Custom Gst.Element in GTK3

[Manuel]

Hi,

thanks for pointing me in the right direction.
VideoFilter might be what I was looking for. Is there any simple example
code available?

Because this short snippet does not work: http://pastebin.com/GdiYhxzf

My do_transform_frame_ip method is never called.
I read in the BaseTransform-docs that BaseTransform provides already a
sinkpad and sourcepad. Or do I have to specify the sink- and src-pads by
myself? Because the sinkpad field is None.
Or do I have to override some of BaseTransform do_* methods?
What am I missing? :)

Best regards


17.07.2014 12:39 AM, Jan Alexander Steffens:
> BaseTransform is in GstBase, not Gst. VideoFilter is in GstVideo.
> 
> On Thu, Jul 17, 2014 at 12:24 PM, Manuel <manuel at wenns-um-email-geht.de> wrote:
>> 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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