videotestsrc Creates a test video stream @GST_VIDEO_TEST_SRC_SMPTE: @GST_VIDEO_TEST_SRC_SNOW: @GST_VIDEO_TEST_SRC_BLACK: @GST_VIDEO_TEST_SRC_WHITE: @GST_VIDEO_TEST_SRC_RED: @GST_VIDEO_TEST_SRC_GREEN: @GST_VIDEO_TEST_SRC_BLUE: @GST_VIDEO_TEST_SRC_CHECKERS1: @GST_VIDEO_TEST_SRC_CHECKERS2: @GST_VIDEO_TEST_SRC_CHECKERS4: @GST_VIDEO_TEST_SRC_CHECKERS8: @GST_VIDEO_TEST_SRC_CIRCULAR: