#!/bin/bash

# Set the MIXER_NORM_CONTROL to the name of the ALSA control you want to use to
# "normalize" all control values.  This value is used to determine the current
# volume before calculating the desired new volume, so using a control with
# high resolution allow you to use small volume adjustments without "getting
# stuck."
# If, for example, you're using a volume change that's less than
# 100/resolution, the volume will stick at the point where changing the control
# value by one results in a greater percentage change (after rounding) than
# requested.
# Note that PCM controls often have a resolution of 30, whereas Center,
# Surround, and LFE may have a resolution of 100.
MIXER_NORM_CONTROL=PCM
#MIXER_NORM_CONTROL=Center

# Set the MIXER_ADJ_AMOUNT to the desired percentage by which you want to
# adjust the volume.  Note that if using a control whose resolution is less than
# 100, the MIXER_ADJ_AMOUNT should be approximately 100/resolution or greater
# (i.e. for a PCM control with a resolution of 30, use 3 or higher) to prevent
# "getting stuck" at any particular volume.
MIXER_ADJ_AMOUNT=3

# Set the VOLUME_CONTROLS to the space separated list of volume controls you
# want the script to adjust.  Use single quotes around the list.
VOLUME_CONTROLS='PCM Surround Center LFE'

# Set the BROADCAST_ADDRESS to the address of the frontend on which you want to
# display the volume OSD.  Using 127.0.0.1 will generally work.
BROADCAST_ADDRESS='127.0.0.1'

# Relies on amixer reporting volume in the format "[90%]" in any line of output
# Please test that your version of amixer does this or you may blow out your
# speakers.
VOLUME=`amixer sget $MIXER_NORM_CONTROL | awk '/[.*%]/ {split($0,a,"["); split(a[2],a,"%"); print a[1]; exit}'`

case "$1" in
  up|down)
    if [ $1 = "down" ]; then
      MIXER_ADJ_AMOUNT=-$MIXER_ADJ_AMOUNT
    fi
    NEW_VOLUME="$(($VOLUME + $MIXER_ADJ_AMOUNT))"
    if [ $NEW_VOLUME -lt 0 ]; then
      NEW_VOLUME=0
    elif [ $NEW_VOLUME -gt 100 ]; then
      NEW_VOLUME=100
    fi
    mythtvosd --bcastaddr="$BROADCAST_ADDRESS" \
              --template='alert' \
              --alert_text="Volume: ${NEW_VOLUME}%" > /dev/null 2>&1 &
    for control in $VOLUME_CONTROLS; do
      amixer -q set $control ${NEW_VOLUME}% &
    done
    ;;
  mute|unmute)
    mythtvosd --bcastaddr="$BROADCAST_ADDRESS" \
              --template='alert' --alert_text="$1" > /dev/null 2>&1 &
    for control in $VOLUME_CONTROLS; do
      amixer -q set $control $1 &
    done
    ;;
  *)
    echo "Usage: $0 {up|down|mute|unmute}"
    ;;
esac