fix webcam bug and also consider webcam Input var value

device/device.go

@@ -60,5 +60,5 @@ type AVDevice interface {
 type MultiError []error
 
 func (me MultiError) Error() string {
-	return fmt.Sprintf("%v", me)
+	return fmt.Sprintf("%v", []error(me))
 }

device/webcam/webcam.go

@@ -54,6 +54,7 @@ var (
 	errBadBitrate   = errors.New("bitrate bad or unset, defaulting")
 	errBadWidth     = errors.New("width bad or unset, defaulting")
 	errBadHeight    = errors.New("height bad or unset, defaulting")
+	errBadInputPath = errors.New("input path bad or unset, defaulting")
 )
 
 // Webcam is an implementation of the AVDevice interface for a Webcam. Webcam
@@ -75,6 +76,12 @@ func New(l config.Logger) *Webcam {
 // added to the multiError and a default value is used.
 func (w *Webcam) Set(c config.Config) error {
 	var errs device.MultiError
+	if c.InputPath == "" {
+		const defaultInputPath = "/dev/video0"
+		errs = append(errs, errBadInputPath)
+		c.InputPath = defaultInputPath
+	}
+
 	if c.Width == 0 {
 		errs = append(errs, errBadWidth)
 		c.Width = defaultWidth

revid/revid.go

@@ -467,7 +467,7 @@ func (r *Revid) Update(vars map[string]string) error {
 	for key, value := range vars {
 		switch key {
 		case "Input":
-			v, ok := map[string]uint8{"raspivid": config.InputRaspivid, "rtsp": config.InputRTSP}[strings.ToLower(value)]
+			v, ok := map[string]uint8{"raspivid": config.InputRaspivid, "rtsp": config.InputRTSP, "v4l": config.InputV4L}[strings.ToLower(value)]
 			if !ok {
 				r.cfg.Logger.Log(logger.Warning, pkg+"invalid input var", "value", value)
 				break