I have a simple pipeline set up as below with Gstreamer 1.0. When I try to create pull samples from the appsink, the code stalls at "sample = appsink.emit('pull-sample')" . The weird part is that if I remove that line, the code works as expected, continually printing "trying to pull sample". I get the same stall if I try to skip the first 100 samples or so as well as changing the properties on the appsink. Anyone have an idea of what's going on?
gst-launch-1.0 v4l2src device="/dev/video0" ! videorate ! video/x raw,height=480,width=640,framerate=15/1 ! appsink
def createASink():
asink = Gst.ElementFactory.make('appsink', 'asink')
asink.set_property('sync', False)
asink.set_property('emit-signals', True)
asink.set_property('drop', True)
asink.connect('new-sample', new_sample)
return asink
def new_sample(appsink):
print "Trying to pull sample"
sample = appsink.emit('pull-sample')
return False
So this is a hack workaround but it still works. If someone knows a better solution please let me know.
I can use a filesink to output the byte array and then read from that continuously. I use the multiprocessing module in python to run gstreamer and my consumer at the same time.
def consumeStream():
fp = "gst_data"
with open(fp, "r+b") as data_file:
data_file.truncate()
while True:
where = data_file.tell()
line = data_file.readline()
if not line:
time.sleep(.05)
data_file.seek(where)
else:
data_file.truncate()
print "Got data"
Related
I have just learned the basics of Python, and I am trying to make a few projects so that I can increase my knowledge of the programming language.
Since I am rather paranoid, I created a script that uses PycURL to fetch my current IP address every x seconds, for VPN security. Here is my code[EDITED]:
import requests
enterIP = str(input("What is your current IP address?"))
def getIP():
while True:
try:
result = requests.get("http://ipinfo.io/ip")
print(result.text)
except KeyboardInterrupt:
print("\nProccess terminated by user")
return result.text
def checkIP():
while True:
if enterIP == result.text:
pass
else:
print("IP has changed!")
getIP()
checkIP()
Now I would like to expand the idea, so that the script asks the user to enter their current IP, saves that octet as a string, then uses a loop to keep running it against the PycURL function to make sure that their IP hasn't changed? The only problem is that I am completely stumped, I cannot come up with a function that would take the output of PycURL and compare it to a string. How could I achieve that?
As #holdenweb explained, you do not need pycurl for such a simple task, but nevertheless, here is a working example:
import pycurl
import time
from StringIO import StringIO
def get_ip():
buffer = StringIO()
c = pycurl.Curl()
c.setopt(pycurl.URL, "http://ipinfo.io/ip")
c.setopt(c.WRITEDATA, buffer)
c.perform()
c.close()
return buffer.getvalue()
def main():
initial = get_ip()
print 'Initial IP: %s' % initial
try:
while True:
current = get_ip()
if current != initial:
print 'IP has changed to: %s' % current
time.sleep(300)
except KeyboardInterrupt:
print("\nProccess terminated by user")
if __name__ == '__main__':
main()
As you can see I moved the logic of getting the IP to separate function: get_ip and added few missing things, like catching the buffer to a string and returning it. Otherwise it is pretty much the same as the first example in pycurl quickstart
The main function is called below, when the script is accessed directly (not by import).
First off it calls the get_ip to get initial IP and then runs the while loop which checks if the IP has changed and lets you know if so.
EDIT:
Since you changed your question, here is your new code in a working example:
import requests
def getIP():
result = requests.get("http://ipinfo.io/ip")
return result.text
def checkIP():
initial = getIP()
print("Initial IP: {}".format(initial))
while True:
current = getIP()
if initial == current:
pass
else:
print("IP has changed!")
checkIP()
As I mentioned in the comments above, you do not need two loops. One is enough. You don't even need two functions, but better do. One for getting the data and one for the loop. In the later, first get initial value and then run the loop, inside which you check if value has changed or not.
It seems, from reading the pycurl documentation, like you would find it easier to solve this problem using the requests library. Curl is more to do with file transfer, so the library expects you to provide a file-like object into which it writes the contents. This would greatly complicate your logic.
requests allows you to access the text of the server's response directly:
>>> import requests
>>> result = requests.get("http://ipinfo.io/ip")
>>> result.text
'151.231.192.8\n'
As #PeterWood suggested, a function would be more appropriate than a class for this - or if the script is going to run continuously, just a simple loop as the body of the program.
EDIT: I think I've figured out a solution using subprocess.Popen with separate .py files for each stream being monitored. It's not pretty, but it works.
