Conversion of cv::Mat to GstBuffer

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Conversion of cv::Mat to GstBuffer

Saurabh Bora
Hi Experts!!, 

I am trying to read opencv images locally and push them into gstreamer pipeline. I am using appsrc element with "need-data" signal attached to call-back function.
Please look at the code below. 

//------------------------------------------------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width* channels;

// Copy cv::Mat to GstBuffer
buffer = gst_buffer_new_allocate(NULL, size, NULL);
gst_buffer_map(buffer, &map, GST_MAP_WRITE);
memcpy((guchar *)map.data, data1, gst_buffer_get_size(buffer));

//Convert GstBuffer back to cv::Mat and write it, to check if data was correctly copied. //This is where I get to know that data is not correct.
cv::Mat img2(cv::Size(134, 134), CV_8UC3, (char*)(buffer));
cv::imwrite("C:/Users/212730892.LOGON/Desktop/dummy1.jpg", img2);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//-------------------------------------------------------------------------------------------------------------------------------------

In cb_need_data, the part where copying I am copying to GstBuffer seems to be wrong and it does not work as expected. 
Can anyone, please help me understand, how can I copy the image data perfectly and pass it downstream to other elements without losing any data?

--
Thanks and Regards,
Saurabh Bora

PH NO : 7038166900
             [hidden email]

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Re: Conversion of cv::Mat to GstBuffer

Michael Gruner
Hi Saurabh

Yo may convert from a cv::Mat to a GstBuffer without a memory copy by using gst_buffer_new_wrapped:


Something like: 
buffer = gst_buffer_new_wrapped (mat.data, mat.total()*mat.elemSize());

In order to make a cv::Mat from a GstBuffer you first need to take the data out of the buffer. 

GstMapInfo info;
gst_buffer_map (buffer, &info, GST_MAP_READ); // or write
mat = cv::Mat(height, width, CV_8C3, map.data); // change your format accordingly
...
gst_buffer_unmap (buffer, &info);

Hope it helps.

Michael

On Mar 13, 2019, at 7:15 AM, Saurabh Bora <[hidden email]> wrote:

Hi Experts!!, 

I am trying to read opencv images locally and push them into gstreamer pipeline. I am using appsrc element with "need-data" signal attached to call-back function.
Please look at the code below. 

//------------------------------------------------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width* channels;

// Copy cv::Mat to GstBuffer
buffer = gst_buffer_new_allocate(NULL, size, NULL);
gst_buffer_map(buffer, &map, GST_MAP_WRITE);
memcpy((guchar *)map.data, data1, gst_buffer_get_size(buffer));

//Convert GstBuffer back to cv::Mat and write it, to check if data was correctly copied. //This is where I get to know that data is not correct.
cv::Mat img2(cv::Size(134, 134), CV_8UC3, (char*)(buffer));
cv::imwrite("C:/Users/212730892.LOGON/Desktop/dummy1.jpg", img2);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//-------------------------------------------------------------------------------------------------------------------------------------

In cb_need_data, the part where copying I am copying to GstBuffer seems to be wrong and it does not work as expected. 
Can anyone, please help me understand, how can I copy the image data perfectly and pass it downstream to other elements without losing any data?

--
Thanks and Regards,
Saurabh Bora

PH NO : 7038166900
             [hidden email]
_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel

_______________________________________________
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[hidden email]
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Re: Conversion of cv::Mat to GstBuffer

Saurabh Bora
Hi Michael, 

Thanks! for your input. I tried what you suggested as below:

//---------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img2;
cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
cv::cvtColor(img, img2, cv::COLOR_BGR2RGB);

height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width * channels * sizeof(guchar);

std::cout << "cb_need_data called" << std::endl;

buffer = gst_buffer_new_wrapped(img2.data, img2.total() * img2.elemSize());

GstMapInfo info;
gst_buffer_map(buffer, &info, GST_MAP_READ);
cv::Mat mat(height, width, CV_8UC3, info.data);
cv::imshow("Output", mat);
//gst_buffer_unmap(buffer, &info);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//----------------------------------------------------------------------------------------------

It still does not work as expected. It would be a great help if you could point out where I am going wrong.
Thanks!!

On Wed, Mar 13, 2019 at 7:40 PM Michael Gruner <[hidden email]> wrote:
Hi Saurabh

Yo may convert from a cv::Mat to a GstBuffer without a memory copy by using gst_buffer_new_wrapped:


Something like: 
buffer = gst_buffer_new_wrapped (mat.data, mat.total()*mat.elemSize());

In order to make a cv::Mat from a GstBuffer you first need to take the data out of the buffer. 

GstMapInfo info;
gst_buffer_map (buffer, &info, GST_MAP_READ); // or write
mat = cv::Mat(height, width, CV_8C3, map.data); // change your format accordingly
...
gst_buffer_unmap (buffer, &info);

Hope it helps.

