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• Realtime output from ffmpeg and livestreamer using subprocess.Popen

  6 mars 2016, par Roger B

  In ffmpeg and livestreamer i only get a few lines in realtime then i get the rest of them when the process is done...

  I have tried two codes :

  from subprocess import *
  
  p = Popen('ffmpeg -i infile.mp4 outfile.mp4', stderr=STDOUT, stdout=PIPE)
  
  for line in iter(p.stdout.readline(), b'')
  
     print line.rstrip()

  and

  from subprocess import *
  
  p = Popen('ffmpeg -i infile.mp4 outfile.mp4', stderr=STDOUT, stdout=PIPE)
  
  while p.poll is None:
  
     line = p.stdout.readline()
  
     print line.rstrip()

  Both of them prints first :

  ffmpeg version N-72805-g913685f Copyright (c) 2000-2015 the FFmpeg developers
  
    built with gcc 4.9.2 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
  
  isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
  
  le-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --
  
  enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm --enable-l
  
  ibilbc --enable-libmodplug --enable-libmfx --enable-libmp3lame --enable-libopenc
  
  ore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --ena
  
  ble-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable
  
  -libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enabl
  
  e-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable
  
  -libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --e
  
  nable-lzma --enable-decklink --enable-zlib
  
    libavutil      54. 27.100 / 54. 27.100
  
    libavcodec     56. 41.100 / 56. 41.100
  
    libavformat    56. 36.100 / 56. 36.100
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 16.101 /  5. 16.101
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.100 /  1.  2.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'a.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf56.10.100
  
    Duration: 01:34:36.14, start: 0.021333, bitrate: 6205 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720,
  
   5938 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, flt
  
  p, 256 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
  [mp4 @ 05013ce0] Codec for stream 0 does not use global headers but container fo
  
  rmat requires global headers
  
  [mp4 @ 05013ce0] Codec for stream 1 does not use global headers but container fo
  
  rmat requires global headers
  
  Output #0, mp4, to 'b.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf56.36.100
  
      Stream #0:0(und): Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 1280x720, q
  
  =2-31, 5938 kb/s, 30 fps, 30 tbr, 15360 tbn, 15360 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac ([64][0][0][0] / 0x0040), 48000 Hz, stereo, 256
  
   kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:1 -> #0:1 (copy)
  
  Press [q] to stop, [?] for help

  Then when the convert process is done the rest of the log turns up...

  How can i get all stdout in realtime ??

  EDIT :

  If i use a text file to write to it get all in realtime.

  from subprocess import *
  
  out_file = open('stdout.txt','a')
  
  Popen('ffmpeg -i infile.mp4 outfile.mp4', stderr=STDOUT, stdout=out_file)

  But i want it print out stdout in realtime..

  Why does it work in realtime to a file but not direct print ?

• avutil/mathematics : speed up av_gcd by using Stein’s binary GCD algorithm

  11 octobre 2015, par Ganesh Ajjanagadde

  avutil/mathematics : speed up av_gcd by using Stein’s binary GCD algorithm
  This uses Stein’s binary GCD algorithm :
  
  https://en.wikipedia.org/wiki/Binary_GCD_algorithm
  
  to get a roughly 4x speedup over Euclidean GCD on standard architectures
  
  with a compiler intrinsic for ctzll, and a roughly 2x speedup otherwise.
  
  At the moment, the compiler intrinsic is used on GCC and Clang due to
  
  its easy availability.
  Quick note regarding overflow : yes, subtractions on int64_t can, but the
  
  llabs takes care of that. The llabs is also guaranteed to be safe, with
  
  no annoying INT64_MIN business since INT64_MIN being a power of 2, is
  
  shifted down before being sent to llabs.
  The binary GCD needs ff_ctzll, an extension of ff_ctz for long long (int64_t). On
  
  GCC, this is provided by a built-in. On Microsoft, there is a
  
  BitScanForward64 analog of BitScanForward that should work ; but I can’t confirm.
  
  Apparently it is not available on 32 bit builds ; so this may or may not
  
  work correctly. On Intel, per the documentation there is only an
  
  intrinsic for _bit_scan_forward and people have posted on forums
  
  regarding _bit_scan_forward64, but often their documentation is
  
  woeful. Again, I don’t have it, so I can’t test.
  As such, to be safe, for now only the GCC/Clang intrinsic is added, the rest
  
  use a compiled version based on the De-Bruijn method of Leiserson et al :
  
  http://supertech.csail.mit.edu/papers/debruijn.pdf.
  Tested with FATE, sample benchmark (x86-64, GCC 5.2.0, Haswell)
  
  with a START_TIMER and STOP_TIMER in libavutil/rationsl.c, followed by a
  
  make fate.
  aac-am00_88.err :
  
  builtin :
  
  714 decicycles in av_gcd,    4095 runs,      1 skips
  de-bruijn :
  
  1440 decicycles in av_gcd,    4096 runs,      0 skips
  previous :
  
  2889 decicycles in av_gcd,    4096 runs,      0 skips
  Signed-off-by : Ganesh Ajjanagadde <gajjanagadde@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavutil/intmath.h
  • [DH] libavutil/mathematics.c

• dnxhddata : Fix 10-bit DNxHD quant matrices

  1er octobre 2015, par Joseph Artsimovich

  dnxhddata : Fix 10-bit DNxHD quant matrices
  Convert them to zigzag order, as the rest of them are.
  When I was adding support for 10-bit DNxHD, I just copy-pasted the
  
  missing quant matrices from the spec. Now it turns out the existing
  
  matrices in dnxhddata.c were in zigzag order. This resulted in wrong
  
  quantization for 10-bit DNxHD. The attached patch fixes the problem by
  
  converting 10-bit quant matrices to zigzag order.
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DBH] libavcodec/dnxhddata.c
  • [DBH] tests/ref/vsynth/vsynth1-dnxhd-720p-10bit
  • [DBH] tests/ref/vsynth/vsynth2-dnxhd-720p-10bit