Add virtual source to ffmpeg (for testing)

internal/ffmpeg/ffmpeg.go

@@ -7,6 +7,7 @@ import (
 	"github.com/AlexxIT/go2rtc/internal/app"
 	"github.com/AlexxIT/go2rtc/internal/ffmpeg/device"
 	"github.com/AlexxIT/go2rtc/internal/ffmpeg/hardware"
+	"github.com/AlexxIT/go2rtc/internal/ffmpeg/virtual"
 	"github.com/AlexxIT/go2rtc/internal/rtsp"
 	"github.com/AlexxIT/go2rtc/internal/streams"
 	"github.com/AlexxIT/go2rtc/pkg/ffmpeg"
@@ -193,6 +194,11 @@ func parseArgs(s string) *ffmpeg.Args {
 		if err != nil {
 			return nil
 		}
+	} else if strings.HasPrefix(s, "virtual?") {
+		var err error
+		if args.Input, err = virtual.GetInput(s[8:]); err != nil {
+			return nil
+		}
 	} else {
 		args.Input = inputTemplate("file", s, query)
 	}

internal/ffmpeg/virtual/virtual.go

@@ -0,0 +1,59 @@
+package virtual
+
+import (
+	"net/url"
+)
+
+func GetInput(src string) (string, error) {
+	query, err := url.ParseQuery(src)
+	if err != nil {
+		return "", err
+	}
+
+	// set defaults (using Add instead of Set)
+	query.Add("source", "testsrc")
+	query.Add("size", "1920x1080")
+	query.Add("decimals", "2")
+
+	// https://ffmpeg.org/ffmpeg-filters.html
+	source := query.Get("source")
+	input := "-re -f lavfi -i " + source
+
+	sep := "=" // first separator
+	for key, values := range query {
+		value := values[0]
+
+		// https://ffmpeg.org/ffmpeg-utils.html#video-size-syntax
+		switch key {
+		case "color", "rate", "duration", "sar":
+		case "size":
+			switch value {
+			case "720":
+				value = "1280x720"
+			case "1080":
+				value = "1920x1080"
+			case "2K":
+				value = "2560x1440"
+			case "4K":
+				value = "3840x2160"
+			case "8K":
+				value = "7680x4230" // https://reolink.com/blog/8k-resolution/
+			}
+		case "decimals":
+			if source != "testsrc" {
+				continue
+			}
+		default:
+			continue
+		}
+
+		input += sep + key + "=" + value
+		sep = ":" // next separator
+	}
+
+	if s := query.Get("format"); s != "" {
+		input += ",format=" + s
+	}
+
+	return input, nil
+}