title: error: undefined reference to 'av_free_packet(AVPacket*)' when use NDK to compile ffmpeg
body: <p>I compiled my cpps to use ffmpeg liberary with ANDROID NDK by my android MK as follow :</p>
  
  <pre><code>    LOCAL_PATH := $(call my-dir)
      DEFINES += -DTARGET_POSIX \
                 -DTARGET_LINUX \
             -D_LINUX \
             -DTARGET_ANDROID \
             -D__STDC_CONSTANT_MACROS 
  
      include $(CLEAR_VARS)  
      LOCAL_MODULE := libavcodec
      LOCAL_SRC_FILES := lib/lib/libavcodec.so 
      include $(PREBUILT_SHARED_LIBRARY)  
  
      include $(CLEAR_VARS)  
      LOCAL_MODULE := libavfilter  
      LOCAL_SRC_FILES := lib/lib/libavfilter.so 
      include $(PREBUILT_SHARED_LIBRARY)  
  
      include $(CLEAR_VARS)  
      LOCAL_MODULE := libavformat  
      LOCAL_SRC_FILES := lib/lib/libavformat.so  
      include $(PREBUILT_SHARED_LIBRARY)  
  
      include $(CLEAR_VARS)  
      LOCAL_MODULE := libavutil  
      LOCAL_SRC_FILES := lib/lib/libavutil.so  
      include $(PREBUILT_SHARED_LIBRARY)  
  
      include $(CLEAR_VARS)  
      LOCAL_MODULE := libpostproc  
      LOCAL_SRC_FILES := lib/lib/libpostproc.so   
      include $(PREBUILT_SHARED_LIBRARY)  
  
      include $(CLEAR_VARS)  
      LOCAL_MODULE := libswresample  
      LOCAL_SRC_FILES := lib/lib/libswresample.so   
      include $(PREBUILT_SHARED_LIBRARY)  
  
      include $(CLEAR_VARS)  
      LOCAL_MODULE := libswscale  
      LOCAL_SRC_FILES := lib/lib/libswscale.so
      include $(PREBUILT_SHARED_LIBRARY)  
  
      include $(CLEAR_VARS)
      LOCAL_MODULE:= player
      base := $(LOCAL_PATH)
      LOCAL_SRC_FILES += cores/PlayDemux.cpp \
                     cores/PlayDemuxFFmpeg.cpp \
                     cores/PlayFactoryDemuxer.cpp
  
      LOCAL_C_INCLUDES += $(LOCAL_PATH) \
              $(LOCAL_PATH)/lib \
              $(LOCAL_PATH)/lib/include \
              $(LOCAL_PATH)/cores/player \
      LOCAL_CPPFLAGS += -Wall -fexceptions $(DEFINES)
      include $(BUILD_STATIC_LIBRARY)
  
      include $(CLEAR_VARS)
      LOCAL_MODULE:= testmain
  
      LOCAL_SRC_FILES := \
          testmain.cpp \
  
      LOCAL_C_INCLUDES += $(LOCAL_PATH) \
                  $(LOCAL_PATH)/lib 
      LOCAL_CPPFLAGS += -Wall -fexceptions $(DEFINES)
  
      LOCAL_SHARED_LIBRARIES := libavcodec \
                  libavformat \
                  libavfilter \
                  libavutil \
                  libpostproc \
                  libswscale \
                  libswresample 
  
