sdl2.0示例

• // gcc -o testDrone2_video testDrone2_video.c -lavcodec -lavformat -lswscale -lSDL2 // g++ -o testDrone2_video testDrone2_video.c -lavcodec -lavformat -lswscale -lSDL2 #ifdef __cplusplus extern "C" { #endif #include "libavcodec/avcodec.h" #include "libavformat/avformat.h" #include "libswscale/swscale.h" #ifdef __cplusplus } #endif #include "SDL2/SDL.h" int main(int argc, char* argv[]) {      // 3.0. Initializes the video subsystem *must be done before anything other!!   if (SDL_Init(SDL_INIT_VIDEO) < 0) {     fprintf(stderr, "Unable to init SDL: %s\n", SDL_GetError());     return -1;   }      // prepare variables   // decoding   char              *drone_addr = "http://192.168.1.1:5555";   AVFormatContext   *pFormatCtx = NULL;   AVCodecContext    *pCodecCtx;   AVCodec           *pCodec;   AVPacket          packet;   AVFrame           *pFrame;   int               terminate, frameDecoded;      // converting   AVFrame           *pFrame_YUV420P;   uint8_t           *buffer_YUV420P;   struct SwsContext *pConvertCtx_YUV420P;      AVFrame           *pFrame_BGR24;   uint8_t           *buffer_BGR24;   struct SwsContext *pConvertCtx_BGR24;      // displaying   SDL_Window        *pWindow1;   SDL_Renderer      *pRenderer1;   SDL_Texture       *bmpTex1;   uint8_t           *pixels1;   int               pitch1, size1;      SDL_Window        *pWindow2;   SDL_Renderer      *pRenderer2;   SDL_Texture       *bmpTex2;   uint8_t           *pixels2;   int               pitch2, size2;      // SDL event handling   SDL_Event         event;       // 1.1 Register all formats and codecs   av_register_all();   avcodec_register_all();   avformat_network_init();      // 1.2. Open video file   while(avformat_open_input(&pFormatCtx, drone_addr, NULL, NULL) != 0)     printf("Could not open the video file\nRetrying...\n");      // 1.3. Retrieve stream information   avformat_find_stream_info(pFormatCtx, NULL);   // Dump information about file to standard output   av_dump_format(pFormatCtx, 0, drone_addr, 0);      // 1.4. Get a pointer to the codec context for the video stream   // and find the decoder for the video stream   pCodecCtx = pFormatCtx->streams[0]->codec;   pCodec    = avcodec_find_decoder(pCodecCtx->codec_id);      // 1.5. Open Codec   avcodec_open2(pCodecCtx, pCodec, NULL);         // 2.1.1. Prepare format conversion for diplaying with SDL   // Allocate an AVFrame structure   pFrame_YUV420P = avcodec_alloc_frame();   if(pFrame_YUV420P == NULL) {     fprintf(stderr, "Could not allocate pFrame_YUV420P\n");     return -1;   }   // Determine required buffer size and allocate buffer   buffer_YUV420P = (uint8_t *)av_malloc(avpicture_get_size(PIX_FMT_YUV420P,                                             pCodecCtx->width, pCodecCtx->height));     // Assign buffer to image planes   avpicture_fill((AVPicture *)pFrame_YUV420P, buffer_YUV420P,                       PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);   // format conversion context   pConvertCtx_YUV420P = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,                                        pCodecCtx->width, pCodecCtx->height, PIX_FMT_YUV420P,                                        SWS_SPLINE, NULL, NULL, NULL);      // 2.2.1. Prepare format conversion for OpenCV   // Allocate an AVFrame structure   pFrame_BGR24 = avcodec_alloc_frame();   if(pFrame_BGR24 == NULL) {     fprintf(stderr, "Could not allocate pFrame_YUV420P\n");     return -1;   }   // Determine required buffer size and allocate buffer   buffer_BGR24 = (uint8_t *)av_malloc(avpicture_get_size(PIX_FMT_BGR24,                                             pCodecCtx->width, pCodecCtx->height));     // Assign buffer to image planes   avpicture_fill((AVPicture *)pFrame_BGR24, buffer_BGR24,                       PIX_FMT_BGR24, pCodecCtx->width, pCodecCtx->height);   // format conversion context   pConvertCtx_BGR24 = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,                                      pCodecCtx->width, pCodecCtx->height, PIX_FMT_BGR24,                                      