Passing extra data from an element to C program.

[rary]

Hi
I want to pass metadata (computed for each frame) from an element to C
program.
The metadata is something like histogram, so I need to know relation between
metadata and frames.

The pipeline is like this.
v4l2src -> myhistogram -> bayer2rgb -> appsink
I want to compute on Bayer image.

I've came up some solutions.
1. use signals
  1.1. g_signal_connect() to register callback function.
  1.2. g_signal_emit_by_name () to get metadata.
2. use tee and compute in C program.
v4l2src -> tee -> bayer2rgb -> appsink
                       -> appsink  (for computation)
 
I could not find any examples which uses gst_buffer_add_meta() in element
and gst_buffer_get_meta () in C.
Is this possible?

I would like to ask if someone know better way.
Thank you.




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