[gst-devel] Volenv and Adder Plugins

[Andy Wingo]

On Thu, 21 Feb 2002, Marc Mulcahy wrote:

> Hi All,
> 
> I'm new to gstreamer, but have been working with GNOME 2.0 in my real job as
> a part of the GNOME accessibility effort for Sun for almost a year now.

welcome :)

> I'm trying to write an online radio station application based on gstreamer,
> and really like the architecture you all have designed-- keep up the good
> work!

neat.

> I'm having trouble with the volenv and adder plugins-- the example mixer
> included with gst-plugins doesn't seem to be working at the moment, so I
> concluded it wasn't just me...  to help me learn, I've made a simple
> application which attempts to play two ogg vorbis files at once.  I'm using
> two GstFilesrcs connected to two GstVorbisDecs connected to two GstVolenvs
> finally connected to one GstAdder.  the adder is crashing in the
> loop_iterate function with an unknown audio format.  What I think is
> happening is that the pads connected to the adder don't get their caps set
> at connection time, so when the first iteration of the loop happens, the
> adder doesn't know what format audio is coming in.

bingo. we changed out capsnego (caps negotiation) code a few weeks ago,
and some of the lesser-used plugins have not been updated. volenv for
instance. i'll see what i can do about fixing it. the rest of the
plugins in your pipeline have been updated.

ok, so now i'm looking into volenv. the code is dodgy.
 - if "rise" is set before capsnego it will segfault
 - mixture of many different capsnego ideas

i'll see what i can do about fixing it up. imo though, the Right Way to
do things isn't quite tested yet at this point, using steve baker's
dynamic parameters to control a simple volume element. see
http://gstreamer.net/wiki/?GstDynamicParams .

best regards,

wingo.