Michael

On Mar 13, 2019, at 7:15 AM, Saurabh Bora <[hidden email]> wrote:

Hi Experts!!, 

I am trying to read opencv images locally and push them into gstreamer pipeline. I am using appsrc element with "need-data" signal attached to call-back function.
Please look at the code below. 

//------------------------------------------------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width* channels;

// Copy cv::Mat to GstBuffer
buffer = gst_buffer_new_allocate(NULL, size, NULL);
gst_buffer_map(buffer, &map, GST_MAP_WRITE);
memcpy((guchar *)map.data, data1, gst_buffer_get_size(buffer));

//Convert GstBuffer back to cv::Mat and write it, to check if data was correctly copied. //This is where I get to know that data is not correct.
cv::Mat img2(cv::Size(134, 134), CV_8UC3, (char*)(buffer));
cv::imwrite("C:/Users/212730892.LOGON/Desktop/dummy1.jpg", img2);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//-------------------------------------------------------------------------------------------------------------------------------------

In cb_need_data, the part where copying I am copying to GstBuffer seems to be wrong and it does not work as expected. 
Can anyone, please help me understand, how can I copy the image data perfectly and pass it downstream to other elements without losing any data?

--
Thanks and Regards,
Saurabh Bora

PH NO : 7038166900
             [hidden email]
_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel


--
Thanks and Regards,
Saurabh Bora

PH NO : 7038166900
             [hidden email]

_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
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Re: Conversion of cv::Mat to GstBuffer

Michael Gruner
It looks like img2, being a local variable, ends  its life when “cb_need_data” ends. That leaves the pointer in “buffer” invalid. For this one you’re better off with the copy. 

Another option is to alloc img2 on the heap, and use gst_buffer_new_wrapped_full to carry img2 along with buffer and free then together.

Michael

On Mar 13, 2019, at 10:51 AM, Saurabh Bora <[hidden email]> wrote:

Hi Michael, 

Thanks! for your input. I tried what you suggested as below:

//---------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img2;
cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
cv::cvtColor(img, img2, cv::COLOR_BGR2RGB);

height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width * channels * sizeof(guchar);

std::cout << "cb_need_data called" << std::endl;

buffer = gst_buffer_new_wrapped(img2.data, img2.total() * img2.elemSize());

GstMapInfo info;
gst_buffer_map(buffer, &info, GST_MAP_READ);
cv::Mat mat(height, width, CV_8UC3, info.data);
cv::imshow("Output", mat);
//gst_buffer_unmap(buffer, &info);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//----------------------------------------------------------------------------------------------

It still does not work as expected. It would be a great help if you could point out where I am going wrong.
Thanks!!

On Wed, Mar 13, 2019 at 7:40 PM Michael Gruner <[hidden email]> wrote:
Hi Saurabh

Yo may convert from a cv::Mat to a GstBuffer without a memory copy by using gst_buffer_new_wrapped:


Something like: 
buffer = gst_buffer_new_wrapped (mat.data, mat.total()*mat.elemSize());

In order to make a cv::Mat from a GstBuffer you first need to take the data out of the buffer. 

GstMapInfo info;
gst_buffer_map (buffer, &info, GST_MAP_READ); // or write
mat = cv::Mat(height, width, CV_8C3, map.data); // change your format accordingly
...
gst_buffer_unmap (buffer, &info);

Hope it helps.

Michael

On Mar 13, 2019, at 7:15 AM, Saurabh Bora <[hidden email]> wrote:

Hi Experts!!, 

I am trying to read opencv images locally and push them into gstreamer pipeline. I am using appsrc element with "need-data" signal attached to call-back function.
Please look at the code below. 

//------------------------------------------------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width* channels;

// Copy cv::Mat to GstBuffer
buffer = gst_buffer_new_allocate(NULL, size, NULL);
gst_buffer_map(buffer, &map, GST_MAP_WRITE);
memcpy((guchar *)map.data, data1, gst_buffer_get_size(buffer));

//Convert GstBuffer back to cv::Mat and write it, to check if data was correctly copied. //This is where I get to know that data is not correct.
cv::Mat img2(cv::Size(134, 134), CV_8UC3, (char*)(buffer));
cv::imwrite("C:/Users/212730892.LOGON/Desktop/dummy1.jpg", img2);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//-------------------------------------------------------------------------------------------------------------------------------------

In cb_need_data, the part where copying I am copying to GstBuffer seems to be wrong and it does not work as expected. 
Can anyone, please help me understand, how can I copy the image data perfectly and pass it downstream to other elements without losing any data?

--
Thanks and Regards,
Saurabh Bora

PH NO : 7038166900
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--
Thanks and Regards,
Saurabh Bora

PH NO : 7038166900
             [hidden email]
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Re: Conversion of cv::Mat to GstBuffer

filnet
Note that there a quite a few existing opencv plugins in gst-plugins-bad.

Most of them extend gstopencvvideofilter which provides the logic for converting a cv::Mat to a GstBugger (and the other way around).






