Populating ModelForm hidden FileField with audio recording captured in browser

I am trying to capture a user-generated audio recording in browser (using the MediaRecorder API) and use the generated audio file to fill out a hidden field in a ModelForm. Could anyone suggest the best way of going about this?

I don’t know what would be “best”, but if I were tasked to do something like this, I’d submit it as if it were a file upload in the post data. (My second choice would be to convert it to base64 and submit it as a large text area field.)

Depending upon the size of the expected recording, I might also consider setting up a separate endpoint, and sending in chunks of data while the recording is taking place.