Record display, webcam and pulseaudio using ffmpeg

ffmpeg-grab-cam-display.sh

#!/bin/sh

# 1. create v4l2loopback device /dev/video42 using
#    $ sudo modprobe v4l2loopback video_nr=42 max_buffers=2 exclusive_caps=1

ts=$(date +%Y-%m-%dT%H:%M:%SZ-%s)

PREFIX=/mnt/data/Videos

CAMERA_INPUT=/dev/video0
CAMERA_LOOPBACK=/dev/video42
CAMERA_OUTPUT="${PREFIX}/cap-${ts}/${ts}-camera.mp4"
DISPLAY_OUTPUT="${PREFIX}/cap-${ts}/${ts}-display.mp4"
DISPLAY_OFFSET=2560
DISPLAY_SIZE=2560x1440

[ -z "$DISPLAY" ] && {
    echo 'ERROR: Environment variable DISPLAY is not set' 1>&2
    exit 1
}

mkdir -p "${PREFIX}/cap-${ts}"

exec ffmpeg \
    -hide_banner \
    -y \
    -hwaccel cuda \
    -vsync cfr \
    -f v4l2 \
      -thread_queue_size 512 \
      -video_size 1920x1080 \
      -input_format mjpeg \
      -framerate 30 \
      -i $CAMERA_INPUT \
    -f x11grab \
      -thread_queue_size 512 \
      -video_size $DISPLAY_SIZE \
      -i $DISPLAY+$DISPLAY_OFFSET \
    -f pulse \
      -thread_queue_size 512 \
      -i default \
    -map 0 \
    -map 2 \
      -c:v hevc_nvenc \
      -c:a libfdk_aac \
      -movflags +faststart \
      $CAMERA_OUTPUT \
    -map 1 \
    -map 2 \
      -c:v hevc_nvenc \
      $DISPLAY_OUTPUT \
    -map 0 \
      -c:v rawvideo \
      -f v4l2 \
      -pix_fmt yuv420p \
      $CAMERA_LOOPBACK