最简单的基于FFmpeg的AVDevice例子(读取摄像头)

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本程序实现了本地摄像头数据的获取解码和显示。是基于FFmpeg的libavdevice类库最简单的例子。通过该例子,可以学习FFmpeg中 libavdevice类库的使用方法。
本程序在Windows下可以使用2种方式读取摄像头数据:
1.VFW: Video for Windows 屏幕捕捉设备。注意输入URL是设备的序号,从0至9。
2.dshow: 使用Directshow。注意作者机器上的摄像头设备名称是“Integrated Camera”,使用的时候需要改成自己电脑上摄像头设备的名称。
在Linux下则可以使用video4linux2读取摄像头设备。

/**
 * 最简单的基于FFmpeg的AVDevice例子(读取摄像头)
 * Simplest FFmpeg Device (Read Camera)
 *
 * 雷霄骅 Lei Xiaohua
 * leixiaohua1020@126.com
 * 中国传媒大学/数字电视技术
 * Communication University of China / Digital TV Technology
 * http://blog.csdn.net/leixiaohua1020
 *
 * 本程序实现了本地摄像头数据的获取解码和显示。是基于FFmpeg
 * 的libavdevice类库最简单的例子。通过该例子,可以学习FFmpeg中
 * libavdevice类库的使用方法。
 * 本程序在Windows下可以使用2种方式读取摄像头数据:
 *  1.VFW: Video for Windows 屏幕捕捉设备。注意输入URL是设备的序号,
 *          从0至9。
 *  2.dshow: 使用Directshow。注意作者机器上的摄像头设备名称是
 *         “Integrated Camera”,使用的时候需要改成自己电脑上摄像头设
 *          备的名称。
 * 在Linux下则可以使用video4linux2读取摄像头设备。
 *
 * This software read data from Computer's Camera and play it.
 * It's the simplest example about usage of FFmpeg's libavdevice Library. 
 * It's suiltable for the beginner of FFmpeg.
 * This software support 2 methods to read camera in Microsoft Windows:
 *  1.gdigrab: VfW (Video for Windows) capture input device.
 *             The filename passed as input is the capture driver number,
 *             ranging from 0 to 9.
 *  2.dshow: Use Directshow. Camera's name in author's computer is 
 *             "Integrated Camera".
 * It use video4linux2 to read Camera in Linux.
 * 
 */
 
 
#include <stdio.h>
 
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "libavdevice/avdevice.h"
    //SDL
#include "sdl/SDL.h"
#include "sdl/SDL_thread.h"
};
 
//Output YUV420P 
#define OUTPUT_YUV420P 0
//'1' Use Dshow 
//'0' Use VFW
#define USE_DSHOW 0
 
 
//Refresh Event
#define SFM_REFRESH_EVENT  (SDL_USEREVENT + 1)
 
int thread_exit=0;
 
int sfp_refresh_thread(void *opaque)
{
    while (thread_exit==0) {
        SDL_Event event;
        event.type = SFM_REFRESH_EVENT;
        SDL_PushEvent(&event);
        SDL_Delay(40);
    }
    return 0;
}
 
 
//Show Device
void show_dshow_device(){
    AVFormatContext *pFormatCtx = 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(&pFormatCtx,"video=dummy",iformat,&options);
    printf("========================\n");
}
 
//Show Device Option
void show_dshow_device_option(){
    AVFormatContext *pFormatCtx = 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(&pFormatCtx,"video=Integrated Camera",iformat,&options);
    printf("========================\n");
}
 
//Show VFW Device
void show_vfw_device(){
    AVFormatContext *pFormatCtx = avformat_alloc_context();
    AVInputFormat *iformat = av_find_input_format("vfwcap");
    printf("VFW Device Info======\n");
    avformat_open_input(&pFormatCtx,"list",iformat,NULL);
    printf("=====================\n");
}
 
 
 
int main(int argc, char* argv[])
{
 
    AVFormatContext *pFormatCtx;
    int             i, videoindex;
    AVCodecContext  *pCodecCtx;
    AVCodec         *pCodec;
     
    av_register_all();
    avformat_network_init();
    pFormatCtx = avformat_alloc_context();
     
    //Open File
    //char filepath[]="src01_480x272_22.h265";
    //avformat_open_input(&pFormatCtx,filepath,NULL,NULL)
 
    //Register Device
    avdevice_register_all();
 
//Windows
#ifdef _WIN32
 
    //Show Dshow Device
    show_dshow_device();
    //Show Device Options
    show_dshow_device_option();
    //Show VFW Options
    show_vfw_device();
 
