flags=%d,", v4fmt.flags);
		strcat(disp,temp);
		
		sprintf(temp,"description=%s,", v4fmt.description);
		strcat(disp,temp);
		
		sprintf(temp,"pixelformat=%c%c%c%c,", p[0],p[1],p[2],p[3]);
		strcat(disp,temp);
		
		sprintf(temp,"reserved=%d\n", v4fmt.reserved[0]);
		strcat(disp,temp);
		
	}
	
	close(fd);
	
	//dhl:MJPG支持的所有分辨率如下
	fd = open(device_name, O_RDWR);
	if(fd < 0)
	{
		perror("打开设备失败");
		return;
	}
	struct v4l2_frmsizeenum frmsize;
	frmsize.index = 0;
	frmsize.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	printf("MJPEG格式支持所有分辨率如下:\n");
	//frmsize.pixel_format = V4L2_PIX_FMT_YUYV;
	frmsize.pixel_format = V4L2_PIX_FMT_MJPEG;
	sprintf(temp,"MJPG支持的分辨率:\n");
	strcat(disp,temp);
	line_num=1;
	while(ioctl(fd,VIDIOC_ENUM_FRAMESIZES,&frmsize) == 0){
		printf("frame_size<%d*%d>\n",frmsize.discrete.width,frmsize.discrete.height);
		frmsize.index++;
		if ((line_num % 5) != 0) { 
			sprintf(temp,"MJPEG frame_size<%d*%d>, ",frmsize.discrete.width,frmsize.discrete.height);
		}else {
			sprintf(temp,"MJPEG frame_size<%d*%d>\n",frmsize.discrete.width,frmsize.discrete.height);
		}
		strcat(disp,temp);
		line_num++;
		if (line_num == 6) {
			line_num = 1;
		}
	}
	close(fd);
	sprintf(temp,"%s","\n");
	strcat(disp,temp);
	
	
	//dhl:YUV支持所有分辨率如下
	fd = open(device_name, O_RDWR);
	if(fd < 0)
	{
		perror("打开设备失败");
		return;
	}
	//struct v4l2_frmsizeenum frmsize;
	frmsize.index = 0;
	frmsize.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	printf("MJPEG格式支持所有分辨率如下:\n");
	frmsize.pixel_format = V4L2_PIX_FMT_YUYV;
	//frmsize.pixel_format = V4L2_PIX_FMT_MJPEG;
	sprintf(temp,"YUV支持的分辨率:\n");
	strcat(disp,temp);
	line_num = 1;
	while(ioctl(fd,VIDIOC_ENUM_FRAMESIZES,&frmsize) == 0){
		printf("frame_size<%d*%d>\n",frmsize.discrete.width,frmsize.discrete.height);
		frmsize.index++;
		if ((line_num % 5) != 0) { 
			sprintf(temp,"YUYV frame_size<%d*%d>, ",frmsize.discrete.width,frmsize.discrete.height);
		}else {
			sprintf(temp,"YUYV frame_size<%d*%d>\n",frmsize.discrete.width,frmsize.discrete.height);
			
		}
		strcat(disp,temp);
		line_num++;
		if (line_num == 6) {
			line_num = 1;
		}
	}
	
	close(fd);
	
	
	gtk_text_buffer_set_text(buffer,disp,-1);
	sprintf(disp,"%s","");
	
}



//dhl:视频预览
void button3_clicked(GtkWidget *widget, gpointer data)
{

	AVFormatContext *pFormatCtx;
    int             i, videoindex;
    AVCodecContext  *pCodecCtx;
    AVCodec         *pCodec;
    int ret = -1;

    int win_width=0, win_height=0;
    gchar device_name[128];
    gchar win_size[128];
    gchar frame_rate_t[128];
    
    
    int iRet=getWHR(device_name,win_size,&win_width,&win_height, frame_rate_t);
    if (iRet!=0) {
		return;
	}
  
 
    
    const char * out_path = "out_yuyv422.yuv";
    FILE* outFile = fopen(out_path, "wb");
    if (!outFile) {
        printf("Could not open %s\n", out_path);
        return;
    }
    
    if (SDL_Init(SDL_INIT_VIDEO)) {
        printf("Could not initialize SDL - %s\n", SDL_GetError());
        return;
    }else{
		
		printf("initialize SDL ok\n");
	}
    
    sdl_window = SDL_CreateWindow("视频预览"
			,SDL_WINDOWPOS_CENTERED
			,SDL_WINDOWPOS_CENTERED
			,win_width
			,win_height
			,SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
    if(sdl_window == NULL){
        printf("SDL_window创建失败\n");
        return;
    }



	sdl_renderer = SDL_CreateRenderer(sdl_window
            ,-1
            ,SDL_RENDERER_ACCELERATED);
 
	sdl_texture = SDL_CreateTexture(sdl_renderer
			//,SDL_PIXELFORMAT_IYUV
			,SDL_PIXELFORMAT_YUY2
            ,SDL_TEXTUREACCESS_TARGET
            ,win_width
            ,win_height);
    
