How to encode a partial video by using "encodebin"?

[Victor]

Thanks, ShilVin.
> On which element did you try gst_element_seek_simple.
The entire pipeline. I didn't even know that it's allowed to seek in 
individual elements inside a pipeline.
> seek may not work on all the element. Most of the time seek is handled by
> demuxer.
Below is the pipeline description:

filesrc name=SRC         \
! decodebin name=DECODER \
DECODER.                 \
! video/x-raw            \
! timeoverlay            \
! ENCODER.video_0        \
DECODER.                 \
! audio/x-raw            \
! ENCODER.audio_0        \
encodebin name=ENCODER 
profile=video/x-matroska:video/x-theora:audio/x-vorbis \
! filesink name=DST

I just tried calling gst_eleemnt_seek_simple on the encoder, but it 
still doesn't work.
Below is the link to the image converted from the .dot file that was 
created when the pipeline is in playing state.
https://imgur.com/TVCdcSK

Regards,
Victor