[Update] jul.27.2024 : Recompiled by using updated git commit "182e0d5" on "demuxers/Matroska"
----------------
                           
Avidemux2's stable release version is "2.8.1" (sep.21.2022).
And current development stage of avidemux2 seems to be a kind of BETA version of next '2.8.2" release.

cmake/avidemuxVersion.cmake
[code]
#
#
#
#SET(RELEASE 1)
#
#
include(admTimeStamp)
SET(CPACK_PACKAGE_VERSION_MAJOR "2")
SET(CPACK_PACKAGE_VERSION_MINOR "8")
SET(CPACK_PACKAGE_VERSION_P     "2")
SET(AVIDEMUX_MAJOR_MINOR "${CPACK_PACKAGE_VERSION_MAJOR}.${CPACK_PACKAGE_VERSION_MINOR}")
SET(CPACK_PACKAGE_VERSION_PATCH "${CPACK_PACKAGE_VERSION_P}")
IF(NOT AVIDEMUX_VERSION)
    SET(AVIDEMUX_VERSION "${CPACK_PACKAGE_VERSION_MAJOR}.${CPACK_PACKAGE_VERSION_MINOR}.${CPACK_PACKAGE_VERSION_PATCH}")
ENDIF(NOT AVIDEMUX_VERSION)
SET(AVIDEMUX_API_VERSION "${CPACK_PACKAGE_VERSION_MAJOR}.${CPACK_PACKAGE_VERSION_MINOR}")
IF(NOT RELEASE)
        # use date instead of subversion, we use git now
        ADM_TIMESTAMP(date)
        SET(CPACK_PACKAGE_VERSION_PATCH "${CPACK_PACKAGE_VERSION_PATCH}-${date}")
ENDIF(NOT RELEASE)

 cmake/admFFmpegVersion.cmake
[code]
set(FFMPEG_VERSION "7.0.1")

I created an avidemux2 package for slackware64-current using the latest git source of Avidemux2 git repository.

Sources I used were ...
※ I created those tar balls for my packaging, and placed those souce tar balls in my MEGA drive.
     SOURCE DL: avidemux_2.8.2.182e0d5.tar.xz

avidemux.SlackBuild
The base slackbuild was made by AlienBoB(Eric Hameleers).
I only changed SOURCE parts in the slackbuild.
Thanks to Eric Harmeleers for making the slackbuild publicly available.
[code]
#!/bin/sh
# $Id: avidemux.SlackBuild,v 1.21 2022/10/17 19:34:27 root Exp root $
# Copyright 2009, 2010, 2011, 2013, 2017, 2021, 2022  Eric Hameleers, Eindhoven, NL
# All rights reserved.
#
#   Permission to use, copy, modify, and distribute this software for
#   any purpose with or without fee is hereby granted, provided that
#   the above copyright notice and this permission notice appear in all
#   copies.
#
#   THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
#   WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
#   MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
#   IN NO EVENT SHALL THE AUTHORS AND COPYRIGHT HOLDERS AND THEIR
#   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
#   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
#   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
#   USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
#   ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
#   OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
#   OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
#   SUCH DAMAGE.
# -----------------------------------------------------------------------------
#
# Slackware SlackBuild script
# ===========================
# By:         Eric Hameleers <alien@slackware.com>
# For:        avidemux
# Descr:      versatile video editor with a Qt gui
# URL:        http://avidemux.org/
# Needs:      aften,faac,faad2,libdca,libfdk-aac,opencore-amr,
#             twolame,x264,x265,xvidcore
# Changelog:  
# 2.4.4-1:    19/May/2009 by Eric Hameleers <alien@slackware.com>
#             * Initial build. If Qt4 is present the Qt4 GUI will be built
#               and used by default from the menu entry.
# 2.4.4-2:    28/May/2009 by Eric Hameleers <alien@slackware.com>
#             * Add aften (ac3 encoder) as a dependency
# 2.5.2-1:    30/Jan/2010 by Eric Hameleers <alien@slackware.com>
#             * New release. Add support for AMR audio.
# 2.5.3-1:    02/jun/2010 by Eric Hameleers <alien@slackware.com>
#             * New release.
# 2.5.4-1:    11/may/2011 by Eric Hameleers <alien@slackware.com>
#             * New release. Added VP8 support.
# 2.6.0-1:    15/oct/2013 by Eric Hameleers <alien@slackware.com>
#             * New release, built for Slackware 14.
# 2.6.7-1:    21/dec/2013 by Eric Hameleers <alien@slackware.com>
#             * New release, built for Slackware 14 and newer.
# 2.6.20-1:   04/may/2017 by Eric Hameleers <alien@slackware.com>
#             * Update.
# 2.8.0-1:    29/dec/2021 by Eric Hameleers <alien@slackware.com>
#             * Update.
# 2.8.1-1:    17/oct/2022 by Eric Hameleers <alien@slackware.com>
#             * Update.
# 2.8.2-RC git source build
#             23/jul/2024 by J_W(Shinichi Abe)
#             * TEST package
# 2.8.2.182e0d5-1jw  update git source to commit:182e0d5(2024-07-27) commit on "demuxers/Matroska"
# Run 'sh avidemux.SlackBuild' to build a Slackware package.
# The package (.txz) and .txt file as well as build logs are created in /tmp .
# Install it using 'installpkg'.
#
# -----------------------------------------------------------------------------

