Documenting the ffmpeg-android-maker-2.sh

ffmpeg-android-maker-2.sh

@@ -1,12 +1,34 @@
-source scripts/export-core-variables.sh
+# Defining essential directories
-source scripts/export-host-variables.sh
-source scripts/parse-arguments.sh
 
+# The root of the project
+export BASE_DIR="$( cd "$( dirname "$0" )" && pwd )"
+# Directory that contains source code for FFmpeg and its dependencies
+# Each library has its own subdirectory
+# Multiple versions of the same library can be stored inside librarie's directory
+export SOURCES_DIR=${BASE_DIR}/sources
+# Directory to place some statistics about the build.
+# Currently - the info about Text Relocations
+export STATS_DIR=${BASE_DIR}/stats
+# Directory that contains helper scripts and
+# scripts to download and build FFmpeg and each dependency separated by subdirectories
+export SCRIPTS_DIR=${BASE_DIR}/scripts
+# The directory to use by Android project
+# All FFmpeg's libraries and headers are copied there
+export OUTPUT_DIR=${BASE_DIR}/output
 
+# Directory to use as a place to build/install FFmpeg and its dependencies
+BUILD_DIR=${BASE_DIR}/build
+# Separate directory to build FFmpeg to
+export BUILD_DIR_FFMPEG=$BUILD_DIR/ffmpeg
+# All external libraries are installed to a single root
+# to make easier referencing them when FFmpeg is being built.
+export BUILD_DIR_EXTERNAL=$BUILD_DIR/external
+
+# Function that copies *.so files and headers of the current ANDROID_ABI
+# to the proper place inside OUTPUT_DIR
 function prepareOutput() {
   OUTPUT_LIB=${OUTPUT_DIR}/lib/${ANDROID_ABI}
   mkdir -p ${OUTPUT_LIB}
-  # CURRENT_INSTALL_PATH !
   cp ${BUILD_DIR_FFMPEG}/${ANDROID_ABI}/lib/*.so ${OUTPUT_LIB}
 
   OUTPUT_HEADERS=${OUTPUT_DIR}/include/${ANDROID_ABI}
@@ -14,11 +36,12 @@ function prepareOutput() {
   cp -r ${BUILD_DIR_FFMPEG}/${ANDROID_ABI}/include/* ${OUTPUT_HEADERS}
 }
 
+# Saving stats about text relocation presence.
+# If the result file doesn't have 'TEXTREL' at all, then we are good.
+# Otherwise the whole script is interrupted
 function checkTextRelocations() {
-  # Saving stats about text relocation presence.
-  # If the result file doesn't have 'TEXTREL' at all, then we are good.
   TEXT_REL_STATS_FILE=${STATS_DIR}/text-relocations.txt
-  ${CROSS_PREFIX}readelf --dynamic ${BUILD_DIR_FFMPEG}/${ABI}/lib/*.so | grep 'TEXTREL\|File' >> ${TEXT_REL_STATS_FILE}
+  ${CROSS_PREFIX}readelf --dynamic ${BUILD_DIR_FFMPEG}/${ANDROID_ABI}/lib/*.so | grep 'TEXTREL\|File' >> ${TEXT_REL_STATS_FILE}
 
   if grep -q TEXTREL ${TEXT_REL_STATS_FILE}; then
     echo "There are text relocations in output files:"
@@ -27,41 +50,74 @@ function checkTextRelocations() {
   fi
 }
 
+# Actual work of the script
+
+# Clearing previously created binaries
 rm -rf ${BUILD_DIR}
 rm -rf ${STATS_DIR}
 rm -rf ${OUTPUT_DIR}
 mkdir -p ${STATS_DIR}
 mkdir -p ${OUTPUT_DIR}
 
+# Exporting more necessary variabls
+source ${SCRIPTS_DIR}/export-host-variables.sh
+source ${SCRIPTS_DIR}/parse-arguments.sh
+
+# Treating FFmpeg as just a module to build after its dependencies
 COMPONENTS_TO_BUILD=${EXTERNAL_LIBRARIES[@]}
 COMPONENTS_TO_BUILD+=( "ffmpeg" )
 
+# Get the source code of component to build
 for COMPONENT in ${COMPONENTS_TO_BUILD[@]}
 do
-  export ENSURE_SOURCE_DIR=$SOURCES_DIR/$COMPONENT
+  echo "Getting source code of the component: ${COMPONENT}"
-  mkdir -p ${ENSURE_SOURCE_DIR}
+  SOURCE_DIR_FOR_COMPONENT=${SOURCES_DIR}/${COMPONENT}
-  source scripts/${COMPONENT}/download.sh
+
+  mkdir -p ${SOURCE_DIR_FOR_COMPONENT}
+  cd ${SOURCE_DIR_FOR_COMPONENT}
+
+  # Executing the component-specific script for downloading the source code
+  source ${SCRIPTS_DIR}/${COMPONENT}/download.sh
+
+  # The download.sh script has to export SOURCES_DIR_$COMPONENT variable
+  # with actual path of the source code. This is done for possiblity to switch
+  # between different verions of a component.
+  # If it isn't set, consider SOURCE_DIR_FOR_COMPONENT as the proper value
+  COMPONENT_SOURCES_DIR_VARIABLE=SOURCES_DIR_${COMPONENT}
+  if [[ -z "${!COMPONENT_SOURCES_DIR_VARIABLE}" ]]; then
+     export SOURCES_DIR_${COMPONENT}=${SOURCE_DIR_FOR_COMPONENT}
+  fi
+
+  # Returning to the rood directory. Just in case.
+  cd ${BASE_DIR}
 done
 
