Pipeline using filesrc and appsink

[Manuel Schneckenreither]

Hi,

I am pretty new to gstreamer and face some (probably simple) problem
with my pipeline:

    filesrc location=tests/test.mp4 !
    decodebin !
    videoconvert  !
    video/x-raw,format=YUY2,width=640,height=480,framerate=30/1 !
    glupload !
    glfilterbin filter=glcolorscale !
    video/x-raw,format=RGBA,width=300,height=300 !
    videoconvert !
    video/x-raw,format=RGB,width=300,height=300 !
    videobox autocrop=True !
    video/x-raw,width=300,height=300 !
    appsink name=appsink emit-signals=true max-buffers=1 drop=True sync=False

When I use this in my (python-) app to process the input video the EOS
is reached almost immediately. If I run the exact same pipeline with
gst-launch-1.0 the pipeline is executed in the speed of the video input,
which is what I desire for my application as well. If I use the 
`gtksink` instead of the `appsink` the video is also displayed
correctly.

So why is this happening to me in the code, while gst-launch-1.0 process
it correctly?