Abstract

ion. However, they are not actually abstract data types. Far from it, all HTK data types are very concrete. The full definition of each type is visible outside of the module that defines it and the program which uses that type is free to manipulate its innards. Thus, from a software engineering perspective, the construction of HTK is unsafe since it is all too easy for an external agent to corrupt the internal operation of a module. Furthermore, it is necessary for an external agent to have a detailed understanding of each library module data type in order to use it effectively. Again, the HMMDef type provides a good example since this type represents a large hierarchical structure which HTK tools need to traverse and manipulate. To do this they have to access and manipulate the structure directly and since it is complex, this kind of operation will be prone to error. There are several reasons why HTK has been constructed like this. Firstly, and perhaps most importantly, it is very har...

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