Run an Android emulator with a fake webcam

emulator-with-fake-webcam.sh

#!/bin/bash

export REAL_DEVICE="/dev/video0"
export FAKE_DEVICE="/dev/video1"

export DURATION="5"
export SIZE="320x240"

export AVD="Nexus_5X_API_25"

export VIDEO_FILE="./webcam.avi"

record_webcam()
{
	declare video_fp="${1}"
	ffmpeg \
		-loglevel "quiet" \
	  -y \
		-f "v4l2" \
	  -r "30" \
	  -s "${SIZE}" \
	  -i "${REAL_DEVICE}" \
		-pix_fmt "yuv420p" \
	  -vcodec "libx264" \
		-ss "00:00:0.0" -t "${DURATION}" \
		"${video_fp}"
}

fake_webcam()
{
	declare video_fp="${1}"
	ffmpeg \
		-loglevel "quiet" \
		-re \
		-f "lavfi" \
		-i "movie=filename=${video_fp}:loop=0, setpts=N/(FRAME_RATE*TB)" \
		-f "v4l2" "${FAKE_DEVICE}"
}

run_emulator()
{
	cd "${ANDROID_HOME}/tools"
	./emulator @${AVD} -camera-back "webcam1"
	cd -
}

main()
{
  sudo modprobe "v4l2loopback"
	declare action="${1:-"run"}"
	shift
	case "${action}" in
		"run")
				(
					fake_webcam "${VIDEO_FILE}"
				) &
				declare ffmpeg_pid="${!}"

				run_emulator
				
				pkill -TERM -P "${ffmpeg_pid}"
			;;
		"record")
				record_webcam "${VIDEO_FILE}"
			;;
	esac
}

main "${@}"