Tagging a music library for use with a Sonos system

I migrated my iTunes music library to a NAS built with a Raspberry Pi so it could be shared with my Sonos system. Before this the only thing reading any metadata on the files was iTunes which can sometimes do weird things. Coupled with that, I've previously used TuneUp to fix broken metadata within iTunes. It works very well in that context but it seems that the metadata it writes is non-standard in some way and other programs will not read it. All this manifests in some of my music only appearing in the track listing part of the Sonos interface, being listed by filename rather than track name and not being listed by album or artist at all.

What do I need?

Sonos reads standard id3 tags - apparently v1 or any of the v2 options. The files need to be tagged in one of these formats.

Fixing things up

My files are kept in a consistent directory structure looking like this:

blah/Music/Gun/Swagger/01 Stand in line.mp3

My first plan was to use a Linux command line utility for reading and writing id3 tags and pull the required information from the directory path using some clever scripting. I've been away from work for over a week so my brain isn't really up to the required "clever" scripting at the moment. Fortunately, when building the NAS as per my last post I made all my music available over a samba share so it was easy to mount that on my desktop machine and get access to the files that way.

There are dozens of GUI id3 editors. I chose to use mp3tag (my desktop is a Windows machine) and hoped I could somehow convert the tags produced by TuneUp and used in iTunes to something more standard. Unfortunely mp3tag lists the TuneUp tags as "Bad Tags". Drat. Well, at least that explains the problem.

So, armed with my new clicky it's back to plan 1. Having found the files which needed attention I used the "filename-tag" converter with this pattern:

%artist%\%album%\%track% %title%

Slashes reversed because we're in a Windows environment now.

This solved the vast majority of the problems. There were still a few albums tagged in a bizarre way - with no track numbers and a title of something like "01 Intro". I didn't want to completely nuke the existing tags for these as they included Album Art so it was time to break out the "tag-tag" converter which lets you use existing information in the tag to populate other fields.

We need two different filters here, applied in this order because the second removes information needed for the first.

Field: TRACK
Pattern: $left(%TITLE%,2)

then

Field: TITLE
Pattern: $cutLeft(%TITLE%,3)

These methods came from the scripting section of the mp3tag documentation. It turns out it's quite powerful, even if the methods don't always do exactly what the docs suggest they will do.

Job done.

Next steps

My album art is all extremely patchy. Sonos is now my primary playout system at home and it takes an age to load album art so I'm not too bothered about fixing it, however if I change my mind there are a couple of options. Firstly, mp3tag lets you paste album art into the box rather than having to use a presaved photo. I can look up album art in iTunes and copy from there for the occasional simple fix.

If I want to do a proper, automatic job I'll probably take a look at Album Art Downloader which is apparently very good and can be run as a tool within mp3tag. That's fun for another day though.

Using a Raspberry Pi as a headless media store on a Sonos network

This is to build a headless media centre and is also being built that way - that is, I'm not going to plug a screen or keyboard/mouse directly into the Pi. This means that I can install the version of Debian without the window manager which makes it far lighter on the processor.

It's not difficult, but I've compiled my notes and written some English to link them together as someone may find them useful. I'm going to assume some basic Linux and home networking knowledge.

You will need

• a Raspberry Pi
• an SD card
• a case for the Pi
• a power lead
• an ethernet cable

Sourced from Amazon, total cost (at time of writing, without hunting around) is: £47.60

You'll also need some USB hard drives. The Pi (model B here) only has USB 2.0 ports so you can use older drives if you're not planning on plugging them in anywhere else. Also, the Pi runs on very low power so you really want powered drives or a powered USB hub to sit between them. If you want to back up your data, you're going to need two drives. If you don't, you can ignore all the stuff about rsync that comes up later.

