====== Tone with MPD In Linux ======

===== System Preparatione =====

==== Disable PulseAudio for Tone2 Pro, Tone1, and other Khadas Audio Devices ====

For maximum performance, you need to use the native [[https://en.wikipedia.org/wiki/Advanced_Linux_Sound_Architecture|Linux-ALSA]] stack! Please avoid PulseAudio if you want to obtain the best audio quality from your Tone2 Pro or Tone1.

You can skip this step if PulseAudio not installed in your system. To check, use the command:

```shell
$ which pulseaudio || echo PulseAudio not installed
```
If PulseAudio is installed, it is very easy to create a custom configuration file!
```sh install-pulse-audio-udev-rules.sh
sudo tee /etc/udev/rules.d/89-pulseaudio-usb.rules <<END
# Disable PulseAudio for next usb-audio devices by usb-id
# Tone2 Pro
ATTRS{idVendor}=="3353", ATTRS{idProduct}=="a002", ENV{PULSE_IGNORE}="1"
# Tone2
ATTRS{idVendor}=="3353", ATTRS{idProduct}=="a004", ENV{PULSE_IGNORE}="1"
# Tone1
ATTRS{idVendor}=="3353", ATTRS{idProduct}=="a001", ENV{PULSE_IGNORE}="1"
# Tea
ATTRS{idVendor}=="3353", ATTRS{idProduct}=="a005", ENV{PULSE_IGNORE}="1"
# Tea Pro
ATTRS{idVendor}=="3353", ATTRS{idProduct}=="a006", ENV{PULSE_IGNORE}="1"
# Tone1 with XMOS usbid
ATTRS{idVendor}=="20b1", ATTRS{idProduct}=="000a", ENV{PULSE_IGNORE}="1"

# just one line for all XMOS devices
ATTRS{idVendor}=="20b1", ENV{PULSE_IGNORE}="1"
# just one line for all Khadas Audio devices
ATTRS{idVendor}=="3353", ENV{PULSE_IGNORE}="1"

END
```
Now just re-plug your Tone2 Pro or Tone1 device to your machine for the new configuration to take effect.

==== Check If Native DSD Playback is Supported on Your Tone2 Pro or Tone1 ====

Enter the following command into Terminal:
```shell
$ grep -H DSD_U32_BE /proc/asound/card?/stream0 && echo Native DSD support - ok
```

==== What should I do, if DSD is not supported? ====

Your Linux system is using an old kernel! Please check your kernel version using the command ''uname -r'', and check this topic [[https://forum.khadas.com/t/does-the-v2-00-firmware-sound-better/10176/6]], and then upgrade your Linux kernel.

===== How to Display All Supported Formats =====

Get a list of all supported audio file formats using Terminal:
```shell
$ grep "" /proc/asound/card?/stream0
# or 
$ grep -e usb -e Format -e Bits -e Rates /proc/asound/card?/stream0
```
Example Output:
```shell
Khadas Tone2 Pro at usb-0000:03:00.4-1, high speed : USB Audio
    Format: S32_LE
    Rates: 44100, 48000, 88200, 96000, 176400, 192000, 352800, 384000, 705600, 768000
    Bits: 32
    Format: S32_LE
    Rates: 44100, 48000, 88200, 96000, 176400, 192000, 352800, 384000, 705600, 768000
    Bits: 24
    Format: SPECIAL DSD_U32_BE
    Rates: 44100, 48000, 88200, 96000, 176400, 192000, 352800, 384000, 705600, 768000
    Bits: 32
```

===== Use MPD Audio Player with Tone2 Pro and Tone1 =====

==== About MPD ====

[[https://www.musicpd.org/|Music Player Daemon (MPD)]] is a flexible, powerful, server-side application for playing music. Through plugins and libraries it can play a variety of sound files while being controlled by its network protocol.

