The CPU keeps rising when I use h264-nvmpi with this jetson-ffmpeg

[katehe]

I build FFmpeg with this jetson-ffmpeg, and the build is success, and h264-nvmpi works too.
But the CPU keeps rising when and never stops anyway.
I tried ffmpeg-6.1.2 and ffmpeg-8.0.
They both have the same CPU-rising problem.
My test FFmpeg command is 'ffmpeg -c:v h264_nvmpi -i input -f null -'.

As the testing time went on, the CPU usage kept increasing.
When decoding, the GPU usage is not 0, and NVDEC frequence if 1.2GHz.

Does anyone meet this problem and know what the reason is ?

[Keylost]

Hi! Which NVIDIA board are you using, and which JetPack version?
How quickly does the CPU load increase?
Does the load rise on just one core or across all cores?
How did you measure this?
If the decoding process runs long enough, will the CPU usage reach 100% across all cores?
What are the parameters of the input video you're using?

I tried decoding a video with the following parameters:
"Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc, bt709, progressive), 2464x2056, 16443 kb/s, 25 fps, 25 tbr, 90k tbn (default), Duration: 00:35:37.24"
on a Jetson AGX Orin (mode MaxN + jetson_clocks) with JetPack 6.2 and FFmpeg 8.0.
The video was fully decoded in (elapsed=0:04:56.41).
CPU usage remained roughly the same on average throughout the process.

[katehe]

I use NVIDIA Jetson-AGX - [L4T 35.6.0] JetPack version 5.1.4
At first, the CPU increased by 1%-5% per second, and later by 0.1%-0.3% per second, and then 0.1% every 2 seconds.
I measure this use jtop and see the total CPU% output of the process ffmpeg.
When the decoding process runs long enough, the CPU usage reach 100% and even more.
Not all cores increase and only one or two cores.

The parameters of the input video is:
1.input1.mp4: Video:h264(High) avc1 yuv420p 3840x2160 60fps.
2.input2.mp4: Video:h264(High) avc1 yuv420p 1920x1080 30fps.
Both of these two resolutions of streams have this problem.
The 1080p stream increase slowly than the 4K stream.

When I use -c:v h264 soft decode the 4K stream input1.mp4, the CPU also increase by at frist the 40% per second later 3% per second.The total CPU of FFmpeg reached more than 500% quickly.

When I use -c:v h264_nvmpi hard decode the same 4K stream, the total CPU reached more than 100% then.

h264_nvmpi seems to be working, the frame content doesn't have much change. It's also not a picture running very fast.
Why the cpu never stop during the mp4 file time 00:07:35.