[@Mr.Dave]
Hi, Dear. Thanks for your understanding. Your comment is the most useful one until now. Add the function of using a microphone and transcribe the audio stream will be considered. But there are already some useful and free tools in the market.
Anyway, I am looking for a “free” solution to transcribe an audio file into text. Many tools are developing some features based on the Google API but charge more money. Why not let the users have the opportunity to use the API directly just like the developers? This could not only help them boost productivity but save more money. I think it is not a bad thing.