Ticket #9407: 00-commands.sh

#!/bin/bash

main()
(:
  version_info
  make_files
  analyze_files
  conclusion
)

version_info()
{
  echo 'Versions:'
  echo '========'

  version bash
  version tee
  version sed
  version --all ffmpeg -version
  version identify -version
  version md5sum
  version diff
}

version()
{
  if [[ $1 == --all ]]; then
    printf '\n  %s:\n\n' "$2"
    "$2" "${3:---version}" | wrap
  else
    printf '\n  %s:\n\n' "$1"
    "$1" "${2:---version}" | sed -n 'p;q' | wrap
  fi
}

wrap()
{
  fold -s -w 65 | indent
}

indent()
{
  sed -e "s/^/    &/"
}

make_files()
{
  local args f

  echo
  echo 'Making files:'
  echo '============'
  echo

  args=(
    -hide_banner
    -loglevel quiet
    -f lavfi -i '
      color=0x7FFFD4:size=480x270, format=rgb24,
        setparams=prog:pc:bt709:iec61966-2-1:bt709
    '
    -frames 1
  )

  f=01-rgb24.png
  exists || ffmpeg "${args[@]}" "$f"

  f=02-rbg24-to-yuv444p-to-rgb24.png
  exists || ffmpeg "${args[@]}" -vf '
    scale=out_range=pc, format=yuv444p,
      scale=out_range=pc, format=rgb24
    ' "$f"

  f=03-rbg24-to-yuv444p10le-to-rgb24.png
  exists || ffmpeg "${args[@]}" -vf '
    scale=out_range=pc, format=yuv444p10le,
      scale=out_range=pc, format=rgb24
    ' "$f"

  f=04-rbg24-to-yuv444p10le-to-yuv444p-to-rgb24.png
  exists || ffmpeg "${args[@]}" -vf '
    scale=out_range=pc, format=yuv444p10le,
      scale=out_range=pc, format=yuv444p,
        scale=out_range=pc, format=rgb24
    ' "$f"

  f=05-rbg24-to-yuv444p10le-to-rgb24-to-yuv444p-to-rgb24.png
  exists || ffmpeg "${args[@]}" -vf '
    scale=out_range=pc, format=yuv444p10le,
      scale=out_range=pc, format=rgb24,
        scale=out_range=pc, format=yuv444p,
          scale=out_range=pc, format=rgb24
    ' "$f"
}

exists()
{
  printf '  %s' "$f"
  [[ -e $f ]] || { echo; return 1; }
  spaces='                                                        '
  echo "${spaces:${#f}}" '(already exists)'
}

analyze_files()
{
  echo
  echo 'Analyzing:'
  echo '========='

  md5sums
  show_lossiness_of_yuv444p
  show_bonkers_conversion_between_yuvs
}

md5sums()
{
  echo
  echo '  md5sums':
  echo

  local h f i=0 files
  local -A same

  while read h f; do
    same[$h]+=" $i"
    files[i]=$f
    ((++i)) || { echo 'ERROR: Overflow?'; return 1; }
  done < <(md5sum *.png)

  for h in "${!same[@]}"; do
    echo '   ' "$h:"
    echo
    for i in ${same[$h]}; do
      echo '     ' "${files[i]}"
    done
    echo
  done
}

show_lossiness_of_yuv444p()
{
  echo '  rgb24 -> yuv444p is imperceptibly lossy:'
  echo

  diff -u \
    <(identify -verbose 01-rgb24.png) \
    <(identify -verbose 02-rbg24-to-yuv444p-to-rgb24.png) \
      | sed '1,2d' | indent
}

show_bonkers_conversion_between_yuvs()
{
  echo
  echo '  yuv444p10le -> yuv444p is bonkers:'
  echo '  (it SHOULD be the same as rgb24 -> yuv444p)'
  echo

  diff -u \
    <(identify -verbose 02-rbg24-to-yuv444p-to-rgb24.png) \
    <(identify -verbose 04-rbg24-to-yuv444p10le-to-yuv444p-to-rgb24.png) \
      | sed '1,2d' | indent
}

conclusion()
{
  cat <<'EOF'

Conclusion:
==========

  As indicated by the hashes, the *workaround* is to convert
  "yuv444p10le" to some other class of pixel format (like "rgb24")
  before converting to another "yuv*" pixel format:

    scale=out_range=pc, format=yuv444p10le,
      scale=out_range=pc, format=rgb24,     <--------- workaround
        scale=out_range=pc, format=yuv444p

  Nevertheless, a workaround should not even be necessary. There
  is a bug that should be investigated and fixed.

  (As an aside, look at all that "out_range" gibberish; it should
  not be necessary to do that little dance.)
EOF
}

main | tee 06-log.txt