Golang : Activate web camera and broadcast out base64 encoded images



Tags : golang go-openCV web-camera streaming-images base64

For this tutorial, we will learn how to activate web camera with Golang + OpenCV and stream out base64 encoded images via HTTP server. This tutorial is derived from the lesson that I use to teach my son on the subject of computer vision and Golang. It is based on the Go-OpenCV tutorial on activating web camera (https://github.com/lazywei/go-opencv/blob/master/samples/webcam.go). The program will activate the web camera when you point your web browser to localhost:8080 and begin streaming out base64 encoded images. You will have to scroll down the see the new images. LOL! Good enough to get a 3 years old kid excited about computer vision. Before you start. go get github.com/lazywei/go-opencv Here you go! package main import ( "bytes" "encoding/base64" "fmt" "github.com/lazywei/go-opencv/opencv" "image/png" "net/http" ) func broadcast(w http.ResponseWriter, r *http.Request) { webCamera := opencv.NewCameraCapture(0) if webCamera == nil { panic("Unable to open camera") defer webCamera.Release() for { if webCamera.GrabFrame() { imgFrame := webCamera.RetrieveFrame(1) if imgFrame != nil { //fmt.Println(imgFrame.ImageSize()) //fmt.Println(imgFrame.ToImage()) // convert IplImage(Intel Image Processing Library) // to image.Image goImgFrame := imgFrame.ToImage() // and then convert to []byte // with the help of png.Encode() function frameBuffer := new(bytes.Buffer) //frameBuffer := make([]byte, imgFrame.ImageSize()) err := png.Encode(frameBuffer, goImgFrame) if err != nil { panic(err) // convert the buffer bytes to base64 string - use buf.Bytes() for new image imgBase64Str := base64.StdEncoding.EncodeToString(frameBuffer.Bytes()) // Embed into an html without PNG file img2html := "<html><body><img src=\"data:image/png;base64," + imgBase64Str + "\" /></body></html>" w.Write([]byte(fmt.Sprintf(img2html))) // TODO : // encode frames to stream via WebRTC fmt.Println("Streaming....") func main() { fmt.Println("Broadcasting...") mux := http.NewServeMux() mux.HandleFunc("/", broadcast) http.ListenAndServe(":8080", mux) streaming out base64 encoded images to browser NOTES: In case you get these error messages : No package 'opencv' found Package opencv was not found in the pkg-config search path. Perhaps you should add the directory containing `opencv.pc' to the PKGCONFIGPATH environment variable Fix this problem by installing openCV. On MacOSX : >brew install homebrew/science/opencv References: https://github.com/lazywei/go-opencv/blob/master/opencv/goimage.go https://www.socketloop.com/tutorials/golang-how-to-stream-file-to-client-browser-or-write-to-http-responsewriter https://www.socketloop.com/references/golang-net-http-servecontent-function-example http://stackoverflow.com/questions/35667501/golang-seeking-through-a-video-serving-as-bytes

  See also : Golang : Save webcamera frames to video file



Tags : golang go-openCV web-camera streaming-images base64

By Adam Ng

IF you gain some knowledge or the information here solved your programming problem. Please consider donating to the less fortunate or some charities that you like. Apart from donation, planting trees, volunteering or reducing your carbon footprint will be great too.


Advertisement

Advertisement

Advertisement

Advertisement