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  24 mars 2010, par kent1 — Log

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• Revision 3273 : On utilise notation et on définit un critère _dist pour notation plutot

  18 avril 2010, par kent1 — Log

  On utilise notation et on définit un critère _dist pour notation plutot

• ffmpeg not reading string correctly in Swift MacOS app

  21 octobre 2019, par NCrusher

  I’m so close to having a working app that does a simple audio conversion calling ffmpeg but I’m stuck on what appears to be the silliest error.

  in the Console, ffmpeg prints the following error when I try to run the conversion :

  "Unrecognized option ’c copy’. Error splitting the argument list :
  Option not found"

  Which is strange because that’s not the argument I’m giving it. My method for producing the string it’s getting its argument from is as follows :

  func conversionSelection() {
  
      if inputFileUrl != nil {
  
          let conversionChoice = conversionOptionsPopup.indexOfSelectedItem
  
          switch conversionChoice {
  
              case 1 :
  
                  outputExtension = ".mp3"
  
                  ffmpegFilters = "-c:a libmp3lame -ac 1 -ar 22050 -q:a 9"
  
              case 2 :
  
                  outputExtension = ".mp3"
  
                  ffmpegFilters = "-c:a libmp3lame -ac 2 -ar 44100 -q:a 5"
  
              case 3 :
  
                  outputExtension = ".mp3"
  
                  ffmpegFilters = "-c:a libmp3lame -ac 1 -ar 22050 -b:a 32k"
  
              case 4:
  
                  outputExtension = ".flac"
  
                  ffmpegFilters = "-c:a flac"
  
              default :
  
                  outputExtension = ".m4b"
  
                  ffmpegFilters = "-c copy"
  
          }
  
      }
  
  }

  Then the code I use to launch ffmpeg is as follows :

  func ffmpegConvert(inputPath: String, filters: String, outputPath: String) {
  
      guard let launchPath = Bundle.main.path(forResource: "ffmpeg", ofType: "") else { return }
  
      do {
  
          let compressTask: Process = Process()
  
          compressTask.launchPath = launchPath
  
          compressTask.arguments = [
  
              "-y",
  
              "-i", inputPath,
  
              filters,
  
              outputPath
  
          ]
  
          compressTask.standardInput = FileHandle.nullDevice
  
          compressTask.launch()
  
          compressTask.waitUntilExit()
  
  
  
      }
  
  }

  Which I call when my "Start Conversion" button is clicked :

  @IBAction func startConversionClicked(_ sender: Any) {
  
      ffmpegConvert(inputPath: inputFilePath, filters: ffmpegFilters, outputPath: outputFilePath)
  
  }

  (inputFilePath and outputFilePath are strings obviously generated by other methods which appear to be working fine.)

  So it appears the only obstacle to my having a working app here is that for some reason, I’m losing that hyphen at the start of the ffmpegFilters string.

  How is that happening and what do I need to do to fix it ?

  EDIT : Having tried the basic script I’m trying to create in XCode from the Terminal, I realized I’d forgotten to take into account the fact that paths with spaces in them need to have the spaces converted to "\ ". So that may actually be the cause and the error is misleading ? Which is strange because ffmpeg gives me the exact error in Terminal so maybe not ?

  FURTHER EDIT : Upon further experimentation, I discovered it would recognize the hyphen at the beginning of the argument string as long as I used two hyphens—which I should have realized sooner because duh, mathematical operator, just like && and ==.

  But it’s still telling me Unrecognized option '-c copy' which really makes no sense, because "-c copy" is definitely a valid ffmpeg argument.

  I tried converting the file paths with the .addingPercentEncoding option, and it was still giving me the error about the argument rather than saying the file/directory being invalid, so either XCode was already passing a perfectly formatted file path string to ffmpeg, or ffmpeg is too busy complaining about the invalid argument to get around to telling me I have an invalid path.

  AND A STILL FURTHER EDIT : I’m still battering my head against this issue, because I’m convinced it’s going to be something stupid and minor. I’m just throwing things at the wall and seeing what sticks.

  I put a whitespace at the beginning of the arguments string inside my quotes for the filters argument (so it reads " -c copy" instead of "-c copy") and that seemed to make a little headway. It actually read the metadata of my input file before telling me :

  Unable to find a suitable output format for ’ -c copy’
  -c copy : Invalid argument

  Which suggests to me that the issue is that the method for stringing together all the strings might not be either putting (or not putting ?) whitespace between the adjacent strings where appropriate ?

  Because of course a whitespace needs to go between the inputFilePath string and the ffmpegFilters string. A whitespace also needs to go between the ffmpegFilters string and the outputFilePath string, but NOT between the individual components comprising the output string.

  If that’s the issue, it’s actually going to a little tough to troubleshoot at my current level of understanding, because the output path is composed of different components derived from different methods.

  This is the method I use to pull it all together, which yields a string that gets displayed in a text field, and also provides the outputFilePath I use in the ffmpegConvert process.

  func updateOutputText(outputString: String, outputField: NSTextField) {
  
      if inputFileUrl != nil && outputDirectoryUrl == nil {
  
          // derive output path and filename from input and tack on a new extension if a different output format is chosen
  
          let outputFileUrl = inputFileUrl!.deletingPathExtension()
  
          let outputPath = outputFileUrl.path
  
          outputFilePath = outputPath + "\(outputExtension)"
  
      } else if   inputFileUrl != nil && outputDirectoryUrl != nil {
  
          // derive output directory from outputBrowseButton action, derive filename from input file, and derive output extension from conversion format selection
  
          let outputFile = inputFileUrl!.deletingPathExtension()
  
          let outputFilename = outputFile.lastPathComponent
  
          let outputDirectory = outputDirectoryPath
  
          outputFilePath = outputDirectory + "/" + outputFilename + "\(outputExtension)"
  
      }
  
      outputTextDisplay.stringValue = outputFilePath
  
  }

  From the error ffmpeg kicked back this time, either there’s NOT a space between the ffmpegFilters string and the outputFilePath string, or there IS an unwanted space between the outputFilename and "\(outputExtension)" components of the outputFilePath string.

  And it’s such a strangely put together string that I’m not sure what to do if that’s the case.