I would like to compile to following program: With the flages: -lavcodec -lavutil -lavfilter -lavformat -lswscale -lz #include "libavcodec/avcodec.h" #include "libavformat/avformat.h" #include "libswscale/swscale.h" #include <stdio.h> // The flush packet is a non-NULL packet with size 0 and data NULL int decode(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *pkt) { int ret; *got_frame = 0; if (pkt) { ret = avcodec_send_packet(avctx, pkt); // In particular, we don't expect AVERROR(EAGAIN), because we read all // decoded frames with avcodec_receive_frame() until done. if (ret < 0) return ret == AVERROR_EOF ? 0 : ret; } ret = avcodec_receive_frame(avctx, frame); if (ret < 0 && ret != AVERROR(EAGAIN) && ret != AVERROR_EOF) return ret; if (ret >= 0) *got_frame = 1; return 0; } int main(int argc, char *argv[]) { return 0; But I receive: undefined reference to `avcodec_send_packet' undefined reference to `avcodec_receive_frame' ffmpeg version is: ffmpeg version 3.2.4 Copyright (c) 2000-2017 the FFmpeg developers built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609 configuration: libavutil 55. 34.101 / 55. 34.101 libavcodec 57. 64.101 / 57. 64.101 libavformat 57. 56.101 / 57. 56.101 libavdevice 57. 1.100 / 57. 1.100 libavfilter 6. 65.100 / 6. 65.100 libswscale 4. 2.100 / 4. 2.100 libswresample 2. 3.100 / 2. 3.100 Does some one know, Whats the problem? -- Yosef Alon