DM8148 H264 forward and backward

Hello, Ti major:
 I have some development issues need your help.
 
 I develop the function on DM8148. My package version is DVRRDK_02_00_00_23.
 I execute the demo function, use-case 6, to display 4 channels H.264 decoder.
 And I need to implement the forward and backward function(1/2X, 2X, 4X, 8X, 16X) of playback the H264 video file.
 Is there any reference entry point of this function?
 
 Thanks for your answer.