Lightweight and does what you need
I’ve looked at and used a lot of Mac transcription software (what can I say, I’m a cheap grad student). My previous tool is now a little expensive for what you get. Transcriptions is an excellent replacement, and it’s what I’ll be recommending from here on out. It does what you need — timecodes, speed control, text substitutions — with very little interface bloat. Yay! My one request is for a frame capture function so I can grab stills of important moments.
esgoodman about Transcriptions