I'm working on a script to monitor a streaming site for several different accounts and to record when they are online. I am using the livestreamer package for downloading a stream when it comes online, but the problem is that the program will only record one stream at a time. I have the program loop through a list and if a stream is online, start recording with subprocess.call(["livestreamer"... The problem is that once the program starts recording, it stops going through the loop and doesn't check or record any of the other livestreams. I've tried using Process and Thread, but none of these seem to work. Any ideas?
Code below. Asterisks are not literally part of code.
import os,urllib.request,time,subprocess,datetime,random
status = {
"********":False,
"********":False,
"********":False
}
def gen_name(tag):
return stuff <<Bunch of unimportant code stuff here.
def dl(tag):
subprocess.call(["livestreamer","********.com/"+tag,"best","-o",".\\tmp\\"+gen_name(tag)])
def loopCheck():
while True:
for tag in status:
data = urllib.request.urlopen("http://*******.com/" + tag + "/").read().decode()
if data.find(".m3u8") != -1:
print(tag + " is online!")
if status[tag] == False:
status[tag] = True
dl(tag)
else:
print(tag+ " is offline.")
status[tag] = False
time.sleep(15)
loopCheck()
I'm trying to play video in mp4 format but not working.
In console I execute this line and it works:
gst-launch playbin uri=rtmp://localhost:1935/files/video.mp4
But if I change to version 1.0 only works the audio:
gst-launch-1.0 playbin uri=rtmp://localhost:1935/files/video.mp4
in python I have the following code:
self.player = Gst.Pipeline.new("player")
source = Gst.ElementFactory.make("filesrc", "file-source")
demuxer = Gst.ElementFactory.make("mp4mux", "demuxer")
demuxer.connect("pad-added", self.demuxer_callback)
self.video_decoder = Gst.ElementFactory.make("x264enc", "video-decoder")
self.audio_decoder = Gst.ElementFactory.make("vorbisdec", "audio-decoder")
audioconv = Gst.ElementFactory.make("audioconvert", "converter")
audiosink = Gst.ElementFactory.make("autoaudiosink", "audio-output")
videosink = Gst.ElementFactory.make("autovideosink", "video-output")
self.queuea = Gst.ElementFactory.make("queue", "queuea")
self.queuev = Gst.ElementFactory.make("queue", "queuev")
colorspace = Gst.ElementFactory.make("videoconvert", "colorspace")
self.player.add(source)
self.player.add(demuxer)
self.player.add(self.video_decoder)
self.player.add(self.audio_decoder)
self.player.add(audioconv)
self.player.add(audiosink)
self.player.add(videosink)
self.player.add(self.queuea)
self.player.add(self.queuev)
self.player.add(colorspace)
source.link(demuxer)
self.queuev.link(self.video_decoder)
self.video_decoder.link(colorspace)
colorspace.link(videosink)
self.queuea.link(self.audio_decoder)
self.audio_decoder.link(audioconv)
audioconv.link(audiosink)
but I get this error:
Error: Error in the internal data flow. gstbasesrc.c(2865): gst_base_src_loop (): /GstPipeline:player/GstFileSrc:file-source:
streaming task paused, reason not-linked (-1)
What can be happening? think I am no good decoding
You are missing linking the demuxer pads to your queues. Demuxers have 'sometimes' pads so you need to listen to the pad-added signal of them and link in this callback. Remember to check the pad caps once you get them and link to the appropriate branch of your pipeline.
You can read about dynamic pads here: http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/chapter-pads.html#section-pads-dynamic
You have in your code:
demuxer = Gst.ElementFactory.make("mp4mux", "demuxer")
demuxer.connect("pad-added", self.demuxer_callback)
I hope this is a cut/paste error, as demuxing with a mux will not work. I believe for an .mp4 file, the normal demuxer (if you are choosing one by hand) is qtdemux.
You could also use decodebin to decode the file for you.
I have created a data transfer program using python and the pyserial module. I am currently using it to communicate text file over a radio device between a Raspberry Pi and my computer. The problem is, the file I am trying to send, which contains 5000 lines of text and is 93.0 Kb in size is taking quite a while to send. To be exact, it takes about a full minute. I need this to be done within seconds. Here is the following code, I am sure that there are many optimizations that can be made with file reading and such that would increase the data transfer speed. My radio device has a data speed of 250 kbps, which is obviously not being reached. Any help would be greatly appreciated.
