This is my SlackBild of HandBrake-1.7.3.
The base SlackBuild is SBo's script of version 1.5.1.  Thanks to SBo.

There is nothing special on the script.
What I did are ...
1. Changed main source version from 1.5.1 to 1.7.3.
2. Changed contrib source's version to newer ones.
3. Droped "system_x265.diff" patch in the slackbuild.
4. Removed "--disable-gtk-update-checks" option from slackbuild.

src : HandBrake.info
PRGNAM="HandBrake"
VERSION="1.7.3"
HOMEPAGE="https://handbrake.fr/"
DOWNLOAD="https://github.com/HandBrake/HandBrake/releases/download/1.7.3/HandBrake-1.7.3-source.tar.bz2 \
          https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/AMF-1.4.30.tar.gz \
      https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/SVT-AV1-v1.7.0.tar.gz \
          https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/dav1d-1.3.0.tar.bz2 \
          https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/fdk-aac-2.8.2.tar.gz \
          https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/ffmpeg-6.1.tar.bz2 \
          https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/libbluray-1.3.4.tar.bz2 \
          https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/libdvdnav-6.1.1.tar.bz2 \
          https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/libdvdread-6.1.3.tar.bz2 \
          https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/nv-codec-headers-12.1.14.1.tar.gz \
          https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/oneVPL-2023.3.1.tar.gz \
      https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/x265-snapshot-20230403-12776.tar.gz \
          https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/zimg-3.0.5.tar.gz"
MD5SUM="e6ec1b29e1ddb0fd04bb28a99ac33e33 \
        4daebe8bc7aab9eeffe69a32eb1ee956 \
        3f835514c253b587f609015e58c5a65f \
        c8381f8346525dcd4205e9b50d80c5f4 \
        b15f56aebd0b4cfe8532b24ccfd8d11e \
        96e1143403edb2025b9cc0096947d5f0 \
        c744e610f539ba4b31280185ad48f1e1 \
        46c46cb0294fbd1fcb8a0181818dad15 \
        3c58d1624a71a16ff40f55dbaca82523 \
        37f4ded44f9aa9e03fa42f2bb7c9012b \
    a82c72078ccd16c91b816052497b3080 \       
    f5e8f9be0b32951bd3c0c2d3bae4bf05 \
    af2c08cc0e695f4c0c225feed14e9f20"
DOWNLOAD_x86_64=""
MD5SUM_x86_64=""
REQUIRES="libass x264 x265 numactl"
MAINTAINER=""
EMAIL=""

[code] HandBrake.SlackBuild
#!/bin/bash

# Slackware build script for HandBrake

# This slackbuild maintained by Klaatu at klaatu@hackerpublicradio.org
# Modified by David Somero at SlackBuilds.org.
# Modified by Erik Hanson at SlackBuilds.org
# Patched to fix x264 segfault by John Vogel

cd $(dirname $0) ; CWD=$(pwd)

PRGNAM=HandBrake
VERSION=${VERSION:-
1.7.3}
BUILD=${BUILD:-1}
TAG=${TAG:-jw}
PKGTYPE=${PKGTYPE:-txz}
DOCDIR=${DOCDIR:-/usr/doc}

if [ -z "$ARCH" ]; then
  case "$( uname -m )" in
    i?86) ARCH=i686 ;;
    arm*) ARCH=arm ;;
       *) ARCH=$( uname -m ) ;;
  esac
fi

if [ ! -z "${PRINT_PACKAGE_NAME}" ]; then
  echo "$PRGNAM-$VERSION-$ARCH-$BUILD$TAG.$PKGTYPE"
  exit 0
fi

TMP=${TMP:-/tmp/SBo}
PKG=$TMP/package-$PRGNAM
OUTPUT=${OUTPUT:-/tmp}

if [ "$ARCH" = "i586" ]; then
  SLKCFLAGS="-O2 -march=i586 -mtune=i686"
  LIBDIRSUFFIX=""
elif [ "$ARCH" = "i686" ]; then
  SLKCFLAGS="-O2 -march=i686 -mtune=i686"
  LIBDIRSUFFIX=""
elif [ "$ARCH" = "x86_64" ]; then
  SLKCFLAGS="-O2 -fPIC"
  LIBDIRSUFFIX="64"
else
  SLKCFLAGS="-O2"
  LIBDIRSUFFIX=""
fi

SLKCFLAGS="$SLKCFLAGS -fno-aggressive-loop-optimizations"
export CFLAGS="$SLKCFLAGS"
export CXXFLAGS="$SLKCFLAGS"

set -e

rm -rf $PKG
mkdir -p $TMP $PKG $OUTPUT
cd $TMP
rm -rf $PRGNAM-$VERSION
tar xvf $CWD/$PRGNAM-$VERSION-source.tar.bz2
cd $PRGNAM-$VERSION
mkdir -p download
cp -r $CWD/*{gz,bz2} download
chown -R root:root .
find -L . \
 \( -perm 777 -o -perm 775 -o -perm 750 -o -perm 711 -o -perm 555 \
  -o -perm 511 \) -exec chmod 755 {} \; -o \
 \( -perm 666 -o -perm 664 -o -perm 640 -o -perm 600 -o -perm 444 \
  -o -perm 440 -o -perm 400 \) -exec chmod 644 {} \;

