creating custom sink in python fails

[Thibault Saunier]

Hello,

That should work, we have an example in gst-python that implement a
stupid simple sink in python[0]. It is based on GstElement instead of
BaseSink but it should probably be ported.

Regards,

Thibault.

[0] http://cgit.freedesktop.org/gstreamer/gst-python/tree/examples/plugins/python/sinkelement.py

On Tue, Oct 27, 2015 at 2:45 PM, Jan Spurný <JSpurny at seznam.cz> wrote:
> Hi,
>
> I have problem with (probably) python binding for gstreamer-1.0 (1.4.4.0) - I was porting some code from gstreamer-0.10 (pygst) to new gstreamer-1.0 and I'm not able to get elements written in python to work. This is minimal working example (python2.7):
>
> ---------------------------------------------------------------------
> import gi
> gi.require_version('Gst', '1.0')
> from gi.repository import Gst
> from gi.repository import GstBase
> from gi.repository import GObject
>
> GObject.threads_init()
> Gst.init()
>
> class MySink(GstBase.BaseSink):
>     __gstmetadata__ = ('My Sink', 'Sink', 'Sink', 'foo bar')
>     __gsttemplates__  = (
>         Gst.PadTemplate.new("sink",
>             Gst.PadDirection.SINK, Gst.PadPresence.ALWAYS,
>             Gst.caps_from_string('text/plain')),)
>
> def plugin_init(plugin, userarg):
>     t = GObject.type_register(MySink)
>     Gst.Element.register(plugin, 'my_sink', 0, t)
>     return True
>
> version = Gst.version()
> r = Gst.Plugin.register_static_full(
>     version[0], version[1], 'my_plugin', 'my plugin desc',
>     plugin_init, '1.0', 'Proprietary', 'abc', 'def', 'ghi', None)
>
> s = MySink()
> ---------------------------------------------------------------------
>
> and it throws a CRITICAL error:
>
> ---------------------------------------------------------------------
> $ ./mysink.py
> (python2:18618): GStreamer-WARNING **: Element factory metadata for 'my_sink' has no valid long-name field
> ** (python2:18618): CRITICAL **: gst_base_sink_init: assertion 'pad_template != NULL' failedI'm not that worried about the warning, but that CRITICAL error means the element has no sinkpad and can't be linked.
> ---------------------------------------------------------------------
>
> And worst thing - if I remove __gsttemplates__ and __gstmetadata__ completely, NOTHING changes. It seems to me that BaseSink.__init__() doesn't see it.
>
> Does anyone have any idea what I'm doing wrong? Also I would greatly appreciate any documentation, examples or tutorials on python binding for gstreamer-1.0, because I wasn't able to find much
>
> Thanks,
> Jan Spurny
>
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