问题描述
我不知道，因为我的视频捕获不会在每个浏览器中刷新... 我使用cv2开始网络摄像头拍摄，但是图像没有更新。为什么？它可以依靠什么？ 目的是从身体框架区域的运动中检测呼吸频率。但是网络摄像头不会更新，仅显示第一帧。 我在python中的代码是：
import cv2
import queue
import threading
import datetime
import matplotlib
import http.server
import socketserver
import math
from urllib.parse import urlparse,parse_qs
from io import BytesIO
import numpy as np
import PIL.Image as PImage
matplotlib.use('Agg')
import matplotlib.pyplot as plt
DocRoot = "./"
ImgQueue = queue.Queue(3)
ims = None
def calcMotion(region0,region1):
"""
Calculates motion based on Lucas/Kanade optical flow method.
Returns veLocities in x,y
"""
ra0 = np.diff(region0,axis=0)
dyi = (ra0[:,:-1] + ra0[:,1:])
ra1 = np.diff(region0,axis=1)
dxi = (ra1[:-1,:] + ra1[1:,:])
diff = region1 - region0
s1 = diff[:-1,:] + diff[1:,:]
dt = s1[:,1:] + s1[:,:-1:]
x2 = (dxi * dxi).sum()
xy = (dxi * dyi).sum()
y2 = (dyi * dyi).sum()
tx = (dxi * dt).sum()
ty = (dyi * dt).sum()
det = x2 * y2 - xy * xy
det *= 0.5
if abs(det) < 1E-3:
return 0,0
u = (tx * y2 - ty * xy) / det
v = (x2 * ty - xy * tx) / det
mod = math.sqrt(u * u + v * v)
if mod == 0:
return 0,0
return u,v
def flatten(xs,ys):
"""
Substracts linear fit from values ys and
returns result and the value at the middle of the fitted values,ie the avg.
"""
fitted = np.polyval(np.polyfit(xs,ys,1),xs)
return ys - fitted,fitted[len(xs) // 2]
def countCrossing(arr,avg):
"""
Counts how many times the values cross the average.
Only counts when going down.
Returns the count
"""
state = 0
cnt = 0
for i in arr:
if state == 1 and i < avg:
state = 2
cnt += 1
elif state == 2 and i > avg:
state = 1
elif state == 0:
if i > avg:
state = 1
else:
state = 2
return cnt
"""
Use a global variable so we can do running average.
"""
BRate = 0
def genStripChart(figSize,xs,flags):
"""
Creates a strip char using matplotlib.
First flattens the values and then counts the zero crossings.
Returns the chart as PNG in binary form,which is then sent to the browser.
"""
global BRate
fig = plt.figure(figsize=figSize)
ax = fig.add_subplot(111)
xlen = len(xs)
dxs = [0] * xlen
for i in range(1,len(xs)):
dxs[i] = (xs[i] - xs[0]).total_seconds()
ys,avg = flatten(dxs,ys)
cnt = countCrossing(ys,avg)
if dxs[-1] > 0:
cnt = cnt * 60.0 / dxs[-1]
BRate = BRate + (cnt - BRate) * 0.3
ax.plot(dxs,flags)
ax.set_ylim(-1.5,1.5)
ax.grid()
ax.set_title("Breathing Rate = %.0f per min" % (BRate))
ax.set_xlabel("seconds")
plt.close()
out = BytesIO()
fig.savefig(out,format='png')
out.seek(0)
return out.read()
class ImageServerHandler(http.server.SimpleHTTPRequestHandler):
"""
This class handles the HTTP request from clients.
"""
def do_GET(self):
global ImgQueue
try:
# ignore request to favicon
if self.path.endswith('favicon.ico'):
return
parts = urlparse(self.path)
qs = parse_qs(parts.query)
req = parts.path[1:]
reqHandler = self.handlerTable.get(req)
if reqHandler != None:
out,contype = reqHandler(self,req,qs)
else:
out,contype = self.serveFile(req,qs)
self.send_response(200,"OK")
self.send_header("Cache-Control","no-cache,must-revalidate")
self.send_header("Content-Type",contype)
self.end_headers()
self.wfile.write(out)
except Exception as e:
try:
self.send_response(503,"Error")
self.end_headers()
self.send_header("Content-Type",contype)
self.wfile.write(bytes(out,"UTF-8"))
except:
print("Error",e)
def getMimeType(self,fname):
table = [['.js','text/javascript'],['.html','text/html'],['.css','text/css']]
for suf,mtype in table:
if fname.endswith(suf):
return mtype
return 'text/html'
def serveFile(self,qs):
global DocRoot
req = req if len(req) > 0 else "breathingMonitor.html"
contype = self.getMimeType(req)
with open(DocRoot + req,"r") as fh:
content = fh.read()
return bytes(content,"UTF-8"),contype
def log_message(self,format,*args):
return
def getimage(self,qstr):
"""
Gets image from the queue for display.
