I’ve written about using podcasts in my courses in the past, but have some recent insight.  When I record the audio, how do I convert it from the Windows-favorite of .WMA to the more widespread .MP3?  After I pull the files via USB, I have access to work with them via command line and that is my intent.  Let me share what it is that I do.

Mathematics Class Podcasts

I use an Olympus VN-6200PC to record audio in my classrooms. It records to .WMA (unprotected, of course), but MP3 is the format of choice. Using a handful of websites, I now use the script:

#! /bin/bash
# wma to mp3 script by mtron


mplayer -vo null -vc dummy -af resample=22050 -ao pcm:waveheader $1
lame audiodump.wav $2 --lowpass 15 -V 9 --vbr-new -mm -h -q 0 -B 32


rm audiodump.wav

I use mplayer to convert the .WMA files to 22.05 kHz .wav files. Then I use “lame” to convert to variable bitrate .mp3 with a max bitrate of 32 kB/s.

It works pretty well. Now, this is heavily in part to contributors at these two links:

http://stackoverflow.com/questions/2968417/compressing-voice-with-mp3
http://www.wikihow.com/Convert-Unprotected-WMA-Files-Into-MP3-Files

Conclusion

The use of the script now semi-automates the process of converting my audio from the unfriendly Windows media audio file to the MP3.  Although it creates a .WAV file, the script deletes that additional file.  The whole process is relatively quick.

If you have any questions, please leave them below in the comments section.  I look forward to reading them!

Mathematics Class Podcasts
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