gst, queue插件sinkpad buffer探针附加字符串, queue插件srcpad buffer探针获取它, c实现完整列子, 仔细想想

可以使用以下代码实现：

#include <gst/gst.h>

static GstPadProbeReturn
sink_probe_cb (GstPad * pad, GstPadProbeInfo * info, gpointer user_data)
{
  gchar *str = (gchar *) user_data;
  GstBuffer *buf = GST_PAD_PROBE_INFO_BUFFER (info);

  g_print ("%s: Received buffer of size %u\n", str, gst_buffer_get_size (buf));

  return GST_PAD_PROBE_OK;
}

static GstPadProbeReturn
src_probe_cb (GstPad * pad, GstPadProbeInfo * info, gpointer user_data)
{
  gchar *str = (gchar *) user_data;
  GstBuffer *buf = GST_PAD_PROBE_INFO_BUFFER (info);

  g_print ("%s: Received buffer of size %u\n", str, gst_buffer_get_size (buf));

  return GST_PAD_PROBE_OK;
}

int
main (int argc, char *argv[])
{
  GstElement *pipeline, *src, *queue, *sink;
  GstPad *srcpad, *sinkpad;
  GstBus *bus;
  GstMessage *msg;
  GMainLoop *loop;
  gchar *str = "Custom string";

  /* Initialize GStreamer */
  gst_init (&argc, &argv);

  /* Create the elements */
  src = gst_element_factory_make ("videotestsrc", "src");
  queue = gst_element_factory_make ("queue", "queue");
  sink = gst_element_factory_make ("fakesink", "sink");

  /* Create the pipeline */
  pipeline = gst_pipeline_new ("test-pipeline");

  /* Add the elements to the pipeline */
  gst_bin_add_many (GST_BIN (pipeline), src, queue, sink, NULL);

  /* Link the elements together */
  gst_element_link_many (src, queue, sink, NULL);

  /* Get the pads */
  srcpad = gst_element_get_static_pad (src, "src");
  sinkpad = gst_element_get_static_pad (sink, "sink");

  /* Add the probes */
  gst_pad_add_probe (sinkpad, GST_PAD_PROBE_TYPE_BUFFER, sink_probe_cb, str, NULL);
  gst_pad_add_probe (srcpad, GST_PAD_PROBE_TYPE_BUFFER, src_probe_cb, str, NULL);

  /* Start playing */
  gst_element_set_state (pipeline, GST_STATE_PLAYING);

  /* Wait until error or EOS */
  loop = g_main_loop_new (NULL, FALSE);
  bus = gst_element_get_bus (pipeline);
  msg = gst_bus_timed_pop_filtered (bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_ERROR | GST_MESSAGE_EOS);

  /* Free resources */
  if (msg != NULL)
    gst_message_unref (msg);
  gst_object_unref (bus);
  gst_element_set_state (pipeline, GST_STATE_NULL);
  gst_object_unref (pipeline);

  return 0;
}

这段代码演示了如何使用 GStreamer 中的 queue 插件的 sinkpad 和 srcpad 的 buffer 探针。在这个例子中，我们使用了 videotestsrc 元素生成一个视频流，然后将其传递给 queue 元素，最后传递给 fakesink 元素。我们在 sinkpad 和 srcpad 上添加了 buffer 探针，以便在数据流经过这些 pad 时打印一条消息。