Code to send(located on raspberry pi)
def s_file():
print 'start'
readline = lambda : iter(lambda:ser.read(1),"\n")
name = "".join(readline())
print name
file_loc = directory_name + name
sleep(1)
print('Waiting for command from client to send file...')
while "".join(readline()) != "<<SENDFILE>>":
pass
with open(file_loc) as FileObj:
for lines in FileObj:
ser.write(lines)
ser.write("\n<<EOF>>\n")
print 'done'
Code to receive(on my laptop)
def r_f_bird(self): #send command to bird to start func,
if ser_open == True:
readline = lambda : iter(lambda:ser.read(1),"\n")
NAME = self.tb2.get()
ser.write('/' + NAME)
print NAME
sleep(0.5)
ser.write('\n<<SENDFILE>>\n')
start = clock()
with open(str(NAME),"wb") as outfile:
while True:
line = "".join(readline())
if line == "<<EOF>>":
break
print >> outfile, line
elapsed = clock() - start
print elapsed
ser.flush()
else:
pass
Perhaps the overhead of ser.read(1) is slowing things down. It seems like you have a \n at the end of each line, so try using pySerial's readline() method rather than rolling your own. Changing line = "".join(readline()) to line = ser.readline() ought to do it. You will also need to change your loop end condition to == "<<EOF>>\n".
You may also need to add a ser.flush() on the writing side.
So I have two Python3.2 processes that need to communicate with each other. Most of the information that needs to be communicated are standard dictionaries. Named pipes seemed like the way to go so I made a pipe class that can be instantiated in both processes. this class implements a very basic protocol for getting information around.
My problem is that sometimes it works, sometimes it doesn't. There seems to be no pattern to this behavior except the place where the code fails.
Here are the bits of the Pipe class that matter. Shout if you want more code:
class Pipe:
"""
there are a bunch of constants set up here. I dont think it would be useful to include them. Just think like this: Pipe.WHATEVER = 'WHATEVER'
"""
def __init__(self,sPath):
"""
create the fifo. if it already exists just associate with it
"""
self.sPath = sPath
if not os.path.exists(sPath):
os.mkfifo(sPath)
self.iFH = os.open(sPath,os.O_RDWR | os.O_NONBLOCK)
self.iFHBlocking = os.open(sPath,os.O_RDWR)
def write(self,dMessage):
"""
write the dict to the fifo
if dMessage is not a dictionary then there will be an exception here. There never is
"""
self.writeln(Pipe.MESSAGE_START)
for k in dMessage:
self.writeln(Pipe.KEY)
self.writeln(k)
self.writeln(Pipe.VALUE)
self.writeln(dMessage[k])
self.writeln(Pipe.MESSAGE_END)
def writeln(self,s):
os.write(self.iFH,bytes('{0} : {1}\n'.format(Pipe.LINE_START,len(s)+1),'utf-8'))
os.write(self.iFH,bytes('{0}\n'.format(s), 'utf-8'))
os.write(self.iFH,bytes(Pipe.LINE_END+'\n','utf-8'))
def readln(self):
"""
look for LINE_START, get line size
read until LINE_END
clean up
return string
"""
iLineStartBaseLength = len(self.LINE_START)+3 #'{0} : '
try:
s = os.read(self.iFH,iLineStartBaseLength).decode('utf-8')
except:
return Pipe.READLINE_FAIL
if Pipe.LINE_START in s:
#get the length of the line
sLineLen = ''
while True:
try:
sCurrent = os.read(self.iFH,1).decode('utf-8')
except:
return Pipe.READLINE_FAIL
if sCurrent == '\n':
break
sLineLen += sCurrent
try:
iLineLen = int(sLineLen.strip(string.punctuation+string.whitespace))
except:
raise Exception('Not a valid line length: "{0}"'.format(sLineLen))
#read the line
sLine = os.read(self.iFHBlocking,iLineLen).decode('utf-8')
#read the line terminator
sTerm = os.read(self.iFH,len(Pipe.LINE_END+'\n')).decode('utf-8')
if sTerm == Pipe.LINE_END+'\n':
return sLine
return Pipe.READLINE_FAIL
else:
return Pipe.READLINE_FAIL
def read(self):
"""
read from the fifo, make a dict
"""
dRet = {}
sKey = ''
sValue = ''
sCurrent = None
def value_flush():
nonlocal dRet, sKey, sValue, sCurrent
if sKey:
dRet[sKey.strip()] = sValue.strip()
sKey = ''
sValue = ''
sCurrent = ''
if self.message_start():
while True:
sLine = self.readln()
if Pipe.MESSAGE_END in sLine:
value_flush()
return dRet
elif Pipe.KEY in sLine:
value_flush()
sCurrent = Pipe.KEY
elif Pipe.VALUE in sLine:
sCurrent = Pipe.VALUE
else:
if sCurrent == Pipe.VALUE:
sValue += sLine
elif sCurrent == Pipe.KEY:
sKey += sLine
else:
return Pipe.NO_MESSAGE
It sometimes fails here (in readln):
try:
iLineLen = int(sLineLen.strip(string.punctuation+string.whitespace))
except:
raise Exception('Not a valid line length: "{0}"'.format(sLineLen))
It doesn't fail anywhere else.
