FFmpeg: Subprocess arguments as list

[iLLiCiTiT]

Issue

Some versions of python (on unix) may not be able to parse subprocess arguments so they can know which part is executable and which parts are arguments. This is mainly issue of ffmpeg arguments where in most of cases use string as full command.

Goal

Pass arguments to subprocess.Popen as list instead of string.

Changes

• list of arguments is used directly everywhere where we know all arguments of the subprocess command
• added function split_command_to_list which should be able return list of arguments created from passed subprocess command
• added function path_to_subprocess_arg which decides if path should be wrapped in quotes in subprocess arguments
  • using always quotes may break split_command_to_list which can't know if quotes are intended or not
• use split_command_to_list where subprocess arguments may not be known (where use settings values etc.)
• use path_to_subprocess_arg for all path arguments in subprocess commands where split_command_to_list is used

How to test

• this should be heavily tested on windows and linux
• ideally all modified plugins
• use paths where spaces are used (ffmpeg path, input or output)

[hound]

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