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rtcp_datagram.py
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rtcp_datagram.py
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# -*- coding: utf-8 -*-
# RTCP Datagram Module
from struct import unpack, pack
debug = 0
# Receiver Reports included in Sender Report
class Report:
SSRC = 0
FractionLost = 0
CumulativeNumberOfPacketsLostH = 0
CumulativeNumberOfPacketsLostL = 0
ExtendedHighestSequenceNumberReceived = 0
InterarrivalJitter = 0
LastSR = 0
DelaySinceLastSR = 0
# Source Description
class SDES:
SSRC = 0
CNAME = ''
NAME = ''
EMAIL = ''
PHONE = ''
LOC = ''
TOOL = ''
NOTE = ''
PRIV = ''
class RTCPDatagram(object):
'RTCP packet parser end generator'
def __init__(self):
self.Datagram = ''
# SR specific
self.SSRC_sender = 0
self.NTP_TimestampH = 0
self.NTP_TimestampL = 0
self.RTP_Timestamp = 0
self.SenderPacketCount = 0
self.SenderOctetCount = 0
self.Reports = []
self.ProfileSpecificExtension = ''
# SDES specific
self.SourceDescriptions = []
def loadDatagram(self, DatagramIn):
self.Datagram = DatagramIn
def parse(self):
# RTCP parsing is complete
# including SDES, BYE and APP
# RTCP Header
(Ver_P_RC,
PacketType,
Length) = unpack('!BBH', self.Datagram[:4])
Version = (Ver_P_RC & 0b11000000) >> 6
Padding = (Ver_P_RC & 0b00100000) >> 5
# Byte offset
off = 4
# Sender's Report
if PacketType == 200:
# Sender's information
(self.SSRC_sender,
self.NTP_TimestampH,
self.NTP_TimestampL,
self.RTP_Timestamp,
self.SenderPacketCount,
self.SenderOctetCount) = unpack('!IIIIII', self.Datagram[off: off + 24])
off += 24
ReceptionCount = Ver_P_RC & 0b00011111
if debug:
print 'SDES: SR from', str(self.SSRC_sender)
# Included Receiver Reports
self.Reports = []
i = 0
for i in range(ReceptionCount):
self.Reports.append(Report())
self.Reports[i].SSRC,
self.Reports[i].FractionLost,
self.Reports[i].CumulativeNumberOfPacketsLostH,
self.Reports[i].CumulativeNumberOfPacketsLostL,
self.Reports[i].ExtendedHighestSequenceNumberReceived,
self.Reports[i].InterarrivalJitter,
self.Reports[i].LastSR,
self.Reports[i].DelaySinceLastSR = unpack('!IBBHIIII', self.Datagram[off: off + 24])
off += 24
# Source Description (SDES)
elif PacketType == 202:
# RC now is SC
SSRCCount = Ver_P_RC & 0b00011111
self.SourceDescriptions = []
i = 0
for i in range(SSRCCount):
self.SourceDescriptions.append(SDES())
SSRC, = unpack('!I', self.Datagram[off: off + 4])
off += 4
self.SourceDescriptions[i].SSRC = SSRC
SDES_Item = -1
# Go on the list of descriptions
while SDES_Item != 0:
SDES_Item, = unpack('!B', self.Datagram[off])
off += 1
if SDES_Item != 0:
SDES_Length, = unpack('!B', self.Datagram[off])
off += 1
Value = self.Datagram[off: off + SDES_Length]
off += SDES_Length
if debug:
print 'SDES:', SDES_Item, Value
if SDES_Item == 1:
self.SourceDescriptions[i].CNAME = Value
elif SDES_Item == 2:
self.SourceDescriptions[i].NAME = Value
elif SDES_Item == 3:
self.SourceDescriptions[i].EMAIL = Value
elif SDES_Item == 4:
self.SourceDescriptions[i].PHONE = Value
elif SDES_Item == 5:
self.SourceDescriptions[i].LOC = Value
elif SDES_Item == 6:
self.SourceDescriptions[i].TOOL = Value
elif SDES_Item == 7:
self.SourceDescriptions[i].NOTE = Value
elif SDES_Item == 8:
self.SourceDescriptions[i].PRIV = Value
# Extra parsing for PRIV is needed
elif SDES_Item == 0:
# End of list. Padding to 32 bits
while (off % 4):
off += 1
# BYE Packet
elif PacketType == 203:
SSRCCount = Ver_P_RC & 0b00011111
i = 0
for i in range(SSRCCount):
SSRC, = unpack('!I', self.Datagram[off: off + 4])
off += 4
print 'SDES: SSRC ' + str(SSRC) + ' is saying goodbye.'
# Application specific packet
elif PacketType == 204:
Subtype = Ver_P_RC & 0b00011111
SSRC, = unpack('!I', self.Datagram[off: off + 4])
Name = self.Datagram[off + 4: off + 8]
AppData = self.Datagram[off + 8: off + Length]
print 'SDES: APP Packet "' + Name + '" from SSRC ' + str(SSRC) + '.'
off += Length
# Check if there is something else in the datagram
if self.Datagram[off:]:
self.Datagram = self.Datagram[off:]
self.parse()
def generateRR(self):
# Ver 2, Pad 0, RC 1
Ver_P_RC = 0b10000001
# PT 201, Length 7, SSRC 0xF00F - let it be our ID
Header = pack('!BBHI', Ver_P_RC, 201, 7, 0x0000F00F)
NTP_32 = (self.NTP_TimestampH & 0x0000FFFF) + ((self.NTP_TimestampL & 0xFFFF0000) >> 16)
# No lost packets, no delay in receiving data, RR sent right after receiving SR
# Instead of self.SenderPacketCount should be proper value
ReceiverReport = pack('!IBBHIIII', self.SSRC_sender, 0, 0, 0, self.SenderPacketCount, 1, NTP_32, 1)
return Header + ReceiverReport