With Google Speech API you can convert speech to text file based or live stream
The https://cloud.google.com/speech/ and is part of https://cloud.google.com/products/ to allow for speech to text conversion.
When using a live stream words are returned almost realtime. This is limited by 1 minute or when paused for ~1 second. When using an asynchronous file the speech to text can be as long as 80 minutes. See https://cloud.google.com/speech/limits
For more see https://cloud.google.com/speech/docs/