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• Running an FFprobe process in Xcode to return file duration data

  24 octobre 2019, par NCrusher

  Using this example, I was able to create a process to run ffmpeg from the main resource bundle of a MacOS app. The fact that I was able to get it to work, however, was really dumb luck.

  But now I need to be able to do something similar with ffprobe, along the lines of what is discussed in this post, to get the duration of an audio file in order to trim a set number of seconds off the end of it, using these arguments :

  ffprobe -v 0 -show_entries format=duration -of compact=p=0:nk=1 input.m4b

  But I don’t know how to implement it. This is basically what I want to accomplish :

      func insertTrimArguments() {
  
          conversionSelection()
  
          if trimStartEndClipsCheckbox.state == .on {
  
              ffmpegArguments.insert(contentsOf: ["-ss", "00:00:02.000", /*"-t", "duration minus 4.2secs"]*/, at: 3)
  
          }
  
          else {
  
          }
  
      }

  I haven’t been coding in Swift long and processes are entirely new for me and not something that was ever covered in any of the "fundamentals" tutorials I studied before I began my project. Taking the monkey-see/monkey-do approach from the first example I linked, I can sort of make a start imitating it for my ffprobe function, but I have no idea if I’m doing it right or where to go with it from here.

  This is all I have so far.

      // get file duration and subtract 4.2 seconds if "trim audible clips is enabled, then insert additional arguments into conversionSelection arrays
  
      func getFileDuration() {
  
          guard let ffprobePath = Bundle.main.path(forResource: "ffprobe", ofType: "") else { return }
  
          do {
  
              let ffprobeTask: Process = Process()
  
              ffprobeTask.launchPath = ffprobePath
  
              ffprobeTask.arguments = [
  
                  "-v", "error",
  
                  "-show_entries",
  
                  "format=duration", "-of",
  
                  "compact=p=0:nk=1",
  
                  "\(inputFilePath)"]
  
              ffprobeTask.standardInput = FileHandle.nullDevice
  
              ffprobeTask.launch()
  
              ffprobeTask.waitUntilExit()
  
          }
  
      }

  How do I adapt this process so that instead of converting and outputing a new file, it returning the duration of the input file so that I can do the necessary math and include it in my arguments ?

• Piping cURL output to FFmpeg doesn't work with mp4 files

  8 novembre 2015, par Konstantin

  I would like to pipe cURL output to FFmpeg the following way in my Ruby script to strip off metadata, chapters and maybe set other metadata too in the future :

  #!/usr/bin/ruby
  
  url=ARGV[0]
  
  
  
  fname=url.split("/").last
  
  extension=File.extname(fname)
  
  options=""
  
  case extension 
  
    when /mp4/i
  
      format="mp4"
  
      options=" -movflags frag_keyframe+empty_moov "
  
    when /avi/i
  
      format="avi"
  
    when /mkv/i
  
      format="matroska"
  
    when /wmv/i
  
      format="asf"
  
    else
  
      format="matroska"
  
   end
  
  
  
  cmd=%Q{ curl -b cookie-file.txt #{url} -L -o - | ffmpeg -y -i - -map 0:v -map 0:a -c:v copy -c:a:0 copy -map_metadata -1 -map_chapters -1 #{options} -f #{format} - | cat > #{fname} }
  
  
  
  system cmd

  When the url (ARGV[0]) points to an .avi, .wmv or .mkv file the script do its job. However when it points to an .mp4 or .mov file it doesn’t work, because the input isn’t seekable and FFmpeg at first try to read the whole input. When url points to an mp4 file, output to stdout even doesn’t work, only when options " -movflags frag_keyframe+empty_moov " is used for the output format. Otherwise I got an error message : "muxer does not support non seekable output". Last cat command is needed because this command pipe will work in a CGI script, and will write its output to STDOUT with appropriate HTTP headers. What options should I use for the input pipe to make my script work with mp4 files too ?

• regainplay_analysis : Work around GCC optimizer bug.

  15 juin 2014, par Erik de Castro Lopo

  regainplay_analysis : Work around GCC optimizer bug.
  Discussion : http://lists.xiph.org/pipermail/flac-dev/2014-June/004720.html
  
  Patch-from : lvqcl <lvqcl.mail@gmail.com>
  

  • [DH] src/share/replaygain_analysis/replaygain_analysis.c