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• "Convert regions extracted from wav audio file into Flac audio file " python using FFMPAG in Django

  9 avril 2019, par maryam mehboob

  Regions extracted from wav audio file have "Invalid duration specification for ss"
  For Example in my case duration is in this format

  [(0.006000000000000005, 1.03), (2.0540000000000003, 4.870000000000003)]

  This is for converting regions into Flac format.

       class FLACConverter(object):
  
           # pylint: disable=too-few-public-methods
  
      """
  
           Class for converting a region of an input audio or video file into a FLAC audio file
  
      """
  
  
  
       def __init__(self, source_path, include_before=0.25, include_after=0.25):
  
          self.source_path = source_path
  
          self.include_before = include_before
  
          self.include_after = include_after
  
  
  
  
  
       def __call__(self, region):
  
          try:
  
              print("regions to convert in flac:{}".format(region))
  
              start = region
  
              end = region
  
            #  start = max(0, start - self.include_before)
  
              start = list(map(lambda x: tuple(max(0, y - self.include_before) for y in x), start))
  
              end = list(map(lambda x: tuple(y + self.include_after for y in x), end))
  
              temp = tempfile.NamedTemporaryFile(suffix='.flac', delete=False)
  
              command = ["ffmpeg", "-ss", str(start), "-t", str([tuple(x-y for x, y in zip(x1, x2)) for (x1, x2) in zip(end, start)]),
  
                         "-y", "-i", self.source_path,
  
                         "-loglevel", "error", temp.name]
  
              use_shell = True if os.name == "nt" else False
  
              subprocess.check_output(command)
  
              print(temp.name)
  
              #subprocess.check_output(command, stdin=open(os.devnull), shell=use_shell)
  
              read_data = temp.read()
  
              temp.close()
  
              os.unlink(temp.name)
  
              print("read_data :{}".format(read_data))
  
              print("temp :{}".format(temp.name))
  
  
  
              return read_data
  
  
  
          except KeyboardInterrupt:
  
              return None

  I expect the output of /var/folders/p1/6ttydjfx2sq9zl4cnmjxgjh40000gp/T/tmpwz5n4fnv.flac but it returns an error

  CalledProcessError at /

  Command '['ffmpeg', '-ss', '[(0.006000000000000005, 1.03), (2.0540000000000003, 4.870000000000003)]', '-t', '[(0.5, 0.5), (0.5, 0.5)]', '-y', '-i', '/var/folders/p1/6ttydjfx2sq9zl4cnmjxgjh40000gp/T/tmpuyi5spat.wav', '-loglevel', 'error', '/var/folders/p1/6ttydjfx2sq9zl4cnmjxgjh40000gp/T/tmp0vdewoyd.flac']' returned non-zero exit status 1.```

• FFMPEG is not recording the whole window

  25 mai 2021, par John

  I'm using FFMPEG to record a window as illustrated in the figure below. In all cases, the right hand side of the recorded window is cropped. The command I'm giving is

  



  ffmpeg -f gdigrab -i title="example.txt - Notepad++" output.mkv


  



  Any suggestion on how to fix this problem is much appreciated.

  



  

  



  Here are some additional info :

  



  

  • Running Windows 10

  


  • Using ffmpeg-20181215-011c911-win64-static, but I have the same issue using other versions of FFMPEG

  


  • Desktop resolution is 3200x1800 (dpi scaling issue ?)

  


  



  This is what the recorded area looks like in the example above

  



  

  



  Update 1 :

  



  Recording the whole desktop works fine, however, when recording a region using x and y offsets, the region captured is correct, but the region indicated is wrong. I illustrate this in the image below that shows a screen capture of the desktop during recording. The background image is a grid and the taskbar has been hidden.

  



  

  



  The size of the area to capture is specified to 1280x720, but the region indicated is 1600x900. Also, the x offset is specified to 400px, but the region indicted starts at 500px.

  



  The area recorded is correct ! The image below shows a screenshot of the recording during playback in vlc, note that the "misplaced" region indicator can be seen

  



  

  



  Update 2 :

  



  I noticed that the cursor, the mouse, is not correctly placed when capturing from the desktop, see recording below. Everything looks fine during recording, but at playback the cursor is misplaced.

  



  

  



  The command issued for the recording above was :

  



  ffmpeg -f gdigrab -framerate 30 -offset_x 1820 -offset_y 100 -video_size 1280x720 -i desktop output5.mkv


  



  Windows 10 / ffmpeg-20181215-011c911-win64-static

  


• FFmpeg overwrite an AVPacket

  26 janvier 2019, par Alejandro Ramírez

  Hello guys I am working with video. I wan to encrypt the I-frames of one video compressed in H.264. So I get the AVPacket from the video and compare if (AVPacket.flags & AV_PKT_FLAG_KEY) to know if the packet has an I frame, but when I try to print the AVPacket.data I don’t have any information to encrypt.
  Where can I get the information regarding to I-frame. ahead a put my code, thank you.

