Limit Bluesound sound level while ignoring specificed inputs. E.g. for analog and optical

limit-volume-bluos.sh

#!/bin/bash

# Default values for the script's operation
IP=''
TIMEOUT=50                       # Timeout in milliseconds
LIMIT=-55                        # Volume limit (negative value)
SKIP_INPUTS=('input0' "optical") # Inputs to skip when limiting volume

# Overriding default values with environment variables if they exist
if [ -n "$BLUOS_IP" ]; then
  IP=$BLUOS_IP
fi

if [ -n "$BLUOS_TIMEOUT" ]; then
  TIMEOUT=$BLUOS_TIMEOUT
fi

if [ -n "$BLUOS_LIMIT" ]; then
  LIMIT=$BLUOS_LIMIT
fi

if [ -n "$BLUOS_SKIP_INPUTS" ]; then
  IFS=',' read -r -a SKIP_INPUTS <<<"$BLUOS_SKIP_INPUTS"
fi

# Function to display help information
function help() {
  echo "Usage: limitVolume.sh [-i IP] [-t TIMEOUT] [-l LIMIT] [-s SKIP_INPUTS]"
  echo "Options:"
  echo "  -i IP: IP address of the BluOS device."
  echo "  -t TIMEOUT: Timeout in milliseconds before checking volume."
  echo "  -l LIMIT: Maximum allowed volume (negative value)."
  echo "  -s SKIP_INPUTS: Comma-separated list of input IDs to skip."
  echo ""
  echo "Environment variables can also be used to set these options:"
  echo "  BLUOS_IP, BLUOS_TIMEOUT, BLUOS_LIMIT, BLUOS_SKIP_INPUTS"
}

# Parsing command-line arguments
while getopts "i:t:l:s:" opt; do
  case $opt in
  i) IP=$OPTARG ;;
  t) TIMEOUT=$OPTARG ;;
  l) LIMIT=$OPTARG ;;
  s) IFS=',' read -r -a SKIP_INPUTS <<<"$OPTARG" ;;
  \?)
    echo "Invalid option: -$OPTARG" >&2
    exit 1
    ;;
  :)
    echo "Option -$OPTARG requires an argument." >&2
    exit 1
    ;;
  esac
done

# Show current configuration
echo "IP: $IP"
echo "TIMEOUT: $TIMEOUT ms"
echo "LIMIT: $LIMIT dB"
echo "SKIP_INPUTS: ${SKIP_INPUTS[*]}"
echo "-------------------"

# Validate required arguments
if [ -z "$IP" ]; then
  echo "IP is required."
  help
  exit 1
fi

# Initialize variables to store the last known state
lastDb=0
lastInputId=''

# Function to limit the volume
limitVolume() {
  local ip=$1

  # Base URL for the BluOS device
  local baseUrl="http://$ip:11000"

  # Wait for the specified timeout duration
  sleep $((TIMEOUT / 1000))

  # Fetch current status from the device
  local response=$(curl -s "${baseUrl}/Status")

  # Extract the current input ID
  local inputId=$(echo "$response" | sed -n 's|.*<inputId>\(.*\)</inputId>.*|\1|p')
  if [ -z "$inputId" ]; then
    return
  fi

  # Check if input has changed
  if [ "$inputId" != "$lastInputId" ]; then
    echo "Input: $inputId"
    # Notify if this input is being skipped
    lastInputId=$inputId
    for skip in "${SKIP_INPUTS[@]}"; do
      if [ "$inputId" == "$skip" ]; then
        echo "Skipping volume limit for this input"
        return
      fi
    done
  fi

  # Skip processing for specified inputs
  for skip in "${SKIP_INPUTS[@]}"; do
    if [ "$inputId" == "$skip" ]; then
      return
    fi
  done

  # Extract and process the current volume level
  local db=$(echo "$response" | sed -n 's|.*<db>\(.*\)</db>.*|\1|p' | awk '{print int($1)}')
  if [ -z "$db" ]; then
    echo "Failed to get volume"
    exit 1
  fi

  if [ $db != $lastDb ]; then
    echo "Volume: $db dB"
    lastDb=$db
  fi

  # Limit the volume if it exceeds the set limit
  if [ $db -le $LIMIT ]; then
    return
  fi

  # Send request to adjust the volume
  curl -s -X POST "${baseUrl}/Volume?abs_db=${LIMIT}" >/dev/null
  echo "Limited volume to $LIMIT dB"
}

# Main function to initiate the script
main() {
  limitVolume $IP

  # Continuously monitor and adjust the volume
  while true; do
    limitVolume $IP
  done
}

# Execute the main function
main

https://gist.github.com/mattorp/e88ea4d0f33dfb8e7aacda7283659df2