Create a usecase with the following links:
CaptureLink->ipcFramesOut(M3VPSS) -> ipcFramesIn(HOST/A8)/
You will then receive the YUV frames on A8. The physical address will be populated. Use mmap to get user virtual pointer for the physical address and write to file.
Refer /dvr_rdk/demos/link_api_sd_demo/sd_demo/SD_demo_ipc_frames_exch.c for example code.