# Set initial variables:

PRGNAM=avidemux
VERSION=${VERSION:-2.8.2.182e0d5}
I18N_COMMIT=${I18N_COMMIT:-567c720f222ad700f23dbdb310f6200a631f091b}
BUILD=${BUILD:-1}
NUMJOBS=${NUMJOBS:-" -j$(nproc) "}
#TAG=${TAG:-alien}
TAG=${TAG:-jw}

DOCS="AUTHORS COPYING License.txt scripts"

# Where do we look for sources?
SRCDIR=$(cd $(dirname $0); pwd)

# Place to build (TMP) package (PKG) and output (OUTPUT) the program:
TMP=${TMP:-/tmp/build}
PKG=$TMP/package-$PRGNAM
OUTPUT=${OUTPUT:-/tmp}

SOURCE="$SRCDIR/${PRGNAM}_${VERSION}.tar.xz"
#SRCURL="ftp://plamo.linet.ge.jp/pub/Plamo-test/for-8.x/${PRGNAM}_${VERSION}.tar.xz"
SRCURL="ftp://153.231.160.88/pub/Plamo-test/for-8.x/${PRGNAM}_${VERSION}.tar.xz"
SOURCE2="$SRCDIR/${PRGNAM}2_i18n-${I18N_COMMIT}.tar.gz"
#SRCURL2="ftp://plamo.linet.gr.jp/pub/Plamo-test/for-8.x/${PRGNAM}2_i18n-${I18N_COMMIT}.tar.gz"
SRCURL2="ftp://153.231.160.88/pub/Plamo-test/for-8.x/${PRGNAM}2_i18n-${I18N_COMMIT}.tar.gz"

##
## --- with a little luck, you won't have to edit below this point --- ##
##

# Automatically determine the architecture we're building on:
if [ -z "$ARCH" ]; then
  case "$(uname -m)" in
    i?86) ARCH=i586 ;;
    arm*) readelf /usr/bin/file -A | egrep -q "Tag_CPU.*[4,5]" && ARCH=arm || ARCH=armv7hl ;;
    # Unless $ARCH is already set, use uname -m for all other archs:
    *) ARCH=$(uname -m) ;;
  esac
  export ARCH
fi

# Set CFLAGS/CXXFLAGS and LIBDIRSUFFIX:
case "$ARCH" in
  i?86)      SLKCFLAGS="-O2 -march=${ARCH} -mtune=i686"
             SLKLDFLAGS=""; LIBDIRSUFFIX=""
             ;;
  x86_64)    SLKCFLAGS="-O2 -fPIC"
             SLKLDFLAGS="-L/usr/lib64"; LIBDIRSUFFIX="64"
             ;;
  armv7hl)   SLKCFLAGS="-O2 -march=armv7-a -mfpu=vfpv3-d16"
             SLKLDFLAGS=""; LIBDIRSUFFIX=""
             ;;
  *)         SLKCFLAGS=${SLKCFLAGS:-"-O2"}
             SLKLDFLAGS=${SLKLDFLAGS:-""}; LIBDIRSUFFIX=${LIBDIRSUFFIX:-""}
             ;;
esac

case "$ARCH" in
    arm*)    TARGET=$ARCH-slackware-linux-gnueabi ;;
    *)       TARGET=$ARCH-slackware-linux ;;
esac

