dm8168 encode question

hi:
I use ezsdk of ti-ezsdk_dm816x-evm_5_03_01_15,and I try to encode h264 video file on the dm8168,but I am comfused about that frames in the file are not continuous ,I use the example in SDK,
1.   ./omtb_dm81xxbm_a8host.xv5T  fread_venc_fwrite.oms
2.   ./capture_encode_a8host_debug.xv5T -o sample.h264 -m 1080p -f 60 -b 1000000 -n 1000 -d 1

the two ways encode h264 file that frames are not continuous,the playback screen is not smooth， why? how to solve the question ,thanks.