Cavabar - easily get formatted CAVA output that is suitable for any taskbar.

cavabar.go

// Compile executable with "go build cavabar.go" or just run with "go run cavabar.go"

package main

import (
	"encoding/binary"
	"flag"
	"fmt"
	"io"
	"math"
	"os"
	"os/exec"
	"os/signal"
	"syscall"
)

func checkError(msg string, err error) {
	if err != nil {
		fmt.Fprintf(os.Stderr, msg+": %s", err)
		os.Exit(1)
	}
}

func main() {
	// Parse arguments
	var source, bars, cava string
	var rate, count int
	var mono, help bool

	flag.StringVar(&cava, "cava", "cava", "filename/path to execute cava with")
	flag.StringVar(&source, "source", "pipewire", "cava audio source")
	flag.IntVar(&rate, "rate", 30, "number of updates per second")
	flag.IntVar(&count, "count", 14, "number of bars to display")
	flag.StringVar(&bars, "bars", "▁▂▃▄▅▆▇█", "ordered string of characters to use for the bars")
	flag.BoolVar(&mono, "mono", false, "use averaged single channel for output")
	flag.BoolVar(&help, "help", false, "display this message")
	flag.Parse()

	if help {
		flag.CommandLine.SetOutput(os.Stdout)
		flag.PrintDefaults()
		os.Exit(0)
	}

	channels := "stereo"
	if mono {
		channels = "mono"
	}

	// Create a temporary config file for cava
	cfg, err := os.CreateTemp("", "cavabar-*.conf")
	checkError("failed to create cava config", err)
	defer os.Remove(cfg.Name())
	_, err = fmt.Fprintf(cfg, `[general]
mode = normal
framerate = %d
bars = %d

[input]
source = %s

[output]
channels = %s
method = raw
raw_target = /dev/stdout
data_format = binary
binary_bits = 16bit`, rate, count, source, channels)
	checkError("failed to write config", err)
	cfg.Close()

	// Prepare sub-process and setup a pipe
	cmd := exec.Command(cava, "-p", cfg.Name())
	stdout, err := cmd.StdoutPipe()
	checkError("failed to create pipe", err)
	checkError("failed to start cava", cmd.Start())
	defer cmd.Process.Kill()

	// Initialize buffers and values used for computation
	runes := []rune(bars)
	maxIndex := float64(len(runes) - 1)
	const maxValue float64 = 65530 // Cava docs say 65530, not 65535
	result := make([]rune, count)
	buf := make([]uint16, count)

	// Trap SIGTERM and SIGINT signals, and exit gracefully
	var done bool
	sigs := make(chan os.Signal, 1)
	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
	go func() {
		<-sigs
		done = true
	}()

	// Main loop
	for {
		if done {
			close(sigs)
			break
		}
		if err := binary.Read(stdout, binary.NativeEndian, buf); err != nil {
			if err != io.EOF {
				checkError("error reading from pipe", err)
			}
			break
		}
		for i, pcm := range buf {
			index := int(math.Round((float64(pcm) / maxValue) * maxIndex))
			result[i] = runes[index]
		}
		fmt.Println(string(result))
	}
}

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