Alternative method to create contact sheet

#!/root/powershell/pwsh
# Change the above if your pwsh resides elsewhere in Linux
<#
  caps.ps1 -file <file> [-burn]

Requires: ffmpeg/ffprobe in the system path otherwise edit in the full path to them.
          PowerShell 7+ (Any lesser version and it will just exit)
          It uses the following fonts at lines 65, 68, & 70 - change those lines to use another font:
          Windows font: C:\Windows\fonts\arial.ttf
          Linux font:   /usr/share/fonts/truetype/dejavu/DejaVuSans.ttf
          MacOs font:   /System/Library/Fonts/Arial.ttf

*** NOTE: ONLY tested with:
          Windows 10 Pro x64
          DietPi v 6.33.3 (Raspbian GNU/Linux 10 (buster), Linux 5.4.79-v7l+ )
          Ubuntu 18.04.5 LTS (WSL)
          PowerShell 7.1.0 (Windows/Linux)
          ffmpeg version 2020-12-06-git-2aab42bc40-full_build-www.gyan.dev (Windows)
          ffmpeg version 4.1.6-1~deb10u1+rpt1 (RasPi - DietPi v6.33.3 - Raspbian GNU/Linux 10 (buster), Linux 5.4.79-v7l+ )

Where: file  = full path to the video file
       -burn = [optional] burn in timecodes

*** NOTE: Burning timecodes will not work unless ffmpeg has been compiled with the following option:
            --enable-libfreetype

          If you don't know then enter the following command and search for 'drawtext' in the output:
            ffmpeg -filters

  Generates the contact sheet faster than CTBRec internal method and [optionally] burns in the timecode
  Extreme example: Video 3840x2160, 17.6GB, 2h54m (Ryzen5 3600)
  CTBRec internal:    15 mins 16 secs
  Powershell script:  44 secs
#>


# Parse command line parameters
param (
  [Parameter(Mandatory=$true)][string]$file,
  [switch]$burn
)

function ContactSheet ($infile) {
  $tmpdir = ([System.IO.Path]::GetTempPath() + '~' + ([System.IO.Path]::GetRandomFileName())).Split('.')[0]
  New-Item -Path "$($tmpdir)" -ItemType Directory | Out-Null
  $duration = $(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 -i "$($infile)")
  for ($i = 1; $i -lt 57; $i++) {
    $interval = [int](($i-0.5) * $duration/56)    # calculate position of each frame capture
    [string]$ttext = ([timespan]::fromseconds($interval).tostring()).Replace(':', '\:')  # seconds to xx:xx:xx

    if ($burn) {                                  # skip to calculated position and grab next key frame
      $ffcmd = "ffmpeg -v quiet -y -skip_frame nokey -ss $interval -i `"$file`" -vf scale=-1:720,select=`"eq(pict_type\,I)`",drawtext=`"text='$ttext':fontcolor=white:fontsize=48:box=1:boxcolor=black@0.5:boxborderw=5:x=(w-text_w)/2:y=(h-text_h-10):fontfile=$ffont`" -vframes 1 `"$tmpdir/image$(([string]$i).PadLeft(2, '0')).png`""
    } else {
      $ffcmd = "ffmpeg -v quiet -y -skip_frame nokey -ss $interval -i `"$file`" -vf select=`"eq(pict_type\,I)`" -vframes 1 `"$tmpdir/image$(([string]$i).PadLeft(2, '0')).png`""
    }
    Invoke-Expression $ffcmd
  }
  $ffcmd = "ffmpeg -v quiet -y -i $tmpdir/image%02d.png -vf `"scale=317:-1,tile=8x7:color=0x333333:margin=2:padding=2,scale=2560:-1`" -qscale:v 3 `"./$(([System.IO.FileInfo]$infile).BaseName).jpg`""
  Invoke-Expression $ffcmd                         # create contact sheet from images -> file.jpg
  Remove-Item -Path "$($tmpdir)" -Recurse -Force   # remove images
}

if ($PSVersionTable.PSVersion.Major -ge 7) {       # Check for PS 7+
  if ($IsWindows) {
    $ffont = "C\\:/Windows/fonts/arial.ttf"        # ffmpeg font syntax changes depending on compilation/version, this works with the version I tested it with
  } else {
    if ($IsLinux) {
      $ffont = "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf"
    } else {
      $ffont = "/System/Library/Fonts/Arial.ttf"   # assume MacOS - change this if necessary, I haven't got access to a Mac
    }
  }
} else {
  exit
}

Push-Location "$(Split-Path $file -Parent)"
ContactSheet "$(Split-Path $file -Leaf)"
Pop-Location