Turbo Rom format is now supported. The most important part is making a proper dump of tape to audio file. Conversion works fine for good quality dumps. See examples.
Highpass filter is now optional. It breaks things too often.
Added highpass filter for all turbo formats. It centers signal towards level 0, thus allowing more amplification without loosing information. Conversion from audio to cas/hex can be more reliable now. Cutoff frequency is specific for every format.
Resonant lowpass filter can now be used for all turbo formats. Cutoff frequency is specific for every format. This filter amplifies narrowest impulses (usually they are also weakest) and blocks some of high frequency noise.
Support for Turbo Rom slowly improves.
ToDo list
support for more turbo formats (appropriate tape dumps and Atari utilities needed)
automatic recognition of tape format (standard/turbo/type of turbo) in audio files (probably beyond my skills)