I have been on this project after while (to help my friend doing their paper for graduating) and find the online project doing just fine (although the pi processing the audio is quite lagging the pi, and voltage drop make it freeze as the only way to make it reboot is to unplugged the power cable).
This is the step that I've been working on and it works on raspberry pi 3.
1. Download the required package
This project depend on pulseaudio so grab it and installing by typing:
sudo apt-get update && sudo apt-get install bluez pulseaudio-module-bluetooth python-gobject python-gobject-2 bluez-tools udev
i rather update the firmware of raspberry first before installing them because i have problem with rpi-bluetooth package so i do:
sudo rpi-update
and make it install and advance to next step.
2. Edit Configuration and applied it
First add pi username to the group pulseaudio with
sudo usermod -a -G lp pi
create new config under /etc/bluetooth/audio.conf using text editor and add the following line
[General]:
Enable=Source,Sink,Media,Socket
edit file /etc/bluetooth/main.confusing your preferred text editor (I'm using nano).
Set Bluetooth Class, Modify the following line to:
Class = 0x00041C
0x000041C means that the rpi bluetooth support A2DP protocol.
change /etc/pulse/daemon.conf
add / modify (don't forget to check the code thoroughly before adding them), and change
resample-method = trivial
you can using any method you like, i personally using speex-float-3 for reference you can see this link
start pulseaudio service with:
pulseaudio -D
we are going to use ragusa87 script to automate the bluetooth source to audio sink. First please add new configuration to udev init.d by editing file /etc/udev/rules.d/99-input.rules and add this to the file
SUBSYSTEM="input", GROUP="input", MODE="0660"
KERNEL=="input[0-9]*", RUN+="/usr/lib/udev/bluetooth"
add folder udev to /usr/lib by using mkdir
sudo mkdir /usr/lib/udev && cd /usr/lib/udev
and add this to the file bluetooth (credits ragusa87)
#!/bin/bash
# This script is called by udev when you link a bluetooth device with your computer
# It's called to add or remove the device from pulseaudio
#
#
# Output to this file
LOGFILE="/var/log/bluetooth_dev"
# Name of the local sink in this computer
# You can get it by calling : pactl list short sinks
# AUDIOSINK="alsa_output.platform-bcm2835_AUD0.0.analog-stereo"
AUDIOSINK="alsa_output.0.analog-stereo.monitor"
# User used to execute pulseaudio, an active session must be open to avoid errors
USER="pi"
# Audio Output for raspberry-pi
# 0=auto, 1=headphones, 2=hdmi.
AUDIO_OUTPUT=1
# If on, this computer is not discovearable when an audio device is connected
# 0=off, 1=on
ENABLE_BT_DISCOVER=1
echo "For output see $LOGFILE"
## This function add the pulseaudio loopback interface from source to sink
## The source is set by the bluetooth mac address using XX_XX_XX_XX_XX_XX format.
## param: XX_XX_XX_XX_XX_XX
## return 0 on success
add_from_mac(){
if [ -z "$1" ] # zero params
then
echo "Mac not found" >> $LOGFILE
else
mac=$1 # Mac is parameter-1
# Setting source name
bluez_dev=bluez_source.$mac
echo "bluez source: $mac" >> $LOGFILE
# This script is called early, we just wait to be sure that pulseaudio discovered the device
sleep 1
# Very that the source is present
CONFIRM=`sudo -u pi pactl list short | grep $bluez_dev`
if [ ! -z "$CONFIRM" ]
then
echo "Adding the loopback interface: $bluez_dev" >> $LOGFILE
echo "sudo -u $USER pactl load-module module-loopback source=$bluez_dev sink=$AUDIOSINK rate=44100 adjust_time=0" >> $LOGFILE
# This command route audio from bluetooth source to the local sink..
# it's the main goal of this script
sudo -u $USER pactl load-module module-loopback source=$bluez_dev sink=$AUDIOSINK rate=44100 adjust_time=0 >> $LOGFILE
return $?
else
echo "Unable to find a bluetooth device compatible with pulsaudio using the following device: $bluez_dev" >> $LOGFILE
return -1
fi
fi
}
## This function set volume to maximum and choose the right output
## return 0 on success
volume_max(){
# Set the audio OUTPUT on raspberry pi
# amixer cset numid=3 <n>
# where n is 0=auto, 1=headphones, 2=hdmi.
amixer cset numid=3 $AUDIO_OUTPUT >> $LOGFILE
# Set volume level to 100 percent
amixer set Master 100% >> $LOGFILE
pacmd set-sink-volume 0 65537 >> $LOGFILE
return $?