Le Mercredi 13 mars 2019 19h18, Michael Gruner <[hidden email]> a écrit :


It looks like img2, being a local variable, ends  its life when “cb_need_data” ends. That leaves the pointer in “buffer” invalid. For this one you’re better off with the copy. 

Another option is to alloc img2 on the heap, and use gst_buffer_new_wrapped_full to carry img2 along with buffer and free then together.

Michael

On Mar 13, 2019, at 10:51 AM, Saurabh Bora <[hidden email]> wrote:

Hi Michael, 

Thanks! for your input. I tried what you suggested as below:

//---------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img2;
cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
cv::cvtColor(img, img2, cv::COLOR_BGR2RGB);

height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width * channels * sizeof(guchar);

std::cout << "cb_need_data called" << std::endl;

buffer = gst_buffer_new_wrapped(img2.data, img2.total() * img2.elemSize());

GstMapInfo info;
gst_buffer_map(buffer, &info, GST_MAP_READ);
cv::Mat mat(height, width, CV_8UC3, info.data);
cv::imshow("Output", mat);
//gst_buffer_unmap(buffer, &info);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//----------------------------------------------------------------------------------------------

It still does not work as expected. It would be a great help if you could point out where I am going wrong.
Thanks!!

On Wed, Mar 13, 2019 at 7:40 PM Michael Gruner <[hidden email]> wrote:
Hi Saurabh

Yo may convert from a cv::Mat to a GstBuffer without a memory copy by using gst_buffer_new_wrapped:


Something like: 
buffer = gst_buffer_new_wrapped (mat.data, mat.total()*mat.elemSize());

In order to make a cv::Mat from a GstBuffer you first need to take the data out of the buffer. 

GstMapInfo info;
gst_buffer_map (buffer, &info, GST_MAP_READ); // or write
mat = cv::Mat(height, width, CV_8C3, map.data); // change your format accordingly
...
gst_buffer_unmap (buffer, &info);

Hope it helps.

Michael

On Mar 13, 2019, at 7:15 AM, Saurabh Bora <[hidden email]> wrote:

Hi Experts!!, 

I am trying to read opencv images locally and push them into gstreamer pipeline. I am using appsrc element with "need-data" signal attached to call-back function.
Please look at the code below. 

//------------------------------------------------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width* channels;

// Copy cv::Mat to GstBuffer
buffer = gst_buffer_new_allocate(NULL, size, NULL);
gst_buffer_map(buffer, &map, GST_MAP_WRITE);
memcpy((guchar *)map.data, data1, gst_buffer_get_size(buffer));

//Convert GstBuffer back to cv::Mat and write it, to check if data was correctly copied. //This is where I get to know that data is not correct.
cv::Mat img2(cv::Size(134, 134), CV_8UC3, (char*)(buffer));
cv::imwrite("C:/Users/212730892.LOGON/Desktop/dummy1.jpg", img2);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//-------------------------------------------------------------------------------------------------------------------------------------

In cb_need_data, the part where copying I am copying to GstBuffer seems to be wrong and it does not work as expected. 
Can anyone, please help me understand, how can I copy the image data perfectly and pass it downstream to other elements without losing any data?

--
Thanks and Regards,
Saurabh Bora

PH NO : 7038166900
             [hidden email]
_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel


--
Thanks and Regards,
Saurabh Bora

PH NO : 7038166900
             [hidden email]
_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel



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Re: Conversion of cv::Mat to GstBuffer

Saurabh Bora
In reply to this post by Michael Gruner
Hi Experts!, 

Thanks!! Michael, I tried the approach suggested by you and it works fine. I could verify the conversion of cv::Mat to GstBuffer and vice versa. On cv::write I get exact image that I had copied to GstBuffer.

However, I am unable to get correct image on autovidesink. With current code below, I see a skewed and distorted grayscale image. Note that I had to set width and height of videocaps on appsrc element as 133, 133 respectively, even though dimesnions of my input image is 134*134. If I set width and height as 134, 134 in videocaps, I see a black videosink.

//----------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

static GMainLoop *loop;

void buffer_destroy(gpointer data)
{
cv::Mat* done = (cv::Mat*)data;
delete done;
}

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
GstFlowReturn ret;
char *data1;
GstMapInfo map;

cv::Mat* img = new cv::Mat(cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg"));

std::cout << "cb_need_data called" << std::endl;

gsize sizeInBytes = img->total() * img->elemSize();
std::cout << "Size getting copied: " << sizeInBytes << std::endl;
buffer = gst_buffer_new_wrapped_full((GstMemoryFlags)0, (gpointer)(img->data), sizeInBytes, 0, sizeInBytes, (gpointer)img, (GDestroyNotify)buffer_destroy);

gsize bufferSize = gst_buffer_get_size(buffer);
std::cout << "Buffer Size: " << bufferSize << std::endl;