==== Why MPD? ====

  * Maximum performance - YES
  * Bit-perfect audio playback - YES
  * [[https://en.wikipedia.org/wiki/Direct_Stream_Digital|Native DSD playback]] - YES

==== MPD User Manuals ====

  * https://www.musicpd.org/doc/html/user.html
  * https://wiki.archlinux.org/index.php/Music_Player_Daemon
  * ''man mpd''

==== Install MPD (example) ====

```shell
$ sudo apt-get install mpd mpc ncmpc
```

==== Prepare MPD (example) ====

Create music folders and the mpd config file (your music library must be accessible from these folders).
```shell
$ mkdir -p ~/mpd/music ~/mpd/playlists
```

==== Minimal MPD Config File (example) ====

MPD searches for a config file in ''$XDG_CONFIG_HOME/mpd/mpd.conf'' then ''~/.mpdconf'' then ''/etc/mpd.conf'' or … read more ''man mpd''.

```shell
$ nano ~/.mpdconf
```

```shell
# ~/.mpdconf - minimal mpd configuration for bit-perfect DSD playback

music_directory "~/mpd/music"
playlist_directory "~/mpd/playlists"
db_file "~/mpd/base"
log_file "/dev/null"
pid_file "~/mpd/mpd.pid"
state_file "~/mpd/mpd.state"
sticker_file "~/mpd/sticker.sql"

group "audio"
#bind_to_address "localhost"
bind_to_address "any"
bind_to_address "~/mpd/mpd.socket"
follow_outside_symlinks "yes"
follow_inside_symlinks "yes"
auto_update "yes"
auto_update_depth "6"

#zeroconf_enabled "yes"
#zeroconf_name "Music Player @ %h"

audio_output {
type "alsa"
name "Tone2"
# use only hardware devices for bit-perfect playback
device "hw:CARD=Pro,DEV=0"
# optimal buffer/period size for maximum performance
# about 2% system usage only ;)
buffer_time "409600"
period_time "40960"
# only use hardware volume control
mixer_type "null"
# software volume control, you may/may not need this ;)
# mixer_type "software"

# disable all format conversions
auto_resample "no"
auto_channels "no"
auto_format	"no"
# Disable DSD over PCM, as we have native playback from the Linux kernel
# dop		"yes"
}

audio_output {
type "alsa"
name "Tone1"
device  "hw:CARD=Control,DEV=0"
buffer_time "409600"
period_time "40960"
mixer_type "null"
auto_resample "no"
auto_channels "no"
auto_format "no"
#dop "yes"
}

audio_output {
	type "null"
	name "NULL"
}

filesystem_charset "UTF-8"
audio_buffer_size "512"
#buffer_before_play "5"
```

==== How to Get the Proper ALSA Device Name, to get Bit-Perfect Playback ====

  * ''aplay -L|grep -A1 ^hw:'' - full list
  * ''aplay -L|grep -A1 ^hw:|grep USB -B1'' - only usb list
  * ''aplay -L|grep -A1 ^hw:|grep Tone -B1|head -n1'' - only for Tone board

==== Start MPD service ====

The system will automatically start the MPD service, we need to restart this service with ordinary users.

```shell
$ sudo systemctl stop mpd
$ sudo systemctl stop mpd.socket
$ systemctl --user restart mpd
```

==== Basic MPC Usage Example ====

mpc is a command-line client for the Music Player Daemon (MPD). It connects to a MPD and controls it according to commands and arguments passed to it. If no command is given, the current status is printed (same as ''mpc status'').
```shell
mpc add DSD_test_512.44100.2.dsf
mpc add '09 - Faith No More - Be Aggressive.flac'
mpc add http://s4-webradio.rockantenne.de/alternative
# play it
mpc play
mpc repeat on
mpc
mpc outputs
mpc stop
mpc clear
mpc update
# get full commands list
mpc help
```

==== How to Check Which Output Format and Rate is Currently Used for My Tone Board? ====

```shell
$ cat $(dirname /proc/asound/card?/stream0)/pcm?p/sub?/hw_params
```

Native 512-DSD output example:
```shell
access: RW_INTERLEAVED
format: DSD_U32_BE
subformat: STD
channels: 2
rate: 705600 (705600/1)
period_size: 28902
buffer_size: 131072
```

==== MPD Client Interfaces ====

  * mpc - command-line client (must have)
  * ncmpc - common console GUI (must have)
  * [[https://play.google.com/store/apps/details?id=org.gateshipone.malp|M.A.L.P.]] - android client
  * [[https://github.com/rbackhouse/MaximumMPD|A MPD client for IOS]] - iOS player
  * full list - https://www.musicpd.org/clients/

All are welcome to give comments, replies and suggestions for improvement!