Using BaseTransform class

[vaishnavi]

Hi,
I'm using BaseTransform as parent class. I'm using transform_ip to communicate with the driver.
The incoming buffer will be passed to driver and read back from driver the processed data into the same buffer.
The issue is that it is the buffer contents coming from driver is not pushed out.
The contents to be wriiten and read out of driver is verified using print statements..driver works fine..but somehow the data read from driver is not getting pushed.
I have include the code i have used for transform_ip and prepare_output_buffer
Can you tel me why the contents are not getting changed.

static GstFlowReturn
gst_dummy_prepare_output_buffer (GstBaseTransform * trans,
    GstBuffer * in_buf, gint out_size, GstCaps * out_caps, GstBuffer ** out_buf)
{
  GstDummy *dummy = GST_DUMMY (trans);
    *out_buf = gst_buffer_ref (in_buf);
     *out_buf=gst_buffer_copy(dummy->cpybuf);

  return GST_FLOW_OK;
}


static GstFlowReturn
gst_dummy_transform_ip (GstBaseTransform * trans, GstBuffer * buf)
{
  GstFlowReturn ret = GST_FLOW_OK;
  guint size =1024;
   gint n,x;

  GstDummy *dummy = GST_DUMMY (trans);
g_print("pf_handle_ip%d\n",dummy->pf_handle);
g_print("the first few bytes of buffer%d\t%d\t%d\t",buf->data[0],buf->data[1],buf->data[2]);
  GstClockTime runtimestamp = G_GINT64_CONSTANT (0);

g_print("size before allocation%d\n",GST_BUFFER_SIZE(buf));


 dummy->cpybuf=gst_buffer_copy(buf);
g_print("the first few bytes of cpy buffer%d\t%d\t%d\t",dummy->cpybuf->data[0],dummy->cpybuf->data[1],dummy->cpybuf->data[2]);
  n=write(dummy->pf_handle,GST_BUFFER_DATA(dummy->cpybuf),size);
  if(n<0)
{
g_print("could not write; the contents of cpybuf %d and n is %d\n,GST_BUFFER_DATA(cpybuf),n");
}
x=read(dummy->pf_handle,GST_BUFFER_DATA(dummy->cpybuf),n);
g_print("the first few bytes of buffer after read%d\t%d\t%d\t",dummy->cpybuf->data[0],dummy->cpybuf->data[1],dummy->cpybuf->data[2]);

if(x<0)
{
g_print("could not read\n");
}


if (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_TIMESTAMP (buf)))
    gst_object_sync_values (G_OBJECT (dummy), GST_BUFFER_TIMESTAMP (buf));

  if (dummy->silent == FALSE)
    g_print ("I'm plugged, therefore I'm in Dummy TC.\n");
buf=gst_buffer_copy(dummy->cpybuf);
g_print("the first few bytes of buffer befor return%d\t%d\t%d\t",buf->data[0],buf->data[1],buf->data[2]);

  return ret;
}