tmx3
January 6, 2018, 2:09am
1
This is a follow up discussion of Newbie question: how to install OpenCV and setup the path? - Jetson TX2 - NVIDIA Developer Forums
gst-launch-1.0 nvcamerasrc ! 'video/x-raw(memory:NVMM), format=NV12, width=640, height=480, framerate=30/1' ! tee name=yourname ! queue ! nvvidconv ! 'video/x-raw' ! xvimagesink yourname. ! queue ! nvegltransform ! nveglglessink
which produces two streams of videos from a camera.
How to feed a second camera to the second display window?
In general, what’s the “tee” command that can feed (and perhaps “sync” if possible) multiple video streams?
If you want to send one camera to one window and a second one to a second window without having interactions between both streams, probably the easiest way is to launch two gstreamer pipelines (here I use videotestsrc as second source because I only have the onboard camera):
gst-launch-1.0 nvcamerasrc ! nvvidconv ! 'video/x-raw, format=I420, width=640, height=480' ! xvimagesink | gst-launch-1.0 videotestsrc ! 'video/x-raw, format=I420, width=640, height=480' ! xvimagesink
or
gst-launch-1.0 nvcamerasrc ! nvvidconv ! 'video/x-raw, format=I420, width=640, height=480' ! xvimagesink videotestsrc ! 'video/x-raw, format=I420, width=640, height=480' ! xvimagesink
tee would just duplicate a stream at the point it is in the pipeline.
The opposite may be done with videomixer that can mix two sources:
gst-launch-1.0 -ev videomixer name=mix sink_0::xpos=0 sink_1::xpos=640 ! xvimagesink nvcamerasrc sensor-id=0 ! 'video/x-raw(memory:NVMM), width=(int)640, height=(int)480, format=(string)I420, framerate=(fraction)30/1' ! nvvidconv ! 'video/x-raw, format=I420' ! mix.sink_0 videotestsrc ! 'video/x-raw, width=(int)640, height=(int)480, format=(string)I420, framerate=(fraction)30/1' ! mix.sink_1
Hi tmx3,
You can launch second pipeline with different source.
If you don’t quite understand display windows of tegra, please also ask.
tmx3
January 9, 2018, 1:25am
4
@WayneWWW , thanks for the direction. I’m still struggling about where to insert the second source in the pipeline. Say I have two cameras, one is at sensor-id=0, and the other is at sensor-id=5.
Here is the command I tried:
gst-launch-1.0 nvcamerasrc sensor-id=0 ! ‘video/x-raw(memory:NVMM), format=NV12, width=640, height=480, framerate=30/1’ ! tee name=yourname ! queue ! nvvidconv ! ‘video/x-raw’ ! xvimagesink yourname. ! queue ! nvcamerasrc sensor-id=5 ! ‘video/x-raw(memory:NVMM), width=640, height=480, framerate=30/1, format=NV12’ ! nvoverlaysink
But it failed with a prompt:
WARNING: erroneous pipeline: could not link queue1 to nvcamerasrc1
Can you tell what’s wrong in the command?
Not sure why you are using tee… the error is that queue tries to output into nvcamerasrc which is a pure source, it has no input. Simply try
gst-launch-1.0 nvcamerasrc sensor-id=0 ! 'video/x-raw(memory:NVMM), format=NV12, width=640, height=480, framerate=30/1' ! nvvidconv ! 'video/x-raw' ! xvimagesink nvcamerasrc sensor-id=5 ! 'video/x-raw(memory:NVMM), width=640, height=480, framerate=30/1, format=NV12' ! nvoverlaysink
However, nvoverlaysink may use the full screen, not sure you’ll be able to see the xvimagesink window. This may be easier:
gst-launch-1.0 nvcamerasrc sensor-id=0 ! 'video/x-raw(memory:NVMM), format=NV12, width=640, height=480, framerate=30/1' ! nvvidconv ! 'video/x-raw' ! xvimagesink nvcamerasrc sensor-id=5 ! 'video/x-raw(memory:NVMM), width=640, height=480, framerate=30/1, format=NV12' ! nvoverlaysink overlay-w=640 overlay-h=480
tmx3
January 9, 2018, 7:07pm
6
@Honey_patouceul , it works! Thanks for showing the details. As far as using “tee” or not, it’s not really a concern. I just wanted to find a way to display two cameras in a single command.
Using “nvoverlaysink” will set the display at a fixed position. I found that “nveglglessink” can be used as well if a floating window is desirable. Here is the command:
gst-launch-1.0 nvcamerasrc sensor-id=0 ! ‘video/x-raw(memory:NVMM), format=NV12, width=640, height=480, framerate=30/1’ ! nvvidconv ! ‘video/x-raw’ ! xvimagesink nvcamerasrc sensor-id=5 ! ‘video/x-raw(memory:NVMM), width=640, height=480, framerate=30/1, format=NV12’ ! nvvidconv flip-method=0 ! nvegltransform ! nveglglessink