> Either update your kernel headers or add the following > line to /usr/include/linux/videodev2.h: > #define V4L2_PIX_FMT_H264 v4l2_fourcc('H', '2', '6', '4') > yes, you are right! After I add the line, then V4L2_PIX_FMT_H264 has been defined, thank you very much!