newby help

[James]

> On 29 Mar 2021, at 10:50 pm, gotsring <gotsring at live.com> wrote:
> 
> gst-launch is good for testing pipelines, but it lacks the ability to do any
> monitoring, live changes, error-handling, etc. Building pipelines in code
> takes getting used to, but it allows much more flexibility and robustness.
> 
> For basic pipelines, you can use gst_parse_launch to run a pipeline similar
> to how you would use gst-launch
> 
> For example, a simple pipeline with a tee can be started from the shell
> using:
>    gst-launch-1.0 videotestsrc ! tee name=t \
>     t. ! queue ! videoconvert ! autovideosink \
>     t. ! queue ! videoconvert ! autovideosink
> 
> or in C code using gst_parse_launch:
> 	GError* err = NULL;
> 	GstElement* pipeline = gst_parse_launch(
> 		"videotestsrc ! tee name=t "
> 		"t. ! queue ! videoconvert ! autovideosink "
> 		"t. ! queue ! videoconvert ! autovideosink"
> 		, &err);
> 	gst_element_set_state(pipeline, GST_STATE_PLAYING); // Play it
> 
> 
> You can swap out my test pipeline for whatever you want.
> 
> Not quite sure what you're trying to do in terms of a GUI, but maybe use
> GTK? Check out basic tutorial 5:
> https://gstreamer.freedesktop.org/documentation/tutorials/basic/toolkit-integration.html?gi-language=c


OK perhaps a different track:

I compiled basic_tutorial12.c
The executable runs, pretty picture etc

I changed

pipeline = gst_parse_launch ("playbin uri=https://www.freedesktop.org/software/gstreamer-sdk/data/media/sintel_trailer-480p.webm", NULL);

for
pipeline = gst_parse_launch ("v4l2src device=argv[1] ! tee name=t "  
                     "t. ! queue ! videoscale ! video/x-raw,width=768,height=576 ! "
                      "videoconvert ! xvimagesink force-aspect-ratio=false "
                      " t. ! queue ! videoscale ! video/x-raw,width=768,height=576 ! "
                      "videoconvert ! xvimagesink force-aspect-ratio=false", NULL);

Now running gives me

Unable to set the pipeline to the playing state.

My 'get_parse_lauch' is wrong. Why? Where?

Thanks
James