Added multiplatform webcam streaming

utils.go

@@ -4,13 +4,15 @@ import (
 	"errors"
 	"os"
 	"os/exec"
+	"regexp"
+	"runtime"
 	"strconv"
 	"strings"
 )
 
 // Returns true if file exists, false otherwise.
 // https://stackoverflow.com/questions/12518876/how-to-check-if-a-file-exists-in-go
-func Exists(filename string) bool {
+func exists(filename string) bool {
 	_, err := os.Stat(filename)
 	if err == nil {
 		return true
@@ -22,7 +24,7 @@ func Exists(filename string) bool {
 }
 
 // Checks if the given program is installed.
-func CheckExists(program string) {
+func checkExists(program string) {
 	cmd := exec.Command(program, "-version")
 	if err := cmd.Start(); err != nil {
 		panic(program + " is not installed.")
@@ -59,6 +61,7 @@ func parseFFprobe(input []byte, video *Video) {
 	video.pix_fmt = data["pix_fmt"]
 }
 
+// Parses the given data into a float64.
 func parse(data string) float64 {
 	n, err := strconv.ParseFloat(data, 64)
 	if err != nil {
@@ -67,16 +70,91 @@ func parse(data string) float64 {
 	return n
 }
 
-// func main() {
-// 	os := runtime.GOOS
-// 	switch os {
-// 	case "windows":
-// 		fmt.Println("Windows")
-// 	case "darwin":
-// 		fmt.Println("MAC operating system")
-// 	case "linux":
-// 		fmt.Println("Linux")
-// 	default:
-// 		fmt.Printf("%s.\n", os)
-// 	}
-// }
+// Returns the webcam name used for the -f option with ffmpeg.
+func webcam() string {
+	os := runtime.GOOS
+	switch os {
+	case "linux":
+		return "v4l2"
+	case "darwin":
+		return "avfoundation" // qtkit
+	case "windows":
+		return "dshow" // vfwcap
+	default:
+		panic("Unsupported OS: " + os)
+	}
+}
+
+// For webcam streaming on windows, ffmpeg requires a device name.
+// All device names are parsed and returned by this function.
+func parseDevices(buffer []byte) []string {
+	devices := make([]string, 0)
+	bufferstr := string(buffer)
+
+	index := strings.Index(bufferstr, "DirectShow video devices")
+	if index == -1 {
+		return devices
+	}
+	bufferstr = bufferstr[index:]
+
+	index = strings.Index(bufferstr, "DirectShow audio devices")
+	if index != -1 {
+		bufferstr = bufferstr[:index]
+	}
+	// Find all device names surrounded by quotes. E.g "Windows Camera Front"
+	r := regexp.MustCompile("\"[^\"]+\"")
+	matches := r.FindAllStringSubmatch(bufferstr, -1)
+	for _, match := range matches {
+		device := match[0][1 : len(match[0])-1]
+		// Don't include Alternate Names for devices.
+		// Alternate names start with an '@'.
+		if !strings.HasPrefix(device, "@") {
+			devices = append(devices, device)
+		}
+	}
+
+	return devices
+}
+
+// Parses the webcam metadata (width, height, fps, codec) from ffmpeg output.
+func parseWebcamData(buffer []byte, camera *Camera) {
+	bufferstr := string(buffer)
+	index := strings.Index(bufferstr, "Stream #")
+	if index == -1 {
+		index++
+	}
+	bufferstr = bufferstr[index:]
+	// Dimensions. widthxheight
+	regex := regexp.MustCompile("\\d{2,}x\\d{2,}")
+	match := regex.FindString(bufferstr)
+	if len(match) > 0 {
+		split := strings.Split(match, "x")
+		camera.width = int(parse(split[0]))
+		camera.height = int(parse(split[1]))
+	}
+	// FPS
+	regex = regexp.MustCompile("\\d+(.\\d+)? fps")
+	match = regex.FindString(bufferstr)
+	if len(match) > 0 {
+		index = strings.Index(match, " fps")
+		if index != -1 {
+			match = match[:index]
+		}
+		camera.fps = parse(match)
+	}
+	// Codec
+	regex = regexp.MustCompile("Video: .+,")
+	match = regex.FindString(bufferstr)
+	if len(match) > 0 {
+		match = match[7:]
+		index = strings.Index(match, "(")
+		if index != -1 {
+			match = match[:index]
+		}
+		index = strings.Index(match, ",")
+		if index != -1 {
+			match = match[:index]
+		}
+		camera.codec = strings.TrimSpace(match)
+	}
+}