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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.

• Nginx video streaming - ffmpeg convert to flv, but requsted is mp4

  18 juin 2012, par abrahab

  I am converting videos from different sources with ffmpeg to mp4 with libx264 codec.
  The following command (simplified) :
  ffmpeg -i 1.mp4 -y -f mp4 -vcodec libx264 -crf 28 -threads 2 -strict experimental -acodec aac -ab 56k -ar 44100 -ac 2 temp.mp4

  Then, I can not stream the output file (500 Internal Server Error) with nginx mp4-streaming solution (aka http pseudo streaming). My system administrator found, that if rename file to flv it stream well, so, seems the output file is not mp4, but flv ? Why ? How to correctly convert ? Or, please, suggest how to stream video properly ? I think that mp4 is much better then flv... therefore I choose mp4.

  In other words, the problem is to stream output file like mp4.

  ps i also need to be sure that this video will always work at ipad after convertation. thanks and sorry for my bad english.

  EDIT : I found that if convert video with the same string but without -vcodec libx264 - nginx can serve the output .mp4 file well. where may be the problem ?

• Icecast Ogg format - mp3

  19 février 2013, par user1503606

  I am trying to setup live streaming with html5 and icecast and traktor.

  In tracktor it will only output in Ogg format.

  So i am looking for possible solution as html5 doesnt seem to work with ogg streaming on ipad and iphone.

  Is it possible to some how covert the ogg format to mp3 on the fly with something like this.

  <?php shell_exec("ffmpeg -i http://255.70.84.64:8000/stream soundpollution.mp3 2>&1"); ?>

  But run a loop around this so it polls maybe every 10 seconds

  Just thought id ask the community as i am trying this but not getting very far.

  And looking for a work around

  Thanks.