I downloaded RNASeq bam files from TCGA data portal. I am interested in the expression analysis at isofrom level and wondering how to translate these bam files into counts at each isoform. I have done some analysis at gene level using star or htseq-count but fresh to isoform analysis. Could somebody have me some suggestions. I knew there are softwares such as rMATs for alternative splicing (AS) analysis but what I wanted are the counts for each isoform rather than the AS analysis.