v4l2loopback_script

#!/bin/bash
#
# Usage:
# ./v4l2loopback_script start <videosource> [<total fake sources> <width> <height> <framerate>]
#

set -ex

function start() {
    local SRC=${1}
    local TOTAL=${2:-1}
    local WIDTH=${3:-1280}
    local HEIGHT=${4:-720}
    local FRAMERATE=${5:-25}
    
    local VIDEO_NRS=""
    local CARD_LABELS=""
    local EXCLUSIVE_CAPS=""
    local SET_FPS_COMMANDS=""
    local FFMPEG_DEST=""
    local START_NR=$(ls /dev/video* | wc -l)
    local DRAWTEXT="drawtext=fontfile=/usr/share/fonts/truetype/freefont/FreeSans.ttf:fontcolor=white:fontsize=60:x=0:y=0:box=1:boxcolor=black"
    
    for (( i=${START_NR}; i < $[START_NR + TOTAL]; i++ )); do
        if [ -z "${VIDEO_NRS}" ]; then 
            VIDEO_NRS=${i}
        else 
            VIDEO_NRS=${VIDEO_NRS},${i}
        fi
        if [ -z "${CARD_LABELS}" ]; then 
            CARD_LABELS="Fake Video #${i}"
        else 
            CARD_LABELS="${CARD_LABELS},Fake Video #${i}"
        fi
        if [ -z "${EXCLUSIVE_CAPS}" ]; then 
            EXCLUSIVE_CAPS=1
        else 
            EXCLUSIVE_CAPS=${EXCLUSIVE_CAPS},1
        fi
        if [ -z "${SET_FPS_COMMANDS}" ]; then 
            SET_FPS_COMMANDS="sudo v4l2loopback-ctl set-fps ${FRAMERATE} /dev/video${i}"
        else 
            SET_FPS_COMMANDS="${SET_FPS_COMMANDS} && sudo v4l2loopback-ctl set-fps ${FRAMERATE} /dev/video${i}"
        fi
        FFMPEG_DEST="${FFMPEG_DEST} -vf ${DRAWTEXT}:text=${i} -s ${WIDTH}:${HEIGHT} -r ${FRAMERATE} -pix_fmt yuv420p -vcodec rawvideo -f v4l2 /dev/video${i}"
    done

    sudo /sbin/modprobe v4l2loopback max_buffers=2 \
        video_nr=${VIDEO_NRS} \
        card_label="${CARD_LABELS}" \
        exclusive_caps="${EXCLUSIVE_CAPS}"
    sleep 1
    ${SET_FPS_COMMANDS}

    ffmpeg -re -stream_loop -1 -i "${SRC}" ${FFMPEG_DEST}
    
    sudo rmmod v4l2loopback
}

function stop() {
    sudo rmmod v4l2loopback
}

$@