add prior node version

node/README.md

+<pre>
+shopcam server, prior node version
+
+to clone: git clone https://gitlab.cba.mit.edu/pub/cams.git
+
+to reinitialize: ./init
+
+to run: node cams.js
+
+uses ffmpeg for screen capture
+
+uses convert to make thumbnails
+
+uses compare to measure activity
+
+can use uvcdynctrl -f to list resolutions
+
+can use sudo guvcview to adjust camera
+
+can use http-server-with-auth to serve:  
+http-server-with-auth -p port --username username --password password  
+http-server-with-auth -p port --username username --password password --ssl --cert cert.pem --key key.pem  
+index is at http://this_address:this_port  
+last image is at http://this_address:this_port/oldimage.jpg  
+
+can use Ubuntu MATE on Raspberry Pi 3:  
+sudo apt-get install nodejs-legacy npm ffmpeg imagemagick guvcview  
+sudo npm install -g http-server-with-auth  
+System -> Administration -> Time and Date -> Keep synchronized with internet servers  
+
+can use Logitech C920 HD Webcam
+
+can start cams script on boot with cams.service:  
+edit cams script with port, username, and password
+sudo cp cams.service /lib/systemd/system  
+sudo systemctl daemon-reload  
+sudo systemctl enable cams.service  
+sudo systemctl start cams.service  
+journalctl -u cams.service

node/cams

+#!/bin/bash
+cd /home/fab/cams
+node cams.js &
+http-server-with-auth -p set_port_number --username set_username --password set_password &
+

node/cams.js

+//
+// cams.js
+//    shopcam activity monitor
+//    Neil Gershenfeld
+//    12/11/17
+//
+// settings
+//
+var image_width = 1600
+var image_height = 1200
+var thumbnail_size = 200
+var video_filter = 'vflip,hflip'
+var difference_threshold = .05
+var millisecond_image_delay = 15000
+var days_to_save = 150
+//
+// requires
+//
+const fs = require('fs')
+const exec = require('child_process').exec
+const execSync = require('child_process').execSync
+//
+// image update function
+//
+function update() {
+   //
+   // name image with time
+   //
+   var date = new Date()
+   var year = date.getFullYear()
+   var month = ('0'+(1+parseInt(date.getMonth()))).slice(-2)
+   var day = ('0'+date.getDate()).slice(-2)
+   var hour = ('0'+date.getHours()).slice(-2)
+   var minute = ('0'+date.getMinutes()).slice(-2)
+   var second = ('0'+date.getSeconds()).slice(-2)
+   var name = year+'-'+month+'-'+day+'-'+hour+'-'+minute+'-'+second+'.jpg'
+   //
+   // take new image
+   //
+   console.log('\ncapture '+name)
+   var success = true
+   do {
+      try {
+         execSync('ffmpeg -y -f v4l2 -s '+image_width+'x'+image_height+' -i /dev/video0 -vframes 1 -vf '+video_filter+' image.jpg')
+         }
+      catch(err) {
+         success = false
+         }
+      }
+   while (success != true)
+   //
+   // remove prior images
+   //
+   date.setDate(date.getDate()-days_to_save)
+   var oldyear = date.getFullYear()
+   var oldmonth = ('0'+(1+parseInt(date.getMonth()))).slice(-2)
+   var oldday = ('0'+date.getDate()).slice(-2)
+   var oldhour = ('0'+date.getHours()).slice(-2)
+   var oldminute = ('0'+date.getMinutes()).slice(-2)
+   var prefix = oldyear+'-'+oldmonth+'-'+oldday+'-'+oldhour+'-'+oldminute+'*'
+   console.log('remove '+prefix)
+   execSync('rm -f images/'+prefix+'*')
+   execSync('rm -f thumbnails/'+prefix+'*')
+   //
+   // check if image has changed beyond threshold
+   //
+   try {
+      execSync('compare -metric RMSE image.jpg oldimage.jpg null: 2>&1')
+      }
+   catch(err) {
+      var ret = String(err.stdout).split(' ')
+      var ptrl = ret[1].indexOf('(')
+      var ptrr = ret[1].indexOf(')')
+      var diff = parseFloat(ret[1].slice(ptrl+1,ptrr))
+      console.log('image difference: '+diff)
+      }
+   if (diff > difference_threshold) {
+      //
+      // size has changed, keep image
+      //
+      console.log('activity detected, save image')
+      execSync('convert image.jpg -resize '+thumbnail_size+'x'+thumbnail_size+' thumbnails/'+name)
+      execSync('cp image.jpg images/'+name)
+      //
+      // rebuild day's index
+      //
+      console.log('reindex day')
+      execSync("echo '<html><body>' > index/newindex.html")
+      execSync("echo '<script src=../display.js></script>' > index/newindex.html")
+      execSync('ls images | awk \'/^'+year+'-'+month+'-'+day+'/ { print "<img src=\\"../thumbnails/" $1 "\\" id=\\"" $1 "\\" style=\\"width:20%;height:auto;cursor:pointer;\\" onmousedown=display(\\"" $1 "\\")>" }\' >> index/newindex.html')
+      execSync("mv index/newindex.html index/"+month+"-"+day+".html")
+      //
+      // delay before next image
+      //
+      console.log('delay before next image')
+      execSync('mv image.jpg oldimage.jpg')
+      setTimeout(update,millisecond_image_delay)
+      }
+   else {
+      //
+      // size hasn't changed
+      //
+      console.log('no activity detected, don\'t save image')
+      //
+      // no delay before next image
+      //
+      execSync('mv image.jpg oldimage.jpg')
+      setTimeout(update,0)
+      }
+   }
+//
+// take initial image
+//
+var success = true
+do {
+   try {
+      execSync('ffmpeg -y -f v4l2 -s '+image_width+'x'+image_height+' -i /dev/video0 -vframes 1 -vf '+video_filter+' oldimage.jpg')
+      }
+   catch(err) {
+      success = false
+      }
+   }
+while (success != true)
+//
+// start update
+//
+update()
+

node/cams.service

+[Unit]
+Description=cams
+After=network.target
+
+[Service]
+Type=forking
+ExecStart=/bin/bash /home/fab/cams/cams
+
+[Install]
+WantedBy=multi-user.target
+

node/display.js

+var lastid
+function display(id) {
+   var img = document.getElementById(lastid)
+   if (img != null) {
+      img.src = "../thumbnails/"+id
+      img.style.width = "20%"
+      }
+   var img = document.getElementById(id)
+   img.src = "../images/"+id
+   img.style.width = "100%"
+   lastid = id
+   }

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