      LOCAL_STATIC_LIBRARIES := player 
  
      include $(BUILD_EXECUTABLE)
  </code></pre>
  
  <p>but when i do "ndk-build v=1", After compiling, I got :</p>
  
  <pre><code>    Install        : libavcodec.so =&gt; libs/armeabi-v7a/libavcodec.so
      install -p /cygdrive/d/player/obj/local/armeabi-v7a/libavcodec.so /cygdrive/d/player/libs/armeabi-v7a/libavcodec.so
      /cygdrive/d/android/android-ndk-r8e/toolchains/arm-linux-androideabi-4.6/prebuilt/windows/bin/arm-linux-androideabi-strip --strip-unneeded D:/player/libs/armeabi-v7a/libavcodec.so
      Install        : libavfilter.so =&gt; libs/armeabi-v7a/libavfilter.so
      install -p /cygdrive/d/player/obj/local/armeabi-v7a/libavfilter.so /cygdrive/d/player/libs/armeabi-v7a/libavfilter.so
      /cygdrive/d/android/android-ndk-r8e/toolchains/arm-linux-androideabi-4.6/prebuilt/windows/bin/arm-linux-androideabi-strip --strip-unneeded D:/player/libs/armeabi-v7a/libavfilter.so
      Install        : libavformat.so =&gt; libs/armeabi-v7a/libavformat.so
      install -p /cygdrive/d/player/obj/local/armeabi-v7a/libavformat.so /cygdrive/d/player/libs/armeabi-v7a/libavformat.so
      /cygdrive/d/android/android-ndk-r8e/toolchains/arm-linux-androideabi-4.6/prebuilt/windows/bin/arm-linux-androideabi-strip --strip-unneeded D:/player/libs/armeabi-v7a/libavformat.so
      Install        : libavutil.so =&gt; libs/armeabi-v7a/libavutil.so
      install -p /cygdrive/d/player/obj/local/armeabi-v7a/libavutil.so /cygdrive/d/player/libs/armeabi-v7a/libavutil.so
      /cygdrive/d/android/android-ndk-r8e/toolchains/arm-linux-androideabi-4.6/prebuilt/windows/bin/arm-linux-androideabi-strip --strip-unneeded D:/player/libs/armeabi-v7a/libavutil.so
      Install        : libpostproc.so =&gt; libs/armeabi-v7a/libpostproc.so
      install -p /cygdrive/d/player/obj/local/armeabi-v7a/libpostproc.so /cygdrive/d/player/libs/armeabi-v7a/libpostproc.so
      /cygdrive/d/android/android-ndk-r8e/toolchains/arm-linux-androideabi-4.6/prebuilt/windows/bin/arm-linux-androideabi-strip --strip-unneeded D:/player/libs/armeabi-v7a/libpostproc.so
      Install        : libswresample.so =&gt; libs/armeabi-v7a/libswresample.so
      install -p /cygdrive/d/player/obj/local/armeabi-v7a/libswresample.so /cygdrive/d/player/libs/armeabi-v7a/libswresample.so
      /cygdrive/d/android/android-ndk-r8e/toolchains/arm-linux-androideabi-4.6/prebuilt/windows/bin/arm-linux-androideabi-strip --strip-unneeded D:/player/libs/armeabi-v7a/libswresample.so
      Install        : libswscale.so =&gt; libs/armeabi-v7a/libswscale.so
      install -p /cygdrive/d/player/obj/local/armeabi-v7a/libswscale.so /cygdrive/d/player/libs/armeabi-v7a/libswscale.so
      /cygdrive/d/android/android-ndk-r8e/toolchains/arm-linux-androideabi-4.6/prebuilt/windows/bin/arm-linux-androideabi-strip --strip-unneeded D:/player/libs/armeabi-v7a/libswscale.so
      Executable     : testmain
      /cygdrive/d/android/android-ndk-r8e/toolchains/arm-linux-androideabi-4.6/prebuilt/windows/bin/arm-linux-androideabi-g++  -Wl,--gc-sections  -Wl,-z,nocopyreloc  --sysroot=D:/android/android-ndk-r8e/platforms/android-14/arch-arm  D:/player/obj/local/armeabi-v7a/objs/testmain/testmain.o D:/player/obj/local/armeabi-v7a/libplayer.a D:/android/android-ndk-r8e/sources/cxx-stl/stlport/libs/armeabi-v7a/libstlport_static.a -lgcc D:/player/obj/local/armeabi-v7a/libavcodec.so D:/player/obj/local/armeabi-v7a/libavformat.so D:/player/obj/local/armeabi-v7a/libavfilter.so D:/player/obj/local/armeabi-v7a/libavutil.so D:/player/obj/local/armeabi-v7a/libpostproc.so D:/player/obj/local/armeabi-v7a/libswscale.so D:/player/obj/local/armeabi-v7a/libswresample.so  -no-canonical-prefixes -march=armv7-a  -Wl,--fix-cortex-a8  -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now    -lc -lm  -o D:/player/obj/local/armeabi-v7a/testmain
      D:/android/android-ndk-r8e/toolchains/arm-linux-androideabi-4.6/prebuilt/windows/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld.exe: D:/player/obj/local/armeabi-v7a/libplayer.a(PlayDemuxFFmpeg.o): in function PlayDemuxFFmpeg::Flush():D:/player/jni/lib/DllAvCodec.h:144: error: undefined reference to 'av_free_packet(AVPacket*)'
  </code></pre>
  