Returns image data and mime type
"""
im = ImgQueue.get()
temp = BytesIO()
im.save(temp,format="JPEG")
return temp.getvalue(),"image/jpeg"
def clicked(self,qstr):
global ims
x = float(qstr['inpx'][0])
y = float(qstr['inpy'][0])
t = float(qstr['sigma'][0])
t = min(1,max(0,t))
ims.startMeasurement(x,y,t)
s = "start measurement at x %.0f y %.0f t %.2f" % (x,t)
out = bytes(s,"UTF-8")
contype = "text/plain"
return out,contype
def getChart(self,qstr):
global ims
try:
contype = "image/png"
return genStripChart((5,2.4),ims.tData,ims.mData,"r-"),contype
except KeyboardInterrupt:
return "Aborted","text/plain"
"""
Class table
"""
handlerTable = {
'get': getimage,'clicked': clicked,'chart': getChart
}
#
# End of ImageServerHandler
#
class ImageServer:
"""
This class runs the camera thread and the HTTP request hanlder thread.
"""
def __init__(self):
"""
Initializes the camera connection
"""
self.cam = cv2.VideoCapture(0)
self.cam.set(cv2.CAP_PROP_FRAME_WIDTH,160)
self.cam.set(cv2.CAP_PROP_FRAME_HEIGHT,120)
self.nlen = 256
self.mData = np.array([0.0] * self.nlen)
self.tData = [datetime.datetime.Now()] * self.nlen
self.measureX = 0
self.measureY = 0
self.first = True
self.runAvg = 0
self.runAvg1 = 0
self.sigma = 0.3
self.BoxSize = 35
self.imgWidth,self.imgHeight = 0,0
def camLoop(self):
"""
Reads image from the camera stream and
puts image in the queue.
"""
global ImgQueue
while True:
ret,frame = self.cam.read()
frame = cv2.cvtColor(frame,cv2.COLOR_BGR2RGB)
img = PImage.fromarray(frame)
try:
if ImgQueue.full():
print("full")
ImgQueue.get()
ImgQueue.put_Nowait(img)
except Exception:
print("Queue error")
def processingLoop(self):
global ImgQueue
while True:
img = ImgQueue.get()
w,h = img.size
bwImg = np.array(img.convert("L").getdata()).reshape((h,w))
self.digestimage(bwImg)
def startMeasurement(self,x,t):
size = self.BoxSize
x = min(max(0,x - size / 2),self.imgWidth - size - 1)
y = min(max(0,y - size / 2),self.imgHeight - size - 1)
self.measureX = int(x)
self.measureY = int(y)
self.sigma = t
self.first = True
def digestimage(self,imgBW):
self.imgWidth,self.imgHeight = imgBW.shape
if self.measureX == 0 or self.measureY == 0:
self.measureX = int(self.imgWidth / 2)
self.measureY = int(self.imgHeight / 2)
size = self.BoxSize
x = self.measureX
y = self.measureY
region = imgBW[x:x + size,y:y + size]
if self.first:
self.first = False
self.runAvg = 0
self.runAvg1 = 0
self.lastRegion = region
self.mData = np.array([0.0] * self.nlen)
u,col = calcMotion(region,self.lastRegion)
self.lastRegion = region
t1 = self.sigma
t11 = 0.3
self.runAvg1 = (col - self.runAvg1) * t1 + self.runAvg1
col = self.runAvg = (self.runAvg1 - self.runAvg) * t11 + self.runAvg
self.mData[0:-1] = self.mData[1:]
self.tData[0:-1] = self.tData[1:]
self.mData[-1] = col
self.tData[-1] = datetime.datetime.Now()
def startCamera(self):
thr = threading.Thread(target=self.camLoop)
thr.daemon = True
thr.start()
def startProcessing(self):
thr = threading.Thread(target=self.processingLoop)
thr.daemon = True
thr.start()
def start(self,port):
print("Open http://localhost:%d" % port)
try:
httpd = socketserver.Tcpserver(("0.0.0.0",port),ImageServerHandler)
try:
httpd.serve_forever()
httpd.shutdown()
except KeyboardInterrupt:
return
except:
print("Failed to start HTTP Server")
return
#
# main
#
if __name__ == "__main__":
ims = ImageServer()
ims.startCamera()
ims.startProcessing()
ims.start(5010)
解决方法
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