GStreamer Microsecond Timestamp Overlay
This is an adaptation of the clockoverlay and timeoverlay plugins from gstreamer-base. Stripped bare and just overlaying the Linux epoch time, with a microsecond resolution.
Use-case Examples
A single stream solution can be tested like this:
gst-launch-1.0 \
videotestsrc is-live=true do-timestamp=true \
! msoverlay halignment=left valignment=top \
! video/x-raw,format=RGB,framerate=30/1,width=640,height=480 \
! videoconvert \
! video/x-raw,format=NV12 \
! nvautogpuh264enc tune=3 \
! rtph264pay config-interval=0 pt=96 \
! rtph264depay \
! h264parse \
! nvh264dec \
! msoverlay halignment=left valignment=bottom \
! autovideosink
Take a screenshot of the output above and subtract the top-left number from the bottom-left to see the total pipeline latency.
For a more comprehensive solution we can also make the stream traverse the network stack:
Server:
gst-launch-1.0 videotestsrc is-live=true do-timestamp=true ! msoverlay halignment=left valignment=top ! video/x-raw,format=RGB,framerate=60/1,width=1920,height=1080 ! videoconvert ! video/x-raw,format=NV12 ! nvautogpuh264enc tune=3 ! rtph264pay config-interval=1 pt=96 ! rtpsink uri=rtp://127.0.0.1:5000
Live client:
gst-launch-1.0 rtpsrc uri=rtp://127.0.0.1:5000?encoding-name=H264 ! rtph264depay ! h264parse ! nvh264dec ! msoverlay halignment=left valignment=bottom ! autovideosink
PNG sampling client outputting 5 frames, one per second:
gst-launch-1.0 rtpsrc uri=rtp://127.0.0.1:5000?encoding-name=H264 ! rtph264depay ! h264parse ! nvh264dec ! msoverlay halignment=left valignment=bottom ! videorate drop-only=true ! video/x-raw,framerate=1/1 ! pngenc ! multifilesink num-buffers=10 location="latency_%02d.png"
It is essential both the client and server run on the same machine, unless you really trust your system clock accuracy.
Dependencies
TODO. Basically the same dependencies as for building the gstreamer-plugins-base packages.
Building
# Assuming you're in the project root
# Option A is to use the submodule to fetch the GStreamer sources:
git submodule update --init --recursive
# Older versions require deleting the builddir and omitting the '--reconfigure' option
meson setup --reconfigure builddir
# Option B is to use an existing GStreamer source by specifying the 'gst_root' (the GStreamer mono-repo root)
# meson setup --reconfigure builddir -Dgst_root=${WHERE_I_CLONED_GSTREAMER}/gstreamer
meson compile -C builddir
# This will install the built plugin file
meson install -C builddir
# Confirm installation
gst-inspect-1.0 | grep msoverlay
Verification
This should show you a fairly extensive list of options and details:
gst-inspect-1.0 msoverlay
Author & License
LGPL-2.1 or whatever newer license GStreamer uses. Please see the LICENSE file for the full text.
Please see the upstream project for a full list of authors, at:
https://gitlab.freedesktop.org/gstreamer/gstreamer
Modifications done specific to this plugin by Stefan Hamminga stefan@rbts.co / rbts.co.
Repository
The project can be found here: