x11grab script: Screen record your desktop and audio sources with `ffmpeg` FOR FREE!

x11grab.sh

#!/bin/bash

# Usage:
#
#    AVOUTFILE=screecap.mkv x11grab
#
# Records the screen, the output to the speakers and whatever your default mic recording device is.
# After starting the record, you can toggle which input is recorded with the GUI interface: `pavucontrol`
# or direct this with $PULSE_MIC_SOURCE
# Use `pactl list sources` to list the available sources.


if [ -n "$DEBUG" ]; then
  set -x
fi
FFMPEG=${FFMPEG:-"ffmpeg -hide_banner"}

#####! BEGIN: Configuration Section !#####

# 0-index of which screen to capture on the $DISPLAY
SCREEN=${1:-0}

# The "$W,$H" factor for the offset. What's the offset of the X,Y anchor for the top-left to start recording?
OFFSET=${OFFSET:-${2:-0,0}}

# This was more relevant on a computer with 2 monitors. If you have >1 display, you can include them in this list.
SCREENS=(
'0,0'
)

# If the sizes of the displays are different, you can indicate them here.
SIZES=(
1920x1080
1920x1080
)

# Monitor the output sent to the speakers by using Pulse audio monitor.
PULSE_AUDIO_SOURCE=${PULSE_AUDIO_SOURCE:-alsa_output.pci-0000_00_1f.3.analog-stereo.monitor}
PULSE_MIC_SOURCE=${PULSE_MIC_SOURCE:-alsa_input.usb-Focusrite_Scarlett_2i2_USB_Y8AN6AE31F77B4-00.analog-stereo}

# Set the video and audio codecs to be used in the output.
ACODEC=${ACODEC:-aac}
# h264 is normal CPU; h264_nvenc is NVIDIA GPU-based encoder.
VCODEC=${VCODEC:-h264_nvenc}

# Output file.
AVOUTFILE=${AVOUTFILE:-/tmp/`date +%F`_x11grab.mkv}

# Size of the screen.
SIZE=${SIZE:-${SIZES[$SCREEN]:-$3}}
# Offset is how many pixels from the top-left corner of the screen to offset before capturing the screen.
# NOTE: ffmpeg will complain if you indicate a size that is larger than the screen size.
OFFSET=${OFFSET:-$SIZES[0]}

# This loop allows for basic processing of some command line options in case you don't know the env var names. (read:accessibility)
while getopts 'osavf' opt; do
  case "$opt" in
    o) OFFSET=$OPTARG ;;
    s) SIZE=$OPTARG ;;
    a) ACODEC=$OPTARG ;;
    v) VCODEC=$OPTARG ;;
    f) AVOUTFILE=$OPTARG ;;
  esac
done

#####! END: Configuration Section !#####

QUEUE_SIZE=4096

## Using amix on 2 audio streams can cause CPU delay. Save to separate streams so they don't cause
## in-record stress and combine them in a 2nd-pass over the result.
# FILTER_COMPLEX="[0:a]asetpts=PTS-STARTPTS[first];"
# FILTER_COMPLEX+="[1:a]asetpts=PTS-STARTPTS[second];"
# FILTER_COMPLEX+="[first][second]amix=inputs=2:normalize=0,aresample=async=1:min_hard_comp=0.100:first_pts=0[audio]"

# Video Input options.
VIOPTS=${VIOPTS:-"-thread_queue_size $QUEUE_SIZE -analyzeduration 100M -probesize 100M -framerate ${FRAME_RATE:-30} -draw_mouse 1 -f x11grab -s ${SIZE} -i $DISPLAY+${OFFSET}"}
# Audio Input options.
AIOPTS=${AIOPTS:-"-thread_queue_size $QUEUE_SIZE -ac 2 -channel_layout stereo -f pulse -i $PULSE_AUDIO_SOURCE -thread_queue_size $QUEUE_SIZE -ac 2 -channel_layout stereo -f pulse -i $PULSE_MIC_SOURCE"}

# Video Output options.
VOOPTS=${VOOPTS:-"-c:v ${VCODEC} -rc:v cbr -tune hq -preset p3 -cq:v 19 -b:v 0 -pix_fmt yuv420p -movflags +faststart -fflags +genpts -fps_mode vfr -rtbufsize 256M -map 0:v -metadata:s:v:0 source=screencap"}
# Audio Output options.
AOOPTS=${AOOPTS:-"-c:a ${ACODEC} -af aresample=async=1 -map 1:a -metadata:s:a:0 source=audio -map 2:a -metadata:s:a:0 source=mic -b:a 192k"}

AVOPTS="$VIOPTS $AIOPTS $VOOPTS $AOOPTS -y $AVOUTFILE"

#pkill compton
pkill picom
#trap "$HOME/bin/compton.sh" EXIT

echo "Execute: $FFMPEG $AVOPTS"
eval "$FFMPEG $AVOPTS"