I am recently working on a new Python CV project, which requires connecting to about 30-50 cameras, on a dual-A4000 (Edge) EGX Server hardware configuration. We chose to use DeepStream SDK to do so, even though we don’t infer using DeepStream.
The original problem
Using OpenCV, connecting to these cameras and querying frames causes high CPU usage (Connecting to cameras is done through nimble RTSP, currently using H264 codec - hopefully we’ll be using H265 in the future, each camera is FHD, 12-25FPS).
To solve this problem, we’ve decided to use NVDEC to accelerate video decoding.
First of all, we’ve tried using GStreamer with nvdec plugin on OpenCV, which didn’t work at all - so we transitioned to DeepStream on Python.
Using DeepStream on Pythonwe had great results (on a SINGLE GPU, we got 40 streams on 12FPS, with 20% CPU on a single core) - but we did had to strip down some layers of the deepstream-imagedata-multistream example (those which has things to do with inference).
After stripping down inference-related elements (nvosd, nvinfer, and so on), The resulted pipeline is:
If there is no “nvstreammux”, most DeepStream plugins are not useful for you because they are all working on batch data. Only “nvvideoconvert”, “nvv4l2videodec”, “nvv4l2h264enc”, “nvv4l2h265en” are useful.
In this matter, I will keep the nvstreammux to make our application future-proof, because we’re in the process of inspecting optical flow algorithms (and we might use nvof), and we might use DeepStream for YOLOv5 inference in the future (Using TensorRT).
We’re currently looking into the best options for querying camera frames using hardware - with less complexity, So using the SDK for development is not relevant for us. We have tried FFMpeg, but we had some issues with it, and OpenCV (of course) doesn’t help too much in this issue.
As for the nvstreammux element - does it work with multiple frame sizes in the same batch? For example, if I have some cameras in FHD resolution, and some in 720p, can I connect them all to the mux without concerns? If not, can I scale the frame sizes before that?
Is frame scaling possible down the pipeline anyway (for faster nvof or TRT nvinfer)?
There is no update from you for a period, assuming this is not an issue anymore.
Hence we are closing this topic. If need further support, please open a new one.
nvstreammux will scale all input videos into the resolution you defined by “width” and “height” properties. You don’t need to do anything except to assign the “width” and “height” properties of nvstreammux. Gst-nvstreammux — DeepStream 6.1.1 Release documentation
Please read the document carefully.