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• The Future of the VP8 Bitstream

  17 juin 2010, par noreply@blogger.com (John Luther) — vp8

  Recently we’ve seen software products such as VLC, FFmpeg, Logitech Vid, Flumotion and Tixeo adopting and using WebM and VP8 (the video codec in WebM) in exciting new ways.

  In addition to software developers, many hardware vendors have committed to shipping VP8-accelerated products based on our current bitstream in 2011 . Devices that use hardware acceleration for video are a very small percentage of overall web traffic today, but they are a rapidly growing segment of the market and our project must be mindful of these vendors’ needs. Given the longer lead times for changes in chipsets, hardware companies implementing the codec today need to be confident that it will be stable and supported as VP8 content proliferates.

  Like every codec, WebM is not immune to change ; the difference in our project is that the improvements are publicly visible, and compatibility and implementation issues can be worked through in an open forum.

  So, to maintain codec stability while also allowing for quality and performance improvements in VP8, we have added an experimental branch to the VP8 source tree. The WebM community can use this unstable branch to propose changes to VP8 that will produce the best video codec possible, but without the constraints of a frozen bitstream. At some point in the future, when the experimental branch proves significantly better than the stable branch, we will create a new version of the codec.

  Teams dedicated to improving WebM are actively investigating and evaluating new techniques, and are committed to do so for the long term. We encourage the WebM community to keep contributing as well. To learn more about the experimental branch and get involved, see our repository layout page.

  Jim Bankoski is Codec Engineering Manager at Google.

  

• How to fix selected processor does not support `movw ' when trying to compile x264 for amrv6 ?

  13 mars 2012, par newentry

  I am getting following error when trying to compile x264 for android armv6.

  common/arm/pixel-a.S : Assembler messages :
  common/arm/pixel-a.S:1206 : Error : selected processor does not support

  movw ip,#:lower16:235963'
common/arm/pixel-a.S:1206: Error: selected processor does not support

  movt ip,#:upper16:235963'
  make : * [common/arm/pixel-a.o] Error 1

  my x264 script

  ./configure —extra-ldflags='-march=armv6' —extra-cflags='-march=armv6' —cross-prefix=arm-linux-androideabi- —enable-pic —host=arm-linux

• so Confused, why my build of libffmpeg.so > 17M ?

  24 février 2012, par ghost

  I did build ffmpeg for Android in winxp and scientific linux , ffmpeg is in dolphin player — an open source video player (http://code.google.com/p/dolphin-player/), and i just build the ffmpeg, its seems like the same as in rockplayer 1.7.0, they all use build_andriod.sh below， it worked in both winxp and linux,
  and all successfully got bin/ffmpeg (less than 5MB), but libffmpeg.so ( > 17MB)， when put libffmpeg.so in dolphin-player libs , player can't work, the size 17MB is too large, the original libffmpeg.so in olphin-player libs is less than 5MB, please give some advice.

  #!/bin/bash
  
  
  
  ######################################################
  
  # 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
  
  ######################################################
  
  
  
  ######################################################
  
  # Usage:
  
  #   put this script in top of FFmpeg source tree
  
  #   ./build_android
  
  #
  
  # It generates binary for following architectures:
  
  #     ARMv6 
  
  #     ARMv6+VFP 
  
  #     ARMv7+VFM-ïd16 (Tegra2) 
  
  #     ARMv7+Neon (Cortex-A8)
  
  #
  
  # Customizing:
  
  # 1. Feel free to change ./configure parameters for more features
  
  # 2. To adapt other ARM variants
  
  #       set $CPU and $OPTIMIZE_CFLAGS 
  
  #       call build_one
  
  ######################################################
  
  
  
  export TMPDIR=D:/tmp/android
  
  export NDK=D:/android-ndk-r4
  
  
  
  #PLATFORM=$NDK/build/platforms/android-8/arch-arm/
  
  PLATFORM=$NDK/build/platforms/android-8/arch-arm
  
  #PREBUILT=$NDK/build/prebuilt/darwin-x86/arm-eabi-4.4.0
  
  PREBUILT=$NDK/build/prebuilt/windows/arm-eabi-4.4.0
  
  
  
  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.
  
  #
  
  
  
  #
  
  #--extra-ldflags=-Wl,-T,$PREBUILT/arm-eabi/lib/ldscripts/armelf.x -Wl,-rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib -nostdlib $PREBUILT/lib/gcc/arm-eabi/4.4.0/crtbegin.o $PREBUILT/lib/gcc/arm-eabi/4.4.0/crtend.o -lc -lm -ldl"
  
  #
  
  
  
  ./configure --target-os=linux \
  
      --prefix=$PREFIX \
  
      --enable-cross-compile \
  
      --extra-libs="-lgcc" \
  
      --arch=arm \
  
      --cc=$PREBUILT/bin/arm-eabi-gcc \
  
      --cross-prefix=$PREBUILT/bin/arm-eabi- \
  
      --nm=$PREBUILT/bin/arm-eabi-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 \
  
      --disable-doc \
  
      $ADDITIONAL_CONFIGURE_FLAG
  
  
  
  ##make clean
  
  make  -j4 install
  
  
  
  
  
  $PREBUILT/bin/arm-eabi-ar d libavcodec/libavcodec.a inverse.o
  
  
  
  $PREBUILT/bin/arm-eabi-ld -rpath-link=$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-eabi/4.4.0/libgcc.a
  
  
  
  }
  
  
  
  
  
  #arm v6
  
  CPU=armv6
  
  OPTIMIZE_CFLAGS="-marm -march=$CPU"
  
  PREFIX=./android/$CPU 
  
  ADDITIONAL_CONFIGURE_FLAG=
  
  build_one
  
  
  
  #arm v7vfpv3
  
  CPU=armv7-a
  
  OPTIMIZE_CFLAGS="-mfloat-abi=softfp -mfpu=vfpv3-d16 -marm -march=$CPU "
  
  PREFIX=./android/$CPU 
  
  ADDITIONAL_CONFIGURE_FLAG=
  
  build_one
  
  
  
  #arm v7vfp
  
  CPU=armv7-a
  
  OPTIMIZE_CFLAGS="-mfloat-abi=softfp -mfpu=vfp -marm -march=$CPU "
  
  PREFIX=./android/$CPU-vfp
  
  ADDITIONAL_CONFIGURE_FLAG=
  
  build_one
  
  
  
  #arm v7n
  
  CPU=armv7-a
  
  OPTIMIZE_CFLAGS="-mfloat-abi=softfp -mfpu=neon -marm -march=$CPU -mtune=cortex-a8"
  
  PREFIX=./android/$CPU-neon 
  
  ADDITIONAL_CONFIGURE_FLAG=--enable-neon
  
  build_one
  
  
  
  #arm v6+vfp
  
  CPU=armv6
  
  OPTIMIZE_CFLAGS="-DCMP_HAVE_VFP -mfloat-abi=softfp -mfpu=vfp -marm -march=$CPU"
  
  PREFIX=./android/${CPU}_vfp 
  
  ADDITIONAL_CONFIGURE_FLAG=
  
  build_one