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• What flags should enable to get maximum performance using ffpeg ?

  19 octobre 2017, par Sam

  I am using windows, my application is using opencv and for codecs, we have used ffmpeg. We see the performance is very slow, we want to improve it by compiling ffmpeg with all flags which could take hardware and GPU acceleation into consideration.
  I did ./configure --help inside the ffmpeg source, I see below list option, can you please tell which all can really imporve the performance. Note that we would like to take advantage of hardware and gpu capabilities.

      $ ./configure —help
  
      Usage : configure [options]
  
      Options : [defaults in brackets after descriptions]
      Help options :
  
        —help                   print this message
  
        —quiet                  Suppress showing informative output
  
        —list-decoders          show all available decoders
  
        —list-encoders          show all available encoders
  
        —list-hwaccels          show all available hardware accelerators
  
        —list-demuxers          show all available demuxers
  
        —list-muxers            show all available muxers
  
        —list-parsers           show all available parsers
  
        —list-protocols         show all available protocols
  
        —list-bsfs              show all available bitstream filters
  
        —list-indevs            show all available input devices
  
        —list-outdevs           show all available output devices
  
        —list-filters           show all available filters
      Standard options :
  
        —logfile=FILE           log tests and output to FILE [ffbuild/config.log]
  
        —disable-logging        do not log configure debug information
  
        —fatal-warnings         fail if any configure warning is generated
  
        —prefix=PREFIX          install in PREFIX [/usr/local]
  
        —bindir=DIR             install binaries in DIR [PREFIX/bin]
  
        —datadir=DIR            install data files in DIR [PREFIX/share/ffmpeg]
  
        —docdir=DIR             install documentation in DIR [PREFIX/share/doc/ffmpeg                                                                                                      ]
  
        —libdir=DIR             install libs in DIR [PREFIX/lib]
  
        —shlibdir=DIR           install shared libs in DIR [LIBDIR]
  
        —incdir=DIR             install includes in DIR [PREFIX/include]
  
        —mandir=DIR             install man page in DIR [PREFIX/share/man]
  
        —pkgconfigdir=DIR       install pkg-config files in DIR [LIBDIR/pkgconfig]
  
        —enable-rpath           use rpath to allow installing libraries in paths
  
                                 not part of the dynamic linker search path
  
                                 use rpath when linking programs (USE WITH CARE)
  
        —install-name-dir=DIR   Darwin directory name for installed targets
      Licensing options :
  
        —enable-gpl             allow use of GPL code, the resulting libs
  
                                 and binaries will be under GPL [no]
  
        —enable-version3        upgrade (L)GPL to version 3 [no]
  
        —enable-nonfree         allow use of nonfree code, the resulting libs
  
                                 and binaries will be unredistributable [no]
      Configuration options :
  
        —disable-static         do not build static libraries [no]
  
        —enable-shared          build shared libraries [no]
  
        —enable-small           optimize for size instead of speed
  
        —disable-runtime-cpudetect disable detecting CPU capabilities at runtime (sma                                                                                                      ller binary)
  
        —enable-gray            enable full grayscale support (slower color)
  
        —disable-swscale-alpha  disable alpha channel support in swscale
  
        —disable-all            disable building components, libraries and programs
  
        —disable-autodetect     disable automatically detected external libraries [no                                                                                                      ]
      Program options :
  
        —disable-programs       do not build command line programs
  
        —disable-ffmpeg         disable ffmpeg build
  
        —disable-ffplay         disable ffplay build
  
        —disable-ffprobe        disable ffprobe build
  
        —disable-ffserver       disable ffserver build
      Documentation options :
  
        —disable-doc            do not build documentation
  
        —disable-htmlpages      do not build HTML documentation pages
  
        —disable-manpages       do not build man documentation pages
  
        —disable-podpages       do not build POD documentation pages
  
        —disable-txtpages       do not build text documentation pages
      Component options :
  
