I'm experimenting with using the 
Logitech c920 webcam on Pine 64 with 2GB of RAM. I tried different Android images and I got some interesting results.
android-ver5.1.1-20161208-pine64-32GB.img.gz:
- camera works fine with Hangouts
- video message works in Skype, but calling drops the video after a few seconds
- the microphone doesn't work in any app, looks like it's missing the kernel driver for USB audio 
snd_usb_audio
The list of sound cards is missing the USB sound device:
Code:
# cat /proc/asound/cards                                   
 0 [audiocodec     ]: audiocodec - audiocodec
                      audiocodec
 1 [sndhdmi        ]: sndhdmi - sndhdmi
                      sndhdmi
The 
snd_usb_audio was not build-in and was not available as a module:
Code:
# lsmod | grep snd_usb_audio
# ls /sys/module/ | grep snd_usb_audio
:
- Skype video message works, Skype call and Hangouts doesn't
- microphone doesn't work, although it has the kernel USB audio driver build-in
The USB sound card is present:
Code:
# cat /proc/asound/cards 
 0 [C920           ]: USB-Audio - HD Pro Webcam C920
                      HD Pro Webcam C920 at usb-sunxi-ehci-1, high speed
 1 [audiocodec     ]: audiocodec - audiocodec
                      audiocodec
 2 [sndhdmi        ]: sndhdmi - sndhdmi
                      sndhdmi
 and 
android-7.0-pine-a64-tv-v1.11.0-r67.img.gz:
- no Skype video message, no Hangouts video
- microphone doesn't seem to work, even though it has the necessary kernel USB audio driver build-in
android-7.1-pine-a64-v0.1.1-r2.img.gz
- video doesn't work at all
- microphone works, it has the kernel USB audio driver build-in
I've also fiddled around with the following files:
- 
/system/etc/camera.cfg - contains the configuration of the cameras
- 
/system/etc/audio_policy.conf - contains the configuration of the audio stack
Let me know if you have other suggestions.