Logitech C615 Web Cam: https://amzn.to/2Vnqf94 (Amazon Affiliate)
FFmpeg Web Cam Capture Notes
https://trac.ffmpeg.org/wiki/Capture/Webcam
View Live Web Cam
ffplay -f avfoundation -framerate 30 -video_size 1920x1080 -i "HD Webcam C615" -pixel_format uyvy422 -vf hflip
Capture Web Cam Screenshot
ffmpeg -f avfoundation -framerate 30 -video_size 1920x1080 -i "HD Webcam C615" -pixel_format uyvy422 -vf hflip -f image2 -frames:v 1 screencapture.jpg
Overlay Transparent PNG on Live Video
ffplay -f avfoundation -framerate 30 -video_size 1920x1080 -i "HD Webcam C615" -pixel_format uyvy422 -vf "[in]hflip[vid],movie=screencapture.png[over],[vid][over]overlay[out]"