  #include <iostream>
  
  extern "C" {
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libswscale></libswscale>swscale.h>
  
  #include <libavutil></libavutil>avutil.h>
  
  }
  
  #define INBUF_SIZE 4096
  
  //#define AV_INPUT_BUFFER_PADDING_SIZE 32
  
  int main (int argc, char * argv[])
  
  {
  
      //av_register_all();//omit
  
      //revisar el número de argumentos en el video
  
      AVFormatContext *pFormatCtx = NULL;
  
      AVCodec *dec = NULL;
  
      AVCodecContext *pCodecCtx = NULL;
  
      AVStream *st = NULL;
  
      AVDictionary *opts = NULL;
  
      AVFrame *frame;
  
      AVPacket avpkt;
  
      uint8_t inbuf [INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
  
      FILE *f;
  
      int frame_count;
  
      int video_stream_index = -1;
  
  
  
      //av_init_packet (&amp;avpkt);
  
  
  
      memset (inbuf + INBUF_SIZE, 0, AV_INPUT_BUFFER_PADDING_SIZE);
  
      if (avformat_open_input (&amp;pFormatCtx, argv[1], NULL, NULL) != 0)
  
          return -1;
  
      if (avformat_find_stream_info (pFormatCtx, NULL) &lt; 0)
  
          return -1;
  
      //video_stream_index = av_find_best_stream (pFormatCtx,AVMEDIA_TYPE_VIDEO, -1, -1, &amp;dec,0);
  
      video_stream_index = av_find_best_stream (pFormatCtx,AVMEDIA_TYPE_VIDEO, -1, -1, &amp;dec,0);
  
      if ( video_stream_index &lt; 0)
  
          return -1;
  
      std::cout &lt;&lt; "video_stream; " &lt;&lt; video_stream_index &lt;&lt; "\n";
  
      st = pFormatCtx -> streams [video_stream_index];
  
      std::cout &lt;&lt; "number of frames " &lt;&lt; st -> nb_frames &lt;&lt; "\n";
  
      std::cout &lt;&lt; "event_flags " &lt;&lt; st -> event_flags &lt;&lt; "\n";
  
      //pCodecCtx = st -> codec;//deprecated
  
  
  
      dec = avcodec_find_decoder (st -> codecpar -> codec_id);
  
      std::cout &lt;&lt; "codec_id: " &lt;&lt; st -> codecpar -> codec_id &lt;&lt; "\n";
  
      std::cout &lt;&lt; "AV_CODEC_ID_H264: " &lt;&lt; AV_CODEC_ID_H264 &lt;&lt; "\n";
  
      if (!dec)
  
          return -1;
  
      pCodecCtx = avcodec_alloc_context3 (dec);
  
      if (!pCodecCtx)
  
          return -1;
  
      //av_dict_set (&amp;opts, "refcounted_frames", "0", 0);
  
      avcodec_parameters_to_context (pCodecCtx, st -> codecpar);
  
  
  
  
  
      std::cout &lt;&lt; "todo bien \n";    
  
      if (avcodec_open2 (pCodecCtx, dec, &amp;opts) &lt; 0)
  
          return -1;
  
      /*************hasta aqui buen codigo*********************************************/ 
  
      frame = av_frame_alloc ();
  
      if (!frame)
  
          return -1;
  
      av_init_packet (&amp;avpkt);
  
      avpkt.data = NULL;
  
      avpkt.size = 0;
  
      f = fopen (argv[1], "r");
  
      int times = 1;
  
      while (av_read_frame (pFormatCtx, &amp;avpkt) >= 0){
  
          AVPacket oripkt = avpkt;
  
          if (oripkt.stream_index == video_stream_index){
  
              if (oripkt.flags &amp; AV_PKT_FLAG_KEY){
  
                  std::cout &lt;&lt; "times: " &lt;&lt; times ++ &lt;&lt; "\n";
  
                  std::cout &lt;&lt; "avpkt.flags: " &lt;&lt; oripkt.flags &lt;&lt; "\n";
  
                  std::cout &lt;&lt; "tam avpkt.data: " &lt;&lt; sizeof(oripkt.data) &lt;&lt; "\n";
  
                  std::cout &lt;&lt; "tam avpkt.data: " &lt;&lt; oripkt.data &lt;&lt; "\n";
  
                  std::cout &lt;&lt; "oripkt.size: " &lt;&lt; oripkt.size &lt;&lt; "\n";
  
                  std::cout &lt;&lt; "oripkt.side_date_eme: " &lt;&lt; oripkt.side_data_elems &lt;&lt; "\n";
  
                  if (!oripkt.data)
  
                      std::cout &lt;&lt; "no tengo dinero \n";
  
              }
  
          }
  
      }
  
  
  
      std::cout &lt;&lt; "Fin del programa " &lt;&lt; "\n";
  
  }
  
  </iostream>