For my records: With the upgrade to gstreamer-1.15.1 in #54398, running the example

gst-launch-1.0 v4l2src ! video/x-raw, height=1080, width=1920 ! videoconvert ! x264enc tune=zerolatency ! video/x-h264, profile=high ! mpegtsmux ! srtserversink uri=srt://:8888/

now results in:

Setting pipeline to PAUSED ...
Caught SIGSEGV
Spinning.  Please run 'gdb gst-launch-1.0 17122' to continue debugging, Ctrl-C to quit, or Ctrl-\ to dump core.

sudo gdb /nix/store/nqclksqfvhy4w9pkd6c5dw6283rrsisl-gstreamer-1.15.1-dev/bin/.gst-launch-1.0-wrapped 17122 shows:

(gdb) bt
#0  0x00007f7fc24db318 in nanosleep () from /nix/store/fivq0nbggp4y8mhy3ixprqd7qyn1hy2j-glibc-2.27/lib/libpthread.so.0
#1  0x00007f7fc29d47af in g_usleep () from /nix/store/8q73aw4x32izb0gvzadjvj3a298bbwyy-glib-2.58.2/lib/libglib-2.0.so.0
#2  0x0000000000405592 in fault_handler_sighandler ()
#3  <signal handler called>
#4  0x00007f7fc2266e98 in __strchr_avx2 () from /nix/store/fivq0nbggp4y8mhy3ixprqd7qyn1hy2j-glibc-2.27/lib/libc.so.6
#5  0x00007f7fbea205c7 in g_inet_socket_address_new_from_string () from /nix/store/8q73aw4x32izb0gvzadjvj3a298bbwyy-glib-2.58.2/lib/libgio-2.0.so.0
#6  0x00007f7fbc285516 in gst_srt_object_open_full () from /nix/store/k3qilja4304q8s5xv6qp2bsvclhnjnbs-gst-plugins-bad-1.15.1/lib/gstreamer-1.0/libgstsrt.so
#7  0x00007f7fbc287958 in gst_srt_sink_start () from /nix/store/k3qilja4304q8s5xv6qp2bsvclhnjnbs-gst-plugins-bad-1.15.1/lib/gstreamer-1.0/libgstsrt.so
#8  0x00007f7fbfb444c5 in gst_base_sink_change_state () from /nix/store/jbp0y7lgx3h711hg6py979q35sygqa8k-gstreamer-1.15.1/lib/libgstbase-1.0.so.0
#9  0x00007f7fc2cf05ae in gst_element_change_state () from /nix/store/jbp0y7lgx3h711hg6py979q35sygqa8k-gstreamer-1.15.1/lib/libgstreamer-1.0.so.0
#10 0x00007f7fc2cf0ce9 in gst_element_set_state_func () from /nix/store/jbp0y7lgx3h711hg6py979q35sygqa8k-gstreamer-1.15.1/lib/libgstreamer-1.0.so.0
#11 0x00007f7fc2ccc572 in gst_bin_change_state_func () from /nix/store/jbp0y7lgx3h711hg6py979q35sygqa8k-gstreamer-1.15.1/lib/libgstreamer-1.0.so.0
#12 0x00007f7fc2cf05ae in gst_element_change_state () from /nix/store/jbp0y7lgx3h711hg6py979q35sygqa8k-gstreamer-1.15.1/lib/libgstreamer-1.0.so.0
#13 0x00007f7fc2cf0ce9 in gst_element_set_state_func () from /nix/store/jbp0y7lgx3h711hg6py979q35sygqa8k-gstreamer-1.15.1/lib/libgstreamer-1.0.so.0
#14 0x0000000000404289 in main ()

Probably not a packaging problem though.

• 6 MB closure increase; should be fine

• I cannot reproduce the pipeline crash on account of not having a webcam on this device:

  $ nix-shell -I nixpkgs=$PWD -p gst_all_1.gstreamer gst_all_1.gst-plugins-base gst_all_1.gst-plugins-good gst_all_1.gst-plugins-bad gst_all_1.gst-plugins-ugly --run "gst-launch-1.0 v4l2src ! video/x-raw, height=1080, width=1920 ! videoconvert ! x264enc tune=zerolatency ! video/x-h264, profile=high ! mpegtsmux ! srtserversink uri=srt://:8888/"
  Setting pipeline to PAUSED ...
  ERROR: Pipeline doesn't want to pause.
  ERROR: from element /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: Cannot identify device '/dev/video0'.
  Additional debug info:
  ../sys/v4l2/v4l2_calls.c(609): gst_v4l2_open (): /GstPipeline:pipeline0/GstV4l2Src:v4l2src0:
  system error: No such file or directory
  Setting pipeline to NULL ...
  Freeing pipeline ...

