CODEWITHSUNDEEP
pythongstreamer
Evan Marshall
Evan Marshall

Reputation: 81

Gstreamer, Python, and Appsink

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

Upvotes: 4

Views: 2848

Answers (1)

Evan Marshall
Evan Marshall

Reputation: 81

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"

Upvotes: 1

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