View source for Google Voice Recognition

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Return to Google Voice Recognition.

Personal tools

Convert an Audio-File into text file via voice recognition.

NOTE: The shell script mentioned below can be used on any Linux-Operating System with some software requirements, because the speech recognition is not performed on the local machine.

Because the performance of your Freerunner is too poor for voice recognition, the Google Voice API can be used to convert an recorded Audio file into a text file. Be aware that the audio file will be transmitted to Google and the recognition is not performed on FR. This implies, that you need to have Internet access on your freerunner FR to submit the audio file.

NOTE: You must be aware of the fact, that the follow script is running on your freerunner but it is not a standalone voice recognition software and so you might not want to use this tool for private audio files.

Google Voice API

For using the Google Voice API and the script you need to have the following package installed on your freerunner:

Install the packages from the repositories of the freerunner Distributions.

Script Usage

  • The script uses a the audio file message.wav in the directory of the script. All files are stored in the same directory, so you need write permissions for that directory.
  • SoX converts message.wav into message.flac
  • wget submits the file message.flac to the Google Voice API and writes the return message to message.ret. The language variable in the script is set to German by lang=de-de. If you want to submit a recorded file in US-English use lang=en-us instead.
  • SED extracts the recognized text message.ret by regular expressions and writes the text into message.txt.
  • Temporary files message.flac and message.ret will be deleted after the process.
NOTE: The return code of German audio files needs capitalization of nouns, because all words are return in small caps. A ispell or aspell correction of the message.txt might improve the recognized text.

Basic Script Code

The script code can be tested on any Linux machine with SoX, SED, WGET installed. Modifiy the script according to your demands and storage of your audio files

 echo "1 SoX Sound Exchange - Convert WAV to FLAC with 16000" 
 sox message.wav message.flac rate 16k
 echo "2 Submit to Google Voice Recognition"
 wget -q -U "Mozilla/5.0" --post-file message.flac --header="Content-Type: audio/x-flac; rate=16000" -O - "" > message.ret
 echo "3 SED Extract recognized text" 
 cat message.ret | sed 's/.*utterance":"//' | sed 's/","confidence.*//' > message.txt
 echo "4 Remove Temporary Files"
 rm message.flac
 rm message.ret
 echo "5 Show Text "
 cat message.txt

The parameter lang=de-de is indicating, that the Google Voice API is expecting a German language audio file. Replace lang=de-de by lang=en-us to submit an audio file in US-English.

Script with Language Setting and Command Line Parameter

The script with a command line parameter can be used if you want to use multiple input files for batch file recognition. You will call this script with the basename e.g. message0, message1,... by

  • message0 converts message0.wav into message0.txt
  • message1 converts message1.wav into message1.txt
  • message2 converts message2.wav into message2.txt
  • ....
 echo "1 SoX Sound Exchange - Convert $1.wav to $1.flacC with 16000" 
 sox $1.wav $1.flac rate 16k
 echo "2 Submit to Google Voice Recognition $1.flac"
 wget -q -U "Mozilla/5.0" --post-file $1.flac --header="Content-Type: audio/x-flac; rate=16000" -O - "${LANGUAGE}&client=chromium" > $1.ret
 echo "3 SED Extract recognized text" 
 cat $1.ret | sed 's/.*utterance":"//' | sed 's/","confidence.*//' > $1.txt
 echo "4 Remove Temporary Files"
 rm $1.flac
 rm $1.ret
 echo "5 Show Text "
 cat $1.txt

Future Development

Google API will always need internet access like other speech recognition application for smart phones.

NOTE: Also other Speech recognition apps on Android (FlexT9) or on the iPhone (Dragon Natural Speaking for iPhone) are performing the transcription of an audio sample on the server and returning the transcript to the client mobile phone. That has to be done because of the limitations of the hardware on a mobile phone. This will improve in the future.

In analogy to the commercial apps for the development of OpenSource standalone Software on Linux it might be good to have an OpenSource-Webinterface or an Android app to collect Audio Samples for improving the user independent Speech Recognition Profiles HMM for Speech Recognition of large vocabulary and different languages.

  • Users will get the speech recognition result on the freerunner or any other linux box,
  • The can correct the speech recognition result (transcript) and submit the correction back to the server
  • By the Audio-File-Submit and Text-File-Return of a server based speech recognition the Open Source Speech Recognition on Linux can be improved.