configure

#!/usr/bin/env bash

# Preparation script to build the OpenH264 GStreamer plugin.
#
# This shell script downloads all dependencies and tools needed to build the
# 'gst-plugins-bad' module in a system where the OpenH264 library is installed.
# Doing so has the effect of enabling the generation of an OpenH264 GStreamer
# plugin, during the configuration phase of 'gst-plugins-bad'.



# Shell setup
# -----------

# Bash options for strict error checking
set -o errexit -o errtrace -o pipefail -o nounset

# Trace all commands
set -o xtrace



# Configure Apt
# -------------

# Disable interactive prompts
export DEBIAN_FRONTEND="noninteractive"

# Uncomment system's source repositories.
sed --regexp-extended --in-place \
    's/# *(deb-src.*(main|restricted|universe|multiverse))/\1/' \
    /etc/apt/sources.list

apt-get update



# Install dependencies
# --------------------

SOURCE_NAME="gst-plugins-bad1.0"

apt-get build-dep --yes "$SOURCE_NAME"



# Build gst-plugins-bad
# ---------------------

apt-get source "$SOURCE_NAME"

cd ./"$SOURCE_NAME"*/

# Quick fix for an error that gstopenh264dec raises when starting to decode,
# about trying to handle and unref a null frame.
# This patch was tested to work with gst-plugins-bad 1.14.5; different versions
# may need adjusting. In that case, maybe it makes sense to keep a different
# patch file for each of the GStreamer versions that we want to support.
patch -R ./ext/openh264/gstopenh264dec.cpp \
    ../gstreamer_1.14.5_gstopenh264dec.cpp.diff

# Inspect the 'configure.ac' file to obtain the names of all plugins that
# can be enabled or disabled with '--enable-*' and '--disable-*' flags.
NAMES="$(sed -rn 's/^AG_GST_CHECK_FEATURE\((\w+),.*$/\L\1/p' configure.ac)"

# Convert all names into '--disable-*' arguments
ARGS=""
set +o xtrace
for NAME in $NAMES; do
    ARGS="$ARGS --disable-${NAME}"
done
set -o xtrace

# Run './configure' with almost everything disabled.
# * '--without-plugins' disables all internal plugins that don't depend on any
#   external library.
# * External plugins must be disabled one by one, to end up enabling only the
#   one we are interested in, OpenH264.
#   It is possible to disable all external plugins with '--disable-external',
#   but that would also force disabling the OpenH264 plugin.
export DEB_CONFIGURE_EXTRA_FLAGS=" \
    --disable-dependency-tracking \
    --disable-examples \
    --without-plugins \
    $ARGS \
    --enable-openh264 \
"

# Also disable hardcoded flag to generate documentation
sed -i 's/--enable-gtk-doc/--disable-gtk-doc/' debian/rules

# Launch the build
# Package construction will fail, but only after having built our file
debuild -b -uc -us --target=install-arch || true