Raspberry bluetooth audio device

asound.conf

# http://alsa.opensrc.org/SurroundSound 
# http://alsa.opensrc.org/Low-pass_filter_for_subwoofer_channel_%28HOWTO%29 
# Arch Linux:  pacman -S ladspa blop swh-plugins libsamplerate tap-plugins cmt 
# speaker-test -D upmix_20to51 -c 2 -t wav 
# listplugins 
# analyseplugin cmt 
# http://plugin.org.uk/ladspa-swh/docs/ladspa-swh.html 
pcm.lowpass_21to21 { 
    type ladspa 
    slave.pcm upmix_21to51 
    path "/usr/lib/ladspa" 
    channels 3 
    plugins { 
      0 { 
         id 1098  # Identity (Audio) (1098/identity_audio) 
         policy duplicate 
         input.bindings.0 "Input"; 
         output.bindings.0 "Output"; 
      } 

      1 { 
         id 1052  # High-pass filter 
         policy none 
         input.bindings.0 "Input"; 
         output.bindings.0 "Output"; 
         input { 
            controls [ 100 ] 
         } 
      } 

      2 { 
         id 1052  # High-pass filter 
         policy none 
         input.bindings.1 "Input"; 
         output.bindings.1 "Output"; 
         input { 
            controls [ 100 ] 
         } 
      } 

      3 { 
         id 1051  # Low-pass filter 
         policy none 
         input.bindings.2 "Input"; 
         output.bindings.2 "Output"; 
         input { 
            controls [ 100 ] 
         } 
      } 

   } 
} 


pcm.upmix_20to51 { 
   type plug 
   slave.pcm "lowpass_21to21" 
   slave.channels 3 
   ttable { 
      0.0     1       # left channel 
      1.1     1       # right channel 
      0.2     0.5     # mix left and right ... 
      1.2     0.5     # ... channel for subwoofer 
   } 
} 


pcm.upmix_21to51 { 
   type plug 
   slave.pcm surround51 
   slave.channels 6 
   ttable { 
      0.0     1       # front left 
      1.1     1       # front right 
      0.2     1       # rear left 
      1.3     1       # rear right 

      # Front left/right to center. 
      0.4     0.5 
      1.4     0.5 

      # Subwoofer, more powerful to compensate for bass-removal from other speakers. 
      # Would normally be 1. 
      2.5     2 
    } 
}

bluehemian.ansible.yml

#!/usr/bin/env ansible-playbook -i ../inventory -k -K
#
# Prerequisites:
# - Download Raspbian Stretch Lite
# - Write the image to an SD card
# - Start the Raspberry Pi with the SD card
# - Boot the Pi and set up the SSHD
#

---

- hosts: mizar.fritz.box
  become: yes
  become_user: root
  become_method: sudo

  tasks:

  - name: upgrade dist
    apt: upgrade=dist update_cache=yes

  - name: install required packages
    apt: name={{item}} state=present update_cache=yes install_recommends=no
    with_items:
        - bluealsa
        - python-dbus
        - python-gobject
        - tmux
        - bluez
        - git
        - blop
        - cmt

  - name: securing SSHD
    lineinfile:
      path: /etc/ssh/sshd_config
      regexp: '^PermitRootLogin.*'
      line: 'PermitRootLogin no'

  - name: switch off integrated sound
    lineinfile:
        path: /boot/config.txt
        regexp: '^dtparam=audio=.*'
        line: 'dtparam=audio=off'

  - name: configure bluetooth class
    lineinfile:
        path: /etc/bluetooth/main.conf
        regexp: '.*Class = .*'
        line: 'Class = 0x240428'

  - name: configure bluetooth discoverable timeout
    lineinfile:
        path: /etc/bluetooth/main.conf
        regexp: '.*DiscoverableTimeout = .*'
        line: 'DiscoverableTimeout = 0'

  - name: configure bluetooth pairable timeout
    lineinfile:
        path: /etc/bluetooth/main.conf
        regexp: '.*PairableTimeout = .*'
        line: 'PairableTimeout = 0'

  - name: configure bluetooth audio (1)
    lineinfile:
        create: yes
        path: /etc/bluetooth/audio.conf
        insertbefore: BOF
        line: '[General]'

  - name: configure bluetooth audio (2)
    lineinfile:
        create: yes
        path: /etc/bluetooth/audio.conf
        regexp: '.*Enable=.*'
        line: 'Enable=Source,Sink,Media,Socket'

  - name: get ct scripts from Michael Schmidt
    git: dest=/root/ctscripts repo=https://github.com/ct-Open-Source/ct-Raspi-Bluetooth-Receiver/

  - name: modify service to use upmixed audio (see below)
    lineinfile:
        path: /root/ctscripts/bluealsa-aplay@.service
        regexp: 'ExecStart=/usr/bin/bluealsa-aplay %I'
        line: 'ExecStart=/usr/bin/bluealsa-aplay -dupmix_20to51 %I

  - name: install agent and autoconnect
    command: install -m 755 /root/ctscripts/{{item}} /usr/local/bin
    with_items:
        - a2dp-autoconnect
        - simple-agent

  - name: install services
    shell: 'install /root/ctscripts/*.service /etc/systemd/system'

  - name: fix issue created by bluealsa update
    lineinfile:
        path: /lib/systemd/system/bluealsa.service
        regexp: ExecStart=/usr/bin/bluealsa.*
        line: ExecStart=/usr/bin/bluealsa -p a2dp-sink -p hfp-hf -p hsp-hs --a2dp-volume

  - name: modify modprobe to make USB default audio
    lineinfile:
        create: yes
        path: /etc/modprobe.d/alsa-base.conf
        line: 'options snd_usb_audio index=0'

  - name: create alsa config file for stereo upmix
    copy:
        src: ./asound.conf
        dest: /etc/asound.conf

  - name: enable services
    command: systemctl enable {{item}}
    with_items:
        - simple-agent

  - name: create bluetooth udev rule
    lineinfile: 
        create: yes
        path: /etc/udev/rules.d/99-bluetooth-input.rules
        line: 'KERNEL=="input[0-9]*", RUN+="/usr/local/bin/a2dp-autoconnect"'
      
  - name: reboot
    shell: "sleep 5 && reboot"
    async: 1
    poll: 0