[gst-devel] problems with adder

[till busch]

hi,

i'm new to gstreamer. i think fail to understand some of its concepts.

i'm trying to write an app that uses gstreamer for sound output.
i would like to have gstreamer mix (crossfade) two streams.
all pipes that i tested so far using gst-launch seem to have some problems.
mostly these are negotiation problems.

does anyone have an example how mixing two streams with threads work?

a working example in c would be great, too.

in my observation using spider instead of mad seems to work more frequently, 
though
i'd like it to work with mad direcltly before switching to spider.

i have had limited success with this command-line:
gst-launch-0.8 { filesrc location=Dub_It_Today.mp3 ! mad ! audioscale ! 
audioconvert ! volume ! queue ! adder0.sink%d } { filesrc 
location=Nah_Bow_Down.mp3 ! mad ! audioscale ! audioconvert ! volume ! 
queue ! adder0.sink%d } { adder ! volume ! audioscale ! audioconvert ! 
alsasink }
it works quite often, but sometimes it dies like this:

ERROR: from element /pipeline0/thread2/adder0: Internal GStreamer error: 
negotiation problem.  File a bug.
Additional debug info:
gstadder.c(459): gst_adder_loop: /pipeline0/thread2/adder0:
width is 0
Execution ended after 1 iterations (sum 248004000 ns, average 248004000 ns, 
min 248004000 ns, max 248004000 ns).

any other approach with less threads (e.g. one for all inputs + adder, and one 
for the audio-output) did not work.

thank you for any hints, greetings from burgenland

- till busch