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• 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 ?

• sending variables to subprocess call with spaces - python 2.7

  24 novembre 2015, par Tandy Freeman

  I want to add ffmpeg options to a variable and later use it in a subprocess call. If the variable contains one word, all is well, but if it contains more than one, I get errors. I am working on a larger script and I will need to have extra options such as this for certain codecs. How can I get this working ?

  The following works perfectly for me :

  import subprocess
  
  import sys
  
  
  
  video_codec = 'libx264'
  
  output = sys.argv[1] + '.mkv'
  
  subprocess.call(['ffmpeg',
  
              '-i',sys.argv[1], 
  
              '-c:v',video_codec,
  
              '-c:a','copy',         
  
              output])    

  Once I introduce new options/spaces to video_options as such :

  video_codec = "'libx264', '-pix_fmt', 'yuv420p'"

  I get an ffmpeg error :

  Unknown encoder ''libx264', '-pix_fmt', 'yuv420p''

  If I remove the double quotes and just use
  video_codec = ’libx264’, ’-pix_fmt’, ’yuv420p’

  I get a python error :

  Traceback (most recent call last):
 File "testo.py", line 10, in <module>
   output])<br />
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 524, in call
   return Popen(*popenargs, **kwargs).wait()
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 711, in __init__
   errread, errwrite)
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 1308, in _execute_child
   raise child_exception
TypeError: execv() arg 2 must contain only strings
</module>

• Correct ffmpeg scale command syntax

  10 novembre 2015, par user3132858

  I am new to ffmpeg and need some help with the correct syntax for a scale command I found here.

  Below is my code :

  $width=300;
  
  $height=200;
  
  $aspect=$width/$height;
  
  
  
  
  
  $command = "/usr/local/bin/ffmpeg -y -i 1.mp4 -vf scale=min(1\,gt(iw\,".$width.")+gt(ih\,".$height.")) * (gte(a\,".$aspect.")*".$width." + \
  
  lt(a\,".$aspect.")*((".$height."*iw)/ih)) + not(min(1\,gt(iw\,".$width.")+gt(ih\,".$height.")))*iw : \
  
  min(1\,gt(iw\,".$width.")+gt(ih\,".$height.")) * (lte(a\,".$aspect.")*".$height." + \
  
  gt(a\,".$aspect.")*((".$width."*ih)/iw)) + not(min(1\,gt(iw\,".$width.")+gt(ih\,".$height.")))*ih  -b 1200k -acodec aac -strict -2 2.mp4 ";

  Video is successfully converted however, the scaling does not go trough.

  The code is copied word for word, I only make two changes :

  • removed the " before scale word and from the end
  • replaced the $FW with $width, $FH with $height and $FA with $aspect.

  Any suggestion at what might be wrong ?