The metamodel presented in this Thesis is the result of our work in developing the CLAM framework, which will be presented in next chapter. As already mentioned, developing a framework or any other kind of environment needs an activity of, either implicitly or explicitly, building a model for a particular application or a domain metamodel that will then be instantiated through different models.
As it will be detailed in next chapter, CLAM was not developed as an intellectual exercise in order to find a good metamodel. Rather it evolved iteratively to user requirements until the metamodel emerged. Because of this development process not much attention was payed to already existing environments, only a first brief study was enough to determine that no existing environment offered what was about to be developed.
Nevertheless, once the metamodel is stable enough, it is important to carefully review all the different existing environments in order to extract commonalities and highlight whether CLAM and its metamodel represent an innovative approach. In this chapter we will review a great number of audio and music processing environments, many of them with different initial requirements and even different focus. Due to space limitation it is not possible to give a thorough review of each environment, instead we intend to give a brief conceptual introduction and provide references for further information.