Hi Eunhye,
I can provide you the below links, hope will be in help:
http://processors.wiki.ti.com/index.php/DM81xx_Gstreamer_FAQ#Do_we_have_a_gst-OMX_element_to_capture_live_video_on_the_DM8148_EVM_board
http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/236216.aspx
http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/200419.aspx
Best regards,
Pavel