GStreamer memory leak issue - c++

Question

I have an object to generate videos with GStreamer. Each time I want to generate a new video y create one new object and add frames. After video is finished, I delete the object but GStreamer internal memory looks like is not released.
After several videos generated all RAM is allocated and linux kills the process.
Why is this happening? How can I solve this issue? Is there any other way to do it?
GVideo.h:
#ifndef GVIDEO_H
#define GVIDEO_H
#include <gst/gst.h>
#include <string>
class GVideo
{
public:
GVideo();
~GVideo();
void startVideo(std::string filename);
void endVideo();
void addFrame(GstSample* element);
bool isRecording(){return _isRecording;}
bool isDataNeed(){return _dataNeed;}
private:
void setDataNeed(bool dataNeed){_dataNeed = dataNeed;}
protected:
bool _isRecording;
bool _dataNeed;
int _frameRate;
int _duration;
GstClockTime _timestamp;
GstElement *_pipeline;
GstElement *_source;
};
#endif //GVIDEO_H
GVideo.cpp
#include "GVideo.h"
#include <gst/app/gstappsrc.h>
#include <iostream>
static gboolean bus_video_call(GstBus* bus, GstMessage* msg, void* user_data)
{
//std::cout << "BUS_CALL" << std::endl;
GVideo* video = (GVideo*)user_data;
switch (GST_MESSAGE_TYPE(msg))
{
case GST_MESSAGE_EOS:
{
std::cout << "VIDEO GST_MESSAGE_EOS" << std::endl;
video->endVideo();
break;
}
case GST_MESSAGE_ERROR:
{
std::cout << "GST_MESSAGE_ERROR" << std::endl;
GError *err;
gst_message_parse_error(msg, &err, NULL);
g_error("%s", err->message);
g_error_free(err);
video->endVideo();
break;
}
default:
break;
}
return true;
}
GVideo::GVideo()
: _dataNeed(false), _isRecording(false)
{
_pipeline = NULL;
_source = NULL;
}
GVideo::~GVideo()
{
std::cout << "Deleting GstVideo." << std::endl;
if(_pipeline != NULL)
endVideo();
}
void GVideo::startVideo(std::string filename)
{
_isRecording = true;
_frameRate = 2;
_duration = 5;
_timestamp = 0;
_dataNeed = true;
_pipeline = gst_pipeline_new ("video_pipeline");
_source = gst_element_factory_make ("appsrc" , "video_source");
GstElement* _videorate = gst_element_factory_make ("videorate" , "video_vidrate");
GstElement* _capsfilter = gst_element_factory_make ("capsfilter" , "video_capsfilter");
GstElement* _videoconvert = gst_element_factory_make ("videoconvert", "video_conv");
GstElement* _encoder = gst_element_factory_make ("x264enc" , "video_enc");
GstElement* _muxer = gst_element_factory_make ("mp4mux" , "video_mux");
GstElement* _filesink = gst_element_factory_make ("filesink" , "video_filesink");
// g_object_set (G_OBJECT (_source), "num-buffers", _duration*_frameRate, NULL);
g_object_set (G_OBJECT (_source), "caps",
gst_caps_new_simple ( "video/x-raw",
"format", G_TYPE_STRING, "I420",
"width", G_TYPE_INT, 352,
"height", G_TYPE_INT, 288,
"framerate", GST_TYPE_FRACTION, _frameRate, 1,
NULL), NULL);
/* setup appsrc */
g_object_set (G_OBJECT (_source),
// "do-timestamp", TRUE,
"stream-type", GST_APP_STREAM_TYPE_STREAM,
"format", GST_FORMAT_TIME, NULL);
g_object_set (G_OBJECT (_capsfilter), "caps",
gst_caps_new_simple ("video/x-raw",
// "format", G_TYPE_STRING, "I420",
"framerate", GST_TYPE_FRACTION, 30, 1,
NULL), NULL);
gst_bin_add_many (GST_BIN (_pipeline), _source, _videorate, _capsfilter, _videoconvert, _encoder, _muxer, _filesink, NULL);
gst_element_link_many (_source, _videorate, _capsfilter, _videoconvert, _encoder, _muxer, _filesink, NULL);
g_object_set (G_OBJECT (_filesink), "location", filename.c_str(), NULL);
GstBus* bus = gst_pipeline_get_bus(GST_PIPELINE(_pipeline));
gst_bus_add_watch(bus, bus_video_call, this);
gst_object_unref(bus);
gst_element_set_state (_pipeline, GST_STATE_PLAYING);
}
void GVideo::addFrame(GstSample* element)
{
GstBuffer* buf = gst_sample_get_buffer((GstSample*)element);
GST_BUFFER_PTS (buf) = _timestamp;
GST_BUFFER_DURATION (buf) = gst_util_uint64_scale_int (1, GST_SECOND, _frameRate);
_timestamp += GST_BUFFER_DURATION (buf);
gst_app_src_push_sample(GST_APP_SRC(_source), element);
if(_timestamp >= _duration*GST_SECOND)
{
_dataNeed = false;
gst_app_src_end_of_stream(GST_APP_SRC(_source));
}
}
void GVideo::endVideo()
{
std::cout << "gst_element_set_state." << std::endl;
gst_element_set_state (_pipeline, GST_STATE_NULL);
std::cout << "gst_object_unref." << std::endl;
gst_object_unref(_pipeline);
std::cout << "_pipeline= NULL." << std::endl;
_pipeline = NULL;
std::cout << "setDataNeed." << std::endl;
_isRecording = false;
}

Answer 1

I would guess that whatever is calling addFrame() might need to unref the sample.
https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-appsrc.html#gst-app-src-push-sample
In the docs there it indicates "transfer: none" on the sample parameter, which I believe means the caller needs to unref. For some reason the older method gst_app_src_push_buffer has transfer "full". Dunno why.
https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-appsrc.html#gst-app-src-push-buffer