Let's go

Up and running

1. download Raspbian
   Sadly, the NOOBS install method requires the use of a screen so wont work for us.
2. install Raspbian onto the SD card
   These are the instructions for prepping the card on a Windows machine.
3. put the Pi in the case, plug in the ethernet cable and put in the SD card
4. finally plug in the power cable and we're off

Connect and update

Find the IP address of your Pi, shell to it and log in (default username / password is pi / raspberry). You need to run:

sudo raspi-config

and select the option to expand the root filesystem to fill the SD card. It's important you do this before any of the other steps or you will be starting again.

Next update the operating system via:

sudo apt-get update
sudo apt-get upgrade

This will likely take a while.

Connect the drives

Plugging the drives in will auto-mount them, however if we are using one drive as a backup to the other we need to ensure they are always mounting the same way round on restart. To do this we will identify the drives via their UUID in /etc/fstab:

UUID=0AC4D607C4D5F543 /mount/location ntfs rw,defaults 0 0

To find the UUID of the drives:

blkid /dev/sda1
blkid /dev/sdb1

Remember that if you format a drive, the UUID will change.

Install the software

Time to install some useful software.

Samba shares specified parts of your filesystem on the network. It will allow you to mount the drive on another computer which will let you put files on your media server when it's ready. It is also the shared area that Sonos will be able to search for music files.

Minidlna shares an area of your filesystem via DLNA. This means a DLNA-ready device can locate the share and request any files in it. I use this for watching video on my iPad (my viewing program of choice being 8player).

# install samba
sudo apt-get install samba samba-common-bin

# install minidlna
sudo apt-get install minidlna

I also installed some extra tools to make other tasks easier. You don't need them for this build.

sudo apt-get install tree locate chkconfig

Configure samba

To configure samba you need to edit /etc/samba/smb.conf. You'll want something like this:

[global]
    netbios name = NETBIOS_NAME
    workgroup = WORKGROUP
    security = user
    encrypt passwords = yes
    smb passwd file = /etc/samba/smbpasswd

[media]
    comment = My media
    path = /PATH/TO/SHARE
    writeable = yes
    create mask = 0770
    force create mode = 0770
    locking = yes

Mixed to taste, of course.

Then add the user to the samba password file:

sudo smbpasswd -L -a USERNAME

Restart samba and you should then be able to mount the drive on other machines on the network.

Configure minidlna

The minidlna config file is found at /etc/minidlna.conf

Docs on configuring minidlna are available on the minidlna site. The important bits are:

media_dir=A,/home/user/Music      # Music directory
media_dir=P,/home/user/Pictures   # Pictures directory
media_dir=V,/home/user/Videos     # Video directory
friendly_name=Laptop              # Name of the share
db_dir=/var/cache/minidlna        # Index files (make sure location is writeable)
log_dir=/var/log                  # Log files (make sure location is writeable)
inotify=yes                       # Index new files as they are added

It's important to make sure the minidlna user can read and write to the index and log directories and read the media files. Alternately, if you're lazy like me you can make minidlna run as the main user by editing /etc/init.d/minidlna (around line 68). Obviously this is not recommended for any significant install of anything, but I'm assuming we're at home on a very limited access network.

When starting minidlna you may get an error message claiming to be exceeding the watch limit. To increase this limit, add to /etc/sysctl.d/90-inotify.conf

fs.inotify.max_user_watches = 100000

and restart.

Note that there is a new version of minidlna on the way called ReadyMedia possibly rendering this completely obsolete.

Back up the drives

I wanted to keep a backup of my media on the second drive. I could have used RAID 1 but reading around suggested that the amount of read/write information going across the USB bus would cause a bottleneck and therefore problems serving the files. To get around this, I use rsync to copy everything across on a nightly basis.

Something like this in the crontab will sync the drives each night at 3am:

0 3 * * * rsync /mountpoint/maindrive /mountpoint/backupdrive >> ~/rsync_log.txt 2>&1

And with this, the setup is complete.

Getting the media files in order

Sonos will read the ID3 tags on the music files so they need to correct. Due to the fun of an iTunes crash some time in the past mine are a mess so it's time for some scripting. More on this in a future post.