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• Using a string literal works but passing as arguments does not

  6 mai 2019, par user10204157

  I am passing string literals to my powershell script as follows :

  var spawn = require("child_process").spawn,
  
              child;
  
    child = spawn("powershell.exe", [
  
              "./scripts/ffmpeg_convert.ps1",
  
              `./cache/videos/${tempFileName + "."}${videoType}`,
  
              ` ./cache/converted_videos/${tempFileName + "."}${videoType}`
  
            ]);

  Where spawn is part of node.js Spawn

  And my powershell script is as follows :

  param(
  
      [string]$originFile = $Args[0],
  
      [string]$outputFile = $Args[1]
  
  )
  
  echo "Moving moov atom"
  
  ffmpeg -i $originFile -vcodec copy -acodec copy -movflags +faststart $outputFile

  But, the script will not execute with the argument of

  ./cache/videos/${tempFileName + "."}${videoType}

  However, if I change the argument out for the literal string let’s say
  ./cache/videos/inputVideo.mov

  it executes just fine.

  This is really making me scratch my head.

  I created two test scripts that work with the same principal... So is it just the way ${tempFileName + "."}${videoType} is being translated ? And with that being said, if I echo the arguments they are as expected.

  Script 1

   ./convert_videos.ps1 ./inputVideo.mov outputVideo.mov

  Script 2

   param(
  
      [string]$originFile = $Args[0],
  
      [string]$outputFile = $Args[1]
  
  )
  
  echo "Moving moov atom"
  
  ffmpeg -i $originFile -vcodec copy -acodec copy -movflags +faststart $outputFile

• how the packuswb instruction works ? (in low level bit operation)

  17 avril 2019, par MaikonNascimento

  Studying ffmpeg convertion from yuv to rgb , I came across the equation being implemented in assembly, yuv2rgb_template.c located in ffmpeg/libswscale/x86.

  I want to know how the instruction packuswb works ? Google says it :

  Converts 4 signed word integers from mm and 4 signed word integers from mm/m64 into 8 unsigned byte integers in mm using unsigned saturation.

      DEST[7:0] ← SaturateSignedWordToUnsignedByte DEST[15:0];
  
      DEST[15:8] ← SaturateSignedWordToUnsignedByte DEST[31:16];
  
      DEST[23:16] ← SaturateSignedWordToUnsignedByte DEST[47:32];
  
      DEST[31:24] ← SaturateSignedWordToUnsignedByte DEST[63:48];
  
      DEST[39:32] ← SaturateSignedWordToUnsignedByte SRC[15:0];
  
      DEST[47:40] ← SaturateSignedWordToUnsignedByte SRC[31:16];
  
      DEST[55:48] ← SaturateSignedWordToUnsignedByte SRC[47:32];
  
      DEST[63:56] ← SaturateSignedWordToUnsignedByte SRC[63:48];

  Since I dont know Assembly x86, it is even hard to simulate it or debug the current code.

  I want to know how they fit 16 bits in 8 bits ?

• FFmpeg / python - command works when run from shell but fails when run from python

  4 avril 2019, par artembus

  I have a python script which should run an ffmpeg command with this function :

  def transcode(in_path, out_path):
  
      cmd = ["ffmpeg", "-y", "-i", in_path, '-vf smartblur=lr=1']
  
      cmd += ["-an", out_path]
  
      print("Running:", " ".join(cmd))
  
      subprocess.run(cmd, stdout=cmdout, stderr=cmdout)

  When I run the python script it fails with this ffmpeg error :

  Running: ffmpeg -y -i raid/orig/scenes/train/5786088.mp4 -vf smartblur=lr=1 -an raid/4K/scenes/train/5786088.mp4
  
  ffmpeg version 2.8.15-0ubuntu0.16.04.1 Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.10) 20160609
  
    configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
  
    libavutil      54. 31.100 / 54. 31.100
  
    libavcodec     56. 60.100 / 56. 60.100
  
    libavformat    56. 40.101 / 56. 40.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 40.101 /  5. 40.101
  
    libavresample   2.  1.  0 /  2.  1.  0
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.101 /  1.  2.101
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Unrecognized option 'vf smartblur=lr=1'.
  
  Error splitting the argument list: Option not found

  You can see the command it tries to execute in the first line, when I run it in the command line it works fine. When I run the command in the shell it outputs the same version and parameters of the ffmpeg as written in the error above.

  I feel like I missed something simple yet crucial, anyone can point me to the right direction ?