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|
// Example program that uses blakjack/webcam library
// for working with V4L2 devices.
package main
import (
"bytes"
"flag"
"fmt"
"image"
"image/jpeg"
"log"
"mime/multipart"
"net/http"
"net/textproto"
"os"
"sort"
"strconv"
"time"
"github.com/blackjack/webcam"
)
const (
V4L2_PIX_FMT_PJPG = 0x47504A50
V4L2_PIX_FMT_YUYV = 0x56595559
)
type FrameSizes []webcam.FrameSize
func (slice FrameSizes) Len() int {
return len(slice)
}
//For sorting purposes
func (slice FrameSizes) Less(i, j int) bool {
ls := slice[i].MaxWidth * slice[i].MaxHeight
rs := slice[j].MaxWidth * slice[j].MaxHeight
return ls < rs
}
//For sorting purposes
func (slice FrameSizes) Swap(i, j int) {
slice[i], slice[j] = slice[j], slice[i]
}
var supportedFormats = map[webcam.PixelFormat]bool{
V4L2_PIX_FMT_PJPG: true,
V4L2_PIX_FMT_YUYV: true,
}
func main() {
dev := flag.String("d", "/dev/video0", "video device to use")
fmtstr := flag.String("f", "", "video format to use, default first supported")
szstr := flag.String("s", "", "frame size to use, default largest one")
single := flag.Bool("m", false, "single image http mode, default mjpeg video")
addr := flag.String("l", ":8080", "addr to listien")
fps := flag.Bool("p", false, "print fps info")
flag.Parse()
cam, err := webcam.Open(*dev)
if err != nil {
panic(err.Error())
}
defer cam.Close()
// select pixel format
format_desc := cam.GetSupportedFormats()
fmt.Println("Available formats:")
for _, s := range format_desc {
fmt.Fprintln(os.Stderr, s)
}
var format webcam.PixelFormat
FMT:
for f, s := range format_desc {
if *fmtstr == "" {
if supportedFormats[f] {
format = f
break FMT
}
} else if *fmtstr == s {
if !supportedFormats[f] {
log.Println(format_desc[f], "format is not supported, exiting")
return
}
format = f
break
}
}
if format == 0 {
log.Println("No format found, exiting")
return
}
// select frame size
frames := FrameSizes(cam.GetSupportedFrameSizes(format))
sort.Sort(frames)
fmt.Fprintln(os.Stderr, "Supported frame sizes for format", format_desc[format])
for _, f := range frames {
fmt.Fprintln(os.Stderr, f.GetString())
}
var size *webcam.FrameSize
if *szstr == "" {
size = &frames[len(frames)-1]
} else {
for _, f := range frames {
if *szstr == f.GetString() {
size = &f
}
}
}
if size == nil {
log.Println("No matching frame size, exiting")
return
}
fmt.Fprintln(os.Stderr, "Requesting", format_desc[format], size.GetString())
f, w, h, err := cam.SetImageFormat(format, uint32(size.MaxWidth), uint32(size.MaxHeight))
if err != nil {
log.Println("SetImageFormat return error", err)
return
}
fmt.Fprintf(os.Stderr, "Resulting image format: %s %dx%d\n", format_desc[f], w, h)
// start streaming
err = cam.StartStreaming()
if err != nil {
log.Println(err)
return
}
var (
li chan *bytes.Buffer = make(chan *bytes.Buffer)
fi chan []byte = make(chan []byte)
back chan struct{} = make(chan struct{})
)
go encodeToImage(cam, back, fi, li, w, h, f)
if *single {
go httpImage(*addr, li)
} else {
go httpVideo(*addr, li)
}
timeout := uint32(5) //5 seconds
start := time.Now()
var fr time.Duration
for {
err = cam.WaitForFrame(timeout)
if err != nil {
log.Println(err)
return
}
switch err.(type) {
case nil:
case *webcam.Timeout:
log.Println(err)
continue
default:
log.Println(err)
return
}
frame, err := cam.ReadFrame()
if err != nil {
log.Println(err)
return
}
if len(frame) != 0 {
// print framerate info every 10 seconds
fr++
if *fps {
if d := time.Since(start); d > time.Second*10 {
fmt.Println(float64(fr)/(float64(d)/float64(time.Second)), "fps")
start = time.Now()
fr = 0
}
}
select {
case fi <- frame:
<-back
default:
}
}
}
}
func encodeToImage(wc *webcam.Webcam, back chan struct{}, fi chan []byte, li chan *bytes.Buffer, w, h uint32, format webcam.PixelFormat) {
var (
frame []byte
img image.Image
)
for {
bframe := <-fi
// copy frame
if len(frame) < len(bframe) {
frame = make([]byte, len(bframe))
}
copy(frame, bframe)
back <- struct{}{}
switch format {
case V4L2_PIX_FMT_YUYV:
yuyv := image.NewYCbCr(image.Rect(0, 0, int(w), int(h)), image.YCbCrSubsampleRatio422)
for i := range yuyv.Cb {
ii := i * 4
yuyv.Y[i*2] = frame[ii]
yuyv.Y[i*2+1] = frame[ii+2]
yuyv.Cb[i] = frame[ii+1]
yuyv.Cr[i] = frame[ii+3]
}
img = yuyv
default:
log.Fatal("invalid format ?")
}
//convert to jpeg
buf := &bytes.Buffer{}
if err := jpeg.Encode(buf, img, nil); err != nil {
log.Fatal(err)
return
}
const N = 50
// broadcast image up to N ready clients
nn := 0
FOR:
for ; nn < N; nn++ {
select {
case li <- buf:
default:
break FOR
}
}
if nn == 0 {
li <- buf
}
}
}
func httpImage(addr string, li chan *bytes.Buffer) {
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
log.Println("connect from", r.RemoteAddr, r.URL)
if r.URL.Path != "/" {
http.NotFound(w, r)
return
}
//remove stale image
<-li
img := <-li
w.Header().Set("Content-Type", "image/jpeg")
if _, err := w.Write(img.Bytes()); err != nil {
log.Println(err)
return
}
})
log.Fatal(http.ListenAndServe(addr, nil))
}
func httpVideo(addr string, li chan *bytes.Buffer) {
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
log.Println("connect from", r.RemoteAddr, r.URL)
if r.URL.Path != "/" {
http.NotFound(w, r)
return
}
//remove stale image
<-li
const boundary = `frame`
w.Header().Set("Content-Type", `multipart/x-mixed-replace;boundary=`+boundary)
multipartWriter := multipart.NewWriter(w)
multipartWriter.SetBoundary(boundary)
for {
img := <-li
image := img.Bytes()
iw, err := multipartWriter.CreatePart(textproto.MIMEHeader{
"Content-type": []string{"image/jpeg"},
"Content-length": []string{strconv.Itoa(len(image))},
})
if err != nil {
log.Println(err)
return
}
_, err = iw.Write(image)
if err != nil {
log.Println(err)
return
}
}
})
log.Fatal(http.ListenAndServe(addr, nil))
}
|
