Inquiring About Compute Impact of Fractional Downscale on Jetson Orin NX

[OZD]

Hi NVIDIA Community,

I’ve been working with fractional downscaling on an Jetson Orin NX and have noticed that it tends to increase the compute load significantly. As a result, I’m sometimes unable to maintain the desired FPS. I’m wondering if anyone here has encountered similar issues and if there’s a reference table or documentation that outlines the compute impact for different fractional downscaling ratios on the Jetson Orin.

Any insights or guidance would be greatly appreciated!

[DaneLLL]

Hi,
Please share more information about fractional downscale. We don’t know much about the software stacks.

You can run sudo tegrastats to check if it used GPU engine or CPU cores.

[OZD]

Downscale is fractional if its ratio is non-integer. For example, doing downscale to video from 5MP to 2MP:
original: 2560 x1920 and the output is 1920 x1080
Width downscale ratio: 2560/1920 = 1.333
Heigh downscale ratio: 1920/1080 = 1.778

[DaneLLL]

Hi,
On Jetson devices, there is hardware converter which can do downscaling. It is supported in gstreamer and jetson_miltimedia_api. Which interface is used in your use-case?

[OZD]

We use gstreamer.

[DaneLLL]

Hi,
Please share the gstreamer pipeline for reference. We can check and suggest next.

[OZD]

After we internally re-checked it, we found neglectable difference when the downscale factor is fractional vs non-fractional (using VIC).

Thanks,
Oz

PS: gstreamer pipeline example:

gst-launch-1.0 -e rtspsrc location=rtsp://$username:$password\!@${ip}:554/${stream_url} ! application/x-rtp, media=video, encoding-name=H265 ! queue ! rtph265depay ! h265parse ! nvv4l2decoder ! nvvidconv ! "video/x-raw(memory:NVMM),width=${width},height=$height" ! nvv4l2h264enc ! h264parse ! mp4mux ! filesink location=${output}