lame is in Universe repository. So you have to first enable universe repository.
See this question → How do I enable the "Universe" repository?
Then install lame by the below using commands in a terminal. To open a terminal press Ctrl + Alt + T.
sudo apt-get update
sudo apt-get install lame
Then navigate to the directory by using
cd command to the folder you have the file to convert it. I assume your file is in Desktop directory and it's name is
001.mp3. We also assume your input file is of 128kbps and you want an output file of 32kbps. So, use these commands to compress it
lame -b 32 001.mp3 001-32.mp3
You can use any name for the output file other than the same name as input file which is in this case 001.mp3.
Note that, the conversion will use fixed bitrate as opposed to variable or average bitrate.
See the lame manual page for more help.
If you prefer graphical tools to do this, I suggest you a small and simple tool to do so. It is soundconverter.
Install it with this link → soundconverter or using this command in terminal
sudo apt-get install soundconverter
Open it by searching in Dash with term "soundconverter". To bring Dash, Press Super key which is also known as Windows key.
When it opened, Press the **Add File* button in it's toolbar, and select the file you want to convert.
Then go to Edit → Preference from menu. In Type of result select mp3 and select a quality.
- Very low = 64 kbps
- Low = 96 kbps
- Normal = 128 kbps
- High = 192 kbps
- Very high = 256 kbps.
I think, you should select "Very low" or "Low" depending on your needs. Then click close.
Click Convert button in toolbar to convert it.
That's it. Your file will be converted and stored in the same directory as the input file. You can also change the directory for output folder in Preference Window.