#if USE_DSHOW
    AVInputFormat *ifmt=av_find_input_format("dshow");
    //Set own video device's name
    if(avformat_open_input(&pFormatCtx,"video=Integrated 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(&pFormatCtx,"0",ifmt,NULL)!=0){
        printf("Couldn't open input stream.(无法打开输入流)\n");
        return -1;
    }
#endif
#endif
//Linux
#ifdef linux
    AVInputFormat *ifmt=av_find_input_format("video4linux2");
    if(avformat_open_input(&pFormatCtx,"/dev/video0",ifmt,NULL)!=0){
        printf("Couldn't open input stream.(无法打开输入流)\n");
        return -1;
    }
#endif
 
 
    if(avformat_find_stream_info(pFormatCtx,NULL)<0)
    {
        printf("Couldn't find stream information.(无法获取流信息)\n");
        return -1;
    }
    videoindex=-1;
    for(i=0; i<pFormatCtx->nb_streams; i++) 
        if(pFormatCtx->streams[i]->codec->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=pFormatCtx->streams[videoindex]->codec;
    pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
    if(pCodec==NULL)
    {
        printf("Codec not found.(没有找到解码器)\n");
        return -1;
    }
    if(avcodec_open2(pCodecCtx, pCodec,NULL)<0)
    {
        printf("Could not open codec.(无法打开解码器)\n");
        return -1;
    }
    AVFrame *pFrame,*pFrameYUV;
    pFrame=avcodec_alloc_frame();
    pFrameYUV=avcodec_alloc_frame();
    uint8_t *out_buffer=(uint8_t *)av_malloc(avpicture_get_size(PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height));
    avpicture_fill((AVPicture *)pFrameYUV, out_buffer, PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);
    //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_Surface *screen; 
    screen_w = pCodecCtx->width;
    screen_h = pCodecCtx->height;
    screen = SDL_SetVideoMode(screen_w, screen_h, 0,0);
 
    if(!screen) {  
        printf("SDL: could not set video mode - exiting:%s\n",SDL_GetError());  
        return -1;
    }
    SDL_Overlay *bmp; 
    bmp = SDL_CreateYUVOverlay(pCodecCtx->width, pCodecCtx->height,SDL_YV12_OVERLAY, screen); 
    SDL_Rect rect;
    rect.x = 0;    
    rect.y = 0;    
    rect.w = screen_w;    
    rect.h = screen_h;  
    //SDL End------------------------
    int ret, got_picture;
 
    AVPacket *packet=(AVPacket *)av_malloc(sizeof(AVPacket));
    //Output Information-----------------------------
    printf("File Information(文件信息)---------------------\n");
    av_dump_format(pFormatCtx,0,NULL,0);
    printf("-------------------------------------------------\n");
 
#if OUTPUT_YUV420P 
    FILE *fp_yuv=fopen("output.yuv","wb+");  
#endif  
 
    struct SwsContext *img_convert_ctx;
    img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL); 
    //------------------------------
    SDL_Thread *video_tid = SDL_CreateThread(sfp_refresh_thread,NULL);
    //
    SDL_WM_SetCaption("Simple FFmpeg Read Camera",NULL);
    //Event Loop
    SDL_Event event;
 
    for (;;) {
        //Wait
        SDL_WaitEvent(&event);
        if(event.type==SFM_REFRESH_EVENT){
            //------------------------------
            if(av_read_frame(pFormatCtx, packet)>=0){
                if(packet->stream_index==videoindex){
                    ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
                    if(ret < 0){
                        printf("Decode Error.(解码错误)\n");
                        return -1;
                    }
                    if(got_picture){
                        sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);
 
#if OUTPUT_YUV420P  
                        int y_size=pCodecCtx->width*pCodecCtx->height;    
                        fwrite(pFrameYUV->data[0],1,y_size,fp_yuv);    //Y   
                        fwrite(pFrameYUV->data[1],1,y_size/4,fp_yuv);  //U  
                        fwrite(pFrameYUV->data[2],1,y_size/4,fp_yuv);  //V  
#endif  
 
 
                        SDL_LockYUVOverlay(bmp);
                        bmp->pixels[0]=pFrameYUV->data[0];
                        bmp->pixels[2]=pFrameYUV->data[1];
                        bmp->pixels[1]=pFrameYUV->data[2];     
                        bmp->pitches[0]=pFrameYUV->linesize[0];
                        bmp->pitches[2]=pFrameYUV->linesize[1];   
                        bmp->pitches[1]=pFrameYUV->linesize[2];
                        SDL_UnlockYUVOverlay(bmp); 
                        //测试自己填充数据----------------
                        SDL_DisplayYUVOverlay(bmp, &rect); 
 
                    }
                }
                av_free_packet(packet);
            }else{
                //Exit Thread
                thread_exit=1;
                break;
            }
        }else if(event.type==SDL_QUIT){
            thread_exit=1;
            break;
        }
 
    }
     
 
    sws_freeContext(img_convert_ctx);
 
#if OUTPUT_YUV420P 
    fclose(fp_yuv);
#endif 
 
    SDL_Quit();
 
    av_free(out_buffer);
    av_free(pFrameYUV);
    avcodec_close(pCodecCtx);
    avformat_close_input(&pFormatCtx);
 
    return 0;
}