MPTV2 - script to keep MPV running

mptv2.sh

#!/usr/bin/env bash

# AUTHOR:       mykola2312
# LICENSE:      BSD-2Clause
# REQUIREMENTS: multimedia/mpv textproc/jq net/socat
# mpv:          https://www.freshports.org/multimedia/mpv/
# jq:           https://www.freshports.org/textproc/jq/
# socat:        https://www.freshports.org/net/socat/

MPV="$(which mpv)"
MPV_SOCK="/tmp/mptv2-mpv.sock"
IPTV_URL=""

SPAWN_GRACE_PERIOD=5
INQUIRE_INTERVAL=1
MAX_ATTEMPTS=1

mpv_pid=""
mpv_playback=""
mpv_last_playback=""
mpv_attempt=0

function mpv_running() {
  if [ -z "$mpv_pid" ]; then
    return 1 # false
  else
    ps -p "$mpv_pid" 2>&1 >/dev/null
   return $?
  fi
  return 1
}

function mpv_spawn() {
  $MPV "$IPTV_URL" --input-ipc-server="$MPV_SOCK" </dev/null &>/dev/null &

  mpv_pid="$!"
  sleep "$SPAWN_GRACE_PERIOD"
}

function mpv_kill() {
  kill -9 "$mpv_pid" 2>&1 >/dev/null
}

function mpv_respawn() {
  mpv_attempt="0"
  mpv_playback=""
  mpv_last_playback=""

  mpv_kill
  mpv_spawn
}

function mpv_inquire() {
  reply=$(echo '{ "command": ["get_property", "playback-time"] }' | socat - "UNIX-CONNECT:$MPV_SOCK" 2>&1)
  if [ $? -ne 0 ]; then
    return 1
  fi

  mpv_playback=$(echo "$reply" | jq -e '.data' -)
  if [ $? -ne 0 ]; then
    return 1
  fi
  echo "this $mpv_playback last $mpv_last_playback"
}

mpv_spawn

while true; do
  if mpv_running; then
    if mpv_inquire; then
      if [ -z "$mpv_last_playback" ]; then
        # first inquire - just set last playback
        mpv_last_playback="$mpv_playback"
      elif [ "$mpv_playback" == "$mpv_last_playback" ]; then
        # playback stuck - increment attempt
        mpv_attempt=$((mpv_attempt + 1))
        if [ "$mpv_attempt" -gt "$MAX_ATTEMPTS" ]; then
          mpv_respawn
        fi
      else
        # new inquire returns different playback, unstuck, so reset attempts
        mpv_last_playback="$mpv_playback"
        mpv_attempt="0"
      fi
    else
      # failed to inquire - dead process?
      # SPAWN_GRACE_PERIOD must be long enough, to cover MPV spawn and UNIX socket creation
      # otherwise, respawn loop will happen
      mpv_respawn
    fi
  else
    mpv_respawn
  fi
  sleep "$INQUIRE_INTERVAL"
done