Converting my blog posts to audio files

Yesterday, I discovered the say command on my Mac. Its aim is to convert text to audible speech and that works really well. Then, I had the idea of creating audio files from my blog posts because (1) it’s fun and (2) it could possibly improve accessibility on this website.

The say command generates aiff audio files but that isn’t supported by the audio HTM5 tag. I converted the aiff files to mp3 using the well-known ffmpeg tool.

Please welcome Speaker, my fun work from last evening! Speaker aims to convert my blog posts written in markdown to mp3 files. It is a tiny shell script I enjoyed writing.

USAGE:
  ./speaker [-h] [-d <output directory>] <filename>

I used roundup to test it. I love shell scripts but writing them without any tests is a pain, there is often a condition that is not good, a typo, or something else. That often makes me crazy… Well, problem solved with roundup! Here is my test suite output:

$ ./speaker-test.sh
speaker
it_shows_help_with_no_argv:                      [PASS]
it_shows_help_with_h_option:                     [PASS]
it_creates_mp3_file:                             [PASS]
it_creates_mp3_file_in_existing_directory:       [PASS]
it_creates_mp3_file_in_new_directory:            [PASS]
=========================================================
Tests:    5 | Passed:   5 | Failed:   0

To sanitize the text to speech, I used some regular expressions. It probably needs some improvements but it works pretty well:

# Sanitize markdown content
content=`echo "$content" | sed -e 's/[\*_]//g'`
content=`echo "$content" | sed -e 's/\[\(.*\)\](\(.*\))/\1/g'`
content=`echo "$content" | sed -e 's/:[p|D]/./g'`
...

For the other parts, you can take a look at the code :)

Because I wanted to expose these audio files on this website, I tweaked the template to integrate an audio tag. I also used html5media to render this tag in all major browsers (I don’t know if there is a better solution).

<audio src="/mp3/my-blog-title.mp3" controls preload></audio>

Last, to automagically generate audio files, I wrote a pre-commit script to build the audio file when I commit blog posts.

That’s all folks!