La réception de paquets RTP après RTSP d'installation

Donc,

Après de grosses sessions de googler et wireshark-analyse, j'ai trouvé les bonnes solutions.

Je suis annonce la résultante de démo de code ici .. j'ai pensé qu'il pourrait être utile pour la communauté.

Si vous avez toujours voulu lire ip-cams avec python et le vidage du flux H264 dans un comestible de fichier, c'est la chose que vous cherchez.

Profitez-en!

"""
A demo python code that ..
1) Connects to an IP cam with RTSP
2) Draws RTP/NAL/H264 packets from the camera
3) Writes them to a file that can be read with any stock video player (say, mplayer, vlc & other ffmpeg based video-players)
Done for educative/demonstrative purposes, not for efficiency..!
written 2015 by Sampsa Riikonen.
"""
import socket
import re
import bitstring # if you don't have this from your linux distro, install with "pip install bitstring"
# ************************ FOR QUICK-TESTING EDIT THIS AREA *********************************************************
ip="192.168.1.74" # IP address of your cam
adr="rtsp://admin:[email protected]" # username, passwd, etc.
clientports=[60784,60785] # the client ports we are going to use for receiving video
fname="stream.h264" # filename for dumping the stream
rn=5000 # receive this many packets
# After running this program, you can try your file defined in fname with "vlc fname" or "mplayer fname" from the command line
# you might also want to install h264bitstream to analyze your h264 file
# *******************************************************************************************************************
dest="DESCRIBE "+adr+" RTSP/1.0\r\nCSeq: 2\r\nUser-Agent: python\r\nAccept: application/sdp\r\n\r\n"
setu="SETUP "+adr+"/trackID=1 RTSP/1.0\r\nCSeq: 3\r\nUser-Agent: python\r\nTransport: RTP/AVP;unicast;client_port="+str(clientports[0])+"-"+str(clientports[1])+"\r\n\r\n"
play="PLAY "+adr+" RTSP/1.0\r\nCSeq: 5\r\nUser-Agent: python\r\nSession: SESID\r\nRange: npt=0.000-\r\n\r\n"
# File organized as follows:
# 1) Strings manipulation routines
# 2) RTP stream handling routine
# 3) Main program
# *** (1) First, some string searching/manipulation for handling the rtsp strings ***
def getPorts(searchst,st):
""" Searching port numbers from rtsp strings using regular expressions
"""
pat=re.compile(searchst+"=\d*-\d*")
pat2=re.compile('\d+')
mstring=pat.findall(st)[0] # matched string .. "client_port=1000-1001"
nums=pat2.findall(mstring)
numas=[]
for num in nums:
numas.append(int(num))
return numas
def getLength(st):
""" Searching "content-length" from rtsp strings using regular expressions
"""
pat=re.compile("Content-Length: \d*")
pat2=re.compile('\d+')
mstring=pat.findall(st)[0] # matched string.. "Content-Length: 614"
num=int(pat2.findall(mstring)[0])
return num
def printrec(recst):
""" Pretty-printing rtsp strings
"""
recs=recst.split('\r\n')
for rec in recs:
print rec
def sessionid(recst):
""" Search session id from rtsp strings
"""
recs=recst.split('\r\n')
for rec in recs:
ss=rec.split()
# print ">",ss
if (ss[0].strip()=="Session:"):
return int(ss[1].split(";")[0].strip())
def setsesid(recst,idn):
""" Sets session id in an rtsp string
"""
return recst.replace("SESID",str(idn))
# ********* (2) The routine for handling the RTP stream ***********
def digestpacket(st):
""" This routine takes a UDP packet, i.e. a string of bytes and ..
(a) strips off the RTP header
(b) adds NAL "stamps" to the packets, so that they are recognized as NAL's
(c) Concantenates frames
(d) Returns a packet that can be written to disk as such and that is recognized by stock media players as h264 stream
"""
startbytes="\x00\x00\x00\x01" # this is the sequence of four bytes that identifies a NAL packet.. must be in front of every NAL packet.
bt=bitstring.BitArray(bytes=st) # turn the whole string-of-bytes packet into a string of bits.  Very unefficient, but hey, this is only for demoing.
lc=12 # bytecounter
bc=12*8 # bitcounter
version=bt[0:2].uint # version
p=bt[3] # P
x=bt[4] # X
cc=bt[4:8].uint # CC
m=bt[9] # M
pt=bt[9:16].uint # PT
sn=bt[16:32].uint # sequence number
timestamp=bt[32:64].uint # timestamp
ssrc=bt[64:96].uint # ssrc identifier
# The header format can be found from:
# https://en.wikipedia.org/wiki/Real-time_Transport_Protocol
lc=12 # so, we have red twelve bytes
bc=12*8 # .. and that many bits
print "version, p, x, cc, m, pt",version,p,x,cc,m,pt
print "sequence number, timestamp",sn,timestamp
print "sync. source identifier",ssrc
# st=f.read(4*cc) # csrc identifiers, 32 bits (4 bytes) each
cids=[]
for i in range(cc):
cids.append(bt[bc:bc+32].uint)
bc+=32; lc+=4;
print "csrc identifiers:",cids
if (x):
# this section haven't been tested.. might fail
hid=bt[bc:bc+16].uint
bc+=16; lc+=2;
hlen=bt[bc:bc+16].uint
bc+=16; lc+=2;
print "ext. header id, header len",hid,hlen
hst=bt[bc:bc+32*hlen]
bc+=32*hlen; lc+=4*hlen;
