Configuring Audio Devices
To debug audio problems, I access the Linux command line via ssh and use some command-line utilities to test and configure.
The Linux audio system is called ALSA. You can install alsa-utils to get some command line tools for testing/configuring audio. Unfortunately, ALSA and Linux audio configuration is complex and hard to figure out.
Install those utilities by giving the command:
sudo apt-get install alsa-utils
Here’s some documentation on ALSA http://www.linuxfromscratch.org/blfs/view/cvs/multimedia/alsa-utils.html1
One command I use is speaker-test. This will cause your audio device to make tones, if everything is properly configured.
Making audio devices work in Linux can be complex and frustrating. Here are some more tips:
Login to the console using ssh from another computer. see Accessing_Zynthian_from_your_computer
Use the following command to list the audio devices that the system knows about:
aplay -l
Also you can try this command for more details:
aplay -L
alsamixer is a Linux command that allows you to set levels for devices and graphically display settings. You just type:
alsamixer
(followed by the Enter key in the terminal/console.)
Here’s a tutorial on how to work with sound on a Raspberry Pi (including aslamixer):
http://blog.scphillips.com/posts/2013/01/sound-configuration-on-raspberry-pi-with-alsa/
1 Bluetooth speakers
A “Bluetooth speaker” is an audio device in its own. In order to get this device working with Zynthian you need to configure it with Jack Audio. See the “audio config” tab in the webconf tool.
However, if you configure the bluetooth device and get it working with Zynthian, I suspect that the latency will be too long for playing/sequencing in real-time. A wireless device like this normally needs a big buffer to avoid “cuts”. In my very first tests I used a BT speaker “just for fun”. Latency was a little less than 1 second, more than enough to make it completley unplayable.
2 Using Raspberry Built-in audio 3.5mm jack
The R-Pi built-in audio has previously been reported to have very poor audio quality.
Available in latest rpi-update firmware (Oct 2017) is a new PWM audio driver that significantly increases the audio quality available from the 3.5mm TRRS jack.
To enable the advanced audio driver, add audio_pwm_mode=2 to /boot/config.txt and reboot.