Problem with audio playback in events on Firefox

[nrbell]

I'm using Zoneminder 1.32.2 from the Ubuntu master PPA and I recently bought a Hikvision DS-2CD2442FWD-IW. It has audio input and the audio is working perfectly with Zoneminder. I have noticed, however, that the audio is not present when playing events in Firefox. The audio control on the video player is turned up. It works with Chrome and Chromium, on both Linux and Windows. Is this a known problem? Is it just some sort of Firefox limitation?

Here are the versions I'm using:

Ubuntu Linux 18.04

• Firefox: 63.0.3

• Chrome: 70.0.3538.77

• Chromium: 70.0.3538.77

Windows 7

• Firefox: 63.0.3

• Chrome: 70.0.3538.110