        —disable-avdevice       disable libavdevice build
  
        —disable-avcodec        disable libavcodec build
  
        —disable-avformat       disable libavformat build
  
        —disable-swresample     disable libswresample build
  
        —disable-swscale        disable libswscale build
  
        —disable-postproc       disable libpostproc build
  
        —disable-avfilter       disable libavfilter build
  
        —enable-avresample      enable libavresample build [no]
  
        —disable-pthreads       disable pthreads [autodetect]
  
        —disable-w32threads     disable Win32 threads [autodetect]
  
        —disable-os2threads     disable OS/2 threads [autodetect]
  
        —disable-network        disable network support [no]
  
        —disable-dct            disable DCT code
  
        —disable-dwt            disable DWT code
  
        —disable-error-resilience disable error resilience code
  
        —disable-lsp            disable LSP code
  
        —disable-lzo            disable LZO decoder code
  
        —disable-mdct           disable MDCT code
  
        —disable-rdft           disable RDFT code
  
        —disable-fft            disable FFT code
  
        —disable-faan           disable floating point AAN (I)DCT code
  
        —disable-pixelutils     disable pixel utils in libavutil
      Individual component options :
  
        —disable-everything     disable all components listed below
  
        —disable-encoder=NAME   disable encoder NAME
  
        —enable-encoder=NAME    enable encoder NAME
  
        —disable-encoders       disable all encoders
  
        —disable-decoder=NAME   disable decoder NAME
  
        —enable-decoder=NAME    enable decoder NAME
  
        —disable-decoders       disable all decoders
  
        —disable-hwaccel=NAME   disable hwaccel NAME
  
        —enable-hwaccel=NAME    enable hwaccel NAME
  
        —disable-hwaccels       disable all hwaccels
  
        —disable-muxer=NAME     disable muxer NAME
  
        —enable-muxer=NAME      enable muxer NAME
  
        —disable-muxers         disable all muxers
  
        —disable-demuxer=NAME   disable demuxer NAME
  
        —enable-demuxer=NAME    enable demuxer NAME
  
        —disable-demuxers       disable all demuxers
  
        —enable-parser=NAME     enable parser NAME
  
        —disable-parser=NAME    disable parser NAME
  
        —disable-parsers        disable all parsers
  
        —enable-bsf=NAME        enable bitstream filter NAME
  
        —disable-bsf=NAME       disable bitstream filter NAME
  
        —disable-bsfs           disable all bitstream filters
  
        —enable-protocol=NAME   enable protocol NAME
  
        —disable-protocol=NAME  disable protocol NAME
  
        —disable-protocols      disable all protocols
  
        —enable-indev=NAME      enable input device NAME
  
        —disable-indev=NAME     disable input device NAME
  
        —disable-indevs         disable input devices
  
        —enable-outdev=NAME     enable output device NAME
  
        —disable-outdev=NAME    disable output device NAME
  
        —disable-outdevs        disable output devices
  
        —disable-devices        disable all devices
  
        —enable-filter=NAME     enable filter NAME
  
        —disable-filter=NAME    disable filter NAME
  
        —disable-filters        disable all filters
  
        —disable-v4l2_m2m       disable V4L2 mem2mem code [autodetect]
      External library support :
        Using any of the following switches will allow FFmpeg to link to the
  
        corresponding external library. All the components depending on that library
  
        will become enabled, if all their other dependencies are met and they are not
  
        explicitly disabled. E.g. —enable-libwavpack will enable linking to
  
        libwavpack and allow the libwavpack encoder to be built, unless it is
  
        specifically disabled with —disable-encoder=libwavpack.
        Note that only the system libraries are auto-detected. All the other external
  
        libraries must be explicitly enabled.
        Also note that the following help text describes the purpose of the libraries
  
        themselves, not all their features will necessarily be usable by FFmpeg.
        —disable-alsa           disable ALSA support [autodetect]
  
        —disable-appkit         disable Apple AppKit framework [autodetect]
  
        —disable-avfoundation   disable Apple AVFoundation framework [autodetect]
  
