Audiobook Player

Raspberry Pi-based audiobook player with easy to use interface and text-to-speech output for book selection.

It is suprisingly difficult to find an easy to use commercial version of a player specifically designed to play audio books with the following requirements:

Very easy to use, in particular for elderly persons with impared eyesight. Tiny displays, tiny buttons, and lots of functions won’t work!
The device should always keep track of the current book and reading position. Turning the device on should automatically continue reading from the last position.
Skipping forward to a particular chapter in a book ist not a requirement.
Device should be able to store lots of audio books. Selection of a particular book should be as simple as possible.

As it seems, a few people had very similar requirements and already built such devices.

For example, there is the One Button Audiobook Player. This is a very cool project with a UI as simple as it gets. However, it can only handle one single book at a time.

Then there is Willem van der Jagt’s BookPlayer, which has all the required features. For selection of a specific audio book, it uses a built-in RFID reader. Each book is associated with an RFID tag and reading the tag selects the book and starts reading. Although using RFID is pretty slick, I did not like the idea of having to deal with a bunch of tags in addition to the player.

I therefore decided to use Willem van der Jagt’s design as a basis, but to remove the RFID feature. Instead, I added a button which allows the user to cycle through the stored books. Author and title of a selected book are read to the user using a text-to-speech engine.

For maintenance or for updating the audio books on the player, I plug a WIFI dongle into an USB port, which automatically connects to my network. I then use ssh for maintenance and sftp for transferring books. On Windows, WinSCP works very well, too.

Hardware

The hardware is pretty straightforward, this is what I used:

Raspberry Pi (I still had a model B Rev. 1, one of the very earliest ones.)
SD card. I used one with 8 GB I had lying around, which is good enough for about 10 books, depending on the size of the MP3 files.
Case. The one I used is called Euro Box from the local electronics store. It is a surprisingly good fit. Being able to detach the front and back panels is pretty handy in case I have to use a LAN cable or if I want to remove the SD card.
Power switch
5 colored push buttons. The ones I used are pretty crappy (and cheap!), but they were the most suitable available at the local store.
LED + socket
USB cable with microB USB plug on one end. I split the cable and cut the micro USB plug open with a sharp knife. The rest of the cable was extended and wired up with the power switch. (I think heat shrink tubing is the most useful stuff ever!)
3.5mm audio jack + socket. The socket goes into the front panel and is connected with the jack which goes into the Raspi’s audio socket. To make it fit, the plastic case of the jack was discarded.
Several old analog CD audio cables

They work very well for connecting buttons and LED to the pin header. There are only three wires per plug, but that can be easily fixed by carefully removing one wire from another spare plug and inserting it into the empty position.

The following picture shows how buttons and LED are wired to the plugs and the position of the plugs on the pin header.

Since my version of the Raspberry Pi had no mounting holes, I used the bottom part of a cheap Raspberry Pi case for mounting. The bottom was glued with epoxy to the mounting posts of the Euro Box, as can be seen in the picture above.

Software

Most stuff regarding installation can be found on Willem van der Jagt’s Blog.

Since did a few things differently, I’ll try to document the full installation process.

Install and Configure Raspbian

Download Raspian and install it on your SD card. The card should be 8GB or greater in order to hold the operating system and a number of books.

Note	The following describes a remote installation because I did not want to bother with attaching keyboard and monitor to the Pi.

Connect the Pi to your network with a LAN cable, boot and logon to the Pi via ssh (or putty on Windows)

$ ssh pi@raspberrypi

Password of user pi is raspberry.

Basic configuration:

$ sudo raspi-config

Make sure to choose Expand Filesystem to make Rasbian use the whole SD card. You should also Change User Password. Under Advanced Options, you may also want to change the hostname of the Pi from raspberry to something more meaningful, e.g. bookplayer.

Finish the configuration dialog with rebooting the Pi and ssh to the Pi again using your changed hostname and password:

$ ssh pi@bookplayer

Update your Raspbian:

$ sudo apt-get update
$ sudo apt-get upgrade

Force audio through the 3.5 Audio jack:

$ sudo amixer cset numid=3 1

WIFI

If you want to use WIFI to access your Pi, it must be configured. I simply used the command line.

Powermanagement caused some problem with my particular WIFI dongle. After some time of inactivity, the dongle shut down and the connection dropped. Using lsusb showed the following:

Bus 001 Device 004: ID 0bda:8176 Realtek Semiconductor Corp. RTL8188CUS 802.11n WLAN Adapter

The solution is to disable power down when the device is idle. This can be achieved by creating file /etc/modprobe.d/8192cu.conf with the following content:

#prevent power down of wireless when idle
options 8192cu rtw_power_mgnt=0 rtw_enusbss=0

Music Player Daemon (MPD)

This software uses the Music Player Daemon as the backend.

$ sudo apt-get install mpd

Keeping track of the current book and autoplaying will be controlled by the client frontend. To avoid potential conflicts, we have to configure MPD to not automatically keep track of the current book and start autoplaying a book on startup. This is done by editing /etc/mpd.conf and by commenting or deleting the line starting with

state_file ...

