GStreamer : Pipeline to connect VNC server and Display/Record the remote GUI

SGaist

A GStreamer pipeline is basically a list of module that you chain to each other from the source to the sink to, for example, read an audio file, decode it and finally send it to your audio output.

From a command line point of view, it's the elements built from the parameters you give to gst-launch.

For example:
Play the mp3 music file "music.mp3" using a libmad-based plugin and output to an OSS device:

gst-launch-1.0 filesrc location=music.mp3 ! mad ! audioconvert ! audioresample ! osssink

The documentation of get-launch gives you more good examples.
The API tutorials are pretty nice to get started.

ODБOï

@SGaist said in GStreamer : understanding the concept of 'pipeline':

Copies from this thread:

Yes, thx, i did a new one because the other thread is turning to spaghetti.
Thx for explanation, it is bit clearer
I will dive into these docs today.

ODБOï

Hi,
I'm testing the GStreamer Hello World exemple, a call to GstMessage * gst_bus_timed_pop_filtered() is underlined in red, and application cant compile
Qt creator autocompletion can find it, but when i call it

msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_ERROR | GST_MESSAGE_EOS)

output : no matching function for call to 'gst_bus_timed_pop_filtered'

What could be the problem please ?

jsulm

@LeLev Header file not included?
Wrong parameters passed?

ODБOï

@jsulm hi
i only include <gst/gst.h>

about parameters, i also tryed to compile the program without passing any parameters to gst_bus_timed_pop_filtered
and had this output :
too few arguments to function 'GstMessage* gst_bus_timed_pop_filtered(GstBus*, GstClockTime, GstMessageType)'
msg = gst_bus_timed_pop_filtered();
^

jsulm

@LeLev said in GStreamer : understanding the concept of 'pipeline':

without passing any parameters

this will for sure not work as the function expects 3 parameters: https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstBus.html#gst-bus-timed-pop-filtered

Can you post the whole error message with the parameters you were passing before?
Maybe the type of "bus" was wrong?

ODБOï

@jsulm

     gst_init (&argc, &argv);
     GstElement *pipeline;
     GstBus *bus;
     GstMessage *msg;

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

       gst_element_set_state (pipeline, GST_STATE_PLAYING);
       
       bus = gst_element_get_bus (pipeline);
       msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_ERROR | GST_MESSAGE_EOS);

output :

no matching function for call to 'gst_bus_timed_pop_filtered'

erreur : invalid conversion from 'int' to 'GstMessageType' [-fpermissive]
        msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_ERROR | GST_MESSAGE_EOS);
                                                                   ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~

jsulm

@LeLev said in GStreamer : understanding the concept of 'pipeline':

GST_MESSAGE_ERROR | GST_MESSAGE_EOS

this is the actual problem. Try to cast it to GstMessageType:

msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE, static_cast<GstMessageType>(GST_MESSAGE_ERROR | GST_MESSAGE_EOS));

ODБOï

i just changed the 3rd parameter and it compiled

msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_EOS);

ODБOï

@jsulm said in GStreamer : understanding the concept of 'pipeline':

ry to cast it to GstMessageType:

Thank you !

jsulm

@LeLev That's why it is important to post all errors: many errors are just follow up errors caused by another error.

ODБOï

@jsulm said in GStreamer : understanding the concept of 'pipeline':

all errors

saved for the next time.

I'm confused about this lib.
In this hello world exemple they say :

If everything built fine, fire up the executable! You should see a window pop up, containing a video being played straight from the Internet, along with audio. Congratulations!

I can't figure out how a window will pop up.
I'm reading the playbin description right now, in my app nothing pops up.

jsulm

@LeLev said in GStreamer : understanding the concept of 'pipeline':

I can't figure out how a window will pop up.

So, you start the app but no window pops up?
Then probably something is wrong. I don't know what. You can debug and see what happens.

ODБOï

@jsulm said in GStreamer : understanding the concept of 'pipeline':

So, you start the app but no window pops up?

