video capturing - high CPU usage

[tirankas]

Hello,
We are using the l4t, 32.5.0 branch, for capturing video from a 13mp camera (4192*3120) to v4l2.
We get a high CPU usage (100% of a single core) for the capturing as well as video is not well streamed for ~10 minutes.
After 10 minutes the CPU usage goes down to ~30% and video goes pretty well.

I tried looking at the gstreamer logs but didn't see anything suspicious, looking at both when it lags and when it starts playing right, logs looks the same.

I am trying to understand what is the flow I should be checking (v4l2, gstreamer, omx), any specific hw acceleration I should be looking for etc.

Anyone aware of such behavior?
Where should I start? Maybe this should go to the gstreamer folks?

Thanks

[tirankas]

Adding:
Running: gst-inspect-1.0 |grep omx
I get nothing.

Running the same on the Nvidia Ubuntu image I get several omx.

What am I missing?
hwcodecs are part of my image recipe, gstreamer1.0-omx-tegra is being picked up in my build and the crresponding lib is part of my image.

Thanks

[madisongh]

You should start by finding out why it's been blacklisted:

$ rm -rf ~/.cache/gstreamer-1.0
$ GST_DEBUG_NO_COLOR=1 GST_DEBUG=4 gst-inspect-1.0 -b &> /tmp/gst.log

Then inspect the log file to see what errors occurred when it tried to load the omx plugin.

[tirankas]

Hi Matt,
I found a fix you did long ago (64600fd#diff-f60f85ee8e4ca2b4fe637b18a7676ce6afee64e36047656b62f0f034be661598) for the exact same issue.
I see this patch is no longer taken and wonder how did you conclude the issue in the first place so that I can check myself on the latest branch.

Thanks

[madisongh]

That was a very long time ago, in a pre-release version of the BSP. I think NVIDIA fixed the build problem that caused me to add that patch as a workaround.

[tirankas]

Progressing a bit:

gst-inspect-1.0 libgstomx.so
Plugin Details:
Name libgstomx.so
Description Plugin for blacklisted file
Filename /usr/lib/gstreamer-1.0/libgstomx.so
Version 0.0.0
License BLACKLIST
Source module BLACKLIST
Binary package BLACKLIST
Origin URL BLACKLIST

0 features:

Where is this blacklist coming from?

Also this:
sudo gst-inspect-1.0 /usr/lib/gstreamer-1.0/libgstomx.so
Plugin Details:
Name omx
Description GStreamer OpenMAX Plug-ins
Filename /usr/lib/gstreamer-1.0/libgstomx.so
Version 1.0.0
License LGPL
Source module gst-omx
Source release date 2013-03-22
Binary package GStreamer OpenMAX Plug-ins source release
Origin URL Unknown package origin

omxmpeg4videodec: OpenMAX MPEG4 Video Decoder
omxh264dec: OpenMAX H.264 Video Decoder
omxh265dec: OpenMAX H.265 Video Decoder
omxvp8dec: OpenMAX VP8 Video Decoder
omxvp9dec: OpenMAX VP9 Video Decoder
omxmpeg2videodec: OpenMAX MPEG2 Video Decoder
omxwmvdec: OpenMAX WMV Video Decoder
omxh264enc: OpenMAX H.264 Video Encoder
omxh265enc: OpenMAX H.265 Video Encoder
omxvp8enc: OpenMAX VP8 Video Encoder
omxvp9enc: OpenMAX VP9 Video Encoder
nvoverlaysink: OpenMax Video Sink

12 features:
+-- 12 elements

[madisongh]

See my comment above. gstreamer will blacklist any plugin that it can't load and initialize. Looking at the error messages that get produced during that process should point you in the right direction.

[madisongh]

I'd also recommend looking at the Accelerated GStreamer chapter of the L4T documentation for more information about the tegra-specific plugins.

[tirankas]

HI Matt,
Apparently there was no issue with the omx plugin.
It doesn't list omx when running the command without sudo.
Running the gst inspect command with a sudo shows omx.

Back to square 1, still need to figure out why capturing from a camera (v4l2) consumes 90% cpu...

Thanks

[dwalkes]

@tirankas you might want to try cross-posting on the NVIDIA developer forum if you haven't already. I typically reproduce with the stock L4T release and no customizations first.