Q on gst_buffer_relace()

[Makoto Harada]

Dear experts,

I'm now working on our custom h264 decoder, and have a couple of questions
regarding the usage of gst_buffer_replace().

First of all, please take a look at the pseudo code below.
What I would like to do is to replace the contents of frame->input_buffer with
my_buffer in special case, otherwise just handling the incoming frame from up 
stream.
I thought this can be possible via gst_buffer_replace().

     my_hundle_frame(GstVideoDecoder * dec, GstVideoCodecFrame * frame)
     {

         if(special_case)
         {
             /* replace input_buffer with buffer_new */
             GstBuffer *my_buffer;
             my_buffer = gst_buffer_new_allocate (NULL, my_size, NULL);
             do_something(my_buffer);
             gst_buffer_replace(&frame->input_buffer, my_buffer);
             gst_buffer_unref(my_buffer); //(*1): Do we need to unref my_buffer ?
         }

         do_h264_decode(frame);
         gst_video_decoder_finish_frame (my_decoder, frame);
     }

When checking the usage of gst_buffer_replace() below, reference count of old 
buffer(frame->input_buffer)
will be decremented, and new buffer (my_buffer) will be incremented by calling 
gst_buffer_replace().
https://developer.gnome.org/gstreamer/stable/gstreamer-GstBuffer.html#gst-buffer-replace

Questions:
     Q1. Do we need to call gst_buffer_unref() at (*1) or not ?

         I thought that it's required since gst_buffer_replace() will increment 
it by one.
         But, when checking the code of official plugins (good, bad, etc..), 
they are not
         consistent. so, I'm a little bit confused. Any comment please ?

         # Case1: do gst_buffer_unref
http://cgit.freedesktop.org/gstreamer/gst-plugins-bad/tree/gst/videoparsers/gsth264parse.c?id=c203fd52e8cbbf7d1c71b4497750f59525c74c22#n721

         # Case2: not do gst_buffer_unref
http://cgit.freedesktop.org/gstreamer/gst-plugins-good/tree/gst/avi/gstavidemux.c?h=1.4#n1913

     Q2. When checking ref count just before and after gst_buffer_replace() by 
using some printing function,
         ref count of new buffer was incremented and the one of old buffer did 
not change at all.
         I can not understand why ref count of old buffer is not changed. Is 
there any special case ?

     Q3. How do I take care of the old buffer in terms of ref count after 
calling gst_buffer_replace()?
         Does gstreamer take care of them automatically, or do I have to do 
something ?

Really appreciated any feedback.

Kind Regards,
Makoto Harada