The software you can use is Vosk-api, a modern speech recognition toolkit based on neural networks. It supports 7+ languages and works on variety of platforms including RPi and mobile.
First you convert the file to the required format and then you recognize it:
ffmpeg -i file.mp3 -ar 16000 -ac 1 file.wav
Then install vosk-api with pip:
pip3 install vosk
Then use these steps:
git clone https://github.com/alphacep/vosk-api
cd vosk-api/python/example
wget https://alphacephei.com/kaldi/models/vosk-model-small-en-us-0.3.zip
unzip vosk-model-small-en-us-0.3.zip
mv vosk-model-small-en-us-0.3 model
python3 ./test_simple.py test.wav > result.json
The result will be stored in json format.
The same directory also contains an srt subtitle output example, which is easier to evaluate and can be directly useful to some users:
python3 -m pip install srt
python3 ./test_srt.py test.wav
The example given in the repository says in perfect American English accent and perfect sound quality three sentences which I transcribe as:
one zero zero zero one
nine oh two one oh
zero one eight zero three
The "nine oh two one oh" is said very fast, but still clear. The "z" of the before last "zero" sounds a bit like an "s".
The SRT generated above reads:
1
00:00:00,870 --> 00:00:02,610
what zero zero zero one
2
00:00:03,930 --> 00:00:04,950
no no to uno
3
00:00:06,240 --> 00:00:08,010
cyril one eight zero three
so we can see that several mistakes were made, presumably in part because we have the understanding that all words are numbers to help us.
Next I also tried with the vosk-model-en-us-aspire-0.2 which was a 1.4GB download compared to 36MB of vosk-model-small-en-us-0.3 and is listed at https://alphacephei.com/vosk/models:
mv model model.vosk-model-small-en-us-0.3
wget https://alphacephei.com/vosk/models/vosk-model-en-us-aspire-0.2.zip
unzip vosk-model-en-us-aspire-0.2.zip
mv vosk-model-en-us-aspire-0.2 model
and the result was:
1
00:00:00,840 --> 00:00:02,610
one zero zero zero one
2
00:00:04,026 --> 00:00:04,980
i know what you window
3
00:00:06,270 --> 00:00:07,980
serial one eight zero three
which got one more word correct.
Tested on vosk-api 7af3e9a334fbb9557f2a41b97ba77b9745e120b3.
Best Answer
Check out Google2Ubuntu.
It comes with a pretty nifty interface, which you can use to define your own commands, etc. Here's a demo.