Linux/TMS320DM8148: Encode video issue in H.264 Encoder 2.0 on HDVICP2

Part Number: TMS320DM8148

Tool/software: Linux

Output clip format is : size 1280x720 Target bitrate=6M, Max bitrate = 9Mbps
Input SDI clip1 format : size 1280x720 bitrate < 300kbps
Input SDI clip2 format : size 1280x720 bitrate > 1Mbps

I encode 9 minutes video.
First 7 minutes is clip1,
when I change clip2,
the video becomes a lot of squares.

When I modify the IH264ENC_RateControlParams
qpMaxP to 20,
the video is okey,
but the output video size becomes much bigger.

reference :
H.264 Encoder 2.0 on HDVICP2 and Media Controller Based Platform User’s Guide
Page 124
usermanual.wiki/.../qpMaxP_5F00_20.mp4:1230:0]H264EncoderHDVICP2UserGuide.1956946871.pdf