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• Interact with ffmpeg from a .NET program ?

  18 septembre 2011, par Shimmy

  I'm trying to create a .NET wrapper for media-file conversion using ffmepg, here is what I've tried :

  static void Main(string[] args)
  
  {
  
    if (File.Exists("sample.mp3")) File.Delete("sample.mp3");
  
  
  
    string result;
  
  
  
    using (Process p = new Process())
  
    {
  
      p.StartInfo.FileName = "ffmpeg";
  
      p.StartInfo.Arguments = "-i sample.wma sample.mp3";
  
  
  
      p.StartInfo.UseShellExecute = false;
  
      p.StartInfo.RedirectStandardOutput = true;
  
  
  
      p.Start();
  
  
  
      //result is assigned with an empty string!
  
      result = p.StandardOutput.ReadToEnd();
  
  
  
      p.WaitForExit();
  
    }
  
  }

  What actually happens is the content of the ffmpeg program is printed out to the Console app, but the result variable is an empty string. I want to control the conversion progress interactively, so the user doesn't even have to know I'm using ffmpeg, but he still knows the conversion progress' details and what percentage etc. the app is up to.

  Basically I would also be happy with a .NET wrapper for a P/Invoke to conversion function ONLY (I am not interested in a whole external library, unless I can extract the PI function from it).

  Anyone with experience in ffmpeg & .NET ?

  Update
  Please view my further question, how to write input to a running ffmpeg process.

• ffmpeg : convert audio-only flv to swf

  5 octobre 2011, par Michael Brewer-Davis

  My Flex application records audio-only FLV files using red5—I'd like to convert these to SWF files so I can embed them in other SWF files. (I could also convert to MP3 and then embed them into SWFs myself, but I'd prefer a one step solution.)

  Anyone have experience doing this ?

  What I've tried :

  The following naive ffmpeg command fails :

  > ffmpeg -i 3139747641.flv -vn movie.swf
  
  FFmpeg version SVN-r21751-snapshot, Copyright (c) 2000-2010 Fabrice Bellard, et al.
  
    built on Feb 11 2010 09:15:42 with gcc 4.2.1 (SUSE Linux)
  
    configuration: --enable-gpl --enable-nonfree
  
    libavutil     50. 9. 0 / 50. 9. 0
  
    libavcodec    52.53. 0 / 52.53. 0
  
    libavformat   52.52. 0 / 52.52. 0
  
    libavdevice   52. 2. 0 / 52. 2. 0
  
    libswscale     0.10. 0 /  0.10. 0
  
  [flv @ 0x8a5e3a0]Could not find codec parameters (Video: 0x0000)
  
  [flv @ 0x8a5e3a0]Estimating duration from bitrate, this may be inaccurate
  
  Input #0, flv, from '3139747641.flv':
  
    Metadata:
  
      audiocodecid    : -1
  
      duration        : 0
  
      videocodecid    : -1
  
      canSeekToEnd    : true
  
    Duration: 00:00:14.88, start: 0.000000, bitrate: N/A
  
      Stream #0.0: Video: 0x0000, 1k tbr, 1k tbn, 1k tbc
  
      Stream #0.1: Audio: nellymoser, 8000 Hz, mono, s16
  
  Output #0, swf, to 'movie.swf':
  
      Stream #0.0: Audio: 0x0000, 8000 Hz, mono, s16, 64 kb/s
  
  Stream mapping:
  
    Stream #0.1 -> #0.0
  
  Encoder (codec id 86017) not found for output stream #0.0

  I've tried adding a dummy video, but this also failed :

  > ffmpeg -i dummy.mov -i 3139747641.flv movie.swf
  
      
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'dummy.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 512
  
      compatible_brands: qt  
  
      encoder         : Lavf52.52.0
  
      encoder-eng     : Lavf52.52.0
  
    Duration: 00:00:00.10, start: 0.000000, bitrate: 62 kb/s
  
      Stream #0.0(eng): Video: mpeg4, yuv420p, 10x10 [PAR 1:1 DAR 1:1], 1 kb/s, 10 fps, 10 tbr, 10 tbn, 10 tbc
  
  [flv @ 0x8a67fa0]Could not find codec parameters (Video: 0x0000)
  
  [flv @ 0x8a67fa0]Estimating duration from bitrate, this may be inaccurate
  
  Input #1, flv, from '3139747641.flv':
  
    Metadata:
  
      audiocodecid    : -1
  
      duration        : 0
  
      videocodecid    : -1
  
      canSeekToEnd    : true
  
    Duration: 00:00:14.88, start: 0.000000, bitrate: N/A
  
      Stream #1.0: Video: 0x0000, 1k tbr, 1k tbn, 1k tbc
  
      Stream #1.1: Audio: nellymoser, 8000 Hz, mono, s16
  
  picture size invalid (0x0)
  
  Cannot allocate temp picture, check pix fmt

• How to add text to a video with ffmpeg and python

  25 janvier 2013, par Jared Glass

  I've been trying to add text to an avi with ffmpeg and I can't seem to get it right.

  Please help :

  import subprocess
  
  
  
  ffmpeg = "C:\\ffmpeg_10_6_11.exe"
  
  inVid = "C:\\test_in.avi"
  
  outVid = "C:\\test_out.avi"
  
  
  
  proc = subprocess.Popen(ffmpeg + " -i " + inVid + " -vf drawtext=fontfile='arial.ttf'|text='test' -y " + outVid , shell=True, stderr=subprocess.PIPE)
  
  proc.wait()
  
  print proc.stderr.read()