Data is none in buffer from GstVideo.VideoFrame (#11) · Issues · GStreamer / gst-python

Data is none in buffer from GstVideo.VideoFrame

Submitted by Dineth W

Description

Hey,

When trying to get buffer data from GstVideo.VideoFrame when inheriting from GstVideo.VideoFilter using do_transform_frame.

Steps to Reproduce:
Run code below and it will show none for buffer

Actual Results:
No data in buffer
Black screen from ximagesink(which may be because i have to push outframe back. Dont know if i need to since i dont change any of the frame.)

Expected Results:
Gives a Gst.Buffer which should hold a full image frame to be manipulated (in the docs here https://lazka.github.io/pgi-docs/GstVideo-1.0/classes/VideoFrame.html it says that a Gst.Buffer will be returned)

Build Date & Hardware:
March 26 2018 on ubuntu 16.04 LTS

Additional Builds and Platforms:
Havnt tested on any other builds

Additional Information:

I believe my Gstreamer version is
gst-launch-1.0 version 1.8.3
GStreamer 1.8.3
https://launchpad.net/distros/ubuntu/+source/gstreamer1.0

This was found by using gst-launch-1.0 --version in the command prompt

The buffer is None. Here is some sample code, let me know if i should post anything else or if i can help. Thanks for your time.

import sys
import gi

gi.require_version('Gst', '1.0')
gi.require_version('GstVideo', '1.0')

from gi.repository import GObject, Gst, GstVideo

Gst.init(sys.argv)
GObject.threads_init()
Gst.segtrap_set_enabled(False)

class GstTimestamp(GstVideo.VideoFilter):
gstmetadata = ('<longname>', '<classification>',
'<description>', '<author>')

gsttemplates = (Gst.PadTemplate.new("sink",
Gst.PadDirection.SINK,
Gst.PadPresence.ALWAYS,
Gst.Caps.new_any()),
Gst.PadTemplate.new("src",
Gst.PadDirection.SRC,
Gst.PadPresence.ALWAYS,
Gst.Caps.new_any()))

def init(self):
GstVideo.VideoFilter.init(self)

def do_transform_frame(self,inframe,outframe):

#this should give me that data for the frame  
data = inframe.buffer  
#data is None  
print data  

#dont know if im properly sending data back since   
#i just get blank screen   
return Gst.FlowReturn.OK

#used for registration
def plugin_init(plugin):
Gst.Element.register(plugin, 'timestamper', 0,
GObject.type_register(GstTimestamp))
return True

def init():
version = Gst.version()
Gst.Plugin.register_static(
version[0], version[1], 'timestamper', 'Timestamper',
plugin_init, '1.0', 'GPL', 'timestamper',
'plugins-demo', 'demo')

init()

def connect(bus, name):
def _connect(f):
bus.connect(name, f)
return f
return _connect

def main():
pipeline = Gst.parse_launch('videotestsrc ! timestamper ! ximagesink')

bus = pipeline.get_bus()
bus.add_signal_watch()
#Gst.debug_set_active(True)
#Gst.debug_set_default_threshold(4)

@connect(bus, "message::error")
def on_error(bus, message):
pipeline.set_state(Gst.State.NULL)
exit(message.parse_error())

@connect(bus, "message::eos")
def on_eos(bus, message):
pipeline.set_state(Gst.State.NULL)
exit(0)

pipeline.set_state(Gst.State.PLAYING)
loop = GObject.MainLoop()
try:
loop.run()
except(KeyboardInterrupt):
pass

pipeline.set_state(Gst.State.NULL)

if name == 'main':
main()