Not able to resume data flow in pipeline after valve plugin is set to False in a timer call back

Issue: I have modified the C sample app inside deepstream sdk 5.1 to add a Valve plugin in the pipeline. My target is to have the frames inferred by nvinfer plugin once for every 5 sec remaining time i want the frames to be dropped. I added a timer callback for this purpose.

When the timer call back triggers for the first time, the gobject of valve drop is set to true and hence the inference stops in the pipeline. the second time the call back triggers and when i set the valve drop to false still the frames are frozen. I could not get the pipeline to resume from the current time.

Help me resolve this issue. I have the code attached below.

Hardware platform : X86_64
Deepstream version: 5.1 (devel container from NGC)
Nvidia GPU - RTX 3060

#include <gst/gst.h>
#include <glib.h>
#include <stdio.h>
#include "gstnvdsmeta.h"

#define MAX_DISPLAY_LEN 64


/* The muxer output resolution must be set if the input streams will be of
 * different resolution. The muxer will scale all the input frames to this
 * resolution. */

/* Muxer batch formation timeout, for e.g. 40 millisec. Should ideally be set
 * based on the fastest source's framerate. */


gint flag =0;
gint frame_number = 0;
gchar pgie_classes_str[4][32] = { "Vehicle", "TwoWheeler", "Person",

GMainLoop *loop = NULL;
GstElement *pipeline = NULL, *source = NULL, *h264parser = NULL,
    *decoder = NULL, *streammux = NULL, *sink = NULL, *pgie = NULL, *nvvidconv = NULL, *val = NULL,
    *nvosd = NULL;

/* osd_sink_pad_buffer_probe  will extract metadata received on OSD sink pad
 * and update params for drawing rectangle, object information etc. */

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;
    guint vehicle_count = 0;
    guint person_count = 0;
    NvDsMetaList * l_frame = NULL;
    NvDsMetaList * l_obj = NULL;
    NvDsDisplayMeta *display_meta = NULL;

    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) {
        NvDsFrameMeta *frame_meta = (NvDsFrameMeta *) (l_frame->data);
        int offset = 0;
        for (l_obj = frame_meta->obj_meta_list; l_obj != NULL;
                l_obj = l_obj->next) {
            obj_meta = (NvDsObjectMeta *) (l_obj->data);
            if (obj_meta->class_id == PGIE_CLASS_ID_VEHICLE) {
            if (obj_meta->class_id == PGIE_CLASS_ID_PERSON) {
        display_meta = nvds_acquire_display_meta_from_pool(batch_meta);
        NvOSD_TextParams *txt_params  = &display_meta->text_params[0];
        display_meta->num_labels = 1;
        txt_params->display_text = g_malloc0 (MAX_DISPLAY_LEN);
        offset = snprintf(txt_params->display_text, MAX_DISPLAY_LEN, "Person = %d ", person_count);
        offset = snprintf(txt_params->display_text + offset , MAX_DISPLAY_LEN, "Vehicle = %d ", vehicle_count);

        /* Now set the offsets where the string should appear */
        txt_params->x_offset = 10;
        txt_params->y_offset = 12;

        /* Font , font-color and font-size */
        txt_params->font_params.font_name = "Serif";
        txt_params->font_params.font_size = 10;
        txt_params-> = 1.0;
        txt_params-> = 1.0;
        txt_params-> = 1.0;
        txt_params->font_params.font_color.alpha = 1.0;

        /* Text background color */
        txt_params->set_bg_clr = 1;
        txt_params-> = 0.0;
        txt_params-> = 0.0;
        txt_params-> = 0.0;
        txt_params->text_bg_clr.alpha = 1.0;

        nvds_add_display_meta_to_frame(frame_meta, display_meta);

    g_print ("Frame Number = %d Number of objects = %d "
            "Vehicle Count = %d Person Count = %d\n",
            frame_number, num_rects, vehicle_count, person_count);
    // if(frame_number>100 && frame_number<200)
    // {
    //     g_object_set(val,"drop",true,nullptr);
    // }
    // else
    // {
    //     g_object_set(val,"drop",false,nullptr);
    // }