        —enable-avisynth        enable reading of AviSynth script files [no]
  
        —disable-bzlib          disable bzlib [autodetect]
  
        —disable-coreimage      disable Apple CoreImage framework [autodetect]
  
        —enable-chromaprint     enable audio fingerprinting with chromaprint [no]
  
        —enable-frei0r          enable frei0r video filtering [no]
  
        —enable-gcrypt          enable gcrypt, needed for rtmp(t)e support
  
                                 if openssl, librtmp or gmp is not used [no]
  
        —enable-gmp             enable gmp, needed for rtmp(t)e support
  
                                 if openssl or librtmp is not used [no]
  
        —enable-gnutls          enable gnutls, needed for https support
  
                                 if openssl is not used [no]
  
        —disable-iconv          disable iconv [autodetect]
  
        —disable-jack           disable libjack support [autodetect]
  
        —enable-jni             enable JNI support [no]
  
        —enable-ladspa          enable LADSPA audio filtering [no]
  
        —enable-libass          enable libass subtitles rendering,
  
                                 needed for subtitles and ass filter [no]
  
        —enable-libbluray       enable BluRay reading using libbluray [no]
  
        —enable-libbs2b         enable bs2b DSP library [no]
  
        —enable-libcaca         enable textual display using libcaca [no]
  
        —enable-libcelt         enable CELT decoding via libcelt [no]
  
        —enable-libcdio         enable audio CD grabbing with libcdio [no]
  
        —enable-libdc1394       enable IIDC-1394 grabbing using libdc1394
  
                                 and libraw1394 [no]
  
        —enable-libfdk-aac      enable AAC de/encoding via libfdk-aac [no]
  
        —enable-libflite        enable flite (voice synthesis) support via libflite [                                                                                                      no]
  
        —enable-libfontconfig   enable libfontconfig, useful for drawtext filter [no]
  
        —enable-libfreetype     enable libfreetype, needed for drawtext filter [no]
  
        —enable-libfribidi      enable libfribidi, improves drawtext filter [no]
  
        —enable-libgme          enable Game Music Emu via libgme [no]
  
        —enable-libgsm          enable GSM de/encoding via libgsm [no]
  
        —enable-libiec61883     enable iec61883 via libiec61883 [no]
  
        —enable-libilbc         enable iLBC de/encoding via libilbc [no]
  
        —enable-libkvazaar      enable HEVC encoding via libkvazaar [no]
  
        —enable-libmodplug      enable ModPlug via libmodplug [no]
  
        —enable-libmp3lame      enable MP3 encoding via libmp3lame [no]
  
        —enable-libopencore-amrnb enable AMR-NB de/encoding via libopencore-amrnb [no                                                                                                      ]
  
        —enable-libopencore-amrwb enable AMR-WB decoding via libopencore-amrwb [no]
  
        —enable-libopencv       enable video filtering via libopencv [no]
  
        —enable-libopenh264     enable H.264 encoding via OpenH264 [no]
  
        —enable-libopenjpeg     enable JPEG 2000 de/encoding via OpenJPEG [no]
  
        —enable-libopenmpt      enable decoding tracked files via libopenmpt [no]
  
        —enable-libopus         enable Opus de/encoding via libopus [no]
  
        —enable-libpulse        enable Pulseaudio input via libpulse [no]
  
        —enable-librsvg         enable SVG rasterization via librsvg [no]
  
        —enable-librubberband   enable rubberband needed for rubberband filter [no]
  
        —enable-librtmp         enable RTMP[E] support via librtmp [no]
  
        —enable-libshine        enable fixed-point MP3 encoding via libshine [no]
  
        —enable-libsmbclient    enable Samba protocol via libsmbclient [no]
  
        —enable-libsnappy       enable Snappy compression, needed for hap encoding [n                                                                                                      o]
  
        —enable-libsoxr         enable Include libsoxr resampling [no]
  
        —enable-libspeex        enable Speex de/encoding via libspeex [no]
  
        —enable-libssh          enable SFTP protocol via libssh [no]
  
