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• FFMpeg on Android, undefined references to libavcodec functions, although it is listed on command line

  24 mars 2019, par dimsuz

  I have a problem with unresolved references to ffmpeg’s libavcodec functions, so far failed to find the answer in other places (including my mind) :)

  Let me describe my setup - it takes space, but is really basic, it might be that I’m failing to see some error...

  I built an FFMPeg with ndk r5 toolchain, ffmpeg port I got from http://bambuser.com/opensource (as recommended in other questions here). It built fine, so I put several static libraries in my project like this :

  <project>/jni/bambuser_ffmpeg/libavcodec.a
  
  <project>/jni/bambuser_ffmpeg/libavformat.a
  
  <project>/jni/bambuser_ffmpeg/libavcore.a
  
  <project>/jni/bambuser_ffmpeg/libavutil.a
  
  </project></project></project></project>

  Next, I created an Android.mk in bambuser_ffmpeg folder to list these libs as a prebuilt ones :

  LOCAL_PATH := $(call my-dir)
  
  
  
  include $(CLEAR_VARS)
  
  LOCAL_MODULE := bambuser-libavcore
  
  LOCAL_SRC_FILES := libavcore.a
  
  include $(PREBUILT_STATIC_LIBRARY)
  
  
  
  include $(CLEAR_VARS)
  
  LOCAL_MODULE := bambuser-libavformat
  
  LOCAL_SRC_FILES := libavformat.a
  
  include $(PREBUILT_STATIC_LIBRARY)
  
  
  
  (same for other two libs)

  Next, I have another module which references these libs in its Android.mk, sets up include paths, etc :

  LOCAL_PATH := $(call my-dir)
  
  
  
  include $(CLEAR_VARS)
  
  
  
  LOCAL_MODULE := ffmpegtest
  
  LOCAL_STATIC_LIBRARIES := bambuser-libavcodec bambuser-libavcore bambuser-libavformat bambuser-libavutil
  
  LOCAL_SRC_FILES := ffmpeg_test.cpp
  
  LOCAL_C_INCLUDES := $(LOCAL_PATH)/../bambuser_ffmpeg/include
  
  LOCAL_LDLIBS    := -llog -lz
  
  
  
  include $(BUILD_SHARED_LIBRARY)

  And finally I have my ffmpeg_test.cpp which is really basic, like this :

  #include 
  
  
  
  extern "C" {
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  }
  
  
  
  extern "C" {
  
      JNIEXPORT jint JNICALL Java_com_the7art_ffmpegtest_PaintThread_testFFMpeg(JNIEnv* env, jobject obj, jstring fileName);
  
  }
  
  
  
  JNIEXPORT jint JNICALL Java_com_the7art_ffmpegtest_PaintThread_testFFMpeg(JNIEnv* env, jobject obj, jstring fileName)
  
  {
  
      av_register_all();
  
      return 0;
  
  }

  When I run ndk-build, it compiles fine, but when linking it prints an unresolved reference to almost every function in libavcodec. Looks like only this lib’s functions are failing to be located :

  /home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(allformats.o): In function `av_register_all':
  
  /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/allformats.c:47: undefined reference to `avcodec_register_all'
  
  /home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o): In function `parse_frame_rate':
  
  /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:3240: undefined reference to `av_parse_video_rate'
  
  /home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o): In function `parse_image_size':
  
  /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:3234: undefined reference to `av_parse_video_size'
  
  /home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o): In function `flush_packet_queue':
  
  /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:1277: undefined reference to `av_free_packet'
  
  /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:1283: undefined reference to `av_free_packet'
  
  /home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o): In function `get_audio_frame_size':
  
  /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:766: undefined reference to `av_get_bits_per_sample'
  
  /home/dimka/src/mobile/android/ffmpegtest/obj/local/armeabi/libavformat.a(utils.o): In function `ff_interleave_add_packet':
  
  /home/dimka/work/suzy/tmp/ffmpeg-android/ffmpeg/libavformat/utils.c:2909: undefined reference to `av_dup_packet'
  
  and so on...

  I fail to figure why this is happening. I tried running ndk-build V=1 to check the actual linking command, and libavcodec is sitting there perfectly right, like it should. All other ffmpeg libs are there too.

  Any hints ?

• Map the second stream when the first stream ends in FFMPEG

  20 août 2021, par Cencode

  I have three ffmpeg commands. First one is used to stream a video.

  


  ffmpeg -re -i /home/Channel/1.mp4 -f mpegts "udp://236.2.2.4:2000"


  


  Second stream will send a looping image.

  


  ffmpeg -loop 1 -i /home/Channel/black.png -c:v libx264 -tune stillimage -shortest -f mpegts "udp://236.2.2.4:2001"


  


  I have a third ffmpeg command to map the above two streams and select a one for the output.

  


  ffmpeg -i "udp://236.2.2.4:2000" -i "udp://236.2.2.4:2001" -map 0 -map 1 -f mpegts "udp://236.1.1.4:2000"


  


  From this ffmpeg command first stream will be played.
Will it be possible to chose the second stream automatically once the first stream is finished ?

  


• Compile ffmpeg, opus & x265 for android

  6 juin 2014, par weter

  I’m trying to compile ffmpeg with libx265 & libopus, but I can’t configure opus with

  ./configure --target=armv7-android-gcc  --sdk-path=/home/weter/android/android-ndk-r9d
  
  configure: error: unrecognized option: `--sdk-path=/home/weter/android/android-ndk-r9d'

  And x265 project based on cmake, but I never compile using cmake for Android.