Making a single-file RA on a Mac with a .m4a file is broken

[joanise]

To reproduce, on a Mac:

cd test; readalongs align -o html data/ej-fra.txt  data/ej-fra.m4a -l fra delme

then open the single-file and see the screen capture at #220 (review)

Problem reproduced by @marctessier on the current main branch. We have not reproduced the problem on Windows or Linux, only on Mac.

[sergeleger]

I can replicate this on my Mac (using ffmpeg from MacPorts).

The issue is related to pydub using mp4a-latm as a default export type on macOS. This is visible in the screen capture - #220 as the declared mime-type is "audio/mp4a-latm".

Howler.js does not support this mime type.

When I edited the delme.html file, and changed the mime type to "audio/mp4" it works correctly.