Tag Archives: foss

foss (post_tag auto created by Wordpresser)

Converting M4B to MP3 and splitting MP3 files

As I was getting some audio-books ready for listening on the road, using an old car-stereo system, I quickly found out that M4B files would not work, while MP3 content would be recognized, up to 320 kbps.

In order to convert M4B to MP3, the superb free and open source ffmpeg software, as expected, did the job at first attempt, with zero surprises: as with the vast majority of situations, all it was required was to explicitly state input and output files. I also was explicit regarding the audio coded (acodec) to be “libmp3lame”.

Here is the the full command-line (CLI) command I used:

ffmpeg -i audiobook.m4b -acodec libmp3lame audiobook.mp3

Some documentation here:

But another problem was on the cards: this old car stereo only recognizes FAT32 USB devices and sometimes forgets where in the MP3 file a listener stops listening. This can be very inconvenient: if the player loses tracks of where to resume, then it resumes at the absolute file start. Moreover, the MP3 player only provides file-based navigation, which means one can only go to next/previous file/track, but can NOT browse inside a specific file/track.

This, of course, is unacceptable for long MP3 audio-books, so I had to find a way to split a big original MP3 file in smaller partials, that would be browsable without much frustration, should a player memory glitch happen.

For the splitting, I used another free and open source tool: “MP3SPLT”.
More about it, here:

Here is the the full command-line (CLI) command I used to organize the book in 5 minutes chapters:

mp3splt.exe audiobook.mp3 -t 5.0

That was it, everything is ready for the road.

How to download courses from Coursera, in 2021

To download COURSERA.ORG courses one subscribes to, either one writes its own bot, which will have to solve the authentication challenge and be able to crawl, identify and fetch all the relevant course files, or one learns to use the “COURSERA-DL” free and open source project (FOSS), mostly written in the language Python, available from:

The first option is great for learning the correspondent skills, but it is hard work.

The second option is immediately available and is much more sensible for instantaneous results, mainly for those who are only focused in getting the course materials, for offline studying.

This post is about installing and using COURSERA-DL. The post assumes “Python” is properly installed. The commands shown were tested on a Python installation on Windows 10.

To install or update COURSERA-DL, the following sequence of commands will work. Enter the commands from any command-line console (CMD.EXE on Windows). Even if COURSERA-DL is already installed, it will remain so, keeping its configuration, and it will only be updated. The commands go a bit beyond COURSERA-DL, because I also care about EDX courses.
One project similar to COURSERA-DL is EDX-DL, for courses at EDX.ORG. Both learning sites have materials on YOUTUBE.COM, so yet another related FOSS is YOUTUBE-DL.

python -m pip install --upgrade pip
pip install --upgrade coursera-dl
pip install --upgrade edx-dl
pip install --upgrade youtube-dl

Once these FOSS solutions are made available on the system, they can be called from the command-line.

To know the technical name of a COURSERA.ORG course, pay attention to its URL, when learning in a browser session. For example, when starting to learn the Coursera course named “Build a Modern Computer From First Principles”, the URL is

The technical name is “build-a-computer“, i.e., the string after “https://www.coursera.org/learn/” and before the subsequent forward-slash (“/”). This parsing rule should work for any course.

To download a COURSERA.ORG course named “XPTO”, logging-in as “user@email.com”, having password “1234”, in theory, it should suffice to launch a command-line window (CMD.EXE on any Windows) and enter:

coursera-dl -u "user@email.com" -p "1234" "XPTO"

These days, this will probably FAIL, due to the introduction of CAPTCHAS which defeat many bots.

As of February 2021, COURSERA-DL does NOT defeat the COURSERA CAPTCHA, about picking images which solve some challenge. Defeating CAPTCHAs can be quite a project on its own, so it is understandable that this is happening. The workaround is easy, but not automatable.

For each COURSERA.ORG course you are subscribed to, when you use a web browser to learn it, a cookie named “CAUTH” for domain “.coursera.org” is created on the local computer. In my case, I always use Firefox and the extension “cookie quick manager”, to see the cookies for domains. Using that extension, or equivalent, just observe, text-select, and copy the string value for the CAUTH cookie, which can be a long string (hundreds of chars).

Then, provide the value of that string upon calling COURSERA-DL:

coursera-dl -u "user@email.com" -p "1234" "XPTO" -ca "hundreds of chars go here"

That is it.
For a better workflow, find the folder where the Python script for coursera-dl is; i.e. search for the local file “coursera-dl.py“.

If you have Python installed at


the file will be at


In the scripts folder, create a NEW text file named “coursera.conf“, consisting of the sensitive data and other eventual arguments you can learn about by reading COURSERA-DL’s documentation.

For example:

-u "user@email.com" -p "1234" --subtitle-language en --download-quizzes

The text above is the content inside the text file “coursera.conf“, saved in the same folder that contains the coursera-dl.py script.

Now, to download course “XPTO”, just do:

coursera-dl "XPTO" -ca "hundreds of chars go here"