C.A.V.A. (M.P.)

Console-based Audio Visualizer for ALSA (MPD and Pulseaudio)

thanks to anko for the gif, here is the recipe.

Table of Contents generated with DocToc

What it is
Build requirements
Getting started
Capturing audio
Running via ssh
Font notes
- In ttys
- In terminal emulators
Latency notes
Usage
- Controls
Configuration

What it is

C.A.V.A. is a bar spectrum analyzer for audio using ALSA for input. Its frequency range is limited to 50-10,000Hz. I know that the human ear can hear from 20 up to 20,000 Hz (and probably "sense" even higher frequencies), but the frequencies between 50-10,000Hz seem to me to be the most distinguishable. (I believe telephones used to be limited to as low as 8kHz.)

This program is not intended for scientific use.

This is my first published code. I am not a professional programmer so the source code is probably, by all conventions, a complete mess. Please excuse all the typos as I am both dyslexic and foreign.

Any tips or comments would be much appreciated.

Build requirements

FFTW
ncursesw dev files (bundled in ncurses in arch)
ALSA dev files
Pulseaudio dev files

Only FFTW is actually required for CAVA to compile, but for maximum usage and preformance ncurses and pulseaudio and/or alsa dev files are recommended. Not sure how to get the pulseaudio dev files for other distros than debian/ubuntu or if they are bundled in pulseaudio.

All these can be installed easily in all major distros:

Debian/Raspbian:

apt-get install libfftw3-dev libasound2-dev libncursesw5-dev libpulse-dev

ArchLinux:

pacman -S base-devel fftw ncurses

openSUSE:

zypper install alsa-devel ncurses-devel fftw3-devel

Fedora:

dnf install alsa-lib-devel ncurses-devel fftw3-devel

A system-wide installation of Iniparser will also be used if it is installed, if not the bundled version will be used.

To run the autogen script you will also need automake, libtool and git.

Getting started

./autogen.sh
./configure
make

You can use the following for compilation options:

--enable-debug          enable debug messages and frequency table output

For example, turning on debugging messages:

./configure --enable-debug

Installing manually

Install cava to default /usr/local:

make install

Or you can change PREFIX, for example:

./configure --prefix=PREFIX

Uninstalling

make uninstall

openSUSE

On openSUSE you need to add jubalh's home repository to install cava via zypper. For example for Tumbleweed do:

zypper ar -f http://download.opensuse.org/repositories/home:/jubalh/openSUSE_Tumbleweed/home:jubalh.repo
zypper in cava

If you use 13.2 or 13.1 just replace openSUSE_Tumbleweed with openSUSE_13.2, adjust it to your version.

Fedora

RPM spec file

Arch

Cava is in AUR.

yaourt -S cava

All distro specific instalations sources might be out of date.

Capturing audio

From Pulseaudio monitor source (Easy, default if supported)

First make sure you have installed pulseaudio dev files and that cava has been built with pulseaudio support (it should be automatically if the dev files are found).

If you're lucky all you have to do is to uncomment this line in the config file under input:

method = pulse

If nothing happens you might have to use a different source than the default. The default might also be your microphone. Look at the config file for help.

From ALSA-loopback device (Tricky)

If you want to capture audio straight fom the output (not just mic or line-in), you must create an ALSA loopback interface, then output the audio simultaneously to both the loopback and your normal interface.

To create a loopback interface simply run:

sudo modprobe snd_aloop

Hopefully your aplay -l should now contain a loopback interface.

To make it presistent across boot add the line snd-aloop to "/etc/modules". To keep it form beeing loaded as the first soundcard add the line options snd-aloop index=1 to "/etc/modprobe.d/alsa-base.conf", this will load it at '1'. You can replace '1' with whatever makes most senes in your audio setup.

Playing the audio through your Loopback interface makes it possible for cava to to capture it, but there will be no sound in your speakers. :(

Not to worry! There are (at least) two ways of sending the audio output to the loopback and your actual audio interface at the same time:

PulseAudio combined-sink (easy)

First create the loopback device as explained in the section above.

To /etc/pulse/default.pa, add the line load-module module-combine-sink (in PulseAudio versions <1.0, the module was only called module-combine). Then restart PulseAudio. For some reason, I had to turn off realtime scheduling for this to work on a Raspberry Pi (set realtime-scheduling = no in /etc/pulse/daemon.conf).

PulseAudio setup can also be done in paprefs (Debian: sudo apt-get install paprefs && paprefs): In the far right tab check the box "Simultaneous Output".

