bool multichannel_mapping_mode = false; // Implicitly true if input_mapping_filename is nonempty.
std::string input_mapping_filename; // Empty for none.
std::string midi_mapping_filename; // Empty for none.
bool multichannel_mapping_mode = false; // Implicitly true if input_mapping_filename is nonempty.
std::string input_mapping_filename; // Empty for none.
std::string midi_mapping_filename; // Empty for none.