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• Compiling ffmpeg : how to force it to link to a specific libx264 ?

  29 août 2012, par PaulJ

  I'm trying to compile the newest version of ffmpeg (in CentOS 5.3). I first downloaded the latest version of libx264, compiled it with --enable-static and installed it in /usr/local/. However, when I then compile ffmpeg I get this error message :

  libavcodec/libavcodec.a(libx264.o): In function `X264_init':
  
  /usr/local/src/ffmpeg/libavcodec/libx264.c:494: undefined reference to `x264_encoder_open_125'
  
  collect2: ld returned 1 exit status
  
  make: *** [ffmpeg_g] Error 1

  Searching on the net, I see that this can happen if ffmpeg is picking up an older version of libx264, which I indeed have (in /usr/lib) and can't uninstall because other pieces of software depend on it. The question is then : how can I force ffmpeg to link against the libx264 that I want ? The last time I had to do this (admittedly a year ago) I also had 2 versions of libx264, and I don't remember having to do anything special. Is there a configure switch that I'm forgetting ?

• FFMPEG for Android - missing alsa format

  24 août 2012, par user1545779

  @rowntreerob has an android-ffmpeg implementation that build successfully using the default file settings.

  When you remove disble-avdevice and disbale-devices from the configure_ffmpeg script, ndk-build fails. The following is the error message :

  CP ffmpeg
  STRIP ffmpeg
   /android-ffmpeg/Project/jni
   /android-ffmpeg/Project/jni
   /android-ffmpeg/Project/jni
  jasongipsyblues@android-master : /android-ffmpeg/Project/jni$ ndk-build
  Compile thumb : ffmpeg <= ffmpeg.c
  Compile thumb : ffmpeg <= cmdutils.c
  Executable : ffmpeg
  /home/jasongipsyblues/android-ffmpeg/Project/obj/local/armeabi- >v7a/objs/ffmpeg/ffmpeg/ffmpeg.o : In function `main' :

  /home/jasongipsyblues/android-ffmpeg/Project/jni/ffmpeg/ffmpeg.c:6130 : undefined >reference to `avdevice_register_all'
  

  /home/jasongipsyblues/android-ffmpeg/Project/obj/local/armeabi- >v7a/objs/ffmpeg/ffmpeg/cmdutils.o : In function `print_all_libs_info' :

  /home/jasongipsyblues/android-ffmpeg/Project/jni/ffmpeg/cmdutils.c:639 : undefined >reference to `avdevice_configuration'

  /home/jasongipsyblues/android-ffmpeg/Project/jni/ffmpeg/cmdutils.c:639 : undefined >reference to `avdevice_version'
  
  collect2 : ld returned 1 exit status

  make : ** [/home/jasongipsyblues/android-ffmpeg/Project/obj/local/armeabi-v7a/ffmpeg] >Error 1

  Please pardon my poor formating skills, I still dont get the formating thing. It appears the deletion of the references is to avdevices is definitely affecting the use of ndk-build.

  All the alsa source files exist in the ffmpeg code. How does one build ffmpeg in such a way that alsa is included in the formats ?

• Need help correcting Access Violation with FFmpeg DLL

  26 septembre 2012, par James

  I'm trying to use the FFmpeg dll's using Visual Studio 2012 and I'm getting a run time access violation when I call avcodec_find_encoder. Here is the code :

  // TestFFmpeg.cpp : Defines the entry point for the console application.
  
  //
  
  
  
  #include "stdafx.h"
  
  
  
  extern "C" {
  
  #include "libavcodec\avcodec.h"
  
  #include "libavformat\avformat.h"
  
  }
  
  
  
  #define INBUF_SIZE 4096
  
  
  
  int _tmain(int argc, _TCHAR* argv[])
  
  {
  
      AVCodec *codec;
  
  
  
      const char *videoFilename = "C:\\Users\\Public\\Videos\\Sample Videos\\Wildlife.wmv";
  
  
  
      av_register_all(); // This works; however, no parameters or return values.
  
  
  
      codec = avcodec_find_encoder(CODEC_ID_WMV3);  // Run time Access Violation HERE
  
      if (!codec) {
  
      fprintf(stderr, "Codec not found\n");
  
          exit(1);
  
      }
  
  
  
      return 0;
  
  }

  Here is the error message :

  Unhandled exception at 0x75C18B60 (msvcrt.dll) in TestFFmpeg.exe : 0xC0000005 : Access violation reading location 0x00000049.

  The stack trace is :

      msvcrt.dll!_strcmp()    Unknown
  
      avcodec-54.dll!6a56caac()   Unknown
  
      [Frames below may be incorrect and/or missing, no symbols loaded for avcodec-54.dll]    
  
  >   TestFFmpeg.exe!wmain(int argc, wchar_t * * argv) Line 23    C++
  
      TestFFmpeg.exe!__tmainCRTStartup() Line 533 C
  
      TestFFmpeg.exe!wmainCRTStartup() Line 377   C
  
      kernel32.dll!@BaseThreadInitThunk@12()  Unknown
  
      ntdll.dll!___RtlUserThreadStart@8() Unknown
  
      ntdll.dll!__RtlUserThreadStart@8()  Unknown

  I'm guessing there's a problem with returning the codec pointer, but I'm new to C++ and have no idea how to correct it. I tried the cdecl, stdcall, and fastcall calling conventions — none corrected the issue. I'm using the latest 32-bit DLL from Zeranoe. Any suggestions ?

  EDIT :
  I've called other functions in the DLL and they work. For example, avformat_open_input works properly. I can pass parameters and the function returns a successful return value (0) and populates the format context structure. av_find_stream_info works as well. I still can't figure out why avcodec_find_decoder creates an access violation.