# Exit the script on errors:
set -e
trap 'echo "$0 FAILED at line ${LINENO}" | tee $OUTPUT/error-${PRGNAM}.log' ERR
# Catch unitialized variables:
set -u
P1=${1:-1}

# Save old umask and set to 0022:
_UMASK_=$(umask)
umask 0022

# Create working directories:
mkdir -p $OUTPUT          # place for the package to be saved
mkdir -p $TMP/tmp-$PRGNAM # location to build the source
mkdir -p $PKG             # place for the package to be built
rm -rf $PKG/*             # always erase old package's contents
rm -rf $TMP/tmp-$PRGNAM/* # remove the remnants of previous build
rm -rf $OUTPUT/{configure,make,install,error,makepkg,patch}-$PRGNAM.log
rm -rf $OUTPUT/{build*-$PRGNAM.log
                          # remove old log files

# Source file availability:
if ! [ -f ${SOURCE} ]; then
  echo "Source '$(basename ${SOURCE})' not available yet..."
  # Check if the $SRCDIR is writable at all - if not, download to $OUTPUT
  [ -w "$SRCDIR" ] || SOURCE="$OUTPUT/$(basename $SOURCE)"
  if [ -f ${SOURCE} ]; then echo "Ah, found it!"; continue; fi
  if ! [ "x${SRCURL}" == "x" ]; then
    echo "Will download file to $(dirname $SOURCE)"
    wget  --no-check-certificate -nv -T 20 -O "${SOURCE}" "${SRCURL}" || true
    wget  --no-check-certificate -nv -T 20 -O "${SOURCE2}" "${SRCURL2}" || true
    if [ $? -ne 0 -o ! -s "${SOURCE}" ]; then
      echo "Downloading '$(basename ${SOURCE})' failed... aborting the build."
      mv -f "${SOURCE}" "${SOURCE}".FAIL
      exit 1
    fi
  else
    echo "File '$(basename ${SOURCE})' not available... aborting the build."
    exit 1
  fi
fi

if [ "$P1" == "--download" ]; then
  echo "Download complete."
  exit 0
fi

# --- PACKAGE BUILDING ---

echo "++"
echo "|| $PRGNAM-$VERSION"
echo "++"

cd $TMP/tmp-$PRGNAM
echo "Extracting the source archive(s) for $PRGNAM..."
tar -xvf ${SOURCE}
cd ${PRGNAM}_${VERSION}/avidemux/qt4/i18n
tar --strip-components=1 -xvf ${SOURCE2}
cd ../../../

touch $OUTPUT/patch-${PRGNAM}.log

# We use a much more recent FriBiDi library:
sed -e 's#0.19#1.0#' -i avidemux_plugins/ADM_videoFilters6/ass/CMakeLists.txt

if [ "$ARCH" != "x86_64" ]; then
  # 2.8.1 won't compile on 32bit otherwise:
  sed -i avidemux/common/ADM_audioFilter/src/ADM_soundtouch/STTypes.h \
      -e '/#define SOUNDTOUCH_ALLOW_SSE/d'
fi

chown -R root:root .
chmod -R u+w,go+r-w,a+rX-st .

echo "Building..."
# The Qt5 gui is the default now:
bash bootStrap.bash --with-core --with-cli --with-plugins \
  2>&1 | tee $OUTPUT/configure-${PRGNAM}.log

make -C buildCore DESTDIR=$PKG install \
  2>&1 | tee $OUTPUT/buildCore-${PRGNAM}.log
make -C buildCli DESTDIR=$PKG install \
  2>&1 | tee $OUTPUT/buildCli-${PRGNAM}.log
make -C buildQt5 DESTDIR=$PKG install \
  2>&1 | tee $OUTPUT/buildQt5-${PRGNAM}.log

make -C buildPluginsCommon DESTDIR=$PKG install \
  2>&1 | tee $OUTPUT/buildPluginsCommon-${PRGNAM}.log
make -C buildPluginsQt5 DESTDIR=$PKG install \
  2>&1 | tee $OUTPUT/buildPluginsQt5-${PRGNAM}.log
make -C buildPluginsCLI DESTDIR=$PKG install \
  2>&1 | tee $OUTPUT/buildPluginsCLI-${PRGNAM}.log

