Dynamic cropping by nvvideoconvert

Accelerated Computing Intelligent Video Analytics DeepStream SDK
1

• Hardware Platform (Jetson / GPU) GPU
• DeepStream Version 5.0.1

Hi, my pipeline need dynamic crop size before nvstreammux.
However, sometimes it not work. Any advices? Thanks very much!

my code’s here:
GstPad* conv_src_pad = gst_element_get_static_pad(crop_conv, “src”);
gst_pad_add_probe(conv_src_pad, GST_PAD_PROBE_TYPE_IDLE, vidconv_src_pad_idle_probe, usrdata, NULL);
gst_object_unref(conv_src_pad);

in vidconv_src_pad_idle_probe
gchar src_crop[32] = { };
g_snprintf(src_crop, 31, “%u:%u:%u:%u”, x, y, w, h);
GstPad* conv_src_pad = gst_element_get_static_pad(crop_conv, “src”);
GstPad* queue_sink_pad = gst_element_get_static_pad(src_queue, “sink”);
if (!gst_pad_unlink(conv_src_pad, queue_sink_pad))
{
NVGSTDS_ERR_MSG_V(“Failed to unlink pad ‘%s’”, elem_name);
}
gst_element_set_state(crop_conv, GST_STATE_READY);
g_object_set(G_OBJECT(crop_conv), “src-crop”, src_crop, NULL);
if (gst_pad_link(conv_src_pad, queue_sink_pad) != GST_PAD_LINK_OK)
{
NVGSTDS_ERR_MSG_V(“Failed to link pad ‘%s’”, elem_name);
}
gst_element_set_state(crop_conv, GST_STATE_PLAYING);
gst_pad_add_probe(queue_sink_pad, GST_PAD_PROBE_TYPE_EVENT_DOWNSTREAM, consume_eos_prop, NULL, NULL);

3

What will happen if you set property directly without unlinking/linking the pad and changing the element state?

4

Hi, Fiona.Chen
The property src-crop would not take effects!

5

By gst-inspect-1.0 nvvideoconvert

It shows src-crop could only been changed when element state at GST_STATE_READY or NULL

6

For change state, it is better to set state first and then check the state of the return value to decide whether it is the right state to unlink pad.

7

However, there’s no return value for set state, and the value can be set, but the frame was not cropped. no effects applied.

8

gst_element_get_state can be used to confirm that the state change has finished.
https://gstreamer.freedesktop.org/documentation/gstreamer/gstelement.html?gi-language=c#gst_element_get_state