B frames not recommended in nvv4l2h265enc gstreamer plugin

Running gst-inspect-1.0 nvv4l2h265enc shows:

  num-B-Frames        : Number of B Frames between two reference frames (not recommended)(Supported only on Xavier)
                        flags: readable, writable, changeable only in NULL or READY state
                        Unsigned Integer. Range: 0 - 2 Default: 0

I am wondering why this setting is “(not recommended)”.

In our tests we see worse video quality when B frames are present, so by default we encode into I/P frames. Yo may enable B frames and check if PSNR is good and meets the expectation.

For comparing PSNR please refer to
Random blockiness in the picture RTSP server-client -Jetson TX2 - #5 by DaneLLL

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