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• Splitting/saving h264 rtsp stream and de-payloading headers with ffmpeg without decoding/encoding in C++

  22 juin 2016, par autonomy

  I want to receive an h264-encoded stream over rtsp, read the metadata from the packet headers (to save into a database), split and save the video to disk without decoding/encoding the stream. The length of the split video segments can be fixed to, say, 5-10 minutes. I want to do this using the FFMpeg API in C++ (NOT command line !) with as little CPU overhead as possible because I need the headers. Can this be done using FFMpeg ? Dare I ask if anyone can suggest tutorials ? (I couldn’t find anything other than command line examples)

• Decoding then re-encoding frames in reverse order with ffmpeg

  21 août 2014, par user3875919

  I am pretty new to ffmpeg, and now I want to decode the frames and encode it back in reverse order. I have used this tutorial for decoding the video and this example to encode it back. I can decode the frames properly, but when I re-encode it, I get a dummy image rather than clear video. How can I get the actual reversed video ?

  static void video_encode_example(const char *filename, int codec_id)
  
  {
  
      AVCodec *codec;
  
      AVCodecContext *c= NULL;
  
      int i, ret, x, y, got_output;
  
      FILE *f;
  
      struct SwsContext *sws_ctx = NULL;
  
      AVFrame *frame;
  
      AVFrame *frameRGB = NULL;
  
      AVPacket pkt;
  
      uint8_t endcode[] = { 0, 0, 1, 0xb7 };
  
  
  
      printf("Encode video file %s\n", filename);
  
  
  
      /* find the mpeg1 video encoder */
  
      codec = avcodec_find_encoder(codec_id);
  
      if (!codec) {
  
          fprintf(stderr, "Codec not found\n");
  
          exit(1);
  
      }
  
  
  
      c = avcodec_alloc_context3(codec);
  
      if (!c) {
  
          fprintf(stderr, "Could not allocate video codec context\n");
  
          exit(1);
  
      }
  
  
  
      /* put sample parameters */
  
      c->bit_rate = 400000;
  
      /* resolution must be a multiple of two */
  
      c->width = 352;
  
      c->height = 288;
  
      /* frames per second */
  
      c->time_base = (AVRational){1,25};
  
      /* emit one intra frame every ten frames
  
       * check frame pict_type before passing frame
  
       * to encoder, if frame->pict_type is AV_PICTURE_TYPE_I
  
       * then gop_size is ignored and the output of encoder
  
       * will always be I frame irrespective to gop_size
  
       */
  
      c->gop_size = 10;
  
      c->max_b_frames = 1;
  
      c->pix_fmt = AV_PIX_FMT_YUV420P;
  
  
  
      if (codec_id == AV_CODEC_ID_H264)
  
          av_opt_set(c->priv_data, "preset", "slow", 0);
  
  
  
      /* open it */
  
      if (avcodec_open2(c, codec, NULL) < 0) {
  
          fprintf(stderr, "Could not open codec\n");
  
          exit(1);
  
      }
  
  
  
      f = fopen(filename, "wb");
  
      if (!f) {
  
          fprintf(stderr, "Could not open %s\n", filename);
  
          exit(1);
  
      }
  
  
  
      frame = av_frame_alloc();
  
      if (!frame) {
  
          fprintf(stderr, "Could not allocate video frame\n");
  
          exit(1);
  
      }
  
      frame->format = c->pix_fmt;
  
      frame->width  = c->width;
  
      frame->height = c->height;
  
  
  
      /* the image can be allocated by any means and av_image_alloc() is
  
       * just the most convenient way if av_malloc() is to be used */
  
      ret = av_image_alloc(frame->data, frame->linesize, c->width, c->height,
  
                           c->pix_fmt, 32);
  
      if (ret < 0) {
  
          fprintf(stderr, "Could not allocate raw picture buffer\n");
  
          exit(1);
  
      }
  
  
  
      /* encode 1 second of video */
  
      for (i = 0; i < 25; i++) {
  
          av_init_packet(&pkt);
  
          pkt.data = NULL;    // packet data will be allocated by the encoder
  
          pkt.size = 0;
  
  
  
          fflush(stdout);
  
          /* prepare a dummy image */
  
          /* Y */
  
          for (y = 0; y < c->height; y++) {
  
              for (x = 0; x < c->width; x++) {
  
                  frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
  
              }
  
          }
  
  
  
          /* Cb and Cr */
  
          for (y = 0; y < c->height/2; y++) {
  
              for (x = 0; x < c->width/2; x++) {
  
                  frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
  
                  frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
  
              }
  
          }
  
  
  
          frame->pts = i;
  
  
  
          /* encode the image */
  
          ret = avcodec_encode_video2(c, &pkt, frame, &got_output);
  
          if (ret < 0) {
  
              fprintf(stderr, "Error encoding frame\n");
  
              exit(1);
  
          }
  
  
  
          if (got_output) {
  
              // Convert the image from its native format to RGB
  
              sws_scale
  
              (
  
                  sws_ctx,
  
                  (uint8_t const * const *)frame->data,
  
                  frame->linesize,
  
                  0,
  
                  c->height,
  
                  frameRGB->data,
  
                  frameRGB->linesize
  
              );
  
              printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
              fwrite(pkt.data, 1, pkt.size, f);
  
              av_free_packet(&pkt);
  
          }
  
      }
  
  
  
      /* get the delayed frames */
  
      for (got_output = 1; got_output; i++) {
  
          fflush(stdout);
  
  
  
          ret = avcodec_encode_video2(c, &pkt, NULL, &got_output);
  
          if (ret < 0) {
  
              fprintf(stderr, "Error encoding frame\n");
  
              exit(1);
  
          }
  
  
  
          if (got_output) {
  
              printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
              fwrite(pkt.data, 1, pkt.size, f);
  
              av_free_packet(&pkt);
  
          }
  
      }
  
  
  
      /* add sequence end code to have a real mpeg file */
  
      fwrite(endcode, 1, sizeof(endcode), f);
  
      fclose(f);
  
  
  
      avcodec_close(c);
  
      av_free(c);
  
      av_freep(&frame->data[0]);
  
      av_frame_free(&frame);
  
      printf("\n");
  
  }

• adobe premiere command line calls for encoding/decoding [on hold]

  2 février 2016, par rishi007bansod

  Is there any command line instruction set for adobe premiere like that we have in ffmpeg encoder. I basically need to replace encoding tasks done by ffmpeg encoder in my program by adobe premiere encoder. So are there any command line instructions that can set encoding parameters(e.g. gop size, frame rate, quality parameter) in adobe premiere.