Environment:
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Libva:          
(staging)8be6d274d931d8041934efa63caaee75a5984755
Libva_intel_driver:             (staging)bd630edd844b88ea543a027654db296ff7da16cd

Command line:
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1. /opt/X11R7/bin/avcenc 720 576 iceage_720x576_491.yuv iceage_720x576_491.yuv.enc.h264 qp=44 mode=0
2. /root/media_tools/encoder/ldecod.exe -i iceage_720x576_491.yuv.enc.h264 -o iceage_720x576_491.yuv.jm.dump -r iceage_720x576_491.yuv
3. get the psnr value:
   /root/media_tools/encoder/metrics_calc_lite.ia32e -i1 iceage_720x576_491.yuv -i2 iceage_720x576_491.yuv.jm.dump -w 720 -h 576 -nopfm psnr y

Bug Info:
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-It happened when the qp value is equal or gt 40, mode=0, 1, 2;
-The following data is produced from the above command(mode=0);
        h264_size   bitrate  y-psnr
-ivb    3299058     1574     28.87887
-hsw    3561618     1700     28.88024

Besides, gst10_AVC_cqp_encoding had lower pass rate than IVB:
                   HSW         IVB
mode=0            84/84       84/84
mode=1            81/84       84/84
mode=2            74/84       84/84
Cases failed when qp value is bigger than 40 or 44 as well as using avcenc encoding, and mode=2 has the most impact.