Feature: Downmix Stereo-Input to Mono

Platform: macOS 10.13.4 Kap Version: 2.1.2.777

Steps to reproduce

Use a two-channel audio interface and plug in a mono microphone into it. Leave the second input unused. Then record the screen using Kap and speak some instructions/explanations into your microphone.

Current behaviour

Kap will record your audio using both Input 1 and 2, which results in only the left channel being audible, because in the right channel there has not been any input during recording; the input was unused.

Expected behaviour

Add an option to pan both channels of a stereo-interface to center, overlapping them. This way, it doesn’t matter whether you plug in your microphone into channel 1 or 2, because one of them will be silent, but won’t be noticable because the other channel is also panned to center and will fill out both channels.

Workaround

Using such a setup it’s only possible by loading the rendered video into a DAW such as ProTools or CuBase and downmix the stereo-mix to a mono-mix, and then re-export it.

My setup

My setup currently consists of the Behringer UMC 202 HD USB audio interface, recording is done via a mono condenser microphone using channel 1 of the interface. The selection of the audio interface is done using the Kap internal selector.

To get an idea of how strange this sounds, have a look at this video: https://www.youtube.com/watch?v=vStbtF4_grE

[albinekb]

@skllcrn what about adding an option in the settings under the audio input section with something like “mix mono to stereo” and a checkbox?

[albinekb]

I think we could detect mono audio with ffprobe or even before we start recording inside Aperture (the swift stuff might be able to, cc @sindresorhus) and then downmix the one channel to stereo when converting with ffmpeg 🤔 👍