default device selection

Author: noriah

cmd/catnip/config.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/noriah/catnip/dsp"
 	"github.com/noriah/catnip/graphic"
+	"github.com/noriah/catnip/input"
 )
 
 // Config is a temporary struct to define parameters
@@ -58,6 +59,7 @@ type config struct {
 //   - super smooth detail view
 func newZeroConfig() config {
 	return config{
+		backend:                    input.DefaultBackend(),
 		sampleRate:                 44100,
 		sampleSize:                 1024,
 		smoothFactor:               74.15,

cmd/catnip/main.go

@@ -157,8 +157,17 @@ func doFlags(cfg *config) bool {
 
 	switch {
 	case listBackendsCmd.Used:
+		defaultBackend := input.DefaultBackend()
+
+		fmt.Println("all backends. '*' marks default")
+
 		for _, backend := range input.Backends {
-			fmt.Printf("- %s\n", backend.Name)
+			star := ' '
+			if defaultBackend == backend.Name {
+				star = '*'
+			}
+
+			fmt.Printf("- %s %c\n", backend.Name, star)
 		}
 
 		return true

go.mod

@@ -10,4 +10,6 @@ require (
 	gonum.org/v1/gonum v0.11.0
 )
 
-require github.com/mattn/go-runewidth v0.0.9 // indirect
+require (
+	github.com/mattn/go-runewidth v0.0.9 // indirect
+)

go.sum

@@ -8,6 +8,5 @@ github.com/nsf/termbox-go v1.1.1 h1:nksUPLCb73Q++DwbYUBEglYBRPZyoXJdrj5L+TkjyZY=
 github.com/nsf/termbox-go v1.1.1/go.mod h1:T0cTdVuOwf7pHQNtfhnEbzHbcNyCEcVU4YPpouCbVxo=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
-golang.org/x/exp v0.0.0-20191002040644-a1355ae1e2c3 h1:n9HxLrNxWWtEb1cA950nuEEj3QnKbtsCJ6KjcgisNUs=
 gonum.org/v1/gonum v0.11.0 h1:f1IJhK4Km5tBJmaiJXtk/PkL4cdVX6J+tGiM187uT5E=
 gonum.org/v1/gonum v0.11.0/go.mod h1:fSG4YDCxxUZQJ7rKsQrj0gMOg00Il0Z96/qMA4bVQhA=

input/backend.go

@@ -2,6 +2,8 @@ package input
 
 import (
 	"fmt"
+	"os/exec"
+	"runtime"
 
 	"github.com/pkg/errors"
 )
@@ -32,6 +34,55 @@ func RegisterBackend(name string, b Backend) {
 	})
 }
 
+// Get all installed backend names.
+func GetAllBackendNames() []string {
+	out := make([]string, len(Backends))
+	for i, backend := range Backends {
+		out[i] = backend.Name
+	}
+	return out
+}
+
+// Get the default backend depending on
+func DefaultBackend() string {
+	switch runtime.GOOS {
+	case "windows":
+		if HasBackend("ffmpeg-dshow") {
+			return "ffmpeg-dshow"
+		}
+
+	case "darwin":
+		if backend := FindBackend("portaudio"); backend != nil {
+			if HasBackend("portaudio") {
+				return "portaudio"
+			}
+		}
+
+		if HasBackend("ffmpeg-avfoundation") {
+			return "ffmpeg-avfoundation"
+		}
+
+	case "linux":
+		if path, _ := exec.LookPath("pw-cat"); path != "" {
+			if HasBackend("pipewire") {
+				return "pipewire"
+			}
+		}
+
+		if path, _ := exec.LookPath("parec"); path != "" {
+			if HasBackend("parec") {
+				return "parec"
+			}
+		}
+
+		if HasBackend("ffmpeg-alsa") {
+			return "ffmpeg-alsa"
+		}
+	}
+
+	return ""
+}
+
 // FindBackend is a helper function that finds a backend. It returns nil if the
 // backend is not found.
 func FindBackend(name string) Backend {
@@ -43,6 +94,15 @@ func FindBackend(name string) Backend {
 	return nil
 }
 
+func HasBackend(name string) bool {
+	for _, backend := range Backends {
+		if backend.Name == name {
+			return true
+		}
+	}
+	return false
+}
+
 func InitBackend(bknd string) (Backend, error) {
 	backend := FindBackend(bknd)
 	if backend == nil {