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• Mix the each audio track space with specific audio ?

  23 avril 2014, par Dhaval

  I have audio files and it contain some space.

  I want to fill thse space with specific word audio.

  Is it possible with FFMPEG ?

  Please share me command, how to fill each space (contain in audio track) with another audio ?

  Thanks
  Dhaval

• Split list of videos to chunks by silence in Python

  27 mai 2020, par JohnPython

  I have a list of 500 videos that I want split into small chunks by single words.

  



  I was thinking to split it by short silences between words.

  



  Process output is lots of short videos each contains one word.

  



  It would be great if silence length would be adjustable so it can extract words by various talking speech.
Process will run in Google Colab notebook
I tried FFMPEG with no success.

  


• OpenCV and GoPro - empty frames in VideoCapture stream

  19 mai 2014, par Novatar

  I have a GoPro Hero 3+ (Black) which is connected to a video capture card (AverMedia Game Broadcaster HD). I simply want to get the video stream in OpenCV. With a Logitech Webcam there are no problems. The used code is below.

  VideoCapture cap;
  
  cap.open(0);
  
  
  
  waitKey(300);
  
  
  
  //cap.set(CV_CAP_PROP_FRAME_WIDTH, 1280);
  
  //cap.set(CV_CAP_PROP_FRAME_HEIGHT, 720);
  
  
  
  if (cap.isOpened()){
  
      cout << "Cam identified" << endl;
  
  }
  
  
  
  namedWindow("dst", 1);
  
  
  
  while (1){
  
  
  
  Mat frame;
  
  
  
  if (!cap.read(frame)) {
  
      std::cout << "Unable to read frame from video stream" << std::endl;
  
      continue;
  
  }
  
  
  
  imshow("dst", frame);
  
  
  
  [...]
  
  
  
  }

  With the GoPro the following happens : OpenCV is able to open the VideoCapture ("Cam identified") but can’t read any frames (just a gray screen and the output : "Unable to read frame from video stream"). I also checked this with frame.empty() ;.

  I know that the video capture card works correct because Unity opens a WebCamTexture with the GoPro stream without any issues. I read about codec problems in OpenCv and so I already tried to compile OpenCV with FFMPEG support. Now the recorded MP4-Videos of the GoPro can be displayed but the stream still doesn’t work.

  I use OpenCV 2.48, Windows 7 and Visual Studio 2013.

  ---

  EDIT : Here is the code of libVLC solution :

  struct ctx
  
  {
  
  uint8_t* pixeldata;
  
  std::mutex imagemutex;
  
  };
  
  
  
  static void display(void *data, void *id);
  
  static void unlock(void *data, void *id, void *const *p_pixels);
  
  static void *lock(void *data, void **p_pixels);
  
  
  
  struct ctx ctx;
  
  
  
  libvlc_instance_t *inst;
  
  libvlc_media_player_t *mp;
  
  libvlc_media_t *m;
  
  
  
  int main(int argc, char* argv[])
  
  {
  
      ctx.pixeldata = new uint8_t[1280 * 720 * 3];
  
  
  
      char const *vlc_argv[] =
  
      {
  
          "-vvv",
  
          "--no-audio", /* skip any audio track */
  
          "--no-xlib", /* tell VLC to not use Xlib */
  
      };
  
  
  
      int vlc_argc = sizeof(vlc_argv) / sizeof(*vlc_argv);
  
      inst = libvlc_new(vlc_argc, vlc_argv);
  
  
  
      const char *options[] =
  
      {
  
          ":dshow-vdev=AVerMedia HD Capture",
  
          ":dshow-adev=none",
  
          //":dshow-size=1280x720",
  
          ":dshow-fps=24",
  
          ":dshow-chroma=YUY2",
  
          ":dshow-video-input=1",
  
          ":dshow-video-output=1",
  
          ":dshow-aspect-ratio=16\:9",
  
          ":live-caching=80",
  
          NULL
  
      };
  
  
  
      m = libvlc_media_new_location(inst, "dshow://");
  
      for (const char **opt = options; *opt; opt++)
  
          libvlc_media_add_option(m, *opt);
  
  
  
      mp = libvlc_media_player_new_from_media(m);
  
      libvlc_media_release(m);
  
      libvlc_video_set_callbacks(mp, lock, unlock, display, &ctx);
  
      libvlc_video_set_format(mp, "RV24", 1280, 720, 1280 * 3);
  
      libvlc_media_player_play(mp);
  
  
  
      namedWindow("all", 1);
  
  
  
      Mat frame(720, 1280, CV_8UC3);
  
  
  
      while (1){
  
  
  
          ctx.imagemutex.lock();
  
          memcpy(gesamt.data, ctx.pixeldata, 1280 * 720 * sizeof(uint8_t) * 3);
  
          ctx.imagemutex.unlock();
  
  
  
          imshow("all", gesamt);
  
  
  
          if (waitKey(30) == 27) //wait for 'esc' key press for 30ms. If 'esc' key is pressed, break loop
  
          {
  
              cout << "esc key is pressed by user" << endl;
  
              break;
  
          }
  
  
  
      }
  
  
  
      libvlc_media_player_stop(mp);
  
      libvlc_media_player_release(mp);
  
      libvlc_release(inst);
  
      delete[] ctx.pixeldata;
  
  
  
      return 0;
  
  }
  
  
  
  void display(void *data, void *id){
  
      (void)data;
  
      assert(id == NULL);
  
  }
  
  
  
  void unlock(void *data, void *id, void *const *p_pixels){
  
      struct ctx *ctx = (struct ctx*)data;
  
      ctx->imagemutex.unlock();
  
      assert(id == NULL);
  
  }
  
  
  
  void *lock(void *data, void **p_pixels){
  
      struct ctx *ctx = (struct ctx*)data;
  
      ctx->imagemutex.lock();
  
      *p_pixels = ctx->pixeldata;
  
      return NULL;
  
  }