//Convert GstBuffer back to cv::Mat, to check if data was correctly copied
GstMapInfo info;
gst_buffer_map(buffer, &info, GST_MAP_READ);
cv::Mat img2(cv::Size(img->size().height, img->size().width), CV_8UC3, (char*)(info.data));
cv::imwrite("C:/Users/212730892.LOGON/Desktop/dummy1.jpg", img2);

GST_BUFFER_OFFSET(buffer) = 0;
GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 30);
//GST_BUFFER_DURATION(buffer) = GST_CLOCK_TIME_NONE;

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 133,
"height", G_TYPE_INT, 133,
"framerate", GST_TYPE_FRACTION, 1, 30,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);

/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//-------------------------------------------------------------------------

I am new to gstreamer framework and it would be a great help if someone could point me in right direction.

Thanks and Regards,
Saurabh Bora


On Wed, Mar 13, 2019 at 11:48 PM Michael Gruner <[hidden email]> wrote:
It looks like img2, being a local variable, ends  its life when “cb_need_data” ends. That leaves the pointer in “buffer” invalid. For this one you’re better off with the copy. 

Another option is to alloc img2 on the heap, and use gst_buffer_new_wrapped_full to carry img2 along with buffer and free then together.

Michael

On Mar 13, 2019, at 10:51 AM, Saurabh Bora <[hidden email]> wrote:

Hi Michael, 

Thanks! for your input. I tried what you suggested as below:

//---------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img2;
cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
cv::cvtColor(img, img2, cv::COLOR_BGR2RGB);

height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width * channels * sizeof(guchar);

std::cout << "cb_need_data called" << std::endl;

buffer = gst_buffer_new_wrapped(img2.data, img2.total() * img2.elemSize());

GstMapInfo info;
gst_buffer_map(buffer, &info, GST_MAP_READ);
cv::Mat mat(height, width, CV_8UC3, info.data);
cv::imshow("Output", mat);
//gst_buffer_unmap(buffer, &info);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//----------------------------------------------------------------------------------------------

It still does not work as expected. It would be a great help if you could point out where I am going wrong.
Thanks!!

On Wed, Mar 13, 2019 at 7:40 PM Michael Gruner <[hidden email]> wrote:
Hi Saurabh

Yo may convert from a cv::Mat to a GstBuffer without a memory copy by using gst_buffer_new_wrapped:


Something like: 
buffer = gst_buffer_new_wrapped (mat.data, mat.total()*mat.elemSize());

In order to make a cv::Mat from a GstBuffer you first need to take the data out of the buffer. 

GstMapInfo info;
gst_buffer_map (buffer, &info, GST_MAP_READ); // or write
mat = cv::Mat(height, width, CV_8C3, map.data); // change your format accordingly
...
gst_buffer_unmap (buffer, &info);

Hope it helps.

Michael

On Mar 13, 2019, at 7:15 AM, Saurabh Bora <[hidden email]> wrote:

Hi Experts!!, 

I am trying to read opencv images locally and push them into gstreamer pipeline. I am using appsrc element with "need-data" signal attached to call-back function.
Please look at the code below. 

//------------------------------------------------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width* channels;

// Copy cv::Mat to GstBuffer
buffer = gst_buffer_new_allocate(NULL, size, NULL);
gst_buffer_map(buffer, &map, GST_MAP_WRITE);
memcpy((guchar *)map.data, data1, gst_buffer_get_size(buffer));

//Convert GstBuffer back to cv::Mat and write it, to check if data was correctly copied. //This is where I get to know that data is not correct.
cv::Mat img2(cv::Size(134, 134), CV_8UC3, (char*)(buffer));
cv::imwrite("C:/Users/212730892.LOGON/Desktop/dummy1.jpg", img2);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//-------------------------------------------------------------------------------------------------------------------------------------

In cb_need_data, the part where copying I am copying to GstBuffer seems to be wrong and it does not work as expected. 
Can anyone, please help me understand, how can I copy the image data perfectly and pass it downstream to other elements without losing any data?

--
Thanks and Regards,
Saurabh Bora

PH NO : 7038166900
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Saurabh Bora

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Re: Conversion of cv::Mat to GstBuffer

Michael Gruner
Can you run your app with warning logging enabled? Any of the following should work:

./app --gst-debug=2

Or

GST_DEBUG=2 ./app



On Mar 14, 2019, at 2:17 PM, Saurabh Bora <[hidden email]> wrote:

Hi Experts!, 

Thanks!! Michael, I tried the approach suggested by you and it works fine. I could verify the conversion of cv::Mat to GstBuffer and vice versa. On cv::write I get exact image that I had copied to GstBuffer.

However, I am unable to get correct image on autovidesink. With current code below, I see a skewed and distorted grayscale image. Note that I had to set width and height of videocaps on appsrc element as 133, 133 respectively, even though dimesnions of my input image is 134*134. If I set width and height as 134, 134 in videocaps, I see a black videosink.

