NValhalla - a DeepStream demo in Vala

NValhalla performs live redactions on multiple video streams. It is written in Genie, a Vala dialect. Vala is recommended by the gstreamer team for those who want syntactic sugar on top of their GObject C.


  • a GstRtspServer based sink (output) based on Nvidia’s python example code.
  • redaction model and buffer callback is from Nvidia’s deepstream redaction example
  • uridecodebin based sources, so any uri:// should work as input including file:///path/to/video.mp4
  • creates a config folder at ~/.nvalhalla with an inference config, models and .dot files

Many thanks to DaneLLL, amycao, ChrisDing, carolyuu, and the rest of the DeepStream team I might be forgetting for helping me resolve the various issues I ran into writing this app.

It is not very optimized as of yet, so it will run best on a Xavier, however, the next thing I plan on doing is making an int8 calibration file (right now the model is fp32) which should greatly improve the performance.

Please report any issues you run into on the project’s github issue tracker.

v0.1.2 is released.

x86 Docker support is now added. All that is needed is Nvidia Docker and you can do:

docker run --gpus all -p 8554:8554 --rm mdegans/nvalhalla --uri $(youtube-dl -f best -g https://www.youtube.com/watch?v=awdX61DPWf4) --uri $(youtube-dl -f best -g https://www.youtube.com/watch?v=FPs_lU01KoI) --uri $(youtube-dl -f best -g https://www.youtube.com/watch?v=SnMBYMOTwEs) --uri $(youtube-dl -f best -g https://www.youtube.com/watch?v=jYusNNldesc)

(this assumes youtube-dl is installed on the host, otherwise substitute urls such as rtsp streams can be used)

The sink defaults to RTSP in Docker, so you may connect to the output with VLC or with gst-play like this:

gst-play-1.0 rtsp://hostname:8554/nvalhalla

Where “hostname” is the hostname of your docker host.