SWS_SPLINE, NULL, NULL, NULL);      // 3.1.1 prepare SDL for YUV   // allocate window, renderer, texture   pWindow1    = SDL_CreateWindow( "YUV", 0, 0, pCodecCtx->width, pCodecCtx->height, SDL_WINDOW_SHOWN);     pRenderer1  = SDL_CreateRenderer(pWindow1, -1, SDL_RENDERER_ACCELERATED);   bmpTex1     = SDL_CreateTexture(pRenderer1, SDL_PIXELFORMAT_YV12, SDL_TEXTUREACCESS_STREAMING, pCodecCtx->width, pCodecCtx->height);   size1       = pCodecCtx->width * pCodecCtx->height;   if(pWindow1==NULL | pRenderer1==NULL | bmpTex1==NULL) {     fprintf(stderr, "Could not open window1\n%s\n", SDL_GetError());     return -1;   }      // 3.2.1 prepare SDL for BGR   // allocate window, renderer, texture   pWindow2    = SDL_CreateWindow( "BGR", pCodecCtx->width+5, 0, pCodecCtx->width, pCodecCtx->height, SDL_WINDOW_SHOWN);     pRenderer2  = SDL_CreateRenderer(pWindow2, -1, SDL_RENDERER_ACCELERATED);   bmpTex2     = SDL_CreateTexture(pRenderer2, SDL_PIXELFORMAT_BGR24, SDL_TEXTUREACCESS_STREAMING, pCodecCtx->width, pCodecCtx->height);   size2       = pCodecCtx->width * pCodecCtx->height * 3;   if(pWindow2==NULL | pRenderer2==NULL | bmpTex2==NULL) {     fprintf(stderr, "Could not open window2\n%s\n", SDL_GetError());     return -1;   }      // 1.6. get video frames   pFrame = avcodec_alloc_frame();   terminate = 0;   while(!terminate) {     // read frame     if(av_read_frame(pFormatCtx, &packet)<0) {       fprintf(stderr, "Could not read frame!\n");       continue;     }         // decode the frame     if(avcodec_decode_video2(pCodecCtx, pFrame, &frameDecoded, &packet) < 0) {       fprintf(stderr, "Could not decode frame!\n");       continue;     }         if (frameDecoded) {       // 2.1.2. convert frame to YUV for Displaying         sws_scale(pConvertCtx_YUV420P, (const uint8_t * const*)pFrame->data, pFrame->linesize, 0,                   pCodecCtx->height,   pFrame_YUV420P->data, pFrame_YUV420P->linesize);       // 2.2.2. convert frame to GRAYSCALE [or BGR] for OpenCV         sws_scale(pConvertCtx_BGR24,   (const uint8_t * const*)pFrame->data, pFrame->linesize, 0,                   pCodecCtx->height,   pFrame_BGR24->data,   pFrame_BGR24->linesize);              // 3.1.2. copy converted YUV to SDL 2.0 texture       SDL_LockTexture(bmpTex1, NULL, (void **)&pixels1, &pitch1);      memcpy(pixels1,             pFrame_YUV420P->data[0], size1  );      memcpy(pixels1 + size1,     pFrame_YUV420P->data[2], size1/4);    memcpy(pixels1 + size1*5/4, pFrame_YUV420P->data[1], size1/4);       SDL_UnlockTexture(bmpTex1);       SDL_UpdateTexture(bmpTex1, NULL, pixels1, pitch1);       // refresh screen       SDL_RenderClear(pRenderer1);       SDL_RenderCopy(pRenderer1, bmpTex1, NULL, NULL);       SDL_RenderPresent(pRenderer1);              // 3.2.2. copy converted BGR to SDL 2.0 texture       SDL_LockTexture(bmpTex2, NULL, (void **)&pixels2, &pitch2);      memcpy(pixels2,             pFrame_BGR24->data[0], size2);       SDL_UnlockTexture(bmpTex2);       SDL_UpdateTexture(bmpTex2, NULL, pixels2, pitch2);       // refresh screen       SDL_RenderClear(pRenderer2);       SDL_RenderCopy(pRenderer2, bmpTex2, NULL, NULL);       SDL_RenderPresent(pRenderer2);     }         SDL_PollEvent(&event);     switch (event.type) {       case SDL_KEYDOWN:         terminate = 1;         break;     }   }      // release   // *note SDL objects have to be freed before closing avcodec.   // otherwise it causes segmentation fault for some reason.   SDL_DestroyTexture(bmpTex1);   SDL_DestroyTexture(bmpTex2);      SDL_DestroyRenderer(pRenderer1);   SDL_DestroyRenderer(pRenderer2);      SDL_DestroyWindow(pWindow1);   SDL_DestroyWindow(pWindow2);      av_free(pFrame_YUV420P);   av_free(buffer_YUV420P);   sws_freeContext(pConvertCtx_YUV420P);      av_free(pFrame_BGR24);   av_free(buffer_BGR24);   sws_freeContext(pConvertCtx_BGR24);      av_free(pFrame);   avcodec_close(pCodecCtx); // <- before freeing this, all other objects, allocated after this, must be freed   avformat_close_input(&pFormatCtx);      SDL_Quit();      return 0;    }