title: exporting ogg videos from video slideshow (mp4) and audio (wav) using ffmpeg in python
body: <p>I have tried to find a solution already, but just cannot make it work. I want to export an .ogg-video by combining a video slideshow (mp4) with an audio file (wav) by using ffmpeg in python. The audio is shorter than the video and should have an offset of 2000 milliseconds, so that it starts approximately in the middle of the video. The code that I tried is essentially this:</p>
  
  <blockquote>
    <p>subprocess.call('ffmpeg.exe -itsoffset 0 -i slideshows/slideshow.mp4 -itsoffset 2000 -i sounds/audio.wav -codec:v libtheora -codec:a libvorbis output.ogg', shell= True) </p>
  </blockquote>
  
  <p>FYI: I need to create a couple of different video formats from the video and audio input, so substituting the ogg with a different format is no option. I have already successfully created .mp4-video-files and .webm-video-files from the material, but need the .ogg in addition. Also, Power Point does not like any of the exported videos, maybe this might be relevant for finding the problem here (I also unsuccessfully tried to fix this issue).</p>