Yes,

@jsulm said in GStreamer : understanding the concept of 'pipeline':

probably something is wrong

yes, with putenv("GST_DEBUG=2"); i got :

0:00:03.253981299  1536 0000000037E010C0 WARN             souphttpsrc gstsouphttpsrc.c:1379:gst_soup_http_src_parse_status:<source> error: Secure connection setup failed.
0:00:03.254006642  1536 0000000037E010C0 WARN             souphttpsrc gstsouphttpsrc.c:1379:gst_soup_http_src_parse_status:<source> error: TLS/SSL support not available; install glib-networking (6), URL: https://www.freedesktop.org/software/gstreamer-sdk/data/media/sintel_trailer-480p.webm, Redirect to: (NULL)
0:00:03.254067912  1536 0000000037E010C0 WARN                 basesrc gstbasesrc.c:3055:gst_base_src_loop:<source> error: Internal data stream error.
0:00:03.254105765  1536 0000000037E010C0 WARN                 basesrc gstbasesrc.c:3055:gst_base_src_loop:<source> error: streaming stopped, reason error (-5)
0:00:03.254180509  1536 0000000037E010C0 WARN                typefind gsttypefindelement.c:991:gst_type_find_element_chain_do_typefinding:<typefindelement0> error: Stream doesn't contain enough data.
0:00:03.254192057  1536 0000000037E010C0 WARN                typefind gsttypefindelement.c:991:gst_type_find_element_chain_do_typefinding:<typefindelement0> error: Can't typefind stream

i will install glib-networking

jsulm

@LeLev You could try to play a video from a non-SSL (non-HTTPS) URL.

ODБOï

@jsulm That worked thank you!

ODБOï

Can please someone help me to complete this pipeline so it can record the VNC remote desktop to video file and/or show it with
playbin ?
pipeline = gst_parse_launch("rfbsrc host=xx.xx.xx.xx port=5900 password=passw view-only=true",NULL);

SGaist

Use the tee plugin.

ODБOï

@SGaist thank you, I tryed to use tee, but that is more complicated to do, i actually don't want to Watch and Save/record.
I would like to only save the video without displaying it.

after some houres i got this broken pipeline..

I have lot of troubles on how to set up the format for the video and write it to a file
I use ultraVnc server

"rfbsrc host=xx.xx.xx.xx port=5900 password=pw view-only=true   TODO : set up video format    ! mpegtsmux ! filesink location=testvideo.mp4"

i have this output

** (QVNCClient.exe:10252): CRITICAL **: gst_video_info_set_format: assertion 'format != GST_VIDEO_FORMAT_UNKNOWN' failed

** (QVNCClient.exe:10252): CRITICAL **: gst_video_info_to_caps: assertion 'info->finfo->format != GST_VIDEO_FORMAT_UNKNOWN' failed

(QVNCClient.exe:10252): GStreamer-CRITICAL **: gst_event_new_caps: assertion 'caps != NULL' failed

(QVNCClient.exe:10252): GStreamer-CRITICAL **: gst_pad_push_event: assertion 'GST_IS_EVENT (event)' failed

(QVNCClient.exe:10252): GStreamer-CRITICAL **: gst_mini_object_unref: assertion 'mini_object != NULL' failed
0:00:00.737522311 10252 0000000036FDDBC0 WARN                 basesrc gstbasesrc.c:3275:gst_base_src_prepare_allocation:<rfbsrc0> Subclass failed to decide allocation
0:00:00.737604753 10252 0000000036FDDBC0 WARN                 basesrc gstbasesrc.c:3055:gst_base_src_loop:<rfbsrc0> error: Internal data stream error.
0:00:00.737644531 10252 0000000036FDDBC0 WARN                 basesrc gstbasesrc.c:3055:gst_base_src_loop:<rfbsrc0> error: streaming stopped, reason not-negotiated (-4)
This program is linked against GStreamer 1.14.3

THX

SGaist

You have here an example of pipeline with h264 recording.