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• Piwik Mobile est maintenant disponible !

  18 août 2010, par SteveG

  Après quelques mois de développement, l’équipe Piwik est fière de vous présenter le client mobile. Piwik Mobile est déjàdisponible pour les markets des différents téléphones avec IOS (comme iPhone, iPod et iPad) ou Android (1.6 ou supérieure). Piwik Mobile dans les markets : Android : http://www.androidpit.com/en/android/market/apps/app/org.piwik.mobile/Piwik-Mobile-Beta iOS : http://itunes.apple.com/us/app/piwikmobile/id385536442?mt=8 Piwik Mobile a été développé en utilisant [...]

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• Getting a poster frame(thumbnail) with ffmpeg

  3 juillet 2012, par Tyler

  I am trying to get a poster frame from a video file, using ffmpeg.

  I have been following this tutorial and come up with the following code(which is taken/adapted from the link I gave) :

  public bool GetVideoThumbnail(string path, string saveThumbnailTo, int seconds)
  
          {
  
              string parameters = string.Format("-i {0} {1} -vcodec mjpeg -ss {2} -vframes 1 -an -f rawvideo", path, saveThumbnailTo, seconds);
  
  
  
              if (File.Exists(saveThumbnailTo))
  
              {
  
                  return true;
  
              }
  
              else
  
              {
  
                  using (Process process = Process.Start(pathToConvertor, parameters))
  
                  {
  
                      process.WaitForExit();
  
                  }
  
                  return File.Exists(saveThumbnailTo);
  
              }
  
          }

  At the moment this code is successfully creating a file in the correct destination (saveThumbnailTo) only the picture is completely black. I have tried changing the seconds value in the code to ensure that I am not just getting a blank picture from the start of the video. The path refers to where my video is stored, by the way.

  I am currently calling the above code like so :

  GetVideoThumbnail(videoPath, folderPath + "/poster.jpg", 100)

  ..and then passing it out to my view to display the picture. I just wonder whether ".jpg" is the extension I should be giving to this file as I am not entirely sure ?

  Edit : When I run the same command from the command line I get the following errors :

  Incompatible pixel format 'yuv420p' for codec 'mjpeg', auto-selecting
  format 'yuvj420p'

  which appears in yellow, and

  [image2 @ 02S96AE0] Could not get frame filename number 2 from pattern
  'poster.jpg' an_interleaved_write_frame() : Invalid argument

  which appears in red.

  Could anyone help me with getting this working properly as I am completely unfamiliar with the ffmpeg command line and not sure what I am doing wrong. I have tried removing the vcodec parameter and get the same error message.

• Right choice to play audio and video content

  22 juin 2012, par deimus

  What I'm doing :

  I need to play audio and video files that are not supported by Apple on iPhone/iPad for example mkv/mka files which my contain several audio channels.

  I'm using libffmpeg to find audio and video streams in media file.
  Video is being decoded with avcodec_decode_video2 and audio with avcodec_decode_audio3
  the return values are following for each function are following

  • avcodec_decode_video2 - returns AVFrame structure which encapsulates information about the video video frame from the pakcage, specifically is has data field which is a pointer to the picture/channel planes.
  • avcodec_decode_audio3 - returns samples of type int16_t * which I guess is the raw audio data

  So basically I've done all this and successfully decoding the media content.

  What I have to do :
  I've to play the audio and video accordingly using Apples services. The playback I need to perform should support mixing of audio channels while playing video, i.e. let say mkv file contains two audio channel and a video channel. So I would like to know which service will be the appropriate choice for me ? My research showed that AudioQueue service might be useful audio playback, and probably AVFoundation for video.

  Please help to find the right technology for my case i.e. video playeback + audio playback with possible audio channel mixing.