//----------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

static GMainLoop *loop;

void buffer_destroy(gpointer data)
{
cv::Mat* done = (cv::Mat*)data;
delete done;
}

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
GstFlowReturn ret;
char *data1;
GstMapInfo map;

cv::Mat* img = new cv::Mat(cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg"));

std::cout << "cb_need_data called" << std::endl;

gsize sizeInBytes = img->total() * img->elemSize();
std::cout << "Size getting copied: " << sizeInBytes << std::endl;
buffer = gst_buffer_new_wrapped_full((GstMemoryFlags)0, (gpointer)(img->data), sizeInBytes, 0, sizeInBytes, (gpointer)img, (GDestroyNotify)buffer_destroy);

gsize bufferSize = gst_buffer_get_size(buffer);
std::cout << "Buffer Size: " << bufferSize << std::endl;

//Convert GstBuffer back to cv::Mat, to check if data was correctly copied
GstMapInfo info;
gst_buffer_map(buffer, &info, GST_MAP_READ);
cv::Mat img2(cv::Size(img->size().height, img->size().width), CV_8UC3, (char*)(info.data));
cv::imwrite("C:/Users/212730892.LOGON/Desktop/dummy1.jpg", img2);

GST_BUFFER_OFFSET(buffer) = 0;
GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 30);
//GST_BUFFER_DURATION(buffer) = GST_CLOCK_TIME_NONE;

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 133,
"height", G_TYPE_INT, 133,
"framerate", GST_TYPE_FRACTION, 1, 30,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);

/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//-------------------------------------------------------------------------

I am new to gstreamer framework and it would be a great help if someone could point me in right direction.

Thanks and Regards,
Saurabh Bora


On Wed, Mar 13, 2019 at 11:48 PM Michael Gruner <[hidden email]> wrote:
It looks like img2, being a local variable, ends  its life when “cb_need_data” ends. That leaves the pointer in “buffer” invalid. For this one you’re better off with the copy. 

Another option is to alloc img2 on the heap, and use gst_buffer_new_wrapped_full to carry img2 along with buffer and free then together.

Michael

On Mar 13, 2019, at 10:51 AM, Saurabh Bora <[hidden email]> wrote:

Hi Michael, 

Thanks! for your input. I tried what you suggested as below:

//---------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img2;
cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
cv::cvtColor(img, img2, cv::COLOR_BGR2RGB);

height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width * channels * sizeof(guchar);

std::cout << "cb_need_data called" << std::endl;

buffer = gst_buffer_new_wrapped(img2.data, img2.total() * img2.elemSize());

GstMapInfo info;
gst_buffer_map(buffer, &info, GST_MAP_READ);
cv::Mat mat(height, width, CV_8UC3, info.data);
cv::imshow("Output", mat);
//gst_buffer_unmap(buffer, &info);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//----------------------------------------------------------------------------------------------

It still does not work as expected. It would be a great help if you could point out where I am going wrong.
Thanks!!

On Wed, Mar 13, 2019 at 7:40 PM Michael Gruner <[hidden email]> wrote:
Hi Saurabh

Yo may convert from a cv::Mat to a GstBuffer without a memory copy by using gst_buffer_new_wrapped:


Something like: 
buffer = gst_buffer_new_wrapped (mat.data, mat.total()*mat.elemSize());

In order to make a cv::Mat from a GstBuffer you first need to take the data out of the buffer. 

GstMapInfo info;
gst_buffer_map (buffer, &info, GST_MAP_READ); // or write
mat = cv::Mat(height, width, CV_8C3, map.data); // change your format accordingly
...
gst_buffer_unmap (buffer, &info);

Hope it helps.

Michael

On Mar 13, 2019, at 7:15 AM, Saurabh Bora <[hidden email]> wrote:

Hi Experts!!, 

I am trying to read opencv images locally and push them into gstreamer pipeline. I am using appsrc element with "need-data" signal attached to call-back function.
Please look at the code below. 

//------------------------------------------------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width* channels;

// Copy cv::Mat to GstBuffer
buffer = gst_buffer_new_allocate(NULL, size, NULL);
gst_buffer_map(buffer, &map, GST_MAP_WRITE);
memcpy((guchar *)map.data, data1, gst_buffer_get_size(buffer));

//Convert GstBuffer back to cv::Mat and write it, to check if data was correctly copied. //This is where I get to know that data is not correct.
cv::Mat img2(cv::Size(134, 134), CV_8UC3, (char*)(buffer));
cv::imwrite("C:/Users/212730892.LOGON/Desktop/dummy1.jpg", img2);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//-------------------------------------------------------------------------------------------------------------------------------------

In cb_need_data, the part where copying I am copying to GstBuffer seems to be wrong and it does not work as expected. 
Can anyone, please help me understand, how can I copy the image data perfectly and pass it downstream to other elements without losing any data?