        —enable-libtesseract    enable Tesseract, needed for ocr filter [no]
  
        —enable-libtheora       enable Theora encoding via libtheora [no]
  
        —enable-libtwolame      enable MP2 encoding via libtwolame [no]
  
        —enable-libv4l2         enable libv4l2/v4l-utils [no]
  
        —enable-libvidstab      enable video stabilization using vid.stab [no]
  
        —enable-libvmaf         enable vmaf filter via libvmaf [no]
  
        —enable-libvo-amrwbenc  enable AMR-WB encoding via libvo-amrwbenc [no]
  
        —enable-libvorbis       enable Vorbis en/decoding via libvorbis,
  
                                 native implementation exists [no]
  
        —enable-libvpx          enable VP8 and VP9 de/encoding via libvpx [no]
  
        —enable-libwavpack      enable wavpack encoding via libwavpack [no]
  
        —enable-libwebp         enable WebP encoding via libwebp [no]
  
        —enable-libx264         enable H.264 encoding via x264 [no]
  
        —enable-libx265         enable HEVC encoding via x265 [no]
  
        —enable-libxavs         enable AVS encoding via xavs [no]
  
        —enable-libxcb          enable X11 grabbing using XCB [autodetect]
  
        —enable-libxcb-shm      enable X11 grabbing shm communication [autodetect]
  
        —enable-libxcb-xfixes   enable X11 grabbing mouse rendering [autodetect]
  
        —enable-libxcb-shape    enable X11 grabbing shape rendering [autodetect]
  
        —enable-libxvid         enable Xvid encoding via xvidcore,
  
                                 native MPEG-4/Xvid encoder exists [no]
  
        —enable-libxml2         enable XML parsing using the C library libxml2 [no]
  
        —enable-libzimg         enable z.lib, needed for zscale filter [no]
  
        —enable-libzmq          enable message passing via libzmq [no]
  
        —enable-libzvbi         enable teletext support via libzvbi [no]
  
        —disable-lzma           disable lzma [autodetect]
  
        —enable-decklink        enable Blackmagic DeckLink I/O support [no]
  
        —enable-libndi_newtek   enable Newteck NDI I/O support [no]
  
        —enable-mediacodec      enable Android MediaCodec support [no]
  
        —enable-libmysofa       enable libmysofa, needed for sofalizer filter [no]
  
        —enable-openal          enable OpenAL 1.1 capture support [no]
  
        —enable-opencl          enable OpenCL code
  
        —enable-opengl          enable OpenGL rendering [no]
  
        —enable-openssl         enable openssl, needed for https support
  
                                 if gnutls is not used [no]
  
        —disable-sndio          disable sndio support [autodetect]
  
        —disable-schannel       disable SChannel SSP, needed for TLS support on
  
                                 Windows if openssl and gnutls are not used [autodetec                                                                                                      t]
  
        —disable-sdl2           disable sdl2 [autodetect]
  
        —disable-securetransport disable Secure Transport, needed for TLS support
  
                                 on OSX if openssl and gnutls are not used [autodetect                                                                                                      ]
  
        —disable-xlib           disable xlib [autodetect]
  
        —disable-zlib           disable zlib [autodetect]
        The following libraries provide various hardware acceleration features :
  
        —disable-audiotoolbox   disable Apple AudioToolbox code [autodetect]
  
        —disable-cuda           disable dynamically linked Nvidia CUDA code [autodete                                                                                                      ct]
  
        —enable-cuda-sdk        enable CUDA features that require the CUDA SDK [no]
  
        —disable-cuvid          disable Nvidia CUVID support [autodetect]
  
        —disable-d3d11va        disable Microsoft Direct3D 11 video acceleration code                                                                                                       [autodetect]
  
        —disable-dxva2          disable Microsoft DirectX 9 video acceleration code [                                                                                                      autodetect]
  
        —enable-libdrm          enable DRM code (Linux) [no]
  
