Question: Which decoder are we supposed to use on parakeet-tdt_ctc-1.1b model?
That is expected, currently we don't support getting timestamps from tdt/rnnt decoder, so if you are looking for timestamps you could get through CTC, however performance with CTC decoder is a bit degraded compared to tdt decoder but shouldn't be worse. 

I have created this space that gets timestamps from CTC and combines with output from TDT, It might help for your use case. https://huggingface.co/spaces/nvidia/parakeet-tdt_ctc-1.1b Thanks for your answer, @nithinraok . Is getting timestamps from tdt decoding something that will be released later?  Unfortunately, no plans for it yet! 
The default seems to be rnnt but it fails if we specify compute_timestamps=True in decoding config. 
If I switch the decoder on this model to ctc, it works and also provides timestamps, but i see worse performace in terms of WERs.