Does any one know of an application that can convert audio to text? I'm running ubuntu 12.04 LTS.
The software you can use is CMUSphinx. Unlike suggested in another answer Julius is not suitable because it requires models. Models for large vocabulary speech recognition are not available for Julius.
You can use pocketsphinx to convert audio file. Those two commands must do the work. First you convert the file to the required format and then you recognize it:
ffmpeg -i file.mp3 -ar 16000 -ac 1 file.wav
The run pocketsphinx
pocketsphinx_continuous -infile file.wav 2> pocketsphinx.log > result.txt
Result will be stored in result.txt.
I you are looking to convert speech to text you could try opening up your Ubuntu Software Center and search for Julius
"Julius" is a high-performance, two-pass large vocabulary continuous speech recognition (LVCSR) decoder software for speech-related researchers and developers.
Or another option that isn't in the Software Center is Simon
... is an open-source speech recognition program and replaces the mouse and keyboard.
I know this is old, but to expand on Nikolay's answer and hopefully save someone some time in the future, in order to get an up-to-date version of pocketsphinx working you need to compile it from the github or sourceforge repository (not sure which is kept more up to date). Note the -j8 means run 8 separate jobs in parallel if possible; if you have more CPU cores you can increase the number.
git clone https://github.com/cmusphinx/sphinxbase.git cd sphinxbase ./autogen.sh ./configure make -j8 make -j8 check sudo make install cd .. git clone https://github.com/cmusphinx/pocketsphinx.git cd pocketsphinx ./autogen.sh ./configure make -j8 make -j8 check sudo make install cd ..
Then, from: https://sourceforge.net/projects/cmusphinx/files/Acoustic%20and%20Language%20Models/US%20English/
download the newest versions of
tar -xzf cmusphinx-en-us-....tar.gz gunzip en-70k-....lm.gz
Then you can finally proceed with the steps from Nikolay's answer:
ffmpeg -i book.mp3 -ar 16000 -ac 1 book.wav pocketsphinx_continuous -infile book.wav \ -hmm cmusphinx-en-us-8khz-5.2 -lm en-70k-0.2.lm \ 2>pocketsphinx.log >book.txt
Sphinx works alright. I wouldn't rely on it to make a readable version of the text, but it's good enough that you can search it if you're looking for a particular quote. That works especially well if you use a search algorithm like Xapian (http://www.lesbonscomptes.com/recoll/) which accepts wildcards and doesn't require exact search expressions.
Hope this helps.