This recipe is the speaker diarization recipe for The First DIHARD Speech
 Diarization Challenge (DIHARD 2018). There are two tracks in the DIHARD 2018 
 competition , one uses oracle SAD (track1) and the other required that SAD 
 was performed from scratch (track2). This script is for track1.

 The recipe is closely based on the following paper:
 http://www.danielpovey.com/files/2018_interspeech_dihard.pdf but doesn't
 contain the VB refinement. The whole system mainly contains full-covariance
 GMM-UBM, i-vector extractor (T-matrix), PLDA scoring and agglomerative 
 hierarchical clustering. The VoxCeleb datasets are used for training i-vectors 
 and PLDA. The development set of the DIHARD 2018 competition is used as 
 validation set to tune parameters. The system is tested on the DIHARD 2018 
 evaluation set.