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• clang++ : error : linker command failed with exit code 1 (use -v to see invocation) in cpp with ffmpeg

  6 avril 2020, par Pradeep Simba

  clang++: error: linker command failed with exit code 1 (use -v to see invocation)


  



  I saw this link and link2. But, it not done.

  



  My jni folder :

  



  

  



  Android.mk file

  



  LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_C_INCLUDES += ./include
LOCAL_MODULE     := native-lib
LOCAL_CFLAGS := -DSTDC_HEADERS -std=c99
LOCAL_CFLAGS := -Wno-pointer-sign
LOCAL_ARM_MODE := arm
APP_OPTIM := release
LOCAL_SRC_FILES  := \
./native-lib.cpp
LOCAL_LDLIBS := -llog
include $(BUILD_SHARED_LIBRARY)


  



  native-lib.cpp file

  



  #include &#xA;#include <string>&#xA;&#xA;extern "C"&#xA;{&#xA;#include "libavcodec/avcodec.h"&#xA;#include "libavformat/avformat.h"&#xA;#include "libavutil/opt.h"&#xA;}&#xA;&#xA;extern "C" JNIEXPORT jstring JNICALL&#xA;Java_com_example_m_MainActivity_stringFromJNI(&#xA;JNIEnv* env,&#xA;jobject /* this */) {&#xA;std::string hello = "Hello from C&#x2B;&#x2B;";&#xA;av_register_all();&#xA;return env->NewStringUTF(hello.c_str());&#xA;}&#xA;</string>

  



  When I build ndk this error occurs.

  



  D:\Github\n>ndk-build
Android NDK: APP_PLATFORM not set. Defaulting to minimum supported version android-16.
[arm64-v8a] Compile++      : native-lib <= native-lib.cpp
[arm64-v8a] SharedLibrary  : libnative-lib.so
./obj/local/arm64-v8a/objs/native-lib/./libmp3lame/native-lib.o: In function `Java_com_example_m_MainActivity_stringFromJNI':
D:\Github\n/jni/./libmp3lame/native-lib.cpp:16: undefined reference to `av_register_all'
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [D:/install/sdk/ndk/21.0.6113669/build//../build/core/build-binary.mk:725: obj/local/arm64-v8a/libnative-lib.so] Error 1

D:\Github\n>ndk-build -v
GNU Make 4.2.1
Built for x86_64-w64-mingw32
Copyright (C) 1988-2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later /gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

D:\Github\n>


  



  why it comes like this native-lib.cpp:16: undefined reference av_register_all ?

  



  I added all the required libs in my jni folder but, why this error and this native-lib.cpp:16: undefined reference av_register_all comes ?
How can I solve this ?

  


• clang++ : error : linker command failed with exit code 1 (use -v to see invocation) [duplicate]

  1er avril 2020, par Pradeep Simba

  When I build ndk with ffmpeg it occurs error.

  



  

  



  Android.mk file

  



  LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_C_INCLUDES += ./include
LOCAL_MODULE     := native-lib
LOCAL_CFLAGS := -DSTDC_HEADERS -std=c99
LOCAL_CFLAGS := -Wno-pointer-sign
LOCAL_ARM_MODE := arm
APP_OPTIM := release
LOCAL_SRC_FILES  := \
./native-lib.cpp
LOCAL_LDLIBS := -llog
include $(BUILD_SHARED_LIBRARY)


  



  native-lib.cpp file

  



  #include &#xA;#include <string>&#xA;&#xA;extern "C"&#xA;{&#xA;#include "libavcodec/avcodec.h"&#xA;#include "libavformat/avformat.h"&#xA;#include "libavutil/opt.h"&#xA;}&#xA;&#xA;extern "C" JNIEXPORT jstring JNICALL&#xA;Java_com_example_m_MainActivity_stringFromJNI(&#xA;    JNIEnv* env,&#xA;    jobject /* this */) {&#xA;std::string hello = "Hello from C&#x2B;&#x2B;";&#xA;av_register_all();&#xA;return env->NewStringUTF(hello.c_str());&#xA;}&#xA;</string>

  



  When I build ndk this error occurs.

  



  

  



  D:\Github\n>ndk-build
Android NDK: APP_PLATFORM not set. Defaulting to minimum supported version android-16.
[arm64-v8a] Compile++      : native-lib <= native-lib.cpp
[arm64-v8a] SharedLibrary  : libnative-lib.so
./obj/local/arm64-v8a/objs/native-lib/./libmp3lame/native-lib.o: In function `Java_com_example_m_MainActivity_stringFromJNI':
D:\Github\n/jni/./libmp3lame/native-lib.cpp:16: undefined reference to `av_register_all'
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [D:/install/sdk/ndk/21.0.6113669/build//../build/core/build-binary.mk:725: obj/local/arm64-v8a/libnative-lib.so] Error 1

D:\Github\n>ndk-build -v
GNU Make 4.2.1
Built for x86_64-w64-mingw32
Copyright (C) 1988-2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later /gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

D:\Github\n>


  



  why it comes like this native-lib.cpp:16: undefined reference av_register_all ?

  



  I added all the required libs in my jni folder . but, why this error and this native-lib.cpp:16 : undefined reference av_register_all comes ?

  



  How can I solve this ?

  


• ffplay does not exit in forked child

  6 septembre 2019, par user12030145

  ffplay  -autoexit does not exit in a forked child

  I need to pipe my application (stdout) to ffplay (stdin). I do this by forking ffplay as a child and using -i pipe:0 as argument.

  #include 
  
  #include 
  
  #include <sys></sys>types.h>
  
  #include <sys></sys>wait.h>
  
  
  
  int main(int argc, const char** argv)
  
  {
  
  int tube[2];
  
  int c;
  
  FILE* f = fopen(argv[1], "rb");
  
  pid_t pid;
  
  if (argc &lt; 2) return -1;
  
  if (pipe(tube))  {
  
      perror("Pipe");
  
      return -1;
  
    }
  
  
  
  // main process cats a .mlp file to stdout, sent to a child ffplay stdin through a pipe
  
  char* const arg[] = {"-i", "pipe:0", "-f", "mlp", "-nodisp", "-autoexit", NULL};
  
  switch (pid = fork())    {
  
              case -1:
  
                  fprintf(stderr,"%s\n", "Could not launch ffplay");
  
                  break;
  
  
  
              case 0:
  
                  close(tube[1]);
  
                  dup2(tube[0], STDIN_FILENO);
  
                  execv("/usr/bin/ffplay", arg);
  
                  fprintf(stderr, "%s\n", "Runtime failure in ffplay child process");
  
                  return -2;
  
  
  
              default:
  
                  close(tube[0]);
  
                  dup2(tube[1], STDOUT_FILENO);
  
          }
  
  
  
  // Here the main process code sending the .mlp file to stdout...
  
  
  
  while ((c = fgetc(f)) != EOF) putchar(c);
  
  
  
  waitpid(pid, NULL, 0);
  
  fclose(f);
  
  
  
  // main never returns
  
  return 0;
  
  }

  The issue is that in this context, ffplay -autoexit never exits (GNU-Linux platform). In a main process, ffplay -autoexit always exits at the end of a media file.
  Is there a pure C workaround without using system, popen or scripting ?
  Is this a feature or a bug of ffplay (I cannot tell) ?