Analog cameras, qt and gstreamer

mrdebug

Hi. In order to manage v4l video cameras I'm using OpenCV, to manage rtsp video cameras and movies (to read and to create) I'm using ffmpeg.
What do you have to do? My approach is more complicated than use gstreamer but if it is very great and works everywhere.

naggety

I'm so sorry, I was testing some possible workarounds and I forgot this thread.

What I've finally done is using Gstreamer (alone, not QTGstreamer) with qmlglsink element. In my case, I needed some fixes in Gstreamer that are going to be included in version 1.15 but it's working.

About Camera QML element I still don't know if it's supposed to work with analog cameras. I think yes, but I haven't it working yet because I think my driver is a bit buggy, I'll try to fix it.

I have tested using the QML example from Gstreamer, but modifying the pipeline to use my cameras instead of videotestsrc.

This is the original example: https://cgit.freedesktop.org/gstreamer/gst-plugins-good/tree/tests/examples/qt/qmlsink?id=b03df1abf828514b0966db058388bf974ed0cf4f

And this is the pipeline I've used:

    // Pipeline object
    GstElement *pipeline = gst_pipeline_new (NULL);

    // v4l2 src, selecting device /dev/video1
    GstElement *src = gst_element_factory_make("v4l2src", NULL);
    g_object_set (src, "device", "/dev/video1", NULL);

    // caps selection: format, width, height...
    GstElement *capsfilter = gst_element_factory_make("capsfilter", NULL);
    GstCaps *caps = gst_caps_new_simple("video/x-raw",
                    "format", G_TYPE_STRING, "NV12",
                    "width", G_TYPE_INT, 720,
                    "height", G_TYPE_INT, 576,
                    "framerate", GST_TYPE_FRACTION, 5, 1, NULL);
    g_object_set (capsfilter, "caps", caps, NULL);

    // convert to GL texture (as qmlglsink expects, also this force processing the video accelerated by the GPU)
    GstElement *glupload = gst_element_factory_make ("glupload", NULL);

    // convert from original video format NV12 to format accepted by qmlglsink (RGBA)
    GstElement *glcolorconvert = gst_element_factory_make ("glcolorconvert", NULL);

    // QML element sink
    /* the plugin must be loaded before loading the qml file to register the
     * GstGLVideoItem qml item */
    GstElement *sink = gst_element_factory_make ("qmlglsink", NULL);
    g_object_set (sink, "sync", false, NULL);

    // link the elements in the pipeline
    gst_bin_add_many (GST_BIN (pipeline), src, capsfilter, glupload, glcolorconvert, sink, NULL);
    gst_element_link_many (src, capsfilter, glupload, glcolorconvert, sink, NULL);

Pablo J. Rogina

@naggety great that you found a solution. If your issue is solved please don't forget to mark your post as such. Thanks

naggety

Hi @Pablo-J-Rogina, it still remains the question about Camera element from QML. I'd wish to maintain open the post for some days more to see if I solve it and/or anybody can give me some help about it. If not, I will mark as solved in some days.

Pablo J. Rogina

@naggety fair enough

SGaist

Hi,

Might be silly question but, are you sure your pipeline is running properly ?

naggety

Hi @SGaist.

Sorry, I didn't see your reply. I've changed my forum settings to receive an email when someone replies to my posts.

I guess that the pipeline is not running properly, but I can't know since I didn't made the pipeline. In my original post, I was using Camera QML element, and I have no control over the pipeline it tries to create.

In my later reply, I show a pipeline made by me that is working. But it's still no possible to use Camera QML element, which is supposed to handle all this automatically.

SGaist

Did you consider using the QtGStreamer module directly ?

naggety

@SGaist I was considering it, but I read this:

The QtGStreamer C++ bindings are very out of date and unmaintained

here: https://gstreamer.freedesktop.org/bindings/qt.html

Do you think it worth to use it?

SGaist

Do you mean the qmlglsink ? Worth a try yes