Multiple Stream Systems

The specification of the base-class components are given in terms of the Gaussian component. In HTK this is specified for a particular stream of the HMM state. When multiple streams are used there are two situations to consider^9.4.

First, if the streams have the same number of components, then transforms may be shared between different streams. For example it may be decided that the same linear transform is to be used by the static stream, the delta stream and the delta-delta stream.

Second, if the streams have different dimensions associated with them. For this case the root node is a special node for which a transform cannot be generated. It is required to partition the Gaussian components so that all subsequent nodes have the same dimensionality associated with them.