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。
#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：
