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• System.Diagnostics.Process pipe (vertical bar) not accepted as argument

  28 septembre 2019, par emp

  I’m trying to execute this code using System.Diagnostics.Process. It works fine in command line. But in C# it’s failing on the | character.

  var myProcess = new Process();
  
  var p = new ProcessStartInfo();
  
  
  
  var sArgs = " -i emp.mp3 -f wav - | neroAacEnc -ignorelength -q 0.5 -if - -of emp.mp4";
  
  p.FileName = "ffmpeg.exe";
  
  p.CreateNoWindow = false;
  
  p.RedirectStandardOutput = false;
  
  p.UseShellExecute = false;
  
  p.Arguments = sArgs;
  
  
  
  myProcess.StartInfo = p;
  
  
  
  myProcess.Start();
  
  myProcess.WaitForExit();

  It gives the following error :

  Unable to find a suitable output format for ’|’ : Invalid argument

  I’ve looked around on stackoverflow and found the following hint but it is also not working :

  var psi = new ProcessStartInfo("ffmpeg.exe");
  
  psi.Arguments = 
  
      "\"-i emp.mp3 -f wav -\" | \"neroAacEnc -ignorelength -q 0.5 -if - -of emp.mp4\"";
  
  psi.CreateNoWindow = false;
  
  psi.UseShellExecute = false;
  
  
  
  var process = new Process { StartInfo = psi };
  
  
  
  process.Start();
  
  process.WaitForExit();

  gives the following error :

  Unrecognized option ’i emp.mp3 -f wav -’
  Failed to set value ’|’ for option ’i emp.mp3 -f wav -’

• ffmpeg filters inserting escape characters in python [duplicate]

  8 mai 2024, par jdauthre

  I am running ffmpeg in python as a subprocess. I want to burn the subtitles into a video. Just using ffmpeg (commandline without python in windows) the following works :

  


  ffmpeg.exe" -y -i  "input_file" -vf "subtitles= \'input_file_path\' :si=0"  -acodec  copy  "output_file_path"


  


  the \ escape characters are required by ffmpeg for special characters within a filter, However trying to replicate this within a python subprocess has proved problematic, here is one of many failed attempts :

  


  command = ["ffmpeg.exe","-y","-i","input_file_path","-acodec","copy","
-vf","subtitles=",'\"'+"input_file_path"+'\"',":si=0",output_file_path]
print(command)
proc = subprocess.Popen(command, stderr=PIPE,stdin=subprocess.PIPE,universal_newlines=True,encoding='utf-8')


  


  I have also tried making a raw string, another attempt :

  


  command = ["ffmpeg.exe","-y","-i","input_file_path","-acodec","copy","
-vf","subtitles=",r'\"'+"input_file_path"+r'\"',":si=0",output_file_path]


  


  this results in an error in ffmpeg, although the syntax looks ok :

  


   Unable to find a suitable output format for '\"input_file_path\"'
\"C:/temp/two.mp4\": Invalid argument


  


  ffmpeg seems to want to treat it as the output.
I need to get the right combination of Python escape characters and ffmpeg escape characters. Any ideas ?

  


• HLS Streaming on IPad with IOS 7 / 8 causes 10 seconds freezed frame - no clue why

  25 juin 2014, par user3747636

  We have a problem with HLS h.264 mp4 on IPad devices using HLS streaming on IOS 7 and 8 :

  The first 9-15 seconds (the length of the first TS segment) only shows the first key frame (IDR) of the second TS segment, while the sound plays normally. When the second segment begins to play, the video continues as it should.

  HLS segmenter is a wowza with 10 seconds segment length. The encoding software we use is TMPG, latest version (uses x264). The funny thing is, that handbrake, xmedia recode, adobe me deliver videos which work. I am aware of the fact, that this hints to a bug within our encoding software, but if someone already had that problem with another software / segmenter combination and fixed it, I would like to know what the source of the problem was.

  What we already tried :

  • changing almost every setting so that it sticks as close as possible to apple’s recommendations
  • changing GOP structure, GOP length, encoding parameters which influence efficiency of encoding
  • analysis of the TS segments created by wowza, they are fine and begin all with keyframes
  • contact TMPG/Apple/Wowza support

  So, did anyone stumble upon this problem before ? Has anyone solved it ?

  EDIT :

  It seems that TMPGEnc uses a defective x264 implementation. The mediastreamvalidator tool from Apple returned an error stating that our TS segment "does not contain any IDR access unit with a SPS and a PPS" - which it does actually, but obviously in the wrong places if that somehow matters.