Screen capture with audio and webcam overlay with microphone using ffmpeg

capture.sh

# $ pacmd list-sources|awk '/index:/ {print $0}; /name:/ {print $0}; /device\.description/ {print $0}'
#    index: 0
#        name: <alsa_output.pci-0000_00_02.0-platform-hdmi-lpe-audio.stereo-fallback.monitor>
#                device.description = "Monitor of Atom Processor Z36xxx/Z37xxx Series Graphics & Display Stereo"
#    index: 1
#        name: <alsa_output.platform-bytcr_rt5640.HiFi__hw_bytcrrt5640__sink.monitor>
#                device.description = "Monitor of Built-in Audio MonoSpeaker playback + Speaker playback + Headphones playback"
#  * index: 2
#        name: <alsa_input.platform-bytcr_rt5640.HiFi__hw_bytcrrt5640__source>
#                device.description = "Built-in Audio Internal IN3 analog Mic capture + Internal IN1 analog Mic capture + Headset Mic capture + DigitalMics capture"

# Single merged output stream for both Pulseaudio and Mic.
ffmpeg -f x11grab -thread_queue_size 64 -video_size 1366x768 -framerate 30 -i :0 \
       -f v4l2 -thread_queue_size 64 -video_size 320x180 -framerate 30 -i /dev/video0 \
       -f pulse -i alsa_output.platform-bytcr_rt5640.HiFi__hw_bytcrrt5640__sink.monitor \
       -f pulse -i alsa_input.platform-bytcr_rt5640.HiFi__hw_bytcrrt5640__source \
            -acodec aac -strict experimental \
       -filter_complex 'overlay=main_w-overlay_w:main_h-overlay_h:format=yuv444' \
       -filter_complex amerge \
       -vcodec libx265 -preset ultrafast -qp 0 -pix_fmt yuv444p \
       video.mkv

# Two audio streams - one for Pulseaudio and one for Mic.
ffmpeg -f x11grab -thread_queue_size 64 -video_size 1366x768 -framerate 30 -i :0 \
       -f v4l2 -thread_queue_size 64 -video_size 320x180 -framerate 30 -i /dev/video0 \
       -f pulse -i alsa_output.platform-bytcr_rt5640.HiFi__hw_bytcrrt5640__sink.monitor \
       -f pulse -i alsa_input.platform-bytcr_rt5640.HiFi__hw_bytcrrt5640__source \
            -map 2:0 -map 3:0 -acodec aac -strict experimental \
       -metadata:s:a:0 title="Pulseaudio" \
       -metadata:s:a:1 title="Mic" \
       -filter_complex 'overlay=main_w-overlay_w:main_h-overlay_h:format=yuv444' \
       -vcodec libx265 -preset ultrafast -qp 0 -pix_fmt yuv444p \
       video.mkv

# Three audio streams - one for Pulseaudio and one for Mic, and third with previous two merged.
ffmpeg -f x11grab -thread_queue_size 64 -video_size 1366x768 -framerate 30 -i :0 \
       -f v4l2 -thread_queue_size 64 -video_size 320x180 -framerate 30 -i /dev/video0 \
       -f pulse -i alsa_output.platform-bytcr_rt5640.HiFi__hw_bytcrrt5640__sink.monitor \
       -f pulse -i alsa_input.platform-bytcr_rt5640.HiFi__hw_bytcrrt5640__source \
       -acodec aac -strict experimental \
       -map 2:0 -map 3:0 -map '[a]' \
       -filter_complex 'overlay=main_w-overlay_w:main_h-overlay_h:format=yuv444' \
       -filter_complex 'amerge=inputs=2[a]' \
       -metadata:s:a:0 title="Pulseaudio" \
       -metadata:s:a:1 title="Mic" \
       -metadata:s:a:2 title="Pulseaudio & Mic" \
       -vcodec libx265 -preset ultrafast -qp 0 -pix_fmt yuv444p \
       video.mkv

############################################
# Personally for my 1920x1080 lappy:
ffmpeg -f x11grab -thread_queue_size 256 -probesize 42M -video_size 1920x1080 -framerate 30 -i :0 \
       -f v4l2 -thread_queue_size 128 -video_size 320x240 -framerate 30 -i /dev/video0 \
       -f pulse -thread_queue_size 3072 -i alsa_output.pci-0000_00_1f.3.analog-stereo.monitor \
       -f pulse -thread_queue_size 512 -i alsa_input.pci-0000_00_1f.3.analog-stereo \
            -acodec aac -strict experimental \
       -filter_complex 'overlay=main_w-overlay_w:main_h-overlay_h:format=yuv444' \
       -filter_complex amerge \
       -vcodec libx265 -preset superfast -qp 0 -pix_fmt yuv444p \
       video.mkv