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• getruntime() exec() with double quotes in command

  29 décembre 2012, par brux

  I want to execute an ffmpeg command, the method I am using works with every command on my list except the following one which contains double quotes to set a filter (-vf) parameter

  ffmpeg -i 2012-12-27.mp4 -vf "movie=bb.png [movie]; [in] [movie] overlay=0:0 [out]" -vcodec libx264 -acodec copy out.mp4

  I have tried changing the quotes for single quotes with no luck. The command works at the android terminal with both single and double quotes.

  The app I'm developing uses about 5 ffmpeg commands, all work except this one, is this some bug ?

  I can't find a concrete solution to this problem, breaking the args into an array and then passing this to runtime().exec() as suggested elsewhere doesn't seem to work, or simply trying to escape the quotes with \" won't work.

  Both of the files referenced in the above command are located in the sdcard, I removed the concatenation of the command out so that things don't get messy, rest assured these commands work in a terminal when referencing the full paths to the files.
  I contatenate the string passed to getRuntime().exec() using a stringbuilder and`getexternalstorageDirectory().getabsolutepath() to get the path to each file like I have been doing with previous commands when using the process class.

  I am using Jelly Bean 4.2 in case that is of any significance.

• cocoa ffmpeg seamless loop video

  13 décembre 2012, par Marius

  OK i've seen many people having issues with getting videos to loop seamlessly on iOS. If it's a video that you provide with your app (in other words if you have control over the file itself) - there's a way of getting around the problem - by providing the video as self-contained looped MOV file. And it works like a charm. The way you do it is :

  • open an MP4 video in QT (QT7 works fine)
  • re-save it as self-contained movie
  • CMD+A, CMD+C and then CMD+V a bunch of times
  • save

  This will create a slightly bigger file than the original.

  So now i've just gotten curious : could the same thing be done in ffmpeg ? If so - how would one take an MP4 video, save it as self contained MOV and loop it for, let's say, around 60 minutes, without actually cloning video data and increasing file size just slightly ?

  Thanks for your thoughts.

• saving frames from ffmpeg

  12 décembre 2012, par user843681

  I am using ffmpeg in C# to discard a movie to its frame images and save each frame as a .png image. However, I can not save the frames ! the code operates, but then I can not save them to a folder ! I would like to know how can I save the output of ffmpeg to a folder.

  public static void GetVideoFrames(string saveTo)
  
  {
  
      string mpegpath = @"E:\Csharp\ffvideo\";
  
      string ffmpegPath = Path.Combine(mpegpath, "ffmpeg.exe");
  
      string inputMovie = @"E:\Csharp\ffvideo\test.mp4";
  
      string parameters = string.Format("ffmpeg -i {0} -f image2 frame-%1d.png -y {1}",
  
          inputMovie, saveTo);
  
      Process proc = new Process();
  
      proc.StartInfo.FileName = ffmpegPath;
  
      proc.StartInfo.UseShellExecute = false;
  
      proc.StartInfo.Arguments = parameters;
  
      proc.Start();
  
  }