• I also tried nix-shell -I nixpkgs=$PWD -p gst_all_1.gstreamer gst_all_1.gst-plugins-base gst_all_1.gst-plugins-good gst_all_1.gst-plugins-bad gst_all_1.gst-plugins-ugly --run "gst-launch-1.0 videotestsrc ! video/x-raw, height=1080, width=1920 ! videoconvert ! x264enc tune=zerolatency ! video/x-h264, profile=high ! mpegtsmux ! srtserversink uri=srt://:8888/"

  which did not fail but I was not able to play it:

  $ nix-shell -I nixpkgs=$PWD -p gst_all_1.gstreamer gst_all_1.gst-plugins-base gst_all_1.gst-plugins-good gst_all_1.gst-plugins-bad gst_all_1.gst-plugins-ugly --run "gst-launch-1.0 srtclientsrc uri=srt://127.0.0.1:8888/ ! autovideosink"
  Setting pipeline to PAUSED ...
  Pipeline is live and does not need PREROLL ...
  Setting pipeline to PLAYING ...
  New clock: GstSystemClock
  ERROR: from element /GstPipeline:pipeline0/GstAutoVideoSink:autovideosink0/GstXvImageSink:autovideosink0-actual-sink-xvimage: Internal error: can't allocate images
  Additional debug info:
  ../sys/xvimage/xvimagesink.c(997): gst_xv_image_sink_show_frame (): /GstPipeline:pipeline0/GstAutoVideoSink:autovideosink0/GstXvImageSink:autovideosink0-actual-sink-xvimage:
  We don't have a bufferpool negotiated
  Execution ended after 0:00:00.144943384
  Setting pipeline to PAUSED ...
  Setting pipeline to READY ...
  Setting pipeline to NULL ...
  Freeing pipeline ...

  maybe there is someone more familiar with GStreamer that could devise a method to test this.

* I cannot reproduce the pipeline crash on account of not having a webcam on this device:

@jtojnar Reproducing the crash requires running the code from #54398; I have debugged that and filed problem and solution upstream: https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/issues/874

* which did not fail but I was not able to play it:

I too haven't figured out how to actually run this thing yet; I'll post here once I have.

I cannot reproduce the pipeline crash on account of not having a webcam on this device:

Reproducing the crash requires running the code from #54398

@jtojnar I realise I didn't actually address the key thing you mentioned: That you can't test it because of lack of webcam.

Here is how you can test it with a fake video source, videotestsrc:

• In terminal 1:
  • gst-launch-1.0 videotestsrc ! x264enc bitrate=8000 tune=zerolatency key-int-max=15 ! video/x-h264, profile=baseline ! mpegtsmux ! srtserversink uri=srt://0.0.0.0:5000/
• In terminal 2:
  • gst-launch-1.0 srtclientsrc uri=srt://127.0.0.1:5000 ! decodebin ! autovideosink

Note that this is for the version of gstreamer 1.14 on which this PR is based. These commands will change slightly for 1.16, says upstream.

I too haven't figured out how to actually run this thing yet; I'll post here once I have.

I have now successfully tested this stuff and the basic functionality works.

Ready to merge from my side.

Hmm, I cannot seem to find the decode plug-in:

$ nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/31981d2cd9ae4eb3bf77e3fb904f0e8b45ea828d.tar.gz --pure -p gst_all_1.gstreamer gst_all_1.gst-plugins-base gst_all_1.gst-plugins-good gst_all_1.gst-plugins-bad gst_all_1.gst-plugins-ugly --run "gst-launch-1.0 srtclientsrc uri=srt://127.0.0.1:5000 ! decodebin ! autovideosink"
Setting pipeline to PAUSED ...
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock
Missing element: H.264 decoder
ERROR: from element /GstPipeline:pipeline0/GstDecodeBin:decodebin0: Your GStreamer installation is missing a plug-in.
Additional debug info:
../gst/playback/gstdecodebin2.c(4640): gst_decode_bin_expose (): /GstPipeline:pipeline0/GstDecodeBin:decodebin0:
no suitable plugins found:
Missing decoder: H.264 (video/x-h264, stream-format=(string)byte-stream, alignment=(string)nal, parsed=(boolean)true)

Execution ended after 0:00:00.154163330
Setting pipeline to PAUSED ...
Setting pipeline to READY ...
Setting pipeline to NULL ...
Freeing pipeline ...

The server side seems to run without a hitch.

Hmm, I cannot seem to find the decode plug-in:

I think that's because you'll have to run with the #54398 I mentioned, because (unrelated to SRT) nixpkgs current gstreamer modules are built without support for libav based h264 decoding.

Thank you.