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• x86inc : Optimize VEX instruction encoding

  31 mars 2018, par Henrik Gramner

  x86inc : Optimize VEX instruction encoding
  Most VEX-encoded instructions require an additional byte to encode when src2
  
  is a high register (e.g. x|ymm8..15). If the instruction is commutative we
  
  can swap src1 and src2 when doing so reduces the instruction length, e.g.
      vpaddw xmm0, xmm0, xmm8 -> vpaddw xmm0, xmm8, xmm0
  

  • [DH] common/x86/x86inc.asm

• Macros in C++ / FFMPEG

  26 mars 2020, par Derrick Heimerdinger

  I’m new to C++ and I’m trying to build a custom codec for FFMPEG. I’m trying to base it off of PCM but with only one type. I’ve run into a macro and I have no idea what the macro turns into after it compiles.
  The macro looks like this :

  #define ENCODE_PLANAR(type, endian, dst, n, shift, offset)          \
  
  n /= avctx->channels;                                               \
  
  for (c = 0; c < avctx->channels; c++) {                             \
  
      int i;                                                          \
  
      samples_ ## type = (const type *) frame->extended_data[c];      \
  
      for (i = n; i > 0; i--) {                                       \
  
          register type v = (*samples_ ## type++ >> shift) + offset;  \
  
          bytestream_put_ ## endian(&dst, v);                         \
  
      }                                                               \
  
  }

  Would the samples_ declaration line and bytestream_put line be equal to what I put below if endian = byte and type = uint8_t ?

  uint8_t samples_ = (const uint8_t *) frame->extended_data[c];
  
  bytestream_put_byte(&dst, v);

  I find it very confusing and I am unsure if this is correct.

• FFMPEG command doesn't work in PHP. (Incompatibilty with MAMP)

  15 mars 2016, par Charlie Ryan

  I’m a bit of a beginner when it comes to PHP, and I’m trying to create a simple(ish) system where files are input, and then converted to html5 video in various resolutions.

  I’ve sorted out how to handle multiple file uploads etc, but now I’m having a problem.

  I can’t seem to get exec to execute FFMPEG in PHP.

  For example, if I type this into my command line (Terminal on Mac OSX 10.8), It converts the video correctly :

  ffmpeg -i /Users/charlieryan/Desktop/MOV01785.MPG websample.mov

  This correctly outputs the converted video file into my home directory.

  However if I run this in PHP as follows :

  exec('ffmpeg -i /Users/charlieryan/Desktop/MOV01785.MPG websample.mov');

  Absolutely nothing happens ... my stat monitor doesn’t register any change in processor use, and I can’t find the output file anywhere on my system.

  Since I’m a bit of a noob at this, I’m assuming I’m doing something wrong, but what is it ?

  Thanks,

  Charlie