A few simple questions about transform plugin.

[Vadim Shmelev]

Good day everyone,

I'm trying to learn how to implement a gstreamer plugin. The first step: 
I downloaded gsttransform template, compiled it and launched with the 
following command:
gst-launch-1.0 videotestsrc ! mytransform ! autovideosink.
Everything works fine, I see video.

But I need the copy transformation, so I defined the transform function:
static GstFlowReturn gst_my_transform_transform(GstBaseTransform * base, 
GstBuffer *inbuf, GstBuffer *outbuf).
The implementation is simple:
......
outbuf = gst_buffer_copy_deep(inbuf);
....

But there is a problem, now i see a broken image. Can you tell me, what 
I did wrong?

The next question is about caps. I'm going to use application/x-rtp 
buffers as an input data. Do I need to set caps for them, or will ANY be 
sufficient?

My final goal is to write a plugin that sets rtp extension headers (NTP 
time). I plan to write a transform plugin that will be placed after pay 
elements (rtph264pay etc) and will set the headers. Are there any 
examples of such transformation?

Best regards,
Vadim