--
Thanks and Regards,
Saurabh Bora

PH NO : 7038166900
             [hidden email]
_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel


--
Thanks and Regards,
Saurabh Bora

PH NO : 7038166900
             [hidden email]
_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel


--
Thanks and Regards,
Saurabh Bora

PH NO : 7038166900
             [hidden email]
_______________________________________________
gstreamer-devel mailing list
[hidden email]
https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel


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Re: Conversion of cv::Mat to GstBuffer

Saurabh Bora
Thanks Michael, 
It seems there is some problem with the input image itself. I tried different image of 640*480 resolution and code worked just fine.

Regards,
Saurabh Bora

On Fri, Mar 15, 2019 at 2:52 AM Michael Gruner <[hidden email]> wrote:
Can you run your app with warning logging enabled? Any of the following should work:

./app --gst-debug=2

Or

GST_DEBUG=2 ./app



On Mar 14, 2019, at 2:17 PM, Saurabh Bora <[hidden email]> wrote:

Hi Experts!, 

Thanks!! Michael, I tried the approach suggested by you and it works fine. I could verify the conversion of cv::Mat to GstBuffer and vice versa. On cv::write I get exact image that I had copied to GstBuffer.

However, I am unable to get correct image on autovidesink. With current code below, I see a skewed and distorted grayscale image. Note that I had to set width and height of videocaps on appsrc element as 133, 133 respectively, even though dimesnions of my input image is 134*134. If I set width and height as 134, 134 in videocaps, I see a black videosink.

//----------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

static GMainLoop *loop;

void buffer_destroy(gpointer data)
{
cv::Mat* done = (cv::Mat*)data;
delete done;
}

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
GstFlowReturn ret;
char *data1;
GstMapInfo map;

cv::Mat* img = new cv::Mat(cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg"));

std::cout << "cb_need_data called" << std::endl;

gsize sizeInBytes = img->total() * img->elemSize();
std::cout << "Size getting copied: " << sizeInBytes << std::endl;
buffer = gst_buffer_new_wrapped_full((GstMemoryFlags)0, (gpointer)(img->data), sizeInBytes, 0, sizeInBytes, (gpointer)img, (GDestroyNotify)buffer_destroy);

gsize bufferSize = gst_buffer_get_size(buffer);
std::cout << "Buffer Size: " << bufferSize << std::endl;

//Convert GstBuffer back to cv::Mat, to check if data was correctly copied
GstMapInfo info;
gst_buffer_map(buffer, &info, GST_MAP_READ);
cv::Mat img2(cv::Size(img->size().height, img->size().width), CV_8UC3, (char*)(info.data));
cv::imwrite("C:/Users/212730892.LOGON/Desktop/dummy1.jpg", img2);

GST_BUFFER_OFFSET(buffer) = 0;
GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 30);
//GST_BUFFER_DURATION(buffer) = GST_CLOCK_TIME_NONE;

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 133,
"height", G_TYPE_INT, 133,
"framerate", GST_TYPE_FRACTION, 1, 30,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);

/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//-------------------------------------------------------------------------

I am new to gstreamer framework and it would be a great help if someone could point me in right direction.

Thanks and Regards,
Saurabh Bora


On Wed, Mar 13, 2019 at 11:48 PM Michael Gruner <[hidden email]> wrote:
It looks like img2, being a local variable, ends  its life when “cb_need_data” ends. That leaves the pointer in “buffer” invalid. For this one you’re better off with the copy. 

Another option is to alloc img2 on the heap, and use gst_buffer_new_wrapped_full to carry img2 along with buffer and free then together.

Michael

On Mar 13, 2019, at 10:51 AM, Saurabh Bora <[hidden email]> wrote:

Hi Michael, 

Thanks! for your input. I tried what you suggested as below:

//---------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img2;
cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
cv::cvtColor(img, img2, cv::COLOR_BGR2RGB);

height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width * channels * sizeof(guchar);

std::cout << "cb_need_data called" << std::endl;

buffer = gst_buffer_new_wrapped(img2.data, img2.total() * img2.elemSize());

GstMapInfo info;
gst_buffer_map(buffer, &info, GST_MAP_READ);
cv::Mat mat(height, width, CV_8UC3, info.data);
cv::imshow("Output", mat);
//gst_buffer_unmap(buffer, &info);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//----------------------------------------------------------------------------------------------

It still does not work as expected. It would be a great help if you could point out where I am going wrong.
Thanks!!

On Wed, Mar 13, 2019 at 7:40 PM Michael Gruner <[hidden email]> wrote:
Hi Saurabh

Yo may convert from a cv::Mat to a GstBuffer without a memory copy by using gst_buffer_new_wrapped:


Something like: 
buffer = gst_buffer_new_wrapped (mat.data, mat.total()*mat.elemSize());

In order to make a cv::Mat from a GstBuffer you first need to take the data out of the buffer. 

