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• extracting single frame from MediaElemet or FFmpegInterop

  13 janvier 2016, par Jakub Wisniewski

  I am writing app (Windows Phone 8.1 Store App) that allows user to connect to IP Camera. I am using FFmpeg Interop library for ffmpeg which allows me to play eg. rtsp streams in media element. I need now a way to somehow extract a single frame from stream or from media element.

  I have tested other application wchih allows connecting to IP cameras - IP Centcom, and they have working snapshots only for mjpeg streams as far as I now (they were not working for rtsp). Becouse of that I belive that it is impossible or at very least very hard to export frame from media element.

  I have different question - if anyone has ever used FFmpeg Interop and would like to help/explain me how could I modify/extend FFmpegInteropMSS to add method called ’GetThumbnailForStream’ that would work similary to ’GetMediaStreamSource’ but would return single frame (bitmap or jpg) instead of MediaStreamSource ?

  Every help would be appreciated

  EDIT :

  I have found something ;

  in MediaSampleProvider in method WriteAVPacketToStream (line 123) there is line

  auto aBuffer = ref new Platform::Array(avPacket->data, avPacket->size);

  and I belive that this is the place that stores single frame data that is needed to convert into bitmap - now since I do not know c++ too much I have a question : how can I convert it into a form that I could return via public method ?

  When returning :

  Platform::Array^

  I get

  ’FFmpegInterop::MediaSampleProvider’ : a non-value type cannot have any public data members

  EDIT2 :

  Ok I am doing approprate projection to byte according to this microsoft information, now I need to check if this is correct data.

• extracting single frame FFmpeg Interop

  12 janvier 2016, par Jakub Wisniewski

  I am writing app (Windows Phone 8.1 Store App) that allows user to connect to IP Camera. I am using FFmpeg Interop library for ffmpeg which allows me to play eg. rtsp streams in media element. I need now a way to somehow extract a single frame from stream or from media element.

  I have tested other application wchih allows connecting to IP cameras - IP Centcom, and they have working snapshots only for mjpeg streams as far as I now (they were not working for rtsp). Becouse of that I belive that it is impossible or at very least very hard to export frame from media element.

  I have different question - if anyone has ever used FFmpeg Interop and would like to help/explain me how could I modify/extend FFmpegInteropMSS to add method called ’GetThumbnailForStream’ that would work similary to ’GetMediaStreamSource’ but would return single frame (bitmap or jpg) instead of MediaStreamSource ?

  Every help would be appreciated

• Synchronize video subtitle with text-to-speech voice

  8 décembre 2015, par Ahmad

  I try to create a video of a text in which the text is narrated by text-to-speech.

  To create the video file, I use the VideoFileWriter of Aforge.Net as the following :

  VideoWriter = new VideoFileWriter();
  
  
  
  VideoWriter.Open(CurVideoFile, (int)(Properties.Settings.Default.VideoWidth),
  
      (int)(Properties.Settings.Default.VideoHeight), 25, VideoCodec.MPEG4, 800000);

  To read aloud the text I use SpeechSynthesizer class and write the output to a wave stream

  AudioStream = new FileStream(CurAudioFile, FileMode.Create);
  
  synth.SetOutputToWaveStream(AudioStream);

  I want to highlight the word is spoken in the video, so I synchronize them by the SpeakProgress event :

      void synth_SpeakProgress(object sender, SpeakProgressEventArgs e)
  
      {
  
  
  
          curAuidoPosition = e.AudioPosition;
  
          using (Graphics g = Graphics.FromImage(Screen))
  
          {
  
               g.DrawString(e.Text,....); 
  
          }                    
  
          VideoWriter.WriteVideoFrame(Screen, curAuidoPosition);
  
      }

  And finally, I merge the video and audio using ffmpeg

  using (Process process = new Process())
  
  {
  
            process.StartInfo.FileName = exe_path;
  
            process.StartInfo.Arguments = string.Format(@"-i ""{0}"" -i ""{1}"" -y -acodec copy -vcodec copy ""{2}""",
  
                                             avi_path, mp3_path, output_file);
  
  ......

  The problem is that for some voices like Microsoft Hazel, Zira and David, the video is not synchronized with the audio, and the audio is much faster than the shown subtitle. In windows 7, it works for Mircrosoft Sam

  How can I synchronize them so that it works for any text-to-speech voices ?