  <p>I´m using windows 7 + cygwin + NDKR8,but the lib "libavcodec.so ,libavfilter.so,libavformat.so,libavutil.so,libpostproc.so,libswresample.so,libswscale.so " of ffmpeg was compiled with standalone mothed of NDK using "ubuntu + NDK8".
  and i include the extern "c" code in the head file.</p>
  
  <p>so, how to correct the error ? </p>
  
  <p>my DLLavcodec.h is :</p>
  
  <pre><code>#pragma once
  #include "DllAvUtil.h"
  
  extern "C" {
    #include &lt;libavcodec/avcodec.h&gt;
  }
  
  
  class DllAvCodec : public DllAvCodecInterface
  {
  public:
    static CCriticalSection m_critSection;
  
    virtual ~DllAvCodec() {}
    virtual void avcodec_register_all()
    {
      ::avcodec_register_all();
    }
    virtual void avcodec_flush_buffers(AVCodecContext *avctx) { ::avcodec_flush_buffers(avctx); }
    virtual int avcodec_open2(AVCodecContext *avctx, AVCodec *codec, AVDictionary **options)
    {
      return ::avcodec_open2(avctx, codec, options);
    }
    virtual int avcodec_open2_dont_call(AVCodecContext *avctx, AVCodec *codec, AVDictionary **options) { *(volatile int *)0x0 = 0; return 0; }
    virtual int avcodec_close_dont_call(AVCodecContext *avctx) { *(volatile int *)0x0 = 0; return 0; }
    virtual AVCodec *avcodec_find_decoder(enum CodecID id) { return ::avcodec_find_decoder(id); }
    virtual AVCodec *avcodec_find_encoder(enum CodecID id) { return ::avcodec_find_encoder(id); }
    virtual int avcodec_close(AVCodecContext *avctx)
    {
      return ::avcodec_close(avctx);
    }
    virtual AVFrame *avcodec_alloc_frame() { return ::avcodec_alloc_frame(); }
    virtual int avpicture_fill(AVPicture *picture, uint8_t *ptr, PixelFormat pix_fmt, int width, int height) { return ::avpicture_fill(picture, ptr, pix_fmt, width, height); }
    virtual int avcodec_decode_video2(AVCodecContext *avctx, AVFrame *picture, int *got_picture_ptr, AVPacket *avpkt) { return ::avcodec_decode_video2(avctx, picture, got_picture_ptr, avpkt); }
    virtual int avcodec_decode_audio4(AVCodecContext *avctx, AVFrame *frame, int *got_frame_ptr, AVPacket *avpkt) { return ::avcodec_decode_audio4(avctx, frame, got_frame_ptr, avpkt); }
    virtual int avcodec_decode_subtitle2(AVCodecContext *avctx, AVSubtitle *sub, int *got_sub_ptr, AVPacket *avpkt) { return ::avcodec_decode_subtitle2(avctx, sub, got_sub_ptr, avpkt); }
    virtual int avcodec_encode_audio(AVCodecContext *avctx, uint8_t *buf, int buf_size, const short *samples) { return ::avcodec_encode_audio(avctx, buf, buf_size, samples); }
    virtual int avcodec_encode_audio2(AVCodecContext *avctx, AVPacket *avpkt, const AVFrame *frame, int *got_packet_ptr) { return ::avcodec_encode_audio2(avctx, avpkt, frame, got_packet_ptr); }
    virtual int avpicture_get_size(PixelFormat pix_fmt, int width, int height) { return ::avpicture_get_size(pix_fmt, width, height); }
    virtual AVCodecContext *avcodec_alloc_context3(AVCodec *codec) { return ::avcodec_alloc_context3(codec); }
    virtual void avcodec_string(char *buf, int buf_size, AVCodecContext *enc, int encode) { ::avcodec_string(buf, buf_size, enc, encode); }
    virtual void avcodec_get_context_defaults3(AVCodecContext *s, AVCodec *codec) { ::avcodec_get_context_defaults3(s, codec); }
  
