Improve H265 compression artifacts in video recording

[Lettie]

Hi all. I am a beginner that started using gstreamer recently and I’m looking for advice.
I am using Leopard Imaging IMX390 cameras on my Jetson to record from a vehicle and I noticed in my captures that the quality of the video drops significantly when the vehicle is going faster. I’m attaching a frame here to show what I mean. From the look I assume that the most likely cause is compression artifacts in my recording pipeline.

I would like to ask if anyone has any tips or suggestions to improve the quality of the video. I would like to reach a point where every frame looks good enough to be processed and doesn’t show this heavy compression.

This is my pipeline at the moment:

gst-launch-1.0 -v \
nvarguscamerasrc sensor-id=0 num-buffers=18000 ! 'video/x-raw(memory:NVMM), width=(int)1920, height=(int)1080, format=(string)NV12, framerate=(fraction)30/1' ! \
nvv4l2h265enc control-rate=1 bitrate=8000000 ! 'video/x-h265, stream-format=(string)byte-stream' ! \
h265parse ! qtmux ! filesink location=video.mp4

What are the changes that would be worth trying or that would be the most effective? For example increase the bit-rate, use constant bit rate, use different encoders in the gstreamer pipeline?
If anyone has any tips from similar applications I’d be grateful to hear about it.

[DaneLLL]

Hi,
We suggest run in CBR mode and tune virtual buffer size. Please take a look at
Random blockiness in the picture RTSP server-client -Jetson TX2 - #5 by DaneLLL

[Lettie]

Thank you very much! I’ll try this out!
As a general question, how much does the tuning of the H265 encoding affects the recordings performance?
I mean that I have been able to record 4 gmsl cameras without problem using the code above, would changing to CBR mode and virtual buffer size add a lot more load on the CPU or not change it significantly?

[DaneLLL]

Hi,
Setting CBR + virtual buffer size can balance the frame size and provide better PSNR. So suggest you give it a try.

Since there are individual hardware encoders in Xavier NX, you should not see CPU loading increase.