-# Build all libraries for each enabled arch
+# ABIs to build FFmpeg for.
-# ABIS_TO_BUILD=("armeabi-v7a" "arm64-v8a" "x86" "x86_64")
+# x86 is the first, because it is likely to have Text Relocations.
+# In this case the rest ABIs will not be assembled at all.
+# ABIS_TO_BUILD=( "x86" "x86_64" "armeabi-v7a" "arm64-v8a" )
 ABIS_TO_BUILD=("armeabi-v7a")
 
 for ABI in ${ABIS_TO_BUILD[@]}
 do
-  source scripts/export-build-variables.sh ${ABI}
+  # Exporting variables for the current ABI
+  source ${SCRIPTS_DIR}/export-build-variables.sh ${ABI}
 
   for COMPONENT in ${COMPONENTS_TO_BUILD[@]}
   do
     echo "Building the component: ${COMPONENT}"
     COMPONENT_SOURCES_DIR_VARIABLE=SOURCES_DIR_${COMPONENT}
-    echo ${!COMPONENT_SOURCES_DIR_VARIABLE}
+
+    # Going to the actual source code directory of the current component
     cd ${!COMPONENT_SOURCES_DIR_VARIABLE}
+
+    # and executing the component-specific build script
     ${SCRIPTS_DIR}/${COMPONENT}/build.sh
-    cd $BASE_DIR
+
+    # Returning to the root directory. Just in case.
+    cd ${BASE_DIR}
   done
 
-  # Check for text rels
   checkTextRelocations
 
   prepareOutput

scripts/ffmpeg/download.sh

@@ -1,31 +1,24 @@
-# Expecting FFMPEG_SOURCE_TYPE and FFMPEG_SOURCE_VALUE variables
+# Script to download FFmpeg's source code
+# Relies on FFMPEG_SOURCE_TYPE and FFMPEG_SOURCE_VALUE variables
+# to choose the valid origin and version
 
-# Think of that names
+# Exports SOURCES_DIR_ffmpeg - path where actual sources are stored
-
-# Expecting ENSURE_SOURCE_DIR - where source code has to be downloaded
-# Exports SOURCES_DIR_FFMPEG - path where actual sources are stored
-
-echo "Downloading sources for FFmpeg"
-
-echo ${FFMPEG_SOURCE_TYPE}
-echo ${FFMPEG_SOURCE_VALUE}
 
 # Utility function
-# Getting sources of a particular ffmpeg release.
+# Getting sources of a particular FFmpeg release.
-# Same argument (ffmpeg version) produces the same source set.
+# Same argument (FFmpeg version) produces the same source set.
 function ensureSourcesTar() {
-  FFMPEG_SOURCES=${ENSURE_SOURCE_DIR}/ffmpeg-${FFMPEG_SOURCE_VALUE}
+  FFMPEG_SOURCES=ffmpeg-${FFMPEG_SOURCE_VALUE}
 
   if [[ ! -d "$FFMPEG_SOURCES" ]]; then
     TARGET_FILE_NAME=ffmpeg-${FFMPEG_SOURCE_VALUE}.tar.bz2
-    TARGET_FILE_PATH=${ENSURE_SOURCE_DIR}/${TARGET_FILE_NAME}
 
-    curl https://www.ffmpeg.org/releases/${TARGET_FILE_NAME} --output ${TARGET_FILE_PATH}
+    curl https://www.ffmpeg.org/releases/${TARGET_FILE_NAME} --output ${TARGET_FILE_NAME}
-    tar xzf ${TARGET_FILE_PATH} -C ${ENSURE_SOURCE_DIR}
+    tar xzf ${TARGET_FILE_NAME} -C .
-    rm ${TARGET_FILE_PATH}
+    rm ${TARGET_FILE_NAME}
   fi
 
-  export SOURCES_DIR_ffmpeg=$FFMPEG_SOURCES
+  export SOURCES_DIR_ffmpeg=$(pwd)/${FFMPEG_SOURCES}
 }
 
 # Utility function

scripts/parse-arguments.sh

@@ -35,18 +35,18 @@ do
       shift
     ;;
     # Arguments below enable certain external libraries to build into FFmpeg
-    --enable-libaom)
+    # --enable-libaom)
-      EXTERNAL_LIBRARIES+=( "libaom" )
+    #   EXTERNAL_LIBRARIES+=( "libaom" )
-      shift
+    #   shift
-    ;;
+    # ;;
-    --enable-libdav1d)
+    # --enable-libdav1d)
-      EXTERNAL_LIBRARIES+=( "libdav1d" )
+    #   EXTERNAL_LIBRARIES+=( "libdav1d" )
-      shift
+    #   shift
-    ;;
+    # ;;
-    --enable-libmp3lame)
+    # --enable-libmp3lame)
-      EXTERNAL_LIBRARIES+=( "libmp3lame" )
+    #   EXTERNAL_LIBRARIES+=( "libmp3lame" )
-      shift
+    #   shift
-    ;;
+    # ;;
     *)
       echo "Unknown argument $artument"
     ;;