Initial version

.gitignore

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+cam2mjpeg

go.mod

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+module github.com/Luzifer/cam2mjpeg
+
+require (
+	github.com/Luzifer/rconfig/v2 v2.2.1
+	github.com/gofrs/uuid v3.2.0+incompatible
+	github.com/sirupsen/logrus v1.3.0
+)

go.sum

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+github.com/Luzifer/rconfig/v2 v2.2.1 h1:zcDdLQlnlzwcBJ8E0WFzOkQE1pCMn3EbX0dFYkeTczg=
+github.com/Luzifer/rconfig/v2 v2.2.1/go.mod h1:OKIX0/JRZrPJ/ZXXWklQEFXA6tBfWaljZbW37w+sqBw=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/gofrs/uuid v3.2.0+incompatible h1:y12jRkkFxsd7GpqdSZ+/KCs/fJbqpEXSGd4+jfEaewE=
+github.com/gofrs/uuid v3.2.0+incompatible/go.mod h1:b2aQJv3Z4Fp6yNu3cdSllBxTCLRxnplIgP/c0N/04lM=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.3.0 h1:hI/7Q+DtNZ2kINb6qt/lS+IyXnHQe9e90POfeewL/ME=
+github.com/sirupsen/logrus v1.3.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
+github.com/spf13/pflag v1.0.3 h1:zPAT6CGy6wXeQ7NtTnaTerfKOsV6V6F8agHXFiazDkg=
+github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnInEg4=
+github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+golang.org/x/crypto v0.0.0-20180904163835-0709b304e793 h1:u+LnwYTOOW7Ukr/fppxEb1Nwz0AtPflrblfvUudpo+I=
+golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33 h1:I6FyU15t786LL7oL/hn43zqTuEGr4PN7F4XJ1p4E3Y8=
+golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/validator.v2 v2.0.0-20180514200540-135c24b11c19 h1:WB265cn5OpO+hK3pikC9hpP1zI/KTwmyMFKloW9eOVc=
+gopkg.in/validator.v2 v2.0.0-20180514200540-135c24b11c19/go.mod h1:o4V0GXN9/CAmCsvJ0oXYZvrZOe7syiDZSN1GWGZTGzc=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