    return GST_PAD_PROBE_OK;
static gboolean
timeout_cb ()
      if(flag ==0)
        g_print("Valve closed");
        g_print("Valve Open");
//        gst_element_set_state (pipeline, GST_STATE_PLAYING);
  //      g_main_loop_run(loop);

    return TRUE;


static gboolean
bus_call (GstBus * bus, GstMessage * msg, gpointer data)
  GMainLoop *loop = (GMainLoop *) data;
  switch (GST_MESSAGE_TYPE (msg)) {
      g_print ("End of stream\n");
      g_main_loop_quit (loop);
      gchar *debug;
      GError *error;
      gst_message_parse_error (msg, &error, &debug);
      g_printerr ("ERROR from element %s: %s\n",
          GST_OBJECT_NAME (msg->src), error->message);
      if (debug)
        g_printerr ("Error details: %s\n", debug);
      g_free (debug);
      g_error_free (error);
      g_main_loop_quit (loop);
  return TRUE;

main (int argc, char *argv[])

  GstElement *transform = NULL;
  GstBus *bus = NULL;
  guint bus_watch_id;
  GstPad *osd_sink_pad = NULL;

  /* Check input arguments */
  if (argc != 2) {
    g_printerr ("Usage: %s <H264 filename>\n", argv[0]);
    return -1;

  /* Standard GStreamer initialization */
  gst_init (&argc, &argv);
  loop = g_main_loop_new (NULL, FALSE);

  /* Create gstreamer elements */
  /* Create Pipeline element that will form a connection of other elements */
  pipeline = gst_pipeline_new ("dstest1-pipeline");

  /* Source element for reading from the file */
  source = gst_element_factory_make ("filesrc", "file-source");

  /* Since the data format in the input file is elementary h264 stream,
   * we need a h264parser */
  h264parser = gst_element_factory_make ("h264parse", "h264-parser");

  /* Use nvdec_h264 for hardware accelerated decode on GPU */
  decoder = gst_element_factory_make ("nvv4l2decoder", "nvv4l2-decoder");

  /* Create nvstreammux instance to form batches from one or more sources. */
  streammux = gst_element_factory_make ("nvstreammux", "stream-muxer");

  val = gst_element_factory_make("valve", NULL);


  if (!pipeline || !streammux) {
    g_printerr ("One element could not be created. Exiting.\n");
    return -1;

  /* Use nvinfer to run inferencing on decoder's output,
   * behaviour of inferencing is set through config file */
  pgie = gst_element_factory_make ("nvinfer", "primary-nvinference-engine");

  /* Use convertor to convert from NV12 to RGBA as required by nvosd */
  nvvidconv = gst_element_factory_make ("nvvideoconvert", "nvvideo-converter");

  /* Create OSD to draw on the converted RGBA buffer */
  nvosd = gst_element_factory_make ("nvdsosd", "nv-onscreendisplay");

  /* Finally render the osd output */
  transform = gst_element_factory_make ("nvegltransform", "nvegl-transform");
  sink = gst_element_factory_make ("nveglglessink", "nvvideo-renderer");

  if (!source || !h264parser || !decoder || !pgie || !val
      || !nvvidconv || !nvosd || !sink) {
    g_printerr ("One element could not be created. Exiting.\n");
    return -1;

  if(!transform) {
    g_printerr ("One tegra element could not be created. Exiting.\n");
    return -1;

  /* we set the input filename to the source element */
  g_object_set (G_OBJECT (source), "location", argv[1], NULL);

  g_object_set (G_OBJECT (streammux), "width", MUXER_OUTPUT_WIDTH, "height",
      MUXER_OUTPUT_HEIGHT, "batch-size", 1,
      "batched-push-timeout", MUXER_BATCH_TIMEOUT_USEC, NULL);

  /* Set all the necessary properties of the nvinfer element,
   * the necessary ones are : */
  g_object_set (G_OBJECT (pgie),
      "config-file-path", "dstest1_pgie_config.txt", NULL);

  /* we add a message handler */
  bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
  bus_watch_id = gst_bus_add_watch (bus, bus_call, loop);
  gst_object_unref (bus);

