[gst-devel] spider related discussion

[Stefan Kost]

hi hi,

let me please first reintroduce what I am going to do. In the app we would like
to write (something like http://www.buzzmachines.com) the users drags elements
onto a sheet of paper and links them (like gsteditor). Now additionally the user
records events on a timeline and can play that back. The result is a
(media)-composer. We're going to start with audio ;-) only though. The project
is host on http://buzztard.sf.net 9cvs contains test apps and design docs -
thats all right now).

It is desirable that the user does not see low-level stuff. For audio this
means, the user should not need to add elements from class
'Filter/Converter/Audio' like 'audioconvert' and 'float2int'.
Therefore I link elements one-by-one and if that failes, I try to put an spider
instance inbetween.

Problem 1.)
The inserting of the spider works (gst_elements_link_many(src,spider,sink)
returns true), but running the result does not. When setting the pipeline to
play, I get :

** (process:13875): CRITICAL **: how to remove plugins?

(process:13875): GStreamer-CRITICAL **: Factory for `volume' has no type
Segmentation fault (core dumped)

Problem 2.)
I am not be able to find out which elements the spider actually inserts (I have
used --gst-debug="*:4", using higher values made it impossible to locate anything).

Problem 3.)
How can spider work at all. When I link src->spider it can't yet do anything
useful as it does not yet know about the sink. So only if the other end
(siper->sink in our case) has been connected the it can search for required
elements to insert. Is that the way it works?

Problem 4.)
I've tried to write a simple 'spider' for audio-use only. I've started to grab
the GstCaps from the src and sink pads of the elements I want to link. But then
discovered that the caps are quite dumb objects. At least if I should only use
what is in the API docs (and thus is public).

Question 1.)
Wouldn it make sense if one could tell the spider: 'try to link these by only
using elements <a>,<b>,<c>'?

Question 2.)
Now to that point. Which way would you go?
Should the spider be fixed to handle things like 'sinesrc ! spider ! esdsink' (I
 would say so)?
Would you suggest that I care myself about putting the right converters inbetween?

Many thanks in advance for any input.

Ciao
  Stefan
-- 
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