        —enable-libmfx          enable Intel MediaSDK (AKA Quick Sync Video) code via                                                                                                       libmfx [no]
  
        —enable-libnpp          enable Nvidia Performance Primitives-based code [no]
  
        —enable-mmal            enable Broadcom Multi-Media Abstraction Layer (Raspbe                                                                                                      rry Pi) via MMAL [no]
  
        —disable-nvenc          disable Nvidia video encoding code [autodetect]
  
        —enable-omx             enable OpenMAX IL code [no]
  
        —enable-omx-rpi         enable OpenMAX IL code for Raspberry Pi [no]
  
        —enable-rkmpp           enable Rockchip Media Process Platform code [no]
  
        —disable-vaapi          disable Video Acceleration API (mainly Unix/Intel) co                                                                                                      de [autodetect]
  
        —disable-vda            disable Apple Video Decode Acceleration code [autodet                                                                                                      ect]
  
        —disable-vdpau          disable Nvidia Video Decode and Presentation API for                                                                                                       Unix code [autodetect]
  
        —disable-videotoolbox   disable VideoToolbox code [autodetect]
      Toolchain options :
  
        —arch=ARCH              select architecture []
  
        —cpu=CPU                select the minimum required CPU (affects
  
                                 instruction selection, may crash on older CPUs)
  
        —cross-prefix=PREFIX    use PREFIX for compilation tools []
  
        —progs-suffix=SUFFIX    program name suffix []
  
        —enable-cross-compile   assume a cross-compiler is used
  
        —sysroot=PATH           root of cross-build tree
  
        —sysinclude=PATH        location of cross-build system headers
  
        —target-os=OS           compiler targets OS []
  
        —target-exec=CMD        command to run executables on target
  
        —target-path=DIR        path to view of build directory on target
  
        —target-samples=DIR     path to samples directory on target
  
        —tempprefix=PATH        force fixed dir/prefix instead of mktemp for checks
  
        —toolchain=NAME         set tool defaults according to NAME
  
        —nm=NM                  use nm tool NM [nm -g]
  
        —ar=AR                  use archive tool AR [ar]
  
        —as=AS                  use assembler AS []
  
        —ln_s=LN_S              use symbolic link tool LN_S [ln -s -f]
  
        —strip=STRIP            use strip tool STRIP [strip]
  
        —windres=WINDRES        use windows resource compiler WINDRES [windres]
  
        —x86asmexe=EXE          use nasm-compatible assembler EXE [nasm]
  
        —cc=CC                  use C compiler CC [gcc]
  
        —cxx=CXX                use C compiler CXX [g++]
  
        —objcc=OCC              use ObjC compiler OCC [gcc]
  
        —dep-cc=DEPCC           use dependency generator DEPCC [gcc]
  
        —nvcc=NVCC              use Nvidia CUDA compiler NVCC [nvcc]
  
        —ld=LD                  use linker LD []
  
        —pkg-config=PKGCONFIG   use pkg-config tool PKGCONFIG [pkg-config]
  
        —pkg-config-flags=FLAGS pass additional flags to pkgconf []
  
        —ranlib=RANLIB          use ranlib RANLIB [ranlib]
  
        —doxygen=DOXYGEN        use DOXYGEN to generate API doc [doxygen]
  
        —host-cc=HOSTCC         use host C compiler HOSTCC
  
        —host-cflags=HCFLAGS    use HCFLAGS when compiling for host
  
        —host-cppflags=HCPPFLAGS use HCPPFLAGS when compiling for host
  
        —host-ld=HOSTLD         use host linker HOSTLD
  
        —host-ldflags=HLDFLAGS  use HLDFLAGS when linking for host
  
        —host-libs=HLIBS        use libs HLIBS when linking for host
  
        —host-os=OS             compiler host OS []
  
        —extra-cflags=ECFLAGS   add ECFLAGS to CFLAGS []
  
        —extra-cxxflags=ECFLAGS add ECFLAGS to CXXFLAGS []
  
        —extra-objcflags=FLAGS  add FLAGS to OBJCFLAGS []
  
