I am using Gstreamer 1.0 with Python bindings. Below is the pipeline I am trying to build considering Opengl plugins :
gltestsrc -> gltransformation -> glimagesink
I am trying to modify the properties of element 'gltransformation' dynamically based on the values received from external hardware device. Here is the link, for a similar question but it did not help me much in my usecase. Below is the snipped of the python script :
import gi
gi.require_version('Gst','1.0')
from gi.repository import Gst,GstController
#global variables
#the values of a,b,c get updated for certain events dynamically based on external hardware
a = 0
b= 0
c = 0
source = Gst.ElementFactory.make("gltestsrc", "source")
gltrnsfrm = Gst.ElementFactory.make("gltransformation","gltrnsfrm")
sink = Gst.ElementFactory.make("glimagesink", "sink")
# create the empty pipeline
pipeline = Gst.Pipeline.new("test-pipeline")
if not pipeline or not source or not gltrnsfrm or not sink:
print("ERROR: Not all elements could be created")
sys.exit(1)
# build the pipeline
pipeline.add(source,gltrnsfrm,sink)
if not source.link(gltrnsfrm):
print("ERROR: Could not link source to gltrsnfrm")
sys.exit(1)
if not gltrnsfrm.link(sink):
print("ERROR: Could not link gltrsnfrm to sink")
sys.exit(1)
# modify the gltransformation's properties
gltrnsfrm.set_property("rotation-z",a)
gltrnsfrm.set_property("rotation-x",b)
gltrnsfrm.set_property("rotation-y",c)
#dynamic controller
cs = GstController.InterpolationControlSource()
cs.set_property('mode', GstController.InterpolationMode.LINEAR)
cb= Gstcontorller.DirectControlBinding.new(gltrnsfrm,"rotation-x",cs)
gltrnsfrm.add_control_binding(cb)
#modify the values
cs.set(0*Gst.SECOND,b) #use updated values of b
cs.set(1*Gst.SECOND,b)
The above example shows only modification of 1 element property, however, I have other properties as well to be modified based on the values of a,b & c.
Executing the above script gives me the following error:
GStreamer-CRITICAL : gst_object_add_control_binding: assertion 'binding->pspec' failed.
I think I have to set certain more attributes in python to get this working. Does anyone have a hand on this issue?
EDIT: After the suggestions from Hugh Fisher, I tried to trace back to the source of the file. Here is a snippet from the original code :
GST_INFO_OBJECT (object, "trying to put property '%s' under control",
binding->name);
/* check if the object has a property of that name */
if ((pspec =
g_object_class_find_property (G_OBJECT_GET_CLASS (object),
binding->name))) {
GST_DEBUG_OBJECT (object, " psec->flags : 0x%08x", pspec->flags);
/* check if this param is witable && controlable && !construct-only */
if ((pspec->flags & (G_PARAM_WRITABLE | GST_PARAM_CONTROLLABLE |
G_PARAM_CONSTRUCT_ONLY)) ==
(G_PARAM_WRITABLE | GST_PARAM_CONTROLLABLE)) {
binding->pspec = pspec;
} else {
GST_WARNING_OBJECT (object,
"property '%s' on class '%s' needs to "
"be writeable, controlable and not construct_only", binding->name,
G_OBJECT_TYPE_NAME (object));
}
} else {
GST_WARNING_OBJECT (object, "class '%s' has no property '%s'",
G_OBJECT_TYPE_NAME (object), binding->name);
}
gst_object_unref (object);
And this is the log file for my script :
0:00:00.174410648 [336m 8309[00m 0xd1b750 [37mTRACE [00m [00;01;31;44m GST_REFCOUNTING gstobject.c:207:gst_object_init:<GstObject@0x10b0020>[00m 0x10b0020 new
0:00:00.174697421 [336m 8309[00m 0xd1b750 [37mTRACE [00m [00;01;31;44m GST_REFCOUNTING gstobject.c:207:gst_object_init:<GstObject@0x10b20f0>[00m 0x10b20f0 new
0:00:00.174716708 [336m 8309[00m 0xd1b750 [36mINFO [00m [00m gstcontrolbinding gstcontrolbinding.c:144:gst_control_binding_constructor:<gltrnsfrm>[00m trying to put property 'rotation-x' under control
0:00:00.174723927 [336m 8309[00m 0xd1b750 [37mDEBUG [00m [00m gstcontrolbinding gstcontrolbinding.c:150:gst_control_binding_constructor:<gltrnsfrm>[00m psec->flags : 0x000000e3
0:00:00.174729088 [336m 8309[00m 0xd1b750 [33;01mWARN [00m [00m gstcontrolbinding gstcontrolbinding.c:161:gst_control_binding_constructor:<gltrnsfrm>[00m property 'rotation-x' on class 'GstGLTransformation' needs to be writeable, controlable and not construct_only
0:00:00.174733951 [336m 8309[00m 0xd1b750 [37mTRACE [00m [00;01;31;44m GST_REFCOUNTING gstobject.c:264:gst_object_unref:<gltrnsfrm>[00m 0x10a60e0 unref 4->3
(python3:8309): GStreamer-CRITICAL **: 10:37:00.609: gst_object_add_control_binding: assertion 'binding->pspec' failed
As per the man page of 'gltransformation', the properties rotation-x/y/z, are writable and readable. Also here is a link, of an application that takes input from GUI and changes the rotation-x/y/z for 'gltransformation'. I have no clue, why here in my case this is an issue.
#gst-inspect-1.0 gltransformation
translation-x : Translates the video at the X-Axis, in universal [0-1] coordinate.
flags: readable, writable
Float. Range: -3,402823e+38 - 3,402823e+38 Default: 0
translation-y : Translates the video at the Y-Axis, in universal [0-1] coordinate.
flags: readable, writable
Float. Range: -3,402823e+38 - 3,402823e+38 Default: 0
translation-z : Translates the video at the Z-Axis, in universal [0-1] coordinate.
flags: readable, writable
Float. Range: -3,402823e+38 - 3,402823e+38 Default: 0
rotation-x : Rotates the video around the X-Axis in degrees.
flags: readable, writable
Float. Range: -3,402823e+38 - 3,402823e+38 Default: 0
rotation-y : Rotates the video around the Y-Axis in degrees.
flags: readable, writable
Float. Range: -3,402823e+38 - 3,402823e+38 Default: 0
rotation-z : Rotates the video around the Z-Axis in degrees.
flags: readable, writable
Float. Range: -3,402823e+38 - 3,402823e+38 Default: 0
Edit 2: updated the code, with a workaround for issue:
class Thread(object):
def __init__(self):
thread = threading.Thread(target=self.get)
self.gltrnsfrm = Gst.ElementFactory.make("gltransformation","gltrnsfrm")
thread.start()
def get(self):
try:
global a,b,c
while True:
self.gltrnsfrm.set_property("rotation-z",a)
self.gltrnsfrm.set_property("rotation-x",b)
self.gltrnsfrm.set_property("rotation-y",c)
#time.sleep(0.01)
except KeyboardInterrupt:
pass
The rest of the code is the same(with minor adaptation to use the threads) as described before in the post. However, the following code was ommited :
#dynamic controller
cs = GstController.InterpolationControlSource()
cs.set_property('mode', GstController.InterpolationMode.LINEAR)
cb= Gstcontorller.DirectControlBinding.new(gltrnsfrm,"rotation-x",cs)
gltrnsfrm.add_control_binding(cb)
#modify the values
cs.set(0*Gst.SECOND,b) #use updated values of b
cs.set(1*Gst.SECOND,b)