GstMapInfo info;
gst_buffer_map (buffer, &info, GST_MAP_READ); // or write
mat = cv::Mat(height, width, CV_8C3, map.data); // change your format accordingly
...
gst_buffer_unmap (buffer, &info);

Hope it helps.

Michael

On Mar 13, 2019, at 7:15 AM, Saurabh Bora <[hidden email]> wrote:

Hi Experts!!, 

I am trying to read opencv images locally and push them into gstreamer pipeline. I am using appsrc element with "need-data" signal attached to call-back function.
Please look at the code below. 

//------------------------------------------------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width* channels;

// Copy cv::Mat to GstBuffer
buffer = gst_buffer_new_allocate(NULL, size, NULL);
gst_buffer_map(buffer, &map, GST_MAP_WRITE);
memcpy((guchar *)map.data, data1, gst_buffer_get_size(buffer));

//Convert GstBuffer back to cv::Mat and write it, to check if data was correctly copied. //This is where I get to know that data is not correct.
cv::Mat img2(cv::Size(134, 134), CV_8UC3, (char*)(buffer));
cv::imwrite("C:/Users/212730892.LOGON/Desktop/dummy1.jpg", img2);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//-------------------------------------------------------------------------------------------------------------------------------------

In cb_need_data, the part where copying I am copying to GstBuffer seems to be wrong and it does not work as expected. 
Can anyone, please help me understand, how can I copy the image data perfectly and pass it downstream to other elements without losing any data?

--
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Re: Conversion of cv::Mat to GstBuffer

Jan Schmidt-6
Hi,

On 25/3/19 10:36 pm, Saurabh Bora wrote:
Thanks Michael, 
It seems there is some problem with the input image itself. I tried different image of 640*480 resolution and code worked just fine.
For frame sizes that aren't a multiple of 4 bytes, you need to round up and add padding - GStreamer buffers have an implicit stride that's the nearest multiple of 4. Alternatively, you can add a GstVideoMeta to the GstBuffer describing the actual stride.

Cheers,
Jan.

Regards,
Saurabh Bora

On Fri, Mar 15, 2019 at 2:52 AM Michael Gruner <[hidden email]> wrote:
Can you run your app with warning logging enabled? Any of the following should work:

./app --gst-debug=2

Or

GST_DEBUG=2 ./app



On Mar 14, 2019, at 2:17 PM, Saurabh Bora <[hidden email]> wrote:

Hi Experts!, 

Thanks!! Michael, I tried the approach suggested by you and it works fine. I could verify the conversion of cv::Mat to GstBuffer and vice versa. On cv::write I get exact image that I had copied to GstBuffer.

However, I am unable to get correct image on autovidesink. With current code below, I see a skewed and distorted grayscale image. Note that I had to set width and height of videocaps on appsrc element as 133, 133 respectively, even though dimesnions of my input image is 134*134. If I set width and height as 134, 134 in videocaps, I see a black videosink.

//----------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

static GMainLoop *loop;

void buffer_destroy(gpointer data)
{
cv::Mat* done = (cv::Mat*)data;
delete done;
}

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
GstFlowReturn ret;
char *data1;
GstMapInfo map;

cv::Mat* img = new cv::Mat(cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg"));

std::cout << "cb_need_data called" << std::endl;

gsize sizeInBytes = img->total() * img->elemSize();
std::cout << "Size getting copied: " << sizeInBytes << std::endl;
buffer = gst_buffer_new_wrapped_full((GstMemoryFlags)0, (gpointer)(img->data), sizeInBytes, 0, sizeInBytes, (gpointer)img, (GDestroyNotify)buffer_destroy);

gsize bufferSize = gst_buffer_get_size(buffer);
std::cout << "Buffer Size: " << bufferSize << std::endl;

//Convert GstBuffer back to cv::Mat, to check if data was correctly copied
GstMapInfo info;
gst_buffer_map(buffer, &info, GST_MAP_READ);
cv::Mat img2(cv::Size(img->size().height, img->size().width), CV_8UC3, (char*)(info.data));
cv::imwrite("C:/Users/212730892.LOGON/Desktop/dummy1.jpg", img2);

GST_BUFFER_OFFSET(buffer) = 0;
GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 30);
//GST_BUFFER_DURATION(buffer) = GST_CLOCK_TIME_NONE;

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 133,
"height", G_TYPE_INT, 133,
"framerate", GST_TYPE_FRACTION, 1, 30,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);

/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//-------------------------------------------------------------------------

I am new to gstreamer framework and it would be a great help if someone could point me in right direction.

Thanks and Regards,
Saurabh Bora


On Wed, Mar 13, 2019 at 11:48 PM Michael Gruner <[hidden email]> wrote:
It looks like img2, being a local variable, ends  its life when “cb_need_data” ends. That leaves the pointer in “buffer” invalid. For this one you’re better off with the copy. 

Another option is to alloc img2 on the heap, and use gst_buffer_new_wrapped_full to carry img2 along with buffer and free then together.

