For Getting and Displaying Frames

get_and_display_frames.c

@@ -0,0 +1,183 @@
+#include <libavcodec/avcodec.h>
+#include <libavformat/avformat.h>
+#include <libswscale/swscale.h>
+
+#include <SDL.h>
+#include <SDL_thread.h>
+
+#ifdef __MINGW32__
+#undef main /* Prevents SDL from overriding main() */
+#endif
+
+#include <stdio.h>
+
+int main(int argc, char *argv[]) {
+  AVFormatContext *pFormatCtx = NULL;
+  int             i, videoStream;
+  AVCodecContext  *pCodecCtx = NULL;
+  AVCodec         *pCodec = NULL;
+  AVFrame         *pFrame = NULL; 
+  AVPacket        packet;
+  int             frameFinished;
+  //float           aspect_ratio;
+
+  AVDictionary    *optionsDict = NULL;
+  struct SwsContext *sws_ctx = NULL;
+
+  SDL_Overlay     *bmp = NULL;
+  SDL_Surface     *screen = NULL;
+  SDL_Rect        rect;
+  SDL_Event       event;
+
+  if(argc < 2) {
+    fprintf(stderr, "Usage: test <file>\n");
+    exit(1);
+  }
+  // Register all formats and codecs
+  av_register_all();
+
+  if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
+    fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
+    exit(1);
+  }
+
+  // Open video file
+  if(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL)!=0)
+    return -1; // Couldn't open file
+
+  // Retrieve stream information
+  if(avformat_find_stream_info(pFormatCtx, NULL)<0)
+    return -1; // Couldn't find stream information
+
+  // Dump information about file onto standard error
+  av_dump_format(pFormatCtx, 0, argv[1], 0);
+
+  // Find the first video stream
+  videoStream=-1;
+  for(i=0; i<pFormatCtx->nb_streams; i++)
+    if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO) {
+      videoStream=i;
+      break;
+    }
+  if(videoStream==-1)
+    return -1; // Didn't find a video stream
+
+  // Get a pointer to the codec context for the video stream
+  pCodecCtx=pFormatCtx->streams[videoStream]->codec;
+
+  // Find the decoder for the video stream
+  pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
+  if(pCodec==NULL) {
+    fprintf(stderr, "Unsupported codec!\n");
+    return -1; // Codec not found
+  }
+
+  // Open codec
+  if(avcodec_open2(pCodecCtx, pCodec, &optionsDict)<0)
+    return -1; // Could not open codec
+
+  // Allocate video frame
+  pFrame=av_frame_alloc();
+
+  // Make a screen to put our video
+#ifndef __DARWIN__
+        screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 0, 0);
+#else
+        screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 24, 0);
+#endif
+  if(!screen) {
+    fprintf(stderr, "SDL: could not set video mode - exiting\n");
+    exit(1);
+  }
+
+  // Allocate a place to put our YUV image on that screen
+  bmp = SDL_CreateYUVOverlay(pCodecCtx->width,
+				 pCodecCtx->height,
+				 SDL_YV12_OVERLAY,
+				 screen);
+
+  sws_ctx =
+    sws_getContext
+    (
+        pCodecCtx->width,
+        pCodecCtx->height,
+        pCodecCtx->pix_fmt,
+        pCodecCtx->width,
+        pCodecCtx->height,
+        PIX_FMT_YUV420P,
+        SWS_BILINEAR,
+        NULL,
+        NULL,
+        NULL
+    );
+
+  // Read frames and save first five frames to disk
+  i=0;
+  while(av_read_frame(pFormatCtx, &packet)>=0) {
+    // Is this a packet from the video stream?
+    if(packet.stream_index==videoStream) {
+      // Decode video frame
+      avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, 
+			   &packet);
+
+      // Did we get a video frame?
+      if(frameFinished) {
+	SDL_LockYUVOverlay(bmp);
+
+	AVPicture pict;
+	pict.data[0] = bmp->pixels[0];
+	pict.data[1] = bmp->pixels[2];
+	pict.data[2] = bmp->pixels[1];
+
+	pict.linesize[0] = bmp->pitches[0];
+	pict.linesize[1] = bmp->pitches[2];
+	pict.linesize[2] = bmp->pitches[1];
+
+	// Convert the image into YUV format that SDL uses
+    sws_scale
+    (
+        sws_ctx, 
+        (uint8_t const * const *)pFrame->data, 
+        pFrame->linesize, 
+        0,
+        pCodecCtx->height,
+        pict.data,
+        pict.linesize
+    );
+
+	SDL_UnlockYUVOverlay(bmp);
+
+	rect.x = 0;
+	rect.y = 0;
+	rect.w = pCodecCtx->width;
+	rect.h = pCodecCtx->height;
+	SDL_DisplayYUVOverlay(bmp, &rect);
+
+      }
+    }
+
+    // Free the packet that was allocated by av_read_frame
+    av_free_packet(&packet);
+    SDL_PollEvent(&event);
+    switch(event.type) {
+    case SDL_QUIT:
+      SDL_Quit();
+      exit(0);
+      break;
+    default:
+      break;
+    }
+
+  }
+
+  // Free the YUV frame
+  av_free(pFrame);
+
+  // Close the codec
+  avcodec_close(pCodecCtx);
+
+  // Close the video file
+  avformat_close_input(&pFormatCtx);
+
+  return 0;
+}