Custom Gst.Element in GTK3

[Manuel]

Hey,

it seems that Gst 1.0 shipped with Ubuntu 14.04 does not include the
BaseTransform/VideoFilter classes:
	AttributeError: 'gi.repository.Gst' object has no attribute 'BaseTransform'

It would be nice if I could stick with the Gst-code/version shipped with
Ubuntu :)

Is there some documentation about the pool negotiation in python?
As mentioned I just need to get the timestamp of the buffers, for
example to show the current position in a label and show some text using
textoverlay (like subtitles). And then the buffers should just be
forwarded to the next element in the pipeline. I don't need to modify
buffers etc..
Maybe I don't even need to implement my own Gst.Element. :) I just need
the "ticks" to show the subtitles as soon as possible as the video
reaches say position 00:04.140 . Any ideas? :)

Best regards


17.07.2014 11:37 AM, Thibault Saunier:
> Hello,
> 
> I tried the example. But it seems to be broken. For example it uses
>> set_chain_function, which IMHO should be set_chain_function_full.
>> (According to
>>
>> http://lazka.github.io/pgi-docs/Gst-1.0/classes/Pad.html#Gst.Pad.set_chain_function_full
>> ).
>>
> 
> It is overriden:
> http://cgit.freedesktop.org/gstreamer/gst-python/tree/gi/overrides/Gst.py#n109
> it can thus be used like it is in the example (this override has not been
> released yet)
> 
> 
> It looks like you should use Gst.BaseTransform (maybe Gst.VideoFilter)
> instead of using Gst.Element as a baseclass for your element, it would
> handle more things for you (and I guess pool negotation is one of those
> things).
> 
> Regards,
> 
> Thibault
> 
> 
> But I noticed two things:
>> 1.
>> When changing the function names to set_chain_function_full and
>> set_event_function_full and adding a source-pad it almost looks like my
>> TestFilter-class.
>>
>> One difference:
>> In my code the chain-function tries to push the buffer to the next
>> element (self.srcpad.push(buffer)). The example instead just returns
>> Gst.FlowReturn.OK. This is where my code produces the error ("We don't
>> have a bufferpool negotiated") and the example doesn't. Do I have to do
>> something more to be able to push the buffer to the next element?
>>
> 
> Why don't you implement
> 
> 
>> 2.
>> In my last email I mentioned that I even didn't get it (my GTK3-example)
>> playing with textoverlay and autovideosink in the Bin (without my custom
>> element).
>> But when I change the GhostPad's name in my GTK3-example to 'sink'
>> (instead of 'video_sink' like in my GTK2-example) and remove the
>> TestFilter from the Bin then the video is playing fine. I updated the
>> example at pastebin. Now I just need to get my filter to work :)
>>
>> Best regards
>>
>>
>> 17.07.2014 09:29 AM, Thibault Saunier:
>>> Hello,
>>>
>>> I think when you say Gtk3 you mean GStreamer 1.0 with PyGObject.
>>>
>>> Do you have gst-python installed? It is necessary to be able to create
>>> GstElement subclasses.
>>>
>>> You can have a look at that example:
>>>
>> http://cgit.freedesktop.org/gstreamer/gst-python/tree/examples/plugins/python/sinkelement.py
>>>
>>> Regards,
>>>
>>> Thibault Saunier
>>>
>>>
>>> On Thu, Jul 17, 2014 at 12:07 AM, Manuel <manuel at wenns-um-email-geht.de>
>>> wrote:
>>>
>>>> Custom Gst.Element in GTK3
>>>> --------------------------
>>>> Hi all,
>>>>
>>>> I wrote a gst.Element (GTK2), which is a simple filter that just
>>>> forwards all buffers it receives on the sink-pad to the src-pad. Later I
>>>> will grab some information from the buffer before forwarding it. (More
>>>> precisely I will grab the timestamps and show some text based on the
>>>> time, like subtitles). The GTK2-version works fine.
>>>>
>>>> Today I tried to change my code so that it uses the GTK3
>>>> gi.repository-package.
>>>> Although the new class looks almost the same it doesn't work.
>>>>
>>>> This is the error printed on the console:
>>>> Error: Internal error: can't allocate images xvimagesink.c(979):
>>>> gst_xvimagesink_show_frame ():
>>>>
>>>>
>> /GstPlayBin:MultimediaPlayer/GstPlaySink:playsink/GstBin:vbin/GstBin:timed-video-bin/GstAutoVideoSink:autovideosink0/GstXvImageSink:autovideosink0-actual-sink-xvimage:
>>>> We don't have a bufferpool negotiated
>>>>
>>>> Here is my GTK2-version: http://pastebin.com/J2gHfvS4
>>>> And here the GTK3-version: http://pastebin.com/9u8zzcTk
>>>>
>>>> This is a scenario:
>>>> A video-file is played using playbin. The playbin's video-sink is set to
>>>> a Gtk.Bin that combines my own Gst.Element with textoverlay and an
>>>> autovideosink.
>>>>
>>>> NOTE: If you remove the textoverlay from the GTK3 example then at least
>>>> the audio is playing ;)
>>>>
>>>> I would be very grateful for your help. :)
>>>>
>>>> Best Regards
>>>> _______________________________________________
>>>> gstreamer-devel mailing list
>>>> gstreamer-devel at lists.freedesktop.org
>>>> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>>>>
>>>
>>>
>>>
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>>
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> 
> 
> 
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