ffmpeg/test.cc

   1 extern "C" {
   2 #include <libavcodec/avcodec.h>
   3 #include <libavformat/avformat.h>
   4 #include <libswscale/swscale.h>
   5 }
   6
   7 char const video[] = "/home/carl/Films/A town called panic.divx";//Ghostbusters.avi";
   8
   9 static void
  10 save_frame (AVFrame *frame, int width, int height, int N)
  11 {
  12         char filename[32];
  13
  14         sprintf (filename, "frame%d.ppm", N);
  15         FILE* file = fopen (filename, "wb");
  16         if (file == NULL) {
  17                 return;
  18         }
  19
  20         fprintf (file, "P6\n%d %d\n255\n", width, height);
  21
  22         for (int y = 0; y < height; y++) {
  23                 fwrite (frame->data[0] + y * frame->linesize[0], 1, width * 3, file);
  24         }
  25
  26         fclose (file);
  27 }
  28
  29 int
  30 main (int argc, char* argv[])
  31 {
  32         av_register_all ();
  33
  34         AVFormatContext* format_context = NULL;
  35         if (avformat_open_input (&format_context, video, NULL, NULL) != 0) {
  36                 fprintf (stderr, "avformat_open_input failed.\n");
  37                 return -1;
  38         }
  39
  40         if (avformat_find_stream_info (format_context, NULL) < 0) {
  41                 fprintf (stderr, "av_find_stream_info failed.\n");
  42                 return -1;
  43         }
  44
  45         av_dump_format (format_context, 0, video, 0);
  46
  47         int video_stream = -1;
  48         for (uint32_t i = 0; i < format_context->nb_streams; ++i) {
  49                 if (format_context->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
  50                         video_stream = i;
  51                         break;
  52                 }
  53         }
  54
  55         AVCodecContext* codec_context = format_context->streams[video_stream]->codec;
  56
  57         AVCodec* codec = avcodec_find_decoder (codec_context->codec_id);
  58         if (codec == NULL) {
  59                 fprintf (stderr, "avcodec_find_decoder failed.\n");
  60                 return -1;
  61         }
  62
  63         if (avcodec_open2 (codec_context, codec, NULL) < 0) {
  64                 fprintf (stderr, "avcodec_open failed.\n");
  65                 return -1;
  66         }
  67
  68         if (codec_context->time_base.num > 1000 && codec_context->time_base.den == 1) {
  69                 codec_context->time_base.den = 1000;
  70         }
  71
  72         AVFrame* frame = avcodec_alloc_frame ();
  73
  74         AVFrame* frame_RGB = avcodec_alloc_frame ();
  75         if (frame_RGB == NULL) {
  76                 fprintf (stderr, "avcodec_alloc_frame failed.\n");
  77                 return -1;
  78         }
  79
  80         int num_bytes = avpicture_get_size (PIX_FMT_RGB24, codec_context->width, codec_context->height);
  81         uint8_t* buffer = (uint8_t *) malloc (num_bytes);
  82
  83         avpicture_fill ((AVPicture *) frame_RGB, buffer, PIX_FMT_RGB24, codec_context->width, codec_context->height);
  84
  85         int i = 0;
  86         AVPacket packet;
  87         while (av_read_frame (format_context, &packet) >= 0) {
  88
  89                 int frame_finished;
  90
  91                 if (packet.stream_index == video_stream) {
  92                         avcodec_decode_video2 (codec_context, frame, &frame_finished, &packet);
  93
  94                         if (frame_finished) {
  95                                 static struct SwsContext *img_convert_context;
  96
  97                                 if (img_convert_context == NULL) {
  98                                         int w = codec_context->width;
  99                                         int h = codec_context->height;
 100
 101                                         img_convert_context = sws_getContext (
 102                                                 w, h,
 103                                                 codec_context->pix_fmt,
 104                                                 w, h, PIX_FMT_RGB24, SWS_BICUBIC,
 105                                                 NULL, NULL, NULL
 106                                                 );
 107
 108                                         if (img_convert_context == NULL) {
 109                                                 fprintf (stderr, "sws_getContext failed.\n");
 110                                                 return -1;
 111                                         }
 112                                 }
 113
 114                                 sws_scale (
 115                                         img_convert_context, frame->data, frame->linesize, 0,
 116                                         codec_context->height, frame_RGB->data, frame_RGB->linesize
 117                                         );
 118
 119                                 ++i;
 120                                 if (i > 100 && i < 150) {
 121                                         save_frame (frame_RGB, codec_context->width, codec_context->height, i);
 122                                 }
 123                         }
 124                 }
 125
 126                 av_free_packet (&packet);
 127         }
 128
 129         free (buffer);
 130         av_free (frame_RGB);
 131         av_free (frame);
 132         avcodec_close(codec_context);
 133         avformat_close_input (&format_context);
 134
 135         return 0;
 136 }