[gst-devel] Buffer size mismatch in custom plugin

[AlannY]

Hi there, my name is Alan and I have a problems with GStreamer.

I'm writing a custom video filter (as a custom plugin) (still newbie). 
So, in the _chain() function I checked buffer (GstBuffer) size:

(example)
static GstFlowReturn
gst_myfilter_chain (GstPad *pad,
                     GstBuffer *buf)
{
   g_print("%d\n", buf->size);
   g_print("%d\n", width*height*3);

   return gst_pad_push (filter->srcpad, buf);
}

I got the following messages:
153600
230400

As you can see buf->size is smaller then frame size ( width*height*3 ). 
Why? How can I write something in buffer if it's smaller then I 
expected. I got Segmentation fault when trying to do it.

Thank you for your patient.