Demonstration of multipart/x-mixed-replace decoding to get MJPEG frames from web server

mjpegcli.py

#Demonstration of multipart/x-mixed-replace decoding to get MJPEG frames from web server
#by Tim Sheerman-Chase 2014
#This code may be used under the terms of the CC0 license
#https://creativecommons.org/publicdomain/zero/1.0/

import pycurl

class HandleJpegData(object):
	def __init__(self):
		self.count = 0

	def write(self, contentType, dat):
		fi = open("test"+str(self.count)+".jpeg","wb")
		fi.write(dat)
		fi.close()
		self.count += 1

def HandleBinData(contentType, dat):
	print contentType, len(dat)

class DecodeXMixedReplace(object):
	def __init__(self):
		self.boundary = None
		self.rxBuff = ""
		self.inBinarySection = False
		self.contentLength = None
		self.contentType = None
		self.callback = HandleBinData
		self.foundBoundary = 0

	def writeHeader(self, dat):
		print dat
		if dat[:13].lower()=="content-type:":

			valsplit = dat[13:].split(";")

			dataType = valsplit[0].strip()
			if dataType.lower() != "multipart/x-mixed-replace":
				raise Exception("Unexpected mime type: "+dataType)

			boundaryVal = valsplit[1].strip()
			boundarySplit = boundaryVal.split("=")
			self.boundary = boundarySplit[1]

	def writeBody(self, dat):
		self.rxBuff += dat
		eol = 0

		while eol >= 0 and not self.inBinarySection:
			eol = self.rxBuff.find("\r\n")
			if eol < 0: continue

			li = self.rxBuff[:eol]
			#print eol, "'"+str(li[:100])+"'"

			self.rxBuff = self.rxBuff[eol+2:]
			if eol == 0 and self.foundBoundary:
				self.inBinarySection = True
				return

			if li == self.boundary: #Boundary mark
				self.foundBoundary = 1

			if li == "--"+self.boundary: #Two different styles of boundary marks
				self.foundBoundary = 1

			if li[:15].lower()=="content-length:":
				self.contentLength = int(li[15:].strip())
			if li[:13].lower()=="content-type:":
				self.contentType = li[13:].strip()

		if self.inBinarySection and self.contentLength is None:
			#If content length is not specified, look for the end of jpeg
			jpegEnd = '\xff\xd9'
			twoLineBreaks = jpegEnd+'\r\n\r\n'+self.boundary
			eol = self.rxBuff.find(twoLineBreaks)

			if eol >= 0:
				#print ":".join("{0:x}".format(ord(c)) for c in self.rxBuff[eol-10:eol+10])

				binData = self.rxBuff[:eol+2]
				self.callback(self.contentType, binData)

				self.rxBuff = self.rxBuff[eol+2:]
				self.contentLength = None
				self.inBinarySection = False
				self.contentType = None
				self.foundBoundary = 0

		if self.inBinarySection and self.contentLength is not None and len(self.rxBuff) >= self.contentLength:
			binData = self.rxBuff[:self.contentLength]
			self.callback(self.contentType, binData)

			self.rxBuff = self.rxBuff[self.contentLength:]
			self.contentLength = None
			self.inBinarySection = False
			self.contentType = None
			self.foundBoundary = 0

def Get(url, rx, userpass = None):
	c = pycurl.Curl()
	c.setopt(pycurl.URL, url)
	if userpass is not None: c.setopt(pycurl.USERPWD, userpass)

	c.setopt(pycurl.WRITEFUNCTION, rx.writeBody)
	c.setopt(pycurl.HEADERFUNCTION, rx.writeHeader)  

	c.perform()

if __name__=="__main__":

	rx = DecodeXMixedReplace()
	jpegOut = HandleJpegData()
	rx.callback = jpegOut.write

	url = "http://umevakameran.net.umea.se/mjpg/video.mjpg"

	Get(url, rx)