Notes

Converting Audio Files on macOS for Renew Papyrus

Renew Papyrus Solar-Powered Audio Player
Renew Papyrus Solar-Powered Audio Player

The Renew Papyrus is a solar-powered audio player for outreach ministry among oral cultures. It has internal memory preloaded with an audio Bible and can only be changed with a special USB kit. It also plays audio from SD cards, but the audio must be in Windows Media Audio 9 format (WMA9).

I’ve had two of these audio players around for a while. They were donated for ministry, but I’ve been unable to load them with WMA audio from my macOS computer and put them to good use. Nowadays, most people here use their mobile phones and MP3 audio files on micro SD cards.

A situation had me try to get the Papyrus audio players up and running. There are new Christians in an impoverished tea plantation asking for the Bible. One man in particular, kaka (“uncle”), is eager to learn more, but is illiterate and without a mobile phone to listen to recordings on his own. That was all the motivation I needed to learn how to make work what I had available.


WMA9 is backwards compatible with previous WMA formats (like WMA2), which is helpful because it is difficult to find WMA encoding software these days for macOS. The free and open-source software Audacity can export to WMA2. To do so it needs the optional FFmpeg library (details in the Audacity manual). Audacity is the easiest way to convert audio formats. It has been handy software for me to edit audio also. It can apply a “chain” of commands to multiple files, but unfortunately, there is no command available for chains to export to WMA.

I had a folder of Bible stories in MP3 format and a much larger folder of New Testament MP3 audio from Faith Comes By Hearing. The total number of files was about 300, too many to convert in Audacity one at a time. I had to work with FFmpeg directly.

The FFmpeg library can be used on the command-line (like in the Terminal application on macOS) to export multiple files or customize the export options beyond Audacity’s capabilities. Don’t be intimidated if the command-line is new territory! It can be done in just two or three lines.

Converting to WMA

I put all of the audio files into a temporary folder for simplicity, which I called “Audio to Convert” on my Desktop. I downloaded the static build of FFmpeg for macOS and put it in the same folder (there are more FFmpeg download options). I opened the Terminal app on macOS (look for it in “Applications” → “Utilities”). I then typed the following line to change the directory (cd) to this temporary folder (you’ll need to change the path to your folder, beginning with ~ for your home folder):

cd ~/Desktop/Audio\ to\ Convert/

Then I ran the following command to convert all MP3 files to WMA at the default export options (128kpbs) with metadata preserved. You will need to change ./ffmpeg to the path of the FFmpeg download if it is not in the same folder as the audio files as I had done:

for file in *.mp3; do ./ffmpeg -i "${file}"  "${file/.mp3/.wma}"; done

Now let it run. On my computer, to convert 300 files each of about 5 minutes in length, the process took about 5 minutes.

Look at the FFmpeg documentation for custom export options. For example, you can convert from other audio formats besides MP3, or change the bit rate from 128kbps down to something like 64kbps if the kind of audio is simple like speech and small file size is important.

Copying and Ordering the Files

The Renew Papyrus will only play audio files on SD cards that are within folders. It plays audio files in the order in which they were created, which is the order in which they are copied to the SD card. This is a problem if you copy all of the files at once. The files will not copy in order but smaller files will finish copying ahead of larger files. The play order will seem to be random.

You could copy the files one at a time (all 300 of them!), pausing between each one. You have to make sure the files copy in order, otherwise you’ll need to begin copying again from the point it went wrong.

Or use the following command in Terminal do it for you. Be sure you are still in the same folder as the audio files with the cd command above. And change what follows /Volumes/... to the name of the SD card and destination folder. It will copy a file every second (sleep 1), so this will also take 5 minutes for 300 files.

for file in *.wma; do cp "${file}" "/Volumes/SD/NT/"; sleep 1; done

When the files are copied, open the destination folder in Finder, sort by creation date, and double-check the order.

I can now play the converted WMA Bible stories and New Testament on the Renew Papyrus.

There is at least one person, an “uncle” in a nearby tea plantation, who will be happy to hear.


Jan 26, 2018
Added “Copying and Ordering the Files” section