# 20220324 bkw: this fixes the 32-bit build, at the cost of adding
# x265 as a required dep. It's based on Debian's
# 0001-Remove-embedded-downloaded-copies-of-various-librari.patch
# ...but it only affects x265.
#
# ! HandBrake version 1.7.3 doesn't need this patch any more.
#patch -p1 < $CWD/system_x265.diff


# Autodetect onevpl support
if pkg-config --exists vpl ; then qsv="--enable-qsv" ; else qsv="" ; fi

CFLAGS="$SLKCFLAGS" \
CXXFLAGS="$SLKCFLAGS" \
./configure \
  --prefix=/usr \
  --enable-fdk-aac \
  --enable-nvenc \
  --enable-vce \
  --enable-x265 \
  $qsv \
  --arch=$ARCH

cd build
  make
  make install DESTDIR=$PKG
strip $PKG/usr/bin/*

cd $TMP/$PRGNAM-$VERSION

mkdir -p $PKG/$DOCDIR/$PRGNAM-$VERSION
cp -a AUTHORS.markdown COPYING NEWS.markdown THANKS.markdown README.markdown \
 $PKG/$DOCDIR/$PRGNAM-$VERSION
cat $CWD/$PRGNAM.SlackBuild > $PKG/$DOCDIR/$PRGNAM-$VERSION/$PRGNAM.SlackBuild
cat $CWD/fetch-contrib-sources.sh > $PKG/$DOCDIR/$PRGNAM-$VERSION/fetch-contrib-sources.sh

mkdir -p $PKG/install
cat $CWD/slack-desc > $PKG/install/slack-desc
cat $CWD/doinst.sh > $PKG/install/doinst.sh

cd $PKG
/sbin/makepkg -l y -c n $OUTPUT/$PRGNAM-$VERSION-$ARCH-$BUILD$TAG.$PKGTYPE


[code] slack-desc
# HOW TO EDIT THIS FILE:
# The "handy ruler" below makes it easier to edit a package description.
# Line up the first '|' above the ':' following the base package name, and
# the '|' on the right side marks the last column you can put a character in.
# You must make exactly 11 lines for the formatting to be correct.  It's also
# customary to leave one space after the ':' except on otherwise blank lines.

         |-----handy-ruler------------------------------------------------------|
HandBrake: HandBrake (DVD ripper)
HandBrake:
HandBrake: HandBrake is a DVD ripper that reads DVD movies and outputs them
HandBrake: to a variety of video and audio formats, with subtitle options,
HandBrake: options for alternate audio streams, and a number of presets.
HandBrake:
HandBrake: Homepage: http://www.handbrake.fr
HandBrake:
HandBrake:
HandBrake:
HandBrake:


[code] fetch-contrib-sources.sh
#!/bin/bash
#

# HandBrake-1.7.3-source.tar.bz2
# wget https://github.com/HandBrake/HandBrake/releases/download/1.7.3/HandBrake-1.7.3-source.tar.bz2
#
# AMF-1.4.30-slim.tar.gz
wget https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/AMF-1.4.30-slim.tar.gz
# SVT-AV1-v1.7.0.tar.gz
wget https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/SVT-AV1-v1.7.0.tar.gz
# fdk-aac-2.0.2.tar.gz
wget https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/fdk-aac-2.0.2.tar.gz
# nv-codec-headers-12.1.14.0.tar.gz
wget https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/nv-codec-headers-12.1.14.0.tar.gz
# oneVPL-2023.3.1.tar.gz
wget https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/oneVPL-2023.3.1.tar.gz
# x265-snapshot-20230403-12776.tar.gz
wget https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/x265-snapshot-20230403-12776.tar.gz
# zimg-3.0.5.tar.gz
wget https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/zimg-3.0.5.tar.gz
# dav1d-1.3.0.tar.bz2
wget https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/dav1d-1.3.0.tar.bz2
# ffmpeg-6.1.tar.bz2
wget https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/ffmpeg-6.1.tar.bz2
# libbluray-1.3.4.tar.bz2
wget https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/libbluray-1.3.4.tar.bz2
# libdvdnav-6.1.1.tar.bz2
wget https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/libdvdnav-6.1.1.tar.bz2
# libdvdread-6.1.3.tar.bz2
wget https://github.com/HandBrake/HandBrake-contribs/releases/download/contribs/libdvdread-6.1.3.tar.bz2

echo "... Done!"

{Screenshots]
HandBrake-1.7.3_About

HandBrake-1.7.3_snapshot-001

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[Update]