could not link vtdec0 to videobox0

[Who AmI]

Dear all,

I am trying to implement Picture In Picture feature in iPAD using GStreamer.

As a first step, i tried to understand videobox, and executed the below
command
in the command line in MAC.

./gst-launch-1.0 udpsrc port=5000 ! "application/x-rtp,
encoding-name=(string)H264, payload=(int)96, clock-rate=(int)90000" !
rtph264depay ! h264parse ! vtdec   ! videobox top=-10  bottom=-20 !
glimagesink sync=false

The below command works fine.

The same think i tried using GStreamer SDK.


   pipeline = gst_parse_launch("udpsrc port=5000 ! application/x-rtp,
encoding-name=(string)H264, payload=(int)96, clock-rate=(int)90000 !
rtph264depay ! h264parse ! vtdec   ! videobox top=-10  bottom=-20 !
glimagesink sync=false", &error);



Unfortunately i receive the below error:

could not link vtdec0 to videobox0


That is:

*0:00:01.127516000  2660  0x3132860 ERROR           GST_PIPELINE
./grammar.y:616:gint gst_parse_perform_link(link_t *, graph_t *): could not
link vtdec0 to videobox0*

following that,

udpsrc0: Internal data flow error .

Please let me know what is the issue ?
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