# OK, now we enter the NAL packet, as described here:
# 
# https://tools.ietf.org/html/rfc6184#section-1.3
#
# Some quotes from that document:
#
"""
5.3. NAL Unit Header Usage
The structure and semantics of the NAL unit header were introduced in
Section 1.3.  For convenience, the format of the NAL unit header is
reprinted below:
+---------------+
|0|1|2|3|4|5|6|7|
+-+-+-+-+-+-+-+-+
|F|NRI|  Type   |
+---------------+
This section specifies the semantics of F and NRI according to this
specification.
"""
"""
Table 3.  Summary of allowed NAL unit types for each packetization
mode (yes = allowed, no = disallowed, ig = ignore)
Payload Packet    Single NAL    Non-Interleaved    Interleaved
Type    Type      Unit Mode           Mode             Mode
-------------------------------------------------------------
0      reserved      ig               ig               ig
1-23   NAL unit     yes              yes               no
24     STAP-A        no              yes               no
25     STAP-B        no               no              yes
26     MTAP16        no               no              yes
27     MTAP24        no               no              yes
28     FU-A          no              yes              yes
29     FU-B          no               no              yes
30-31  reserved      ig               ig               ig
"""
# This was also very usefull:
# http://stackoverflow.com/questions/7665217/how-to-process-raw-udp-packets-so-that-they-can-be-decoded-by-a-decoder-filter-i
# A quote from that:
"""
First byte:  [ 3 NAL UNIT BITS | 5 FRAGMENT TYPE BITS] 
Second byte: [ START BIT | RESERVED BIT | END BIT | 5 NAL UNIT BITS] 
Other bytes: [... VIDEO FRAGMENT DATA...]
"""
fb=bt[bc] # i.e. "F"
nri=bt[bc+1:bc+3].uint # "NRI"
nlu0=bt[bc:bc+3] # "3 NAL UNIT BITS" (i.e. [F | NRI])
typ=bt[bc+3:bc+8].uint # "Type"
print "F, NRI, Type :", fb, nri, typ
print "first three bits together :",bt[bc:bc+3]
if (typ==7 or typ==8):
# this means we have either an SPS or a PPS packet
# they have the meta-info about resolution, etc.
# more reading for example here:
# http://www.cardinalpeak.com/blog/the-h-264-sequence-parameter-set/
if (typ==7):
print ">>>>> SPS packet"
else:
print ">>>>> PPS packet"
return startbytes+st[lc:]
# .. notice here that we include the NAL starting sequence "startbytes" and the "First byte"
bc+=8; lc+=1; # let's go to "Second byte"
# ********* WE ARE AT THE "Second byte" ************
# The "Type" here is most likely 28, i.e. "FU-A"
start=bt[bc] # start bit
end=bt[bc+2] # end bit
nlu1=bt[bc+3:bc+8] # 5 nal unit bits
if (start): # OK, this is a first fragment in a movie frame
print ">>> first fragment found"
nlu=nlu0+nlu1 # Create "[3 NAL UNIT BITS | 5 NAL UNIT BITS]"
head=startbytes+nlu.bytes # .. add the NAL starting sequence
lc+=1 # We skip the "Second byte"
if (start==False and end==False): # intermediate fragment in a sequence, just dump "VIDEO FRAGMENT DATA"
head=""
lc+=1 # We skip the "Second byte"
elif (end==True): # last fragment in a sequence, just dump "VIDEO FRAGMENT DATA"
head=""
print "<<<< last fragment found"
lc+=1 # We skip the "Second byte"
if (typ==28): # This code only handles "Type" = 28, i.e. "FU-A"
return head+st[lc:]
else:
raise(Exception,"unknown frame type for this piece of s***")
# *********** (3) THE MAIN PROGRAM STARTS HERE ****************
# Create an TCP socket for RTSP communication
# further reading: 
# https://docs.python.org/2.7/howto/sockets.html
s=socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((ip,554)) # RTSP should peek out from port 554
print
print "*** SENDING DESCRIBE ***"
print
s.send(dest)
recst=s.recv(4096)
print
print "*** GOT ****"
print
printrec(recst)
print
print "*** SENDING SETUP ***"
print
s.send(setu)
recst=s.recv(4096)
print
print "*** GOT ****"
print
printrec(recst)
idn=sessionid(recst)
serverports=getPorts("server_port",recst)
clientports=getPorts("client_port",recst)
print "****"
print "ip,serverports",ip,serverports
print "****"
s1=socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s1.bind(("", clientports[0])) # we open a port that is visible to the whole internet (the empty string "" takes care of that)
s1.settimeout(5) # if the socket is dead for 5 s., its thrown into trash
# further reading:
# https://wiki.python.org/moin/UdpCommunication
# Now our port is open for receiving shitloads of videodata.  Give the camera the PLAY command..
print
print "*** SENDING PLAY ***"
print
play=setsesid(play,idn)
s.send(play)
recst=s.recv(4096)
print
print "*** GOT ****"
print
printrec(recst)
print
print
print "** STRIPPING RTP INFO AND DUMPING INTO FILE **"
f=open(fname,'w')
for i in range(rn):
print
print
recst=s1.recv(4096)
print "read",len(recst),"bytes"
st=digestpacket(recst)
print "dumping",len(st),"bytes"
f.write(st)
f.close()
# Before closing the sockets, we should give the "TEARDOWN" command via RTSP, but I am feeling lazy today (after googling, wireshark-analyzing, among other-things).
s.close()
s1.close()

OriginalL'auteur El Sampsa