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• x264 library speed - Altivec vs SSE4 -

  15 août 2015, par Asain Kujovic

  I have simple cheap dualcore intel-3ghz-debian and access to super-expensive powerPc7-Aix.

  And after few days of strugle, i compiled libx264 and tested it on both computers :

  1. GCC : library x264 on intel (with SSE2 capabilities) and
  2. GCC on 16 core powerPc (with altivec).

  ... and result is that cheap intel is x2 times faster ! (with altivec disabled, intel is 10x times faster)

  My question : is this normal ?
  Does all other powerPC-users have same results ? Can powerPc-altivec-optimisation of x264 library work at same speed with intel... or MMX/SSE optimisation is officially at least 2 times faster for this library ?

  I am not interested in multi-thread options. Number of cores and threads are irrelevant. Just simple one-thread x264 encoding with default "medium preset" using rawvideo as source, sse vs altivec.

  Maybe native Aix XLC compiler provide better results ? (i managed only gcc to work)

  ... mac-powerpc-users maybe know something about this.

  powrPc7-Aix:$ time (cat raw10sec.y4m |x264 --input-res 720x576 --fps 50 -o /dev/null -)
  
  x264: 64-bit XCOFF
  
  x264 [info]: using cpu capabilities: Altivec
  
  time: real 0m33.559s
  
  ---
  
  intelDebian:$ time (cat raw10sec.y4m |x264 --input-res 720x576 --fps 50 -o /dev/null -)
  
  x264: ELF 32-bit LSB executable
  
  x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.1 Cache64
  
  time: real 0m16.503s

• PNG sequence to MP4 while looping the animation

  19 avril 2016, par user245115

  So, I’m trying to convert a PNG sequence to an MP4 and loop the animation about 100 times, the only problem is my script doesn’t seem to be working properly.

  What the script is supposed to do is get the number of PNG files in the frames directory, and send them to FFMPEG 100 times. Only problem is my script isn’t working right. Here’s the code.

  #!/bin/bash
  
  
  
  loopcode()
  
  {
  
  tmpdir=frames
  
  picext=png
  
  one=$(ls -l ${tmpdir}/*.png  | wc -l)
  
  two=$(echo "${one}+0" | bc -l)
  
  three=0
  
  while [ ! ${loopi} -eq ${looper} ]; do
  
    while [ ! ${three} -eq ${two} ]; do
  
      three=$(printf "%09d" ${two})
  
      echo ${tmpdir}/${three}.${picext}
  
      two=$(echo "${two}+1" | bc -l)
  
    done
  
    two=0
  
    loopi=$(echo "${loopi}+1" | bc -l)
  
  done
  
  }
  
  
  
  looper=100
  
  loopi=0
  
  outfile=output.mp4
  
  fps=5
  
  convert frames/*.png frames/%09d.jpeg
  
  loopcode && sleep 5
  
  cat $(loopcode) | ffmpeg -framerate 1/5 -i - -c:v libx264 -r 30 -pix_fmt yuv420p "${outfile}"

• FFmpeg av_guess_format returns NULL

  12 septembre 2014, par Kage

  I’m following the example code here : http://cekirdek.pardus.org.tr/ ismail/ffmpeg-docs/output-example_8c-source.html

  My code is as follows :

  fmt = av_guess_format(NULL, filename, NULL);
  
  if (!fmt) {
  
          LOGE(1,"Could not deduce output format from file extension: using MPEG.\n");
  
          fmt = av_guess_format("mp4", NULL, NULL);
  
  }
  
      if (!fmt) {
  
          LOGE(1, "Could not find suitable output format\n");
  
          exit(1);
  
  }

  The two times that I call av_guess_format, it is returning NULL both times.
  I am calling both av_register_all() and avcodec_register_all() beforehand.

  Any ideas as to why this is returning NULL ?

  Thanks in advance.