[gst-devel] gst-python: how to use BaseSink.set_sync()

[Edward Hervey]

Hi,


On 10/20/06, Antoine Pitrou <antoine.pitrou at wengo.fr> wrote:
>
> Hi,
>
> I'm trying to write a sink that needs to receive buffers lazily (for
> streaming purposes), not all at once. For that it seems that the
> set_sync() method in gst.BaseSink is the right one. I've noticed that
> it's how fakesink works (by reading gstfakesink.c).
>
> However, I can't manage to reproduce this behaviour in Python. Although
> I call set_sync(True), when linking a source like audiotestsrc or mad to
> this sink, it still sends buffers greedily (while it does not if use
> fakesink sync=true).

  The sync property is to synchronize the call to render(), it has
nothing to do with the *speed* at which buffers arrive in the sync.

>
> I also tried to define get_times() and render() methods but they never
> get called.

  Those are virtual methods. To implement virtual methods with
pygobject (and therefore gst-python), you need to implement a
do_<virtualmethod name>.
  If you implement do_render() it will be called.

>
> Here is the current code for my sink.  I use gst-python 0.10.4 (as
> shipped with Ubuntu Dapper).
>
>
> class MySink(gst.BaseSink):
>     __gsttemplates__ = (
>         gst.PadTemplate("sink",
>                         gst.PAD_SINK,
>                         gst.PAD_ALWAYS,
>                         gst.caps_new_any()),
>     )
>
>     sink_pad = property(lambda self: self.get_pad("sink"))
>
>     def __init__(self):
>         self.__gobject_init__()
>         logging.info('setting chain/event functions')
>         sink_pad = self.sink_pad
>         sink_pad.set_chain_function(self.sink_chain)
>         sink_pad.set_event_function(self.sink_event)
>         self.num_bytes = 0
>         self.set_sync(True)
>
>     def sink_chain(self, pad, buf):
>         size = buf.size
>         self.num_bytes += size
>         logging.debug("%s timestamp:%d size:%d(%d)",
>             pad, buf.timestamp, size, len(buf.data))
>         return gst.FLOW_OK
>
>     def sink_event(self, pad, event):
>         logging.info("%s event:%r" % (pad, event.type))
>         return True
>
> gobject.type_register(MySink)
>
>
>
> Thanks
>
> Antoine.
>
>
>
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-- 
Edward Hervey
Multimedia editing developer / Fluendo S.A.
http://www.pitivi.org/