OpenGL renderer window..

Sat Feb 10 22:49:16 UTC 2018

I'm not sure I understand all the semantic details of this conversation -
by which, I mean, I'm not quite sure how to do that specifically.

So, CFRunLoop - is imported from CoreFoundation.. which I seem to be able
to obtain via ctypes or PyObjC..

Now how I use that in my python application is another story.. (In
retrospect this might be more approachable in C++)

I'm assuming that CFRunLoopRun is a blocking call, and would need to be
executed at the end of my application code's run loop.

I think I have the perfect place for that to happen in mind.. but the
import details look a little hairy.. I also have to assume that CFRunLoop
would react to SIGINT or SIGTERM..

Lastly, I understand that this problem is slightly outside the scope of
gstreamer. So, if you can respond with meaningful tips, I would be
greatful.. but I do understand that the end of scope is quickly approaching.

On Fri, Feb 9, 2018 at 8:01 PM, Matthew Waters <ystreet00 at gmail.com> wrote:

> On 10/02/18 10:29, Hans Hony wrote:
>
> 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.
>
>
> Unfortunately, no.  The CFRunLoop must be running on the main thread,
> otherwise this will not work.
>
> Cheers
> -Matt
>
>
> 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
>>
>>

-- 

*______________________*
*Hans Hony *Robotics Engineering
San Francisco, CA
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