An extra Output should appear in your sound options called "Simultaneous output to..." Note that when using this method if you turn down the volume on the Simultaneous output, this will effect the visualizer. To avoid this, select the actual output, turn down the volume, then select the Simultaneous output again.

ALSA multi channel (hard)

First create the loopback device as explained in the section above.

Look at the inculded example file example_files/etc/asound.conf. I was able to make this work on my laptop (an Asus UX31 running Elementary OS). I had no luck with the ALSA method on my Rasberry PI (Rasbian) with an USB DAC. The PulseAudio method however works perfectly on my PI.

From mpd's fifo output

Add these lines in mpd:

audio_output {
    type                    "fifo"
    name                    "my_fifo"
    path                    "/tmp/mpd.fifo"
    format                  "44100:16:2"
}

Uncomment and change input method to fifo in the config file.

The path of the fifo can be specified with the source parameter.

I had some trouble with sync (the visualizer was ahead of the sound). Reducing the ALSA buffer in mpd fixed it:

audio_output {
        type            "alsa"
        name            "My ALSA"
        buffer_time     "50000"   # (50ms); default is 500000 microseconds (0.5s)
}

Running via ssh

To run via ssh to an external monitor, redirect output to /dev/console:

 ~# ./cava  <> /dev/console >&0 2>&1

exit with ctrl+z then run 'bg' to keep it running after you log out.

(You must be root to redirect to console. Simple sudo is not enough: Run sudo su first.)

Font notes

Since the graphics are simply based on characters, performance is dependent on the terminal font.

In ttys

If you run this in a TTY the program will change the font to the included cava.psf (actually a slightly modified "unifont").

In console fonts it seems that only 256 Unicode characters are supported, probably because they are bitmap fonts. I could not find a font with Unicode characters 2581-2587 (the 1/8 - 7/8 blocks used on the top of each bar to increase resolution).

So in cava.psf, the characters 1-7 are actually replaced by Unicode characters 2581-2587. When cava exits, it changes the font back. If cava exits abnormally and you notice that 1-7 are replaced by partial blocks, just change the font with setfont.

Actually, setfont is supposed to return the default font, but this usually isn't set. I haven't found another way to get the current font. So cava sets the font to "Lat2-Fixed16" when interrupted. All major distros should have it. It will revert to your default font at reboot.

In terminal emulators

In terminal emulators like xterm, the font settings is chosen in the software and cannot be changed by an application. So find your terminal settings and try out different fonts and settings. Also character spacing affects the look of the bar spectrum.

Speed preformance is also different, urxvt is the best I found so far, while Gnome-terminal is quite slow.

Cava also disables the terminal cursor, and turns it back on on exit, but in case it terminates unexpectedly, run setterm -cursor on to get it back.

Tip: Cava will look much nicer in small font sizes. Use a second terminal emulator for cava and set the font size to 1. Warning, can cause high CPU usage and latency if the terminal window is too large!

Latency notes

If you see latency issues (sound before image) in a terminal emulator, try increasing the font size. This will reduce the number of characters that have to be shown.

If your audio device has a huge buffer, you might experience that cava is actually faster than the audio you hear. This reduces the experience of the visualization. To fix this, you try decreasing the buffer settings in your audio playing software.

Usage

Usage : cava [options]
Visualize audio input in terminal. 

Options:
	    -p          path to config file
	    -v          print version

Exit with ctrl+c or q.

If cava quits unexpectedly or is force killed, echo must be turned on manually with stty -echo.

Controls

Key	Description
`up` / `down`	increase/decrease sensitivity
`left` / `right`	increase/decrease bar width
`c` / `b`	change forground/background color
`r`	Reload configuration
`q` or `CTRL-C`	Quit C.A.V.A.

Configuration

As of version 0.4.0 all options are done in the config file, no more command-line arguments!

By default a configuration file is located in $XDG_CONFIG_HOME/cava/config or $HOME/.config/cava/config, but cava can also be made to use a different file with the -p option. Look in the default config file for details on the different options.

Sending cava a SIGUSR1 signal, will force cava to reload its configuration file. Thus, it behaves as if the user pressed r in the terminal. One might send a SIGUSR1 signal using pkill or killall. For example:

$ pkill -USR1 cava

Examples on how the equalizer works:

[eq]
1=0
2=1
3=0
4=1
5=0

[eq]
1=2
2=2
3=1
4=1
5=0.5

Thanks

Contributors:

Also thanks to dpayne for figuring out how to find the pulseaudio default sink name.

kowalcj0/cava