C.A.V.A.

Console-based Audio Visualizer for ALSA

by Karl Stavestrand

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

Demo video

Updates

4/23/2015 - Fixed terminal window resizing, added smoothenig

4/19/2015 - Added Monstercat style FFT easing (by CelestialWalrus).

9/22/2014 - Added support for mpd FIFO input.

What it is

C.A.V.A. is a bar spectrum analyzer for audio using ALSA for input. Its frequency range is limited to 50-12,000Hz. 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 50-12,000Hz 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

• ALSA dev files
• FFTW

Debian/Raspbian users can install this with:

apt-get install libfftw3-dev libasound2-dev

ArchLinux users can install this with:

pacman -S base-devel fftw

Getting started

make

You can use the following for compilation options, value in italic style is the default value:

Name	Value	Description
debug	0 or 1	Debugging message switch

For example, turning on debugging messages:

make debug=1

Installing

Install cava to default /usr/local:

make install

Or you can change PREFIX, for example:

make PREFIX=$HOME/.local install

Uninstalling

make uninstall

Or:

make PREFIX=$HOME/.local uninstall

Capturing audio

Straight from output

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.

Here is one way to create a loopback interface:

• Copy the file "alsa-aloop.conf" to your "/etc/modprobe.d/" directory. You might have to change the index=1 to match your sound setup. Look at "aplay -l" to se what index is available.
• Add the line "snd-aloop" to /etc/modules
• Run "sudo modprobe snd_aloop"

Hopefully your "aplay -l" should now contain a few "Loopback" interfaces.

Now 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 (easy)

To /etc/pulse/default.pa, add the line load-module module-combine-sink (in PulseAudio versions <2.0, the module is 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, then turn down the volume, then select the Simultaneous output again.

ALSA (hard)

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 with an USB DAC runnig Rasbian. The PulseAudio method however works perfectly on my PI.

Read more about the ALSA method here.

Cava defaults to using the ALSA device hw:1,1. If your loopback interface is not on that index, or you want to capture audio from somewhere else, simply pass the -d flag with the target.

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"
}

Run cava with ./cava -i fifo.

The path of the fifo can be specified with -p.

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 [options] > /dev/console

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.

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.e

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 then 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]

Options:
    -b 1..(console columns/2-1) or 200	 number of bars in the spectrum (default 25 + fills up the console), program wil auto adjust to maxsize if input is to high)

    -i 'input method'			 method used for listnening to audio, supports 'alsa' and 'fifo'

    -d 'alsa device'			 name of alsa capture device (default 'hw:1,1')

    -p 'fifo path'				 path to fifo (default '/tmp/mpd.fifo')

    -c color				 suported colors: red, green, yellow, magenta, cyan, white, blue, black (default: cyan)

    -C backround color			 supported colors: same as above (default: no change)

    -s sensitivity %			 sensitivity in percent, 0 means no respons 100 is normal 50 half 200 double and so forth

    -f framerate 				 max frames per second to be drawn, if you are experiencing high CPU usage, try redcing this (default: 60)

Exit with ctrl+c.

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

Controls

Key	Description
s	Toggle Scientific mode
q or CTRL-C	Quit C.A.V.A.