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• avcodec/x86/videodsp : Remove obsolete MMX, 3dnow, SSE functions

  12 juin 2022, par Andreas Rheinhardt

  avcodec/x86/videodsp : Remove obsolete MMX, 3dnow, SSE functions
  x64 always has MMX, MMXEXT, SSE and SSE2 and this means
  
  that some functions for MMX, MMXEXT, SSE and 3dnow are always
  
  overridden by other functions (unless one e.g. explicitly
  
  disables SSE2). So given that the only systems which benefit
  
  from these functions are truely ancient 32bit x86s they are removed.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/x86/videodsp.asm
  • [DH] libavcodec/x86/videodsp_init.c

• arm : Detect 32 bit cpu features on ARMv8 when running on a 64 bit kernel

  23 juin 2014, par Martin Storsjö

  arm : Detect 32 bit cpu features on ARMv8 when running on a 64 bit kernel
  When running on a 64 bit kernel, /proc/cpuinfo lists different
  
  optional features than on 32 bit kernels (because some of them
  
  are mandatory in the 64 bit implemenations).
  The kernel does list the old features properly if they are queried
  
  via /proc/self/auxv though - however this file is not always readable
  
  (e.g. on most android systems). The getauxval function could also
  
  provide the same info as /proc/self/auxv even if this file isn’t
  
  readable, but this function is not always available (and thus would
  
  need to be loaded with dlsym for compatibility with older android
  
  versions).
  The android cpufeatures library does this slightly differently,
  
  by assuming that these are available if the "CPU architecture"
  
  line is >= 8, see [1] for details.
  It has been suggested to include the old, non-optional features in
  
  /proc/cpuinfo as well, but that suggested patch never was merged.
  
  See [2] for the discussion around this suggestion.
  [1] https://android-review.googlesource.com/91380
  
  [2] http://marc.info/?l=linux-arm-kernel&m=139087240101974
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavutil/arm/cpu.c

• ffmpeg 64bit Xcode

  16 février 2013, par Lupurus

  I'm trying to use the ffmpeg libraries in Xcode on Mac. I want to address to 64bit-systems like Lion and Mountain Lion. I tried to compile with

  ./configure --enable-static --enable-nonfree --enable-version3 --enable-gpl --disable-doc --disable-programs --arch=x86_64 --cc=cc --disable-yasm --host-cflags="-arch x86_64" --host-ldflags="-arch x86_64" --prefix=ffmpeg

  Then I copied the ffmpeg-directory (with lib and include folders) into my project folder. I added the .a-files to my project and added the .a files to "Link binaries with Libraries"). Also I adjusted the header and library folder in the project settings. So far so good.

  I'm a beginner with those libraries, so I started with opening a video. Works fine.

  Now I'm trying to decode a given input file. Therefore I looked at this example file : http://ffmpeg.org/doxygen/1.0/decoding__encoding_8c-source.html

  I copied the video_decode_example function. But at compiling I'm getting the following error :

  Undefined symbols for architecture x86_64:
  
    "_decode_write_frame", referenced from:
  
      _video_decode_example in cutClass.o
  
  ld: symbol(s) not found for architecture x86_64

  What did I wrong at compiling ffmpeg ?