        —extra-ldflags=ELDFLAGS add ELDFLAGS to LDFLAGS []
  
        —extra-ldexeflags=ELDFLAGS add ELDFLAGS to LDEXEFLAGS []
  
        —extra-ldlibflags=ELDFLAGS add ELDFLAGS to LDLIBFLAGS []
  
        —extra-libs=ELIBS       add ELIBS []
  
        —extra-version=STRING   version string suffix []
  
        —optflags=OPTFLAGS      override optimization-related compiler flags
  
        —nvccflags=NVCCFLAGS    override nvcc flags [-gencode arch=compute_30,code=sm                                                                                                      _30 -O2]
  
        —build-suffix=SUFFIX    library name suffix []
  
        —enable-pic             build position-independent code
  
        —enable-thumb           compile for Thumb instruction set
  
        —enable-lto             use link-time optimization
  
        —env="ENV=override"     override the environment variables
      Advanced options (experts only) :
  
        —malloc-prefix=PREFIX   prefix malloc and related names with PREFIX
  
        —custom-allocator=NAME  use a supported custom allocator
  
        —disable-symver         disable symbol versioning
  
        —enable-hardcoded-tables use hardcoded tables instead of runtime generation
  
        —disable-safe-bitstream-reader
  
                                 disable buffer boundary checking in bitreaders
  
                                 (faster, but may crash)
  
        —sws-max-filter-size=N  the max filter size swscale uses [256]
      Optimization options (experts only) :
  
        —disable-asm            disable all assembly optimizations
  
        —disable-altivec        disable AltiVec optimizations
  
        —disable-vsx            disable VSX optimizations
  
        —disable-power8         disable POWER8 optimizations
  
        —disable-amd3dnow       disable 3DNow ! optimizations
  
        —disable-amd3dnowext    disable 3DNow ! extended optimizations
  
        —disable-mmx            disable MMX optimizations
  
        —disable-mmxext         disable MMXEXT optimizations
  
        —disable-sse            disable SSE optimizations
  
        —disable-sse2           disable SSE2 optimizations
  
        —disable-sse3           disable SSE3 optimizations
  
        —disable-ssse3          disable SSSE3 optimizations
  
        —disable-sse4           disable SSE4 optimizations
  
        —disable-sse42          disable SSE4.2 optimizations
  
        —disable-avx            disable AVX optimizations
  
        —disable-xop            disable XOP optimizations
  
        —disable-fma3           disable FMA3 optimizations
  
        —disable-fma4           disable FMA4 optimizations
  
        —disable-avx2           disable AVX2 optimizations
  
        —disable-aesni          disable AESNI optimizations
  
        —disable-armv5te        disable armv5te optimizations
  
        —disable-armv6          disable armv6 optimizations
  
        —disable-armv6t2        disable armv6t2 optimizations
  
        —disable-vfp            disable VFP optimizations
  
        —disable-neon           disable NEON optimizations
  
        —disable-inline-asm     disable use of inline assembly
  
        —disable-x86asm         disable use of standalone x86 assembly
  
        —disable-mipsdsp        disable MIPS DSP ASE R1 optimizations
  
        —disable-mipsdspr2      disable MIPS DSP ASE R2 optimizations
  
        —disable-msa            disable MSA optimizations
  
        —disable-mipsfpu        disable floating point MIPS optimizations
  
        —disable-mmi            disable Loongson SIMD optimizations
  
        —disable-fast-unaligned consider unaligned accesses slow
      Developer options (useful when working on FFmpeg itself) :
  
        —disable-debug          disable debugging symbols
  
        —enable-debug=LEVEL     set the debug level []
  
        —disable-optimizations  disable compiler optimizations
  
        —enable-extra-warnings  enable more compiler warnings
  
        —disable-stripping      disable stripping of executables and shared libraries
  
        —assert-level=level     0(default), 1 or 2, amount of assertion testing,
  
                                 2 causes a slowdown at runtime.
  
