Pipeline creates a 0-length file

[Orestes Mas]

Hello,

I'm a newbie in the (wonderful) GStreamer world, and I need some help and
advice from more experienced developers because I'm facing a weird problem.

I'm trying to do screencasts using gstreamer. I have a command line
pipeline that works perfectly, but when I try to reproduce this pipeline
programmatically, things behave erratically: sometimes it works, but most
of the time the pipeline creates a file of 0 bytes and it seems audio
source isn't sending data.

The working pipeline is:

gst-launch pulsesrc
device=alsa_input.usb-Logitech_Logitech_Wireless_Headset_000D44B63FE3-00-Headset.analog-mono
! audio/x-raw-int,rate=44100,channels=1,depth=16 ! audioconvert ! audiorate
! vorbisenc ! queue ! webmmux writing-app=lekture name=mux ! filesink
location=/home/orestes/tmp/test.webm ximagesrc display-name=:0 screen-num=0
startx=100 starty=100 endx=660 endy=580 ! video/x-raw-rgb,framerate=25/1 !
ffmpegcolorspace ! vp8enc ! queue ! mux.

As my program is written using Qt/KDE libraries, I use QtGstreamer as
GStreamer library wrapper. The function that constructs and starts the
pipeline is:

http://paste.kde.org/709454/

I don't want to make this message too boring to read, so if you need more
details please ask. But I must add (perhaps helps) that if I use an
"alsasrc device=default" (which is pulseaudio emulating an alsa card, in
fact), the programmatically-created pipeline works every time. But I don't
want to rely on this, because I'm not sure pulseaudio will be installed in
every system my program is executed on, nor am I sure that the name of this
emulated card will be always "default".

So, do anyone have a clue about the origin of this problem?

Many, many thanks in advance.

Orestes.
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