Skip to content

Data is none in buffer from GstVideo.VideoFrame

Submitted by Dineth W

Link to original bug (#794744)

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()
Edited by Nicolas Dufresne