Usefulness of graphical pipeline editors and/or visualizers

[dv]

Hello,

I've seen several attempts at writing graphical pipeline editors, 
similar to DirectShow's GraphEdit: http://i.imgur.com/9C1Xl.png

But I wonder how useful it would really be. I only see the following use 
cases:

1) Visualizing complex pipelines (a large gst-launch line for example), 
to see what's wrong with the construction. Kind of like what 
GST_DEBUG_DUMP_DOT_DIR does, except interactive.

2) As a tool for file format conversions and (de)muxing. This is what 
GraphEdit is often used for.

3) As an alternative to gst-launch for pipeline prototyping. Even though 
gst-launch works fine, complex pipelines can benefit from a visual 
representation.

Now, as discussed in the chat, the main problem is that more complex 
pipelines usually are at least partially dynamic. I guess that seriously 
limits what such a tool could do.

Also, what about sometimes pads (like decobin2 has)? I can imagine some 
highlevel abstractions on a per-elementclass basis, but that requires a 
lot of work.

GraphEdit works because the DirectShow pins operate differently. For 
example, a demuxer always has one unconnected pin. When this pin is 
connected, it creates a new pin etc. Of course this works much better 
with visual tools. (GStreamer's sometimes system is nicer to code with, 
though.)

Any thoughts on this?