fix ffmpeg binary path with spaces on Windows

pkg/ffmpeg/ffmpeg.go

@@ -54,7 +54,15 @@ func (a *Args) HasFilters(filters ...string) bool {
 func (a *Args) String() string {
 	b := bytes.NewBuffer(make([]byte, 0, 512))
 
-	b.WriteString(a.Bin)
+	// quote binary path with spaces (ex. C:\Program Files\ffmpeg.exe),
+	// so shell.QuoteSplit keeps it as a single argument
+	if strings.Contains(a.Bin, " ") {
+		b.WriteByte('"')
+		b.WriteString(a.Bin)
+		b.WriteByte('"')
+	} else {
+		b.WriteString(a.Bin)
+	}
 
 	if a.Global != "" {
 		b.WriteByte(' ')

pkg/ffmpeg/ffmpeg_test.go

@@ -0,0 +1,25 @@
+package ffmpeg
+
+import (
+	"testing"
+
+	"github.com/AlexxIT/go2rtc/pkg/shell"
+	"github.com/stretchr/testify/require"
+)
+
+func TestBinWithSpaces(t *testing.T) {
+	args := Args{
+		Bin:    `C:\Program Files\Symcon\ffmpeg.exe`,
+		Global: "-hide_banner",
+		Input:  "-i rtsp://example.com",
+		Output: "-f mjpeg -",
+	}
+
+	s := args.String()
+	require.Equal(t, `"C:\Program Files\Symcon\ffmpeg.exe" -hide_banner -i rtsp://example.com -f mjpeg -`, s)
+
+	// shell.QuoteSplit is how internal/exec parses this string back
+	split := shell.QuoteSplit(s)
+	require.Equal(t, `C:\Program Files\Symcon\ffmpeg.exe`, split[0])
+	require.Equal(t, "-hide_banner", split[1])
+}