OpenGL renderer window..

Fri Feb 9 23:29:20 UTC 2018

Matt,
Thanks for the response.

I'm not sure I follow.. I already have an instance of Glib.MainLoop for the
pipeline to run already.

This is constructed on the main thread just after Gst.init(None) is called.
But.. I am running GLib.MainLoop.run in it's own thread - is this okay?
That Thread is started from the main application, just before the pipeline
is started.

What I have tried so far:

import gi
gi.require_version('GstGL', '1.0')
from gi.repository import GstGL

self._context = Gst.Context.new(GstGL.GL_DISPLAY_CONTEXT_TYPE, True)
self._gldisplay = GstGL.GLDisplay()
self._gldisplay.new()
self._glwindow = self._gldisplay.create_window()
self._glwindow.show()
self._glcontext = GstGL.GLContext.new(self._gldisplay)
GstGL.context_set_gl_display(self._context, self._gldisplay)
outputsink = gst_elem.make('glimagesink')
outputsink.set_context(self._context)
print('----- context: %s' % str(outputsink.get_property('context')))

What I notice is that the constructed Element 'glimagesink' has a context
property which returns 'None' after construction.

I can see that the python rocket bouncing.. so it's attempting to kick the
display.. but no window.

Do I need to override something with the GST_MESSAGE_NEED_CONTEXT, perhaps?

I have attempted to connect this on the bus 'message::need-context', but
get no signal..

On Thu, Feb 8, 2018 at 1:21 AM, Matthew Waters <ystreet00 at gmail.com> wrote:

> Mac OS X is special in that a CFRunLoop is required to be running on the
> main thread in order for glimagesink (and other UI operations) to perform
> correctly.
>
> That either means you need to run one yourself, use a toolkit that runs
> one or run a GMainLoop.
>
> Running your gst-launch-1.0 command with GST_DEBUG=gl*:7 would give you
> more information about what GStreamer is attempting to do, specifically
> around https://cgit.freedesktop.org/gstreamer/gst-plugins-base/
> tree/gst-libs/gst/gl/cocoa/gstgldisplay_cocoa.m#n105.
>
> On 08/02/18 06:49, Hans Hony wrote:
>
> I have a question about launching a simple video pipeline using
> 'glimagesink' with the python3 gi.repository.Gst.ElementFactory..
>
> On Mac OSX I can launch my pipeline with custom plugin:
> gst-launch-1.0 filesrc <avi> ! decodebin ! queue ! my_custom_plugin
> <props> ! autovideosink
>
> The output a default window titled 'OpenGL renderer'.. which I assume is
> gstglwindow_cocoa.m
> <https://github.com/GStreamer/gst-plugins-bad/blob/1.12/gst-libs/gst/gl/cocoa/gstglwindow_cocoa.m#L466> from
> gst-plugins-bad.. ?
>
> Likewise, 'glimagesink' will also open the 'OpenGL renderer' window when
> used in a bash gst-launch-1.0 command in the same way as 'autovideosink'. Also
> I notice when I launch the pipeline under bash, I can see:
>
>     Setting pipeline to PAUSED ...
>
>     Pipeline is PREROLLING ...
>
>     Got context from element 'sink': gst.gl.GLDisplay=context,
> gst.gl.GLDisplay=(GstGLDisplay)"\(GstGLDisplayCocoa\)\ gldisplaycocoa0";
>
>
> However, when I launch the pipeline for gi.repository.Gst.ElementFactory
> (in python3) I have issues:
>
>    1. It fails horribly for ElementFactory.make('autovideosink') with *Illegal
>    instruction: 4* when NULL to READY is propagated.. so to fix that I
>    just didn't use 'autovideosink'..
>
>    2. It will propagate PLAY for ElementFactory.make('glimagesink').. but
>    nothing actually plays.. probably because the chain isn't correct
>
>    3. I cannot figure out how to hook the 'sync_message' to an OSX window
>    object with glimagesink from python?!? I see information in gst-inspect-1.0
>    glimagesink.. but I can't find any examples to do this specifically.
>
>    4. Secondarily, I see that I can use gi.repository.GstGL.GLDisplay(
>    ).new() to create:
>        <__gi__.GstGLDisplayCocoa object at 0x10e05eb88 (GstGLDisplayCocoa
>    at 0x7fc7ba9439c0)>
>    .. which is seemingly what I want!
>
>    5. How to do hook this object up to 'glimagesink' ??
>
>
> You don't need to hook this up to GStreamer, it will create that
> automatically.
>
>
>    1. Finally, do I need to add:
>      pipeline.get_bus().connect('sync-message::element', on_sync_message) with
>    a function on_sync_message(bus, msg) ?
>
>
> This shouldn't be needed.
>
> From the Gtk examples I found there was a function which would update the
> GUI.. I assume that I would need to do this as well.. but the syntax is not
> clear immediately.
> More specifically:
> def on_sync_message(bus, msg): if msg.get_structure().get_name() == '
> prepare-window-handle':
> sink = msg.src
> sink.set_window_handle(<window_handle>)
> sink.set_render_rectangle(0, 0, <window.width>, <window.height>)
>
>
> This is for embedding glimagesink's output inside another application.
>
> Overall, I want to know:
>
>    1. How is it that gst-launch-1.0 works so well?
>
>
> Because, glimagesink is generally created and set to READY on the main
> thread. Otherwise, happy accident.
>
>
>    1. How can I use that functionality in my python3 gi code?
>
>
> Run a CFRunLoop/GMainLoop on the main thread.
>
>
>    1. How can I add another element to trigger that force-aspect-ratio
>    window magic?
>
>
> I'm not sure what you mean by this.
>
> Cheers
> -Matt
>
> $ brew list --versions | grep gst
>
> gst-plugins-bad 1.12.3
>
> gst-plugins-base 1.12.3
>
> gst-plugins-good 1.12.3
>
> gst-plugins-ugly 1.12.3
>
> gst-python 1.12.3
>
> gst-rtsp-server 1.12.3
>
> gstreamer 1.12.3
>
> Thanks,
> Hans
>
>
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