    virtual AVCodecParserContext *av_parser_init(int codec_id) { return ::av_parser_init(codec_id); }
    virtual int av_parser_parse2(AVCodecParserContext *s,AVCodecContext *avctx, uint8_t **poutbuf, int *poutbuf_size,
                      const uint8_t *buf, int buf_size,
                      int64_t pts, int64_t dts, int64_t pos)
    {
      return ::av_parser_parse2(s, avctx, poutbuf, poutbuf_size, buf, buf_size, pts, dts, pos);
    }
    virtual void av_parser_close(AVCodecParserContext *s) { ::av_parser_close(s); }
  
    virtual AVBitStreamFilterContext *av_bitstream_filter_init(const char *name) { return ::av_bitstream_filter_init(name); }
    virtual int av_bitstream_filter_filter(AVBitStreamFilterContext *bsfc,
      AVCodecContext *avctx, const char *args,
      uint8_t **poutbuf, int *poutbuf_size,
      const uint8_t *buf, int buf_size, int keyframe) { return ::av_bitstream_filter_filter(bsfc, avctx, args, poutbuf, poutbuf_size, buf, buf_size, keyframe); }
    virtual void av_bitstream_filter_close(AVBitStreamFilterContext *bsfc) { ::av_bitstream_filter_close(bsfc); }
  
    virtual void avpicture_free(AVPicture *picture) { ::avpicture_free(picture); }
    virtual void av_free_packet(AVPacket *pkt) { ::av_free_packet(pkt); }
    virtual int avpicture_alloc(AVPicture *picture, PixelFormat pix_fmt, int width, int height) { return ::avpicture_alloc(picture, pix_fmt, width, height); }
    virtual int avcodec_default_get_buffer(AVCodecContext *s, AVFrame *pic) { return ::avcodec_default_get_buffer(s, pic); }
    virtual void avcodec_default_release_buffer(AVCodecContext *s, AVFrame *pic) { ::avcodec_default_release_buffer(s, pic); }
    virtual enum PixelFormat avcodec_default_get_format(struct AVCodecContext *s, const enum PixelFormat *fmt) { return ::avcodec_default_get_format(s, fmt); }
    virtual AVCodec *av_codec_next(AVCodec *c) { return ::av_codec_next(c); }
  
    virtual int av_dup_packet(AVPacket *pkt) { return ::av_dup_packet(pkt); }
    virtual void av_init_packet(AVPacket *pkt) { return ::av_init_packet(pkt); }
    virtual int avcodec_fill_audio_frame(AVFrame *frame, int nb_channels, enum AVSampleFormat sample_fmt, const uint8_t *buf, int buf_size, int align) { return ::avcodec_fill_audio_frame(frame, nb_channels, sample_fmt, buf, buf_size, align); }
    virtual void avcodec_free_frame(AVFrame **frame) { return ::avcodec_free_frame(frame); };
  };
  </code></pre>