Adds support local USB cameras

cmd/ffmpeg/device_windows.go

@@ -0,0 +1,59 @@
+package ffmpeg
+
+import (
+	"bytes"
+	"github.com/AlexxIT/go2rtc/pkg/streamer"
+	"os/exec"
+	"strings"
+)
+
+// https://trac.ffmpeg.org/wiki/DirectShow
+const deviceInputPrefix = "-f dshow"
+
+func deviceInputSuffix(videoIdx, audioIdx int) string {
+	video := findMedia(streamer.KindVideo, videoIdx)
+	audio := findMedia(streamer.KindAudio, audioIdx)
+	switch {
+	case video != nil && audio != nil:
+		return `video="` + video.Title + `":audio=` + audio.Title + `"`
+	case video != nil:
+		return `video="` + video.Title + `"`
+	case audio != nil:
+		return `audio="` + audio.Title + `"`
+	}
+	return ""
+}
+
+func loadMedias() {
+	cmd := exec.Command(
+		tpl["bin"], "-hide_banner", "-list_devices", "true", "-f", "dshow", "-i", "",
+	)
+
+	var buf bytes.Buffer
+	cmd.Stderr = &buf
+	_ = cmd.Run()
+
+	lines := strings.Split(buf.String(), "\r\n")
+	for _, line := range lines {
+		var kind string
+		if strings.HasSuffix(line, "(video)") {
+			kind = streamer.KindVideo
+		} else if strings.HasSuffix(line, "(audio)") {
+			kind = streamer.KindAudio
+		} else {
+			continue
+		}
+
+		// hope we have constant prefix and suffix sizes
+		// [dshow @ 00000181e8d028c0] "VMware Virtual USB Video Device" (video)
+		name := line[28 : len(line)-9]
+		media := loadMedia(kind, name)
+		medias = append(medias, media)
+	}
+}
+
+func loadMedia(kind, name string) *streamer.Media {
+	return &streamer.Media{
+		Kind: kind, Title: name,
+	}
+}