AnsweredAssumed Answered

USB 3.0 performance on iMX8M

Question asked by jerome bolduc on Dec 5, 2018
Latest reply on Dec 6, 2018 by jerome bolduc

Hello,

We just received the iMX8M EVK using the NXP image v4.9.88 and we have some issues with the USB 3.0 bandwidth. When using a UVC camera in order to capture video using the following pipeline, we do not achieve the frame rate.

>> gst-launch-1.0 v4l2src device=/dev/video1 ! video/x-raw,width=1920,height=1080,framerate=60/1 ! fpsdisplaysink text-overlay=false sync=false -v

We are getting about 20-25 fps.

However, when we remove the rendering onscreen using the following pipeline:

>> gst-launch-1.0 v4l2src device=/dev/video1 ! video/x-raw,width=1920,height=1080,framerate=60/1 ! fpsdisplaysink video-sink="fakesink sync=false" text-overlay=false sync=false -v

We are getting 37 fps. This pipeline only challenges the USB 3.0 port.

Do you know why we are getting this limitation? Is the USB 3.0 port should be able to handle 1080p60 YUY2, i.e. 250 MB/s?

 

I remember we were using a iMX6 board with a USB 3.0 to PCIe bridge (Renesas chipset) and we were getting similar results. We were wondering if the iMX8 had increased the xhci performance. Looking at our results, it is not the case.

 

Thanks,

Jérôme

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