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• Weird cross platform support in ffmpeg

  31 mai 2022, par LmTinyToon

  I tried to build ffmpeg 4.4 library and link with it and I received multiple unresolved references. I came across on unusual architecture in ffmpeg for multiple platforms.The library has many places with code like this :

  


  void foo()
{
    // DO SOMETHING
    if (ARCH_MIPS) // maybe #if ARCH_MIPS (...) #endif should be used instead?
         foo_mips(...);
    if (ARCH_PPC)
        foo_ppc(c);
    if (ARCH_ARM)
         foo_arm(...);
    if (ARCH_AARCH64)
        foo_aarch64(...);
}


  


  This code leads to linker errors because there is no any stub methods for other platforms. I observed root MakeFile, it optionally includes platform dependent code for each library (path like $(LIB_SUBDIR)/$(ARCH)/MakeFile) where each foo_<arch></arch> is defined.

  


  So, how does it work ? In my opinion preprocessor directive #if should be used, otherwise we will receive unresolved reference on any platform. Maybe I missed something ? because this code appears frequently for example :

  


  

  1. utils.c : ff_yuv2rgb_init_tables_ppc

  


  2. swscale_unscaled.c : ff_get_unscaled_swscale_ppc, ff_get_unscaled_swscale_arm, ff_get_unscaled_swscale_aarch64

  


  3. cpu.c : ff_get_cpu_max_align_x86, ff_get_cpu_max_align_mips

  


  4. float_dsp.c : ff_float_dsp_init_aarch64, ff_float_dsp_init_ppc, ff_float_dsp_init_x86

  


  5. etc.

  


  


• cross compiling ffmpeg with conan fails : x86_64-w64-mingw32-ld : unrecognised emulation mode : 64

  6 février, par ovni jeroqui

  I'm trying to install ffmpeg (and some other libraries, but ffmpeg alone fails too) with conan to cross compile from linux (ubuntu) to windows.

  


  Conan throws an error on Running configure, inside build(). It says that x86_64-w64-mingw32-gcc is unable to create an executable file..

  


  On the config log I discovered it's because of a flag when running tests for x86_64-w64-mingw32-ld.

  


  x86_64-w64-mingw32-ld -m64 -L/home/jeroqui/.conan2/p/b/freetd8d522cfe5ed9/p/lib -L/home/jeroqui/.conan2/p/b/libsv9862cce477f3c/p/lib -L/home/jeroqui/.conan2/p/b/opensf32bb84148b27/p/lib -L/home/jeroqui/.conan2/p/b/vorbib2efb2d738443/p/lib -L/home/jeroqui/.conan2/p/b/libpn1c271e119251a/p/lib -L/home/jeroqui/.conan2/p/b/dav1d0798c06f2d7c3/p/lib -L/home/jeroqui/.conan2/p/b/libaoec0c6ff69236b/p/lib -L/home/jeroqui/.conan2/p/b/cpuin94c00ccfd6939/p/lib -L/home/jeroqui/.conan2/p/b/zlib09a824ccbeb0e/p/lib -L/home/jeroqui/.conan2/p/b/libwedcd84ab019a17/p/lib -L/home/jeroqui/.conan2/p/b/libfdbad6e447d67d4/p/lib -L/home/jeroqui/.conan2/p/b/libmpeb5a9a1a779c7/p/lib -L/home/jeroqui/.conan2/p/b/libvp0218afdff461c/p/lib -L/home/jeroqui/.conan2/p/b/libx2ec0d07d4a0565/p/lib -L/home/jeroqui/.conan2/p/b/libx23198ed0a549b9/p/lib -L/home/jeroqui/.conan2/p/b/opus8d5d63e1681f3/p/lib -L/home/jeroqui/.conan2/p/b/ogg813050272864b/p/lib -L/home/jeroqui/.conan2/p/b/openh3680a2c5cc945/p/lib -L/home/jeroqui/.conan2/p/b/openj09e5e15be595a/p/lib -L/home/jeroqui/.conan2/p/b/brotl58bc227a041f8/p/lib -L/home/jeroqui/.conan2/p/b/bzip2e67b6fd4c7720/p/lib -L/home/jeroqui/.conan2/p/b/libic229c7a1dc80e2/p/lib -L/home/jeroqui/.conan2/p/b/xz_ut8375de634122a/p/lib -m64 -o /tmp/ffconf.eAkkSIml/test.exe /tmp/ffconf.eAkkSIml/test.o
x86_64-w64-mingw32-ld: unrecognised emulation mode: 64
Supported emulations: i386pep i386pe
C compiler test failed.


  


  I've tried to get conan to not add the -m64 flag, but I haven't been able to get it working. Setting env variables like LDFLAGS= doesn't seam to work either on the conan profile, on the conanfile.py or directly on my terminal. Any suggestions ?

  


• How To Stream Video File Cross Browser On Same URL

  18 novembre 2015, par Qasim Khokhar

  I am trying to make Video Streaming Application, I have a controller which can stream mp4 video which is not working with Firefox.

  def get(self, request):
  
  
  
          filename = 'uploads/SampleVideo_1080x720_1mb.mp4' # Select your file here.
  
          wrapper = FileWrapper(file(filename))
  
          response = StreamingHttpResponse(wrapper, content_type='video/ogg; multipart/x-mixed-replace; boundary=frame')
  
          response['Content-Length'] = os.path.getsize(filename)
  
  
  
          return response

  if anyone can guide me to make it for different browsers ll be appreciated.

  actually i want to send stream encoding according to browser or client. dynamically. i am new in python.

  which technique is used by Youtube : how youtube serves videos on blob:https%3A//www.youtube.com/456e268f-bdfe-4ce7-8368-6b646a3ec5e8 what is blob :