Michael

On Mar 13, 2019, at 10:51 AM, Saurabh Bora <[hidden email]> wrote:

Hi Michael, 

Thanks! for your input. I tried what you suggested as below:

//---------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img2;
cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
cv::cvtColor(img, img2, cv::COLOR_BGR2RGB);

height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width * channels * sizeof(guchar);

std::cout << "cb_need_data called" << std::endl;

buffer = gst_buffer_new_wrapped(img2.data, img2.total() * img2.elemSize());

GstMapInfo info;
gst_buffer_map(buffer, &info, GST_MAP_READ);
cv::Mat mat(height, width, CV_8UC3, info.data);
cv::imshow("Output", mat);
//gst_buffer_unmap(buffer, &info);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//----------------------------------------------------------------------------------------------

It still does not work as expected. It would be a great help if you could point out where I am going wrong.
Thanks!!

On Wed, Mar 13, 2019 at 7:40 PM Michael Gruner <[hidden email]> wrote:
Hi Saurabh

Yo may convert from a cv::Mat to a GstBuffer without a memory copy by using gst_buffer_new_wrapped:


Something like: 
buffer = gst_buffer_new_wrapped (mat.data, mat.total()*mat.elemSize());

In order to make a cv::Mat from a GstBuffer you first need to take the data out of the buffer. 

GstMapInfo info;
gst_buffer_map (buffer, &info, GST_MAP_READ); // or write
mat = cv::Mat(height, width, CV_8C3, map.data); // change your format accordingly
...
gst_buffer_unmap (buffer, &info);

Hope it helps.

Michael

On Mar 13, 2019, at 7:15 AM, Saurabh Bora <[hidden email]> wrote:

Hi Experts!!, 

I am trying to read opencv images locally and push them into gstreamer pipeline. I am using appsrc element with "need-data" signal attached to call-back function.
Please look at the code below. 

//------------------------------------------------------------------------------------------------------
#include <gst/gst.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>

static GMainLoop *loop;

static void
cb_need_data(GstElement *appsrc,
guint       unused_size,
gpointer    user_data)
{
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size, depth, height, width, step, channels;
GstFlowReturn ret;
guchar *data1;
GstMapInfo map;

cv::Mat img = cv::imread("C:/Users/212730892.LOGON/Desktop/lena.jpg");
height = img.size().height;
width = img.size().width;
//step = img.widthStep;
channels = img.channels();
//depth = img->depth;
data1 = (guchar *)img.data;
size = height * width* channels;

// Copy cv::Mat to GstBuffer
buffer = gst_buffer_new_allocate(NULL, size, NULL);
gst_buffer_map(buffer, &map, GST_MAP_WRITE);
memcpy((guchar *)map.data, data1, gst_buffer_get_size(buffer));

//Convert GstBuffer back to cv::Mat and write it, to check if data was correctly copied. //This is where I get to know that data is not correct.
cv::Mat img2(cv::Size(134, 134), CV_8UC3, (char*)(buffer));
cv::imwrite("C:/Users/212730892.LOGON/Desktop/dummy1.jpg", img2);

GST_BUFFER_PTS(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = gst_util_uint64_scale_int(1, GST_SECOND, 2);

timestamp += GST_BUFFER_DURATION(buffer);

g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
//gst_buffer_unref(buffer);

if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
g_main_loop_quit(loop);
}
}

gint
main(gint   argc,
gchar *argv[])
{
GstElement *pipeline, *appsrc, *conv, *videosink;

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

/* setup pipeline */
pipeline = gst_pipeline_new("pipeline");
appsrc = gst_element_factory_make("appsrc", "source");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");

/* setup */
g_object_set(G_OBJECT(appsrc), "caps",
gst_caps_new_simple("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"width", G_TYPE_INT, 134,
"height", G_TYPE_INT, 134,
"framerate", GST_TYPE_FRACTION, 1, 1,
NULL), NULL);
gst_bin_add_many(GST_BIN(pipeline), appsrc, conv, videosink, NULL);
gst_element_link_many(appsrc, conv, videosink, NULL);
//g_object_set (videosink, "device", "/dev/video0", NULL);
/* setup appsrc */
g_object_set(G_OBJECT(appsrc),
"stream-type", 0,
"format", GST_FORMAT_TIME, NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), NULL);

/* play */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);

if (gst_element_set_state(pipeline, GST_STATE_NULL) == GST_STATE_CHANGE_FAILURE)
{
g_printerr("Unable to set the pipeline to the playing state.\n");
}

// Free resources
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);

return 0;
}
//-------------------------------------------------------------------------------------------------------------------------------------

In cb_need_data, the part where copying I am copying to GstBuffer seems to be wrong and it does not work as expected. 
Can anyone, please help me understand, how can I copy the image data perfectly and pass it downstream to other elements without losing any data?

--
Thanks and Regards,
Saurabh Bora

PH NO : 7038166900
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Thanks and Regards,
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