Re: GStreamer access to raw audio data

[Torsten Schoenfeld <kaffeetisch gmx de>]

On 16.01.2012 17:06, Zach Morgan wrote:
> First of all, Gtk2, Glib, Gstreamer are all phenomenal bindings. They
> have truly turned a spaghetti nightmare into a gizmo paradise. Thank
> you.

Thanks for the feedback!

> It doesn't look like it will be that easy for audio. 'convert-frame'
> doesn't handle audio caps, and #gstreamer on freenode insists that an
> appsink is the way to capture audio. I have a significant problem with
> appsink, which is that it appsink methods don't appear to work. My
> appsink object is instantiated by the GStreamer::ElementFactory, but
> calling, for example, $appsink->pull_preroll() produces this error:
>
> Can't locate object method "gst_app_sink_pull_preroll" via package
> "Glib::Object::_Unregistered::GstAppSink" at lib/PDL/GStreamer.pm line
> 54.

I cannot comment on whether GstAppSink is the best way to achieve this. 
 But assuming it is, the problem at hand is that we have no bindings 
for it.  GstAppSink seems to be part of the libgstapp library, which in 
turn is part of gst-plugins-base, i.e. not of gstreamer itself.  So I 
think the best way to wrap GstAppSink would be to create a separate Perl 
module GStreamer::App along the lines of the existing module 
GStreamer::Interfaces.  I cannot promise to tackle this soon myself, but 
I would definitely try to provide all the necessary help if someone else 
wanted to give it a shot.

The code in your github repository looks fine to me.  Looking at 
capture_image, though, I'm reminded of how awkward the 
GStreamer::Structure stuff is.  The current bindings are basically a 
one-to-one mapping of the C API.  But in this case I think a more 
natural Perl wrapper would be handy.