How to write code that takes photo using your webcam?

[Радомир Хаџић]

Hello.

I have a small problem. I don't know how to write a program that takes a
photo using a webcam. I know how to do that using *gst-launch-1.0*, though.
*gst-launch-1.0 -e v4l2src device=/dev/video0 num-buffers=1 ! videoconvert
! pngenc ! filesink location=sample.png sync=true*
This works. A photo of me is successfully saved as *sample.png*.

What I'd like to do is to write GStreamer code equivalent to the command
above. Here is my best try.























































*#include <gst/gst.h>int main(int argc, char **argv){    // initialize
return value    int status;    // initialize GStreamer    gst_init(&argc,
&argv);    // create pipeline and other elements to use    GstElement
*pipeline = gst_pipeline_new("pipeline");    GstElement *source =
gst_element_factory_make("v4l2src", "source");    GstElement *converter =
gst_element_factory_make("videoconvert", "converter");    GstElement
*encoder = gst_element_factory_make("pngenc", "encoder");    GstElement
*file = gst_element_factory_make("filesink", "file");    // add all
elements to the pipeline and connect them
gst_bin_add_many(GST_BIN(pipeline), source, converter, encoder, file,
NULL);    gst_element_link_many(source, converter, encoder, file, NULL);
// set the properties    g_object_set(source, "device", "/dev/video0",
"num-buffers", 1, NULL);    g_object_set(file, "location", "sample.png",
"sync", 1, NULL);    // play    gst_element_set_state(pipeline,
GST_STATE_PLAYING);    // wait for EOS    GstBus *bus =
gst_element_get_bus(pipeline);    GstMessage *msg = gst_bus_timed_pop(bus,
GST_CLOCK_TIME_NONE);    // determine return value using msg    switch
(GST_MESSAGE_TYPE(msg))    {        case GST_MESSAGE_ERROR:
status = -1;            break;        case GST_MESSAGE_EOS:
status = 0;            break;        default:            status = 1;
    break;    }    // clean up    gst_element_set_state(pipeline,
GST_STATE_NULL);    if (msg != NULL)        gst_message_unref(msg);
gst_object_unref(bus);    gst_object_unref(pipeline);    // exit from the
program and return status    return status;}*
The problem with this code is that really creates *sample.png*, but the
file is corrupted and cannot be opened. Why the code above doesn't work as
intended and what do I need to change to make it work the way I want?

Thank you for reading this. Have a nice day.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/gstreamer-devel/attachments/20181020/ec0e1b18/attachment.html>