Display polygon on every frame using osd_sink_pad_buffer_probe

Accelerated Computing Intelligent Video Analytics DeepStream SDK
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1

Please provide complete information as applicable to your setup.

**• Hardware Platform (Jetson / GPU)**Orin
• DeepStream Version7.1
**• JetPack Version (valid for Jetson only)**6.1
The following code displays only one line on the first image.
I have four sources in display screen like

tiled-display:
  enable: 1
  rows: 2
  columns: 2
  width: 1280
  height: 720
  gpu-id: 0
  #(0): nvbuf-mem-default - Default memory allocated, specific to particular platform
  #(1): nvbuf-mem-cuda-pinned - Allocate Pinned/Host cuda memory, applicable for Tesla
  #(2): nvbuf-mem-cuda-device - Allocate Device cuda memory, applicable for Tesla
  #(3): nvbuf-mem-cuda-unified - Allocate Unified cuda memory, applicable for Tesla
  #(4): nvbuf-mem-surface-array - Allocate Surface Array memory, applicable for Jetson
  nvbuf-memory-type: 0

But the polygon is displayed on the first image.
How can I make polygon is drawn on all images?

static GstPadProbeReturn
osd_sink_pad_buffer_probe(GstPad *pad, GstPadProbeInfo *info,
                          gpointer u_data)
{
  GstBuffer *buf = (GstBuffer *)info->data;
  guint num_rects = 0;
  NvDsObjectMeta *obj_meta = NULL;
  NvDsMetaList *l_frame = NULL;
  NvDsMetaList *l_obj = NULL;
  NvDsDisplayMeta *display_meta = NULL;
  gboolean is_first_object = TRUE;
  NvDsBatchMeta *batch_meta = gst_buffer_get_nvds_batch_meta(buf);

  for (l_frame = batch_meta->frame_meta_list; l_frame != NULL;
       l_frame = l_frame->next)
  {
    is_first_object = TRUE;
    NvDsFrameMeta *frame_meta = (NvDsFrameMeta *)(l_frame->data);    
    display_meta = nvds_acquire_display_meta_from_pool(batch_meta);
    int p_cnt = 0;
    int start_x = 50;
    int start_y = 50;
    for(int p=0; p < 20; p++){
      NvOSD_LineParams *line_params = &display_meta->line_params[p];
      if(p == 0){
         line_params->x1 = start_x;
         line_params->y1 = start_y;
      }else{
         start_x+=10;
         start_y+=10;
         line_params->x1 = start_x;
         line_params->y1 = start_x;
      }
      line_params->x2 = start_x+10;
      line_params->y2 = start_y+10;
      line_params->line_width = 2;
      line_params->line_color.red = 0.0;
      line_params->line_color.green = 0.0;
      line_params->line_color.blue = 1.0;
      line_params->line_color.alpha = 1.0;
      p_cnt++;
    }
    display_meta->num_lines = p_cnt;
    nvds_add_display_meta_to_frame(frame_meta, display_meta);
    
  }
  frame_number++;
  return GST_PAD_PROBE_OK;
}
3

Could you attach your whole pipeline? And where did you add the probe function?

4

This is the whole code inside osd_sink_pad_buffer_probe
I am using deepstream-parallel-infer app. osd_sink_pad_buffer_probe is in the deepstream_parallel_infer_app.cpp

static GstPadProbeReturn
osd_sink_pad_buffer_probe(GstPad *pad, GstPadProbeInfo *info,
                          gpointer u_data)
{
  GstBuffer *buf = (GstBuffer *)info->data;
  guint num_rects = 0;
  NvDsObjectMeta *obj_meta = NULL;
  NvDsMetaList *l_frame = NULL;
  NvDsMetaList *l_obj = NULL;
  NvDsDisplayMeta *display_meta = NULL;
  gboolean is_first_object = TRUE;
  NvDsBatchMeta *batch_meta = gst_buffer_get_nvds_batch_meta(buf);

  for (l_frame = batch_meta->frame_meta_list; l_frame != NULL;
       l_frame = l_frame->next)
  {
    is_first_object = TRUE;
    NvDsFrameMeta *frame_meta = (NvDsFrameMeta *)(l_frame->data);    
    display_meta = nvds_acquire_display_meta_from_pool(batch_meta);
    int p_cnt = 0;
    int start_x = 50;
    int start_y = 50;
    for(int p=0; p < 20; p++){
      NvOSD_LineParams *line_params = &display_meta->line_params[p];
      if(p == 0){
         line_params->x1 = start_x;
         line_params->y1 = start_y;
      }else{
         start_x+=10;
         start_y+=10;
         line_params->x1 = start_x;
         line_params->y1 = start_x;
      }
      line_params->x2 = start_x+10;
      line_params->y2 = start_y+10;
      line_params->line_width = 2;
      line_params->line_color.red = 0.0;
      line_params->line_color.green = 0.0;
      line_params->line_color.blue = 1.0;
      line_params->line_color.alpha = 1.0;
      p_cnt++;
    }
    display_meta->num_lines = p_cnt;
    nvds_add_display_meta_to_frame(frame_meta, display_meta);
    
  }
  frame_number++;
  return GST_PAD_PROBE_OK;
}
5

OK. You sould add the probe to the sink pad of the tiler plugin instead of the nvsdosd. Because after the tiler plugin, there’s only one video in the batch.

6

Thanks. Which cpp sample I should follow for attaching probe to tiler sink pad?

7

You can just modify the code below from nvdsosd plugin to tiler plugin.

gst_element_get_static_pad(<tiler_plugin>, "sink");

deepstream_parallel_infer_app.cpp

8

Thanks it works now.

9

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