StringTie is a fast and highly efficient assembler of RNA-seq alignments into
potential transcripts. The input can be the alignments of raw reads as usual;
it also accepts longer assembled sequences. The output can be processed by
downstream software including Ballgown, Cuffdiff, etc.

Citation:
Pertea et al. (2015) StringTie enables improved reconstruction of a
transcriptome from RNA-seq reads.
Nature Biotechnology 33: 290-295 doi:10.1038/nbt.3122

WWW: http://www.ccb.jhu.edu/software/stringtie/