[FFmpeg-devel] Best Android Configuration?

[Kevin Kowalewski]

Hi,

We're currently using the following script to generate the appropriate
configuration for Android, but find the performance is still not enough on
a dual core Cortex A9 CPU under Android.

We suspect no hardware acceleration is possible yet with FFMpeg and Android.

Does anyone know of better configuration options?

Kevin

######################################################
# FFmpeg builds script for Android+ARM platform
#
# This script is released under term of
#   CDDL (http://www.opensource.org/licenses/cddl1)
# Wrote by pinxue (~@gmail.com) from RockPlayer.com
#                                   2010-8 ~ 2011-4
######################################################

#NDK=~/android/android-ndk-r4
#PLATFORM=$NDK/build/platforms/android-8/arch-arm/
#PREBUILT=$NDK/build/prebuilt/darwin-x86/arm-eabi-4.4.0

PLATFORM=$NDK/platforms/android-8/arch-arm
PREBUILT=$NDK/toolchains/arm-linux-androideabi-4.4.3/prebuilt/darwin-x86

function build_one
{

# -fasm : required. Android header file uses asm keyword instead of __asm__
, but most of c dialect (like ansi,c99,gnu99) implies -fno-asm.
#
~/android/android-ndk-r4/build/platforms/android-5/arch-arm//usr/include/asm/byteorder.h:
In function '___arch__swab32':
#
~/android/android-ndk-r4/build/platforms/android-5/arch-arm//usr/include/asm/byteorder.h:25:
error: expected ')' before ':' token

# -fno-short-enums : optimized.  Else FFmpeg obj will generate a huge
number of warning for variable-size enums,
#   though we may suppress them by --no-enum-size-warning, it would be
better to avoid it.
#   .../ld: warning: cmdutils.o uses variable-size enums yet the output is
to use 32-bit enums; use of enum values across objects may fail

# --extra-libs="-lgcc" : required. Else cannot solve some runtime function
symbols
#   ... undefined reference to `__aeabi_f2uiz'

# --enable-protocols : required. Without this option, the file open always
fails mysteriously.
#   FFmpeg's av_open_input_file will invoke file format probing functions,
but because most of useful demuxers has flag of zero
#   which cause them are ignored during file format probling and fall to
url stream parsing,
#   if protocols are disabled, the file:// url cannot be opened as well.

# $PREBUILT/bin/arm-eabi-ar d libavcodec/libavcodec.a inverse.o : required.
#   FFmpeg includes two copies of inverse.c both in libavutil and
libavcodec for performance consideration (not sure the benifit yet)
#   Without this step, final ld of generating libffmpeg.so will fail
silently, if invoke ld through gcc, gcc will collect more reasonable error
message.

# -llog: debug only, FFmpeg itself doesn't require it at all.
#   With this option, we may simply includes "utils/Log.h" and use LOGx()
to observe FFmpeg's behavior
#   PS, it seems the toolchain implies -DNDEBUG somewhere, it would be
safer to use following syntax
#    #ifdef NDEBUG
#        #undef NDEBUG
#        #define HAVE_NDEBUG
#    #endif
#    #include "utils/Log.h"
#    #ifdef HAVE_NDEBUG
#        #define NDEBUG
#        #undef HAVE_NDEBUG
#    #endif

# --whole-archive : required. Else ld generate a small .so file (about 15k)

# --no-stdlib : required. Android doesn't use standard c runtime but
invited its own wheal (bionic libc) because of license consideration.

# space before \ of configure lines: required for some options. Else next
line will be merged into previous lines's content and cause problem.
#   Especially the --extra-cflags, the next line will pass to gcc in this
case and configure will say gcc cannot create executable.

# many options mentioned by articles over internet are implied by -O2 or
-O3 already, need not repeat at all.

# two or three common optimization cflags are omitted because not sure
about the trade off yet. invoke NDK build system with V=1 to find them.

# -Wl,-T,$PREBUILT/arm-eabi/lib/ldscripts/armelf.x mentioned by almost
every articles over internet, but it is not required to specify at all.

# -Dipv6mr_interface=ipv6mr_ifindex : required. Android inet header doesn't
use ipv6mr_interface which is required by rfc, seems it generate this user
space header file directly from kernel header file, but Linux kernel has
decided to keep its own name for ever and ask user space header to use rfc
name.

# HAVE_SYS_UIO_H : required. Else:
# In file included from
~/android/android-ndk-r4/build/platforms/android-5/arch-arm//usr/include/linux/socket.h:29,
#                 from
~/android/android-ndk-r4/build/platforms/android-5/arch-arm//usr/include/sys/socket.h:33,
#                 from libavformat/network.h:35,
#                 from libavformat/utils.c:46:
#~/android/android-ndk-r4/build/platforms/android-5/arch-arm//usr/include/linux/uio.h:19:
error: redefinition of 'struct iovec'
#

# --disable-doc : required because of strange bug of toolchain.

./configure --target-os=linux \
    --prefix=$PREFIX \
    --enable-cross-compile \
    --extra-libs="-lgcc" \
    --arch=arm \
    --cc=$PREBUILT/bin/arm-linux-androideabi-gcc \
    --cross-prefix=$PREBUILT/bin/arm-linux-androideabi- \
    --nm=$PREBUILT/bin/arm-linux-androideabi-nm \
    --sysroot=$PLATFORM \
    --extra-cflags=" -O3 -fpic -DANDROID -DHAVE_SYS_UIO_H=1
-Dipv6mr_interface=ipv6mr_ifindex -fasm -Wno-psabi -fno-short-enums
-fno-strict-aliasing -finline-limit=300 $OPTIMIZE_CFLAGS " \
    --disable-shared \
    --enable-static \
    --extra-ldflags="-Wl,-rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib
-nostdlib -lc -lm -ldl -llog" \
    --enable-parsers \
    --disable-encoders  \
    --enable-decoders \
    --disable-muxers \
    --enable-demuxers \
    --enable-swscale  \
    --disable-ffplay \
    --disable-ffprobe \
    --disable-ffserver \
    --enable-network \
    --enable-indevs \
    --disable-bsfs \
    --disable-filters \
    --enable-protocols  \
    --enable-asm \
    --enable-armv5te \
    --enable-armv6t2 \
    --enable-armvfp \
    --enable-memalign-hack \
    $ADDITIONAL_CONFIGURE_FLAG

#make clean
make  -j4 install

$PREBUILT/bin/arm-linux-androideabi-ar d libavcodec/libavcodec.a inverse.o

$PREBUILT/bin/arm-linux-androideabi-ld -rpath-link=$PLATFORM/usr/lib
-L$PLATFORM/usr/lib  -soname libffmpeg.so -shared -nostdlib  -z,noexecstack
-Bsymbolic --whole-archive --no-undefined -o $PREFIX/libffmpeg.so
libavcodec/libavcodec.a libavformat/libavformat.a libavutil/libavutil.a
-lc -lm -lz -ldl -llog  --warn-once  --dynamic-linker=/system/bin/linker
$PREBUILT/lib/gcc/arm-linux-androideabi/4.4.3/libgcc.a

}

##arm v7vfpv3
CPU=armv7-a
OPTIMIZE_CFLAGS="-mfloat-abi=softfp -mfpu=vfpv3 -marm -march=$CPU
-mtune=cortex-a9"
PREFIX=./android/$CPU
DDITIONAL_CONFIGURE_FLAG=--enable-neon
build_one