main.go

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+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"os/exec"
+	"strconv"
+	"sync"
+
+	rconfig "github.com/Luzifer/rconfig/v2"
+	"github.com/gofrs/uuid"
+	log "github.com/sirupsen/logrus"
+)
+
+var (
+	cfg = struct {
+		Device         string `flag:"input,i" default:"/dev/video0" description:"Video device to read from"`
+		FrameRate      int    `flag:"rate,r" default:"10" description:"Frame rate to show in MJPEG"`
+		Height         int    `flag:"height,h" default:"720" description:"Height of video frames"`
+		Listen         string `flag:"listen" default:":3000" description:"Port/IP to listen on"`
+		LogLevel       string `flag:"log-level" default:"info" description:"Log level (debug, info, warn, error, fatal)"`
+		Quality        int    `flag:"quality,q" default:"5" description:"Image quality (2..31)"`
+		VersionAndExit bool   `flag:"version" default:"false" description:"Prints current version and exits"`
+		Width          int    `flag:"width,w" default:"1280" description:"Width of video frames"`
+	}{}
+
+	requester     = map[string]chan []byte{}
+	requesterLock = new(sync.RWMutex)
+
+	version = "dev"
+)
+
+var (
+	beginOfJPEG = []byte{0xff, 0xd8}
+	endOfJPEG   = []byte{0xff, 0xd9}
+)
+
+const maxBacklog = 5
+
+func init() {
+	if err := rconfig.ParseAndValidate(&cfg); err != nil {
+		log.Fatalf("Unable to parse commandline options: %s", err)
+	}
+
+	if cfg.VersionAndExit {
+		fmt.Printf("imgdecode %s\n", version)
+		os.Exit(0)
+	}
+
+	if l, err := log.ParseLevel(cfg.LogLevel); err != nil {
+		log.WithError(err).Fatal("Unable to parse log level")
+	} else {
+		log.SetLevel(l)
+	}
+}
+
+func main() {
+	http.HandleFunc("/mjpeg", handle)
+	go func() {
+		log.WithError(http.ListenAndServe(cfg.Listen, nil)).Fatal("HTTP server has gone")
+	}()
+
+	log.Debug("HTTP server spawned")
+
+	cmd := exec.Command("ffmpeg",
+		"-f", "video4linux2",
+		"-input_format", "yuyv422",
+		"-s", fmt.Sprintf("%dx%d", cfg.Width, cfg.Height),
+		"-r", strconv.Itoa(cfg.FrameRate),
+		"-i", cfg.Device,
+		"-c:v", "mjpeg",
+		"-q:v", strconv.Itoa(cfg.Quality),
+		"-boundary_tag", "ffmpeg",
+		"-f", "image2pipe",
+		"-")
+
+	cmd.Stderr = os.Stderr
+
+	out, err := cmd.StdoutPipe()
+	if err != nil {
+		log.WithError(err).Fatal("Unable to create stdout pipe")
+	}
+
+	if err := cmd.Start(); err != nil {
+		log.WithError(err).Fatal("Unable to spawn ffmpeg")
+	}
+	defer cmd.Process.Kill()
+
+	log.Debug("ffmpeg spawned")
+
+	buf := new(bytes.Buffer)
+
+	for {
+		if _, err := io.CopyN(buf, out, 1024); err != nil {
+			log.WithError(err).Error("Failed to read ffmpeg output")
+			break
+		}
+
+		eoj := bytes.Index(buf.Bytes(), endOfJPEG)
+		if eoj == -1 {
+			continue
+		}
+
+		img := buf.Next(eoj + len(endOfJPEG))
+
+		if !bytes.HasPrefix(img, beginOfJPEG) || !bytes.HasSuffix(img, endOfJPEG) {
+			log.Warn("Found invalid JPEG, skipping")
+			continue
+		}
+
+		go sendImage(img)
+	}
+}
+
+func sendImage(jpg []byte) {
+	requesterLock.RLock()
+	defer requesterLock.RUnlock()
+
+	if len(requester) == 0 {
+		return
+	}
+
+	for _, c := range requester {
+		if len(c) < maxBacklog {
+			c <- jpg
+		}
+	}
+
+	log.WithField("requesters", len(requester)).Debug("sent frame")
+}
+
+func handle(res http.ResponseWriter, r *http.Request) {
+	imgChan := make(chan []byte, 10)
+	uid := uuid.Must(uuid.NewV4()).String()
+
+	defer func() {
+		deregisterImgChan(uid)
+		close(imgChan)
+	}()
+
+	registerImgChan(uid, imgChan)
+
+	handleMJPEG(res, r, imgChan, uid)
+}
+
+func registerImgChan(id string, ic chan []byte) {
+	requesterLock.Lock()
+	defer requesterLock.Unlock()
+
+	requester[id] = ic
+	log.WithField("id", id).Debug("registered new requester")
+}
+
+func deregisterImgChan(id string) {
+	requesterLock.Lock()
+	defer requesterLock.Unlock()
+
+	delete(requester, id)
+	log.WithField("id", id).Debug("removed requester")
+}

mjpeg.go

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+package main
+
+import (
+	"fmt"
+	"mime/multipart"
+	"net/http"
+	"net/textproto"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func handleMJPEG(res http.ResponseWriter, r *http.Request, imgs chan []byte, uid string) {
+	if r.Method != "GET" {
+		http.Error(res, "405 Method Not Allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	logger := log.WithField("id", uid)
+
+	mimeWriter := multipart.NewWriter(res)
+	mimeWriter.SetBoundary("--boundary")
+	defer mimeWriter.Close()
+
+	res.Header().Add("Connection", "close")
+	res.Header().Add("Cache-Control", "no-store, no-cache")
+	res.Header().Add("Content-Type", fmt.Sprintf("multipart/x-mixed-replace;boundary=%s", mimeWriter.Boundary()))
+
+	cn := res.(http.CloseNotifier).CloseNotify()
+	errC := 0
+
+	for {
+		select {
+		case <-cn:
+			return
+
+		case img := <-imgs:
+			partHeader := make(textproto.MIMEHeader)
+			partHeader.Add("Content-Type", "image/jpeg")
+
+			partWriter, err := mimeWriter.CreatePart(partHeader)
+			if err != nil {
+				logger.WithError(err).Error("Unable to create mime part")
+				continue
+			}
+
+			_, err = partWriter.Write(img)
+			if err != nil {
+				logger.WithError(err).Error("Unable to write image")
+				errC++
+
+				if errC > 5 {
+					logger.Error("Too many errors, killing connection")
+					return
+				}
+				continue
+			}
+
+			errC = 0
+		}
+	}
+}