  /* Set up the pipeline */
  /* we add all elements into the pipeline */
  gst_bin_add_many (GST_BIN (pipeline),
      source, h264parser, decoder, streammux, pgie,
      nvvidconv, nvosd, transform, sink, NULL);
  gst_bin_add_many (GST_BIN (pipeline),
      source, h264parser, decoder, streammux, pgie, val,
      nvvidconv, nvosd, sink, NULL);

  GstPad *sinkpad, *srcpad;
  gchar pad_name_sink[16] = "sink_0";
  gchar pad_name_src[16] = "src";

  sinkpad = gst_element_get_request_pad (streammux, pad_name_sink);
  if (!sinkpad) {
    g_printerr ("Streammux request sink pad failed. Exiting.\n");
    return -1;

  srcpad = gst_element_get_static_pad (decoder, pad_name_src);
  if (!srcpad) {
    g_printerr ("Decoder request src pad failed. Exiting.\n");
    return -1;

  if (gst_pad_link (srcpad, sinkpad) != GST_PAD_LINK_OK) {
      g_printerr ("Failed to link decoder to stream muxer. Exiting.\n");
      return -1;

  gst_object_unref (sinkpad);
  gst_object_unref (srcpad);

  /* we link the elements together */
  /* file-source -> h264-parser -> nvh264-decoder ->
   * nvinfer -> nvvidconv -> nvosd -> video-renderer */

  if (!gst_element_link_many (source, h264parser, val, decoder, NULL)) {
    g_printerr ("Elements could not be linked: 1. Exiting.\n");
    return -1;

  if (!gst_element_link_many (streammux, pgie,
      nvvidconv, nvosd, transform, sink, NULL)) {
    g_printerr ("Elements could not be linked: 2. Exiting.\n");
    return -1;
  if (!gst_element_link_many (streammux, pgie,
      nvvidconv, nvosd, sink, NULL)) {
    g_printerr ("Elements could not be linked: 2. Exiting.\n");
    return -1;

  /* Lets add probe to get informed of the meta data generated, we add probe to
   * the sink pad of the osd element, since by that time, the buffer would have
   * had got all the metadata. */
  osd_sink_pad = gst_element_get_static_pad (nvosd, "sink");
  if (!osd_sink_pad)
    g_print ("Unable to get sink pad\n");
    gst_pad_add_probe (osd_sink_pad, GST_PAD_PROBE_TYPE_BUFFER,
        osd_sink_pad_buffer_probe, NULL, NULL);

  g_timeout_add_seconds (5, timeout_cb, loop);

  /* Set the pipeline to "playing" state */
  g_print ("Now playing: %s\n", argv[1]);
  gst_element_set_state (pipeline, GST_STATE_PLAYING);

  /* Wait till pipeline encounters an error or EOS */
  g_print ("Running...\n");
  g_main_loop_run (loop);

  /* Out of the main loop, clean up nicely */
  g_print ("Returned, stopping playback\n");
  gst_element_set_state (pipeline, GST_STATE_NULL);
  g_print ("Deleting pipeline\n");
  gst_object_unref (GST_OBJECT (pipeline));
  g_source_remove (bus_watch_id);
  g_main_loop_unref (loop);
  return 0;

Please provide complete information as applicable to your setup.

• TensorRT Version
• NVIDIA GPU Driver Version (valid for GPU only)

@kayccc - My TensorRT version is 7.2.2-1 + Cuda 11.1

Nvidia GPU driver version: 470.57.02

Please let me know if any other details are required

@Morganh Hi Morganh, Can you help me resolve this issue.

Did this still be an issue?

Code is correct but that code should work with LIVE sources only because with file source buffers will be dropped immediately as pipeline will be faster than realtime. you can achieve what is needed by setting “interval” property on nvinfer component then file source can be used.

@Amycao Thanks for the reply, I now understand why it will not work for the file source but you mentioned that setting the “interval” property will work for file source, the documentation says it will skip the no. of batches/ frames as per the “interval” property, I need time based inference. Start and stop inference every 5 sec.

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