An unexpected change in the maximum fps get from gstreamer pipeline

[d.zhovtukhin]

Hello, I am trying to use gstreamer to read video from usb cameras from python code on Jetson Orin Nano. I use 2 pipelines for different cameras with same model. I need same fps on both cameras. Ideally 30 fps but 20 is also fine.

My command for one camera looks like:

v4l2src device=/dev/video0 io-mode=2 name=source ! image/jpeg, width=640, height=480, type=video, framerate=30/1 ! jpegdec ! videoconvert ! video/x-raw, format=RGB ! appsink max-buffers=1 drop=True name=appsink0

At first everything was working fine, both pipelines were returning 30 fps, but at some moment one of them permanently dropped to 15 fps. I was able to get fps lower than 15 (for example 10) but not higher. I tried multiple times with different pipeline commands. Next, I connected camera with this problem to some program on Windows where I was able to get 30 fps stream from it. After that gstreamer pipeline also started returning images in 30fps on Jetson but another camera decreased to 25 fps. I still can get images lower than 25fps from it but not 30 even if I use framerate=30/1.

Could you please explain what is going on and how to prevent from this behavior? Thanks

[DaneLLL]

Hi,
Since jpegdec and videoconvert plugins use CPU, please execute sudo jetson_clocks to run CPU cores at maximum clock. And please try gst-launch-1.0 command and see if the issue it present:

$ gst-launch-1.0 -v v4l2src device=/dev/video0 io-mode=2 name=source ! image/jpeg, width=640, height=480, type=video, framerate=30/1 ! jpegdec ! videoconvert ! video/x-raw, format=RGB ! fpsdisplaysink text-overlay=0 video-sink=fakesink sync=0

To clarify if it is specific to using appsink

[d.zhovtukhin]

Thanks for the answer. Your command let me get 30fps on both cameras. Also after that I was able read data from two cameras at 30fps from python using my previous command.

So I need to change appsink in my pipeline to avoid similar problems in the future?

[DaneLLL]

Hi,
Please set appsink sync=0 and check if it helps. Ideally if appsink doesn’t hold the buffers longer than expected, it should be able to achieve target frame rate.