	SDL_Rect sdl_rect;
   
   
    char *buffer_pixels = malloc(win_width*win_height*4);

    pFormatCtx = avformat_alloc_context();
    const AVInputFormat *ifmt = av_find_input_format("v4l2");
    
    AVDictionary *option =NULL;
    av_dict_set(&option,"video_size",win_size,0);
    av_dict_set(&option,"framerate",frame_rate_t,0);
    //av_dict_set(&option,"pixel_format","yuv420p12be",0); //指定格式
   
    avformat_open_input(&pFormatCtx, device_name, ifmt,&option);
    
    
    if(avformat_find_stream_info(pFormatCtx, NULL) < 0)
    {
        printf("Couldn't find stream information.\n");
        return;
    }
    
    videoindex = -1;
    for(i = 0; i < pFormatCtx->nb_streams; i++){
        if(pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
        {
            videoindex = i;
            break;
        }
    }
    if(videoindex == -1)
    {
        printf("Didn't find a video stream.\n");
        return;
    }
    else{
        printf("Find a video stream:%d.\n", videoindex);
    }
    
    pCodec = (AVCodec*)avcodec_find_decoder(pFormatCtx->streams[videoindex]->codecpar->codec_id);
    if(pCodec == NULL)
    {
        printf("Codec not found.\n");
        return;
    }
    
    pCodecCtx = avcodec_alloc_context3(pCodec);
    avcodec_parameters_to_context(pCodecCtx, pFormatCtx->streams[videoindex]->codecpar);
    printf("VideoStream:Frame.Width=%d,Height=%d\n",
           pCodecCtx->width, pCodecCtx->height);

    if(avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
    {
        printf("Could not open codec.\n");
        return;
    }
    
    AVPacket *pkt = av_packet_alloc();
    if(!pkt){
        printf("av_packet_alloc错误\n");
        return;
    }

    AVFrame *frame_yuyv422 = av_frame_alloc();
    if(!frame_yuyv422){
        printf("av_frame_alloc错误\n");
        return;
    }


	int frame_count = 0;//记录获取的帧数
    SDL_Event event;
    
    while (av_read_frame(pFormatCtx, pkt) >= 0 ) {
		 if(pkt->stream_index == videoindex){
            //dhl:发送给解码器
            if(avcodec_send_packet(pCodecCtx,pkt) != 0){
                printf("avcodec_send_packet error ...\n");
                break;
            }
            
     
            //dhl:从解码器中得到摄像头的原始视频帧
            int loop=0;
            while(avcodec_receive_frame(pCodecCtx,frame_yuyv422) == 0){
				frame_count++;
				for(int i = 0;i < frame_yuyv422->height;i++){
					
                    memcpy(buffer_pixels+i * frame_yuyv422->linesize[0],frame_yuyv422->data[0] + i * frame_yuyv422->linesize[0],frame_yuyv422->linesize[0]);
				}
				
				SDL_UpdateTexture(sdl_texture,NULL,buffer_pixels,win_width*2);
				
				//dhl:将纹理数据拷贝给渲染器
				sdl_rect.x = 0;
				sdl_rect.y = 0;
				sdl_rect.w = win_width;
				sdl_rect.h = win_height;
				
				
				//dhl:先清空帧画面，再重新绘制
				SDL_RenderClear(sdl_renderer);
				SDL_RenderCopy(sdl_renderer,sdl_texture,NULL,&sdl_rect);
				//dhl:显示帧画面
				SDL_RenderPresent(sdl_renderer);
				//dhl:延时渲染
				//SDL_Delay(frame_rate);//延时
				
			}
		}
		av_packet_unref(pkt);
		for (int ll=0;ll<10;ll++) {
			SDL_PollEvent(&event);
				
		}	
		if (event.type == SDL_QUIT) {
			 break;
		}
	}
    
    fclose(outFile);
    
    sprintf(disp,"预览总帧数：%d",frame_count);
	gtk_text_buffer_set_text(buffer,disp,-1);
	sprintf(disp,"%s","");
    
    av_free(frame_yuyv422);
    av_packet_free(&pkt);
    avformat_close_input(&pFormatCtx);
    free(buffer_pixels);
    
    SDL_DestroyTexture(sdl_texture);
    SDL_DestroyRenderer(sdl_renderer);
	SDL_DestroyWindow(sdl_window );		
	SDL_Quit();
	
	return;
	
}





int main(int argc,char *argv[])
{
	gtk_init(&argc,&argv);
	avdevice_register_all();
    