# Add an icon for the menu entry:
install -D -m0644 avidemux_icon.png $PKG/usr/share/pixmaps/avidemux.png

# Install the man page:
install -D -m0644 man/avidemux.1 -t $PKG/usr/man/man1

# Add this to the doinst.sh:
! [ -d $PKG/install ] && mkdir -p $PKG/install
cat <<EOT >> $PKG/install/doinst.sh
# Update the desktop database:
if [ -x usr/bin/update-desktop-database ]; then
  chroot . /usr/bin/update-desktop-database /usr/share/applications > /dev/null 2>&1
fi

# Update hicolor theme cache:
if [ -d usr/share/icons/hicolor ]; then
  if [ -x /usr/bin/gtk-update-icon-cache ]; then
    chroot . /usr/bin/gtk-update-icon-cache -f -t usr/share/icons/hicolor 1> /dev/null 2>&1
  fi
fi

# Update the mime database:
if [ -x usr/bin/update-mime-database ]; then
  chroot . /usr/bin/update-mime-database usr/share/mime >/dev/null 2>&1
fi

EOT

# Add documentation:
mkdir -p $PKG/usr/doc/$PRGNAM-$VERSION
cp -a $DOCS $PKG/usr/doc/$PRGNAM-$VERSION || true
cat $SRCDIR/$(basename $0) > $PKG/usr/doc/$PRGNAM-$VERSION/$PRGNAM.SlackBuild
mkdir -p $PKG/usr/doc/$PRGNAM-$VERSION/patches
cp -a $SRCDIR/patches/*.{diff,patch} $PKG/usr/doc/$PRGNAM-$VERSION/patches/ || true
chown -R root:root $PKG/usr/doc/$PRGNAM-$VERSION
find $PKG/usr/doc -type f -exec chmod 644 {} \;

# Compress the man page(s):
if [ -d $PKG/usr/man ]; then
  find $PKG/usr/man -type f -name "*.?" -exec gzip -9f {} \;
  for i in $(find $PKG/usr/man -type l -name "*.?") ; do ln -s $( readlink $i ).gz $i.gz ; rm $i ; done
fi

# Strip binaries:
find $PKG | xargs file | grep -e "executable" -e "shared object" \
  | grep ELF | cut -f 1 -d : | xargs strip --strip-unneeded 2> /dev/null

# Add a package description:
mkdir -p $PKG/install
cat $SRCDIR/slack-desc > $PKG/install/slack-desc
cat $SRCDIR/slack-required > $PKG/install/slack-required

# Build the package:
cd $PKG
makepkg --linkadd y --chown n $OUTPUT/${PRGNAM}-${VERSION}-${ARCH}-${BUILD}${TAG}.txz 2>&1 | tee $OUTPUT/makepkg-${PRGNAM}.log
cd $OUTPUT
md5sum ${PRGNAM}-${VERSION}-${ARCH}-${BUILD}${TAG}.txz > ${PRGNAM}-${VERSION}-${ARCH}-${BUILD}${TAG}.txz.md5
cd -
cat $PKG/install/slack-desc | grep "^${PRGNAM}" > $OUTPUT/${PRGNAM}-${VERSION}-${ARCH}-${BUILD}${TAG}.txt
cat $PKG/install/slack-required > $OUTPUT/${PRGNAM}-${VERSION}-${ARCH}-${BUILD}${TAG}.dep

# Restore the original umask:
umask ${_UMASK_}


[Note]
 Regarding with required packages, I upgradedsome of them.

aften          : 0.0.8
faac            : 1.30
faad2           : 2.10.1
libdca          : 0.0.7
libfdk-aac      : 2.0.3
opencore-amr    : 0.1.6
x264            : 20240228_be4f020
x265            : 3.6
xvidcore        : 1.3.7

Now, I'm using this test package for my video editing and converting without any problem.
avidemux-2.8.2.182e0d5_About






---