}
## This function will detect the bluetooth mac address from input device and configure it.
## Lots of devices are seen as input devices. But Mac OS X is not detected as input
## return 0 on success
detect_mac_from_input(){
ERRORCODE=-1
echo "Detecting mac from input devices" >> $LOGFILE
for dev in $(find /sys/devices/virtual/input/ -name input*)
do
if [ -f "$dev/name" ]
then
mac=$(cat "$dev/name" | sed 's/:/_/g')
add_from_mac $mac
# Endfor if the command is successfull
ERRORCODE=$?
if [ $ERRORCODE -eq 0]; then
return 0
fi
fi
done
# Error
return $ERRORCODE
}
## This function will detect the bt mac address from dev-path and configure it.
## Devpath is set by udev on device link
## return 0 on success
detect_mac_from_devpath(){
ERRORCODE=-1
if [ ! -z "$DEVPATH" ]; then
echo "Detecting mac from DEVPATH" >> $LOGFILE
for dev in $(find /sys$DEVPATH -name address)
do
mac=$(cat "$dev" | sed 's/:/_/g')
add_from_mac $mac
# Endfor if the command is successfull
ERRORCODE=$?
if [ $ERRORCODE -eq 0]; then
return 0
fi
done
return $ERRORCODE;
else
echo "DEVPATH not set, wrong bluetooth device? " >> $LOGFILE
return -2
fi
return $ERRORCODE
}
## Detecting if an action is set
if [ -z "$ACTION" ]; then
echo "The script must be called from udev." >> $LOGFILE
exit -1;
fi
## Getting the action
ACTION=$(expr "$ACTION" : "\([a-zA-Z]\+\).*")
# Switch case
case "$ACTION" in
"add")
# Turn off bluetooth discovery before connecting existing BT device to audio
if [ $ENABLE_BT_DISCOVER -eq 1]; then
echo "Stet computer as hidden" >> $LOGFILE
hciconfig hci0 noscan
fi
# Turn volume to max
volume_max
# Detect BT Mac Address from input devices
detect_mac_from_input
OK=$?
# Detect BT Mac address from device path on a bluetooth event
if [ $OK != 0 ]; then
if [ "$SUBSYSTEM" == "bluetooth" ]; then
detect_mac_from_devpath
OK=$?
fi
fi
# Check if the add was successfull, otherwise display all available sources
if [ $OK != 0 ]; then
echo "Your bluetooth device is not detected !" >> $LOGFILE
echo "Available sources are:" >> $LOGFILE
sudo -u $USER pactl list short sources >> $LOGFILE
else
echo "Device successfully added " >> $LOGFILE
fi
;;
"remove")
# Turn on bluetooth discovery if device disconnects
if [ $ENABLE_BT_DISCOVER -eq 1]; then
echo "Set computer as visible" >> $LOGFILE
sudo hciconfig hci0 piscan
fi
echo "Removed" >> $LOGFILE
;;
#
*)
echo "Unsuported action $action" >> $LOGFILE
;;
esac
echo "--" >> $LOGFILE
PLEASE NOTE that your AUDIOSINK might different from mine, check it before using pactl list short sinks
make the script executable by inputting this code
chmod 777 bluetooth
plug in headset to test whether the audio jack working and test with
aplay /usr/share/sounds/alsa/Front_Center.wav
or you can set the default audio routing with
sudo amixer cset numid=3 n
where n could be: 0 = auto 1 = jack 2 = hdmi
3. Pair and Connect the audio
go to terminal and type bluetoothctl. First activate bluetooth with power on and then agent on, set the default agent that you've been editing before with default-agent, and then set discoverable mode and pair mode on with discoverable on; pairable on. You should see raspberrypi bluetooth on your phone or laptop and you can pair it on the phone by clicking it and touch pair. On the terminal you type y. Back to the terminal, you connect to the phone by type connect xx:xx:xx:xx:xx:xx where xx:xx:xx:xx:xx:xx is you phone bluetooth mac address. and don't forget to trust with trust xx:xx:xx:xx:xx:xx where xx:xx:xx:xx:xx:xx is your phone bluetooth mac address And voila you have bluetooth amplifier (or whatever the name is) by using raspberry.
4. Conclusion
after trying and experimenting, i found out the audio quality is low and i rather not using it as the raspberry will be freeze if you using it with the song being streaming to the raspberry. I advice to use UPNP speaker project by using gmediarenderer. The audio is superb and there's no delay and scatter sound and it can play lossless audio file (flac, wav, dll). This is the detailed how to setup it
reference:
jobpassion's tutorial;
ragusa's script;
related work;
