Added ffmpeg check in VideoWriter

camera.go

@@ -63,6 +63,7 @@ func getCameraData(device string, camera *Camera) {
 		"-i", device,
 	)
 
+	camera.cmd = cmd
 	pipe, err := cmd.StderrPipe()
 	if err != nil {
 		panic(err)

utils.go

@@ -91,13 +91,13 @@ func parseDevices(buffer []byte) []string {
 	devices := make([]string, 0)
 	bufferstr := string(buffer)
 
-	index := strings.Index(bufferstr, "DirectShow video devices")
+	index := strings.Index(bufferstr, "DirectShow video device")
 	if index == -1 {
 		return devices
 	}
 	bufferstr = bufferstr[index:]
 
-	index = strings.Index(bufferstr, "DirectShow audio devices")
+	index = strings.Index(bufferstr, "DirectShow audio device")
 	if index != -1 {
 		bufferstr = bufferstr[:index]
 	}

videowriter.go

@@ -36,6 +36,9 @@ type Options struct {
 }
 
 func NewVideoWriter(filename string, width, height int, options *Options) *VideoWriter {
+	// Check if ffmpeg is installed on the users machine.
+	checkExists("ffmpeg")
+
 	writer := VideoWriter{filename: filename}
 
 	writer.width = width