Convert audio (wav file) to text using SAPI?

Question

My task is to convert an Audio file not from Direct Speech from Human into text.

e.g If I have "Hello there" store in wav file to it will transcribe it into text and show "Hello there" string on screen.

Any language code in preferred but priority is C#.

Answer 1

SAPI can certainly do what you want. Start with an in-proc recognizer, connect up your audio as a file stream, set dictation mode, and off you go.

Now the disappointing bit. You probably won't get terribly good results; in fact, I suspect that unless you're very lucky, you'll probably get total garbage.

There are several problems:

1. Dictation really only works well once the SR engine has been trained. If you're lucky (like me), you can get OK results, but if the speaker has an accent, training is a must.
2. Training only works well for a single voice. If you've got multiple speakers in a single audio file, it's not going to work well.
3. The audio model for dictation (and Speech Recognition in general) assumes that you're using a close-talk microphone (i.e., a microphone right next to your face, to minimize noise pickup). If your WAV files have extra noise, accuracy will go down dramatically.

Dragon Naturally Speaking Professional has support for transcription, but it still requires training and a single voice. (I do believe that DNS has a custom audio model that works well for voice recorders.) I haven't used it myself, so I don't know how well it would work in your situation.

Now, if you are looking for specific keywords, other people have had success using "Audio Mining" - running the recognizer looking for a specific keyword on an audio stream