You may also want to change the music_directory parameter to a directory different from /var/lib/mpd/music, for example to a directory under the user’s home directory.

Restart mpd:

$ sudo service mpd restart

Install a simple commandline client for mpd:

$ sudo apt-get install mpc

Next, the python-mpd2 client library must be installed. I used pip for installation, which must be installed first:

$ sudo apt-get install python-pip
$ sudo pip install python-mpd2

Install Sqlite3 database:

$ sudo apt-get install sqlite3

Text to Speech

For text-to-speech conversion I used Google’s SVOX Pico for Android, which provides a much better quality than eSpeak.

I used a precompiled SVOX-Pico Debian package for ARM provided by Andreas Bischoff. After downloading, install it with

$ cd
$ sudo apt-get install libpopt-dev
$ wget http://www.dr-bischoff.de/raspi/pico2wave.deb
$ sudo dpkg --install pico2wave.deb

Installation of BookPlayer

Clone this project to the pi user’s home directory:

$ cd
$ git clone https://github.com/nerk/BookPlayer

To configure the sqlite database, do the following:

$ cd BookPlayer
$ sqlite3 state.db

sqlite> .read db.sql
sqlite> .exit

TTS Language Configuration

The language configuration for the text-to-speech engine is hardcoded in the code and currently set to german. Find the following line in main.py:

subprocess.call(["pico2wave", "-lde-DE", "-w/tmp/tts.wav", text])

To change it to US-english, for example, modify it a follows:

subprocess.call(["pico2wave", "-len-US", "-w/tmp/tts.wav", text])

GPIO Numbering and Board Revisions

Caution

GPIO numbering changed between board revisions. If your board is Rev. 2 (most likely), you must make a small change in file config.py!

gpio_pins = [
    { 'pin_id': 21, 'callback' : 'rewind', 'bounce_time' : 2000 }, # Board Rev. 1
    #{ 'pin_id': 27, 'callback' : 'rewind', 'bounce_time' : 2000 }, # Board Rev. 2
    { 'pin_id': 11, 'callback' : 'toggle_pause', 'bounce_time' : 2000 },
    { 'pin_id': 9, 'callback' : 'next_title', 'bounce_time' : 2000 },
    { 'pin_id': 22, 'callback' : 'volume_down', 'bounce_time' : 1000 },
    { 'pin_id': 10, 'callback' : 'volume_up', 'bounce_time' : 1000 }
]

Autostart on Boot

The player must be configured to start automatically playing the current book when booting the pi.

$ sudo nano /etc/rc.local

After the initial block of comments, add the following line:

/home/pi/BookPlayer/start &

Save and exit the editor. Make the start script executable:

chmod 755 /home/pi/BookPlayer/start

Reboot the Pi:

sudo reboot

Audiobook Structure

Audiobooks must be put into the MPD music_directory folder you configured above. In case you left it unchanged it defaults to /var/lib/mpd/music.

The directory structure for each book is pretty simple and as follows:

author name/
   title of the book/
      01-first track.mp3
      02-second track.mp3
      03-third track.mp3

For a multi-disc book, the tracks of all CDs must be in a common directory with appropriate track numbering, e.g.:

author name/
   title of the book/
      101-first track first cd.mp3
      102-second track first cd.mp3
      201-first track second cd.mp3
      202-second track second cd.mp3

The player will speak the author’s name and the title of the book by reading the directory names. Each track must start with a unique number in correct order, followed by a dash with the suffix of .mp3. The actual name of the track is arbitrary.

A very convenient way to create this structure is to rip CDs with abcde (on your main computer and not on the Pi, of course). It will also handle multi CD books when used with commandline option -W, followed by the number of the CD:

$ abcde -W1 -c abcde_book.conf
$ abcde -W2 -c abcde_book.conf
...

The configuration file abcde_book.conf is included in the main directory of this project. Copy it to the computer you are using for ripping and use it accordingly.

The most important configuration parameter inside this file is OUTPUTFORMAT:

OUTPUTFORMAT='${ARTISTFILE}/${ALBUMFILE}/${TRACKNUM}-${TRACKFILE}'

This will produce track names in the correct format.

Shortcomings and Improvements

Using a switch to simply cut off power is not a good idea. Pi should be shutdown properly.
Checking of changes to the currently selected book in the main loop by polling is not really a good implementation.
The way button presses are handled could be improved. Implementation of an event queue might be a way to ensure that no button events are lost.
Parts of the code might not really be thread-safe, should be reviewed.
The language configuration for the text-to-speech engine is hardcoded. This does not work if the author’s name is in a foreign language or a title contains foreign language words.

Copyright and License

Licensed under MIT License. See LICENSE for details.

nerk / bookplayer Goto Github PK

bookplayer's Introduction

Audiobook Player

Hardware

Software

Install and Configure Raspbian

WIFI

Music Player Daemon (MPD)

Text to Speech

Installation of BookPlayer

TTS Language Configuration

GPIO Numbering and Board Revisions

Autostart on Boot

Audiobook Structure

Shortcomings and Improvements

Copyright and License

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