编译程序 报错 undefined reference to `avcodec_encode_video2'

Question

交叉编译 ffmepg opencv 成功后，编译程序，报错：
../lib/opencv/libopencv_videoio.a(cap_ffmpeg.cpp.o): In function icv_av_write_frame_FFMPEG(AVFormatContext*, AVStream*, unsigned char*, unsigned int, AVFrame*) [clone .isra.5]': cap_ffmpeg.cpp:(.text._ZL25icv_av_write_frame_FFMPEGP15AVFormatContextP8AVStreamPhjP7AVFrame.isra.5+0x24): undefined reference to av_init_packet'
cap_ffmpeg.cpp:(.text._ZL25icv_av_write_frame_FFMPEGP15AVFormatContextP8AVStreamPhjP7AVFrame.isra.5+0x44): undefined reference to avcodec_encode_video2' cap_ffmpeg.cpp:(.text._ZL25icv_av_write_frame_FFMPEGP15AVFormatContextP8AVStreamPhjP7AVFrame.isra.5+0x74): undefined reference to av_rescale_q'
cap_ffmpeg.cpp:(.text._ZL25icv_av_write_frame_FFMPEGP15AVFormatContextP8AVStreamPhjP7AVFrame.isra.5+0x94): undefined reference to av_rescale_q' cap_ffmpeg.cpp:(.text._ZL25icv_av_write_frame_FFMPEGP15AVFormatContextP8AVStreamPhjP7AVFrame.isra.5+0xac): undefined reference to av_rescale_q'
cap_ffmpeg.cpp:(.text._ZL25icv_av_write_frame_FFMPEGP15AVFormatContextP8AVStreamPhjP7AVFrame.isra.5+0xc4): undefined reference to av_write_frame' cap_ffmpeg.cpp:(.text._ZL25icv_av_write_frame_FFMPEGP15AVFormatContextP8AVStreamPhjP7AVFrame.isra.5+0xd0): undefined reference to av_packet_unref'
../lib/opencv/libopencv_videoio.a(cap_ffmpeg.cpp.o): In function `CvCapture_FFMPEG::init()':

Answer 1

编译时找不到所需的ffmpeg库函数，你看看有没有正确安装ffmpeg和opencv库