An example error is:
Not a valid line length: "KE 17"
The fact that it's intermittent says to me that it's due to some kind of race condition, I'm just struggling to figure out what it might be. Any ideas?
EDIT added stuff about calling processes
How the Pipe is used is it is instantiated in processA and ProcessB by calling the constructor with the same path. Process A will then intermittently write to the Pipe and processB will try to read from it. At no point do I ever try to get the thing acting as a two way.
Here is a more long winded explanation of the situation. I've been trying to keep the question short but I think it's about time I give up on that. Anyhoo, I have a daemon and a Pyramid process that need to play nice. There are two Pipe instances in use: One that only Pyramid writes to, and one that only the daemon writes to. The stuff Pyramid writes is really short, I have experienced no errors on this pipe. The stuff that the daemon writes is much longer, this is the pipe that's giving me grief. Both pipes are implemented in the same way. Both processes only write dictionaries to their respective Pipes (if this were not the case then there would be an exception in Pipe.write).
The basic algorithm is: Pyramid spawns the daemon, the daemon loads craze object hierarchy of doom and vast ram consumption. Pyramid sends POST requests to the daemon which then does a whole bunch of calculations and sends data to Pyramid so that a human-friendly page can be rendered. the human can then respond to what's in the hierarchy by filling in HTML forms and suchlike thus causing pyramid to send another dictionary to the daemon, and the daemon sending back a dictionary response.
So: only one pipe has exhibited any problems, the problem pipe has a lot more traffic than the other one, and it is a guarentee that only dictionaries are written to either
EDIT as response to question and comment
Before you tell me to take out the try...except stuff read on.
The fact that the exception gets raised at all is what is bothering me. iLineLengh = int(stuff) looks to me like it should always be passed a string that looks like an integer. This is the case only most of the time, not all of it. So if you feel the urge to comment about how it's probably not an integer please please don't.
To paraphrase my question: Spot the race condition and you will be my hero.
EDIT a little example:
process_1.py:
oP = Pipe(some_path)
while 1:
oP.write({'a':'foo','b':'bar','c':'erm...','d':'plop!','e':'etc'})
process_2.py:
oP = Pipe(same_path_as_before)
while 1:
print(oP.read())
After playing around with the code, I suspect the problem is coming from how you are reading the file.
Specifically, lines like this:
os.read(self.iFH, iLineStartBaseLength)
That call doesn't necessarily return iLineStartBaseLength bytes - it might consume "LI" , then return READLINE_FAIL and retry. On the second attempt, it will get the remainder of the line, and somehow end up giving the non-numeric string to the int() call
The unpredictability likely comes from how the fifo is being flushed - if it happens to flush when the complete line is written, all is fine. If it flushes when the line is half-written, weirdness.
At least in the hacked-up version of the script I ended up with, the oP.read() call in process_2.py often got a different dict to the one sent (where the KEY might bleed into the previous VALUE and other strangeness).
I might be mistaken, as I had to make a bunch of changes to get the code running on OS X, and further while experimenting. My modified code here
Not sure exactly how to fix it, but.. with the json module or similar, the protocol/parsing can be greatly simplified - newline separated JSON data is much easier to parse:
import os
import time
import json
import errno
def retry_write(*args, **kwargs):
"""Like os.write, but retries until EAGAIN stops appearing
"""
while True:
try:
return os.write(*args, **kwargs)
except OSError as e:
if e.errno == errno.EAGAIN:
time.sleep(0.5)
else:
raise
class Pipe(object):
"""FIFO based IPC based on newline-separated JSON
"""
ENCODING = 'utf-8'
def __init__(self,sPath):
self.sPath = sPath
if not os.path.exists(sPath):
os.mkfifo(sPath)
self.fd = os.open(sPath,os.O_RDWR | os.O_NONBLOCK)
self.file_blocking = open(sPath, "r", encoding=self.ENCODING)
def write(self, dmsg):
serialised = json.dumps(dmsg) + "\n"
dat = bytes(serialised.encode(self.ENCODING))
# This blocks until data can be read by other process.
# Can just use os.write and ignore EAGAIN if you want
# to drop the data
retry_write(self.fd, dat)
def read(self):
serialised = self.file_blocking.readline()
return json.loads(serialised)
Try getting rid of the try:, except: blocks and seeing what exception is actually being thrown.
So replace your sample with just:
iLineLen = int(sLineLen.strip(string.punctuation+string.whitespace))
I bet it'll now throw a ValueError, and it's because you're trying to cast "KE 17" to an int.
You'll need to strip more than string.whitespace and string.punctuation if you're going to cast the string to an int.