    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title(GTK_WINDOW(window),"USB摄像头测试程序(v1.0.20230728)");
    //gtk_window_set_resizable(GTK_WINDOW(window),FALSE);
    gtk_window_set_default_size(GTK_WINDOW(window),1280,800);
    gtk_window_set_position(GTK_WINDOW(window),GTK_WIN_POS_CENTER);
	
    fixed = gtk_fixed_new();
    gtk_container_add(GTK_CONTAINER(window),fixed);
    
    text = gtk_text_view_new();
    buffer=gtk_text_view_get_buffer(GTK_TEXT_VIEW(text));
    gtk_text_buffer_set_text(buffer,"",-1);
    gtk_fixed_put(GTK_FIXED(fixed),text,20,480);
    gtk_widget_set_size_request(text,1240,300);
    
    button1 = gtk_button_new_with_label("查询摄像头");
    gtk_fixed_put(GTK_FIXED(fixed),button1,320,14);
    gtk_widget_set_size_request(button1,100,20);
    
    label1 = gtk_label_new("摄像头：");
    gtk_fixed_put(GTK_FIXED(fixed),label1,440,14);
    gtk_widget_set_size_request(label1,50,30);
    
    text1 = gtk_text_view_new();
    buffer1=gtk_text_view_get_buffer(GTK_TEXT_VIEW(text1));
    gtk_text_buffer_set_text(buffer1,"",-1);
    gtk_fixed_put(GTK_FIXED(fixed),text1,500,16);
    gtk_widget_set_size_request(text1,100,28);
    sprintf(disp,"/dev/video0");
	gtk_text_buffer_set_text(buffer1,disp,-1);
    
    button2 = gtk_button_new_with_label("查询配置");
    gtk_fixed_put(GTK_FIXED(fixed),button2,610,14);
    gtk_widget_set_size_request(button2,80,35);
    
    
    label2 = gtk_label_new("分辨率：");
    gtk_fixed_put(GTK_FIXED(fixed),label2,740,18);
    gtk_widget_set_size_request(label2,50,30);
    text2 = gtk_text_view_new();
    buffer2=gtk_text_view_get_buffer(GTK_TEXT_VIEW(text2));
    gtk_text_buffer_set_text(buffer2,"",-1);
    gtk_fixed_put(GTK_FIXED(fixed),text2,800,16);
    gtk_widget_set_size_request(text2,100,28);
    sprintf(disp,"640x480");
	gtk_text_buffer_set_text(buffer2,disp,-1);
    
    
    label3 = gtk_label_new("帧率：");
    gtk_fixed_put(GTK_FIXED(fixed),label3,930,18);
    gtk_widget_set_size_request(label3,50,30);
    text3 = gtk_text_view_new();
    buffer3=gtk_text_view_get_buffer(GTK_TEXT_VIEW(text3));
    gtk_text_buffer_set_text(buffer3,"",-1);
    gtk_fixed_put(GTK_FIXED(fixed),text3,980,16);
    gtk_widget_set_size_request(text3,100,28);
    sprintf(disp,"30");
	gtk_text_buffer_set_text(buffer3,disp,-1);
	
	
	label_line = gtk_label_new("______________________________________________________________________________________________________________________________");
    gtk_fixed_put(GTK_FIXED(fixed),label_line,320,45);
    gtk_widget_set_size_request(label_line,800,3);
    
    
	GtkWidget *labelChild;
	PangoFontDescription *font;
	int fontSize = 10;
	font = pango_font_description_from_string("Sans");				//"Sans"字体名
	pango_font_description_set_size(font, fontSize * PANGO_SCALE);	//设置字体大小
	labelChild = gtk_bin_get_child(GTK_WIDGET(button1));			//取出GtkButton里的label
	gtk_widget_modify_font(GTK_WIDGET(labelChild), font);			//设置label的字体， 这样这个GtkButton上面显示的字体就变了
	
	labelChild = gtk_bin_get_child(GTK_WIDGET(button2));			
	gtk_widget_modify_font(GTK_WIDGET(labelChild), font);			


    button3 = gtk_button_new_with_label("视频预览");
    gtk_fixed_put(GTK_FIXED(fixed),button3,320,80);
    gtk_widget_set_size_request(button3,80,20);
    
    
    g_signal_connect_swapped(G_OBJECT(window),"destroy",G_CALLBACK(gtk_main_quit),NULL);
    
    g_signal_connect_swapped(G_OBJECT(window),"destroy",G_CALLBACK(gtk_main_quit),NULL);
    g_signal_connect(G_OBJECT(button1), "clicked", G_CALLBACK(button1_clicked),NULL);
    g_signal_connect(G_OBJECT(button2), "clicked", G_CALLBACK(button2_clicked),NULL);
    g_signal_connect(G_OBJECT(button3), "clicked", G_CALLBACK(button3_clicked),NULL);	
    
    gtk_widget_show_all(window);
    gtk_main();

    return 0;
}

编译命令：gcc preview_camera.c -o camera_preview `pkg-config --cflags --libs libavdevice libavfilter libavformat libavcodec libavutil libpostproc libswresample libswscale` `pkg-config --cflags --libs sdl2` `pkg-config --cflags --libs gtk+-3.0` -w

运行截图：

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