        —enable-memory-poisoning fill heap uninitialized allocated space with arbitra                                                                                                      ry data
  
        —valgrind=VALGRIND      run "make fate" tests through valgrind to detect memo                                                                                                      ry
  
                                 leaks and errors, using the specified valgrind binary                                                                                                      .
  
                                 Cannot be combined with —target-exec
  
        —enable-ftrapv          Trap arithmetic overflows
  
        —samples=PATH           location of test samples for FATE, if not set use
  
                                 $FATE_SAMPLES at make invocation time.
  
        —enable-neon-clobber-test check NEON registers for clobbering (should be
  
                                 used only for debugging purposes)
  
        —enable-xmm-clobber-test check XMM registers for clobbering (Win64-only ;
  
                                 should be used only for debugging purposes)
  
        —enable-random          randomly enable/disable components
  
        —disable-random
  
        —enable-random=LIST     randomly enable/disable specific components or
  
        —disable-random=LIST    component groups. LIST is a comma-separated list
  
                                 of NAME[:PROB] entries where NAME is a component
  
                                 (group) and PROB the probability associated with
  
                                 NAME (default 0.5).
  
        —random-seed=VALUE      seed value for —enable/disable-random
  
        —disable-valgrind-backtrace do not print a backtrace under Valgrind
  
                                 (only applies to —disable-optimizations builds)
  
        —enable-osfuzz          Enable building fuzzer tool
  
        —libfuzzer=PATH         path to libfuzzer
  
        —ignore-tests=TESTS     comma-separated list (without "fate-" prefix
  
                                 in the name) of tests whose result is ignored
  
        —enable-linux-perf      enable Linux Performance Monitor API
      NOTE : Object files are built at the place where configure is launched.
  

• AAC encoder : Extensive improvements

  11 octobre 2015, par Claudio Freire

  AAC encoder : Extensive improvements
  This finalizes merging of the work in the patches in ticket #2686.
  Improvements to twoloop and RC logic are extensive.
  The non-exhaustive list of twoloop improvments includes :
  
   - Tweaks to distortion limits on the RD optimization phase of twoloop
  
   - Deeper search in twoloop
  
   - PNS information marking to let twoloop decide when to use it
  
     (turned out having the decision made separately wasn’t working)
  
   - Tonal band detection and priorization
  
   - Better band energy conservation rules
  
   - Strict hole avoidance
  For rate control :
  
   - Use psymodel’s bit allocation to allow proper use of the bit
  
     reservoir. Don’t work against the bit reservoir by moving lambda
  
     in the opposite direction when psymodel decides to allocate more/less
  
     bits to a frame.
  
   - Retry the encode if the effective rate lies outside a reasonable
  
     margin of psymodel’s allocation or the selected ABR.
  
   - Log average lambda at the end. Useful info for everyone, but especially
  
     for tuning of the various encoder constants that relate to lambda
  
     feedback.
  Psy :
  
   - Do not apply lowpass with a FIR filter, instead just let the coder
  
     zero bands above the cutoff. The FIR filter induces group delay,
  
     and while zeroing bands causes ripple, it’s lost in the quantization
  
     noise.
  
   - Experimental VBR bit allocation code
  
   - Tweak automatic lowpass filter threshold to maximize audio bandwidth
  
     at all bitrates while still providing acceptable, stable quality.
  I/S :
  
   - Phase decision fixes. Unrelated to #2686, but the bugs only surfaced
  
     when the merge was finalized. Measure I/S band energy accounting for
  
     phase, and prevent I/S and M/S from being applied both.
  PNS :
  
   - Avoid marking short bands with PNS when they’re part of a window
  
     group in which there’s a large variation of energy from one window
  
     to the next. PNS can’t preserve those and the effect is extremely
  
     noticeable.
  M/S :
  
   - Implement BMLD protection similar to the specified in
  
     ISO-IEC/13818:7-2003, Appendix C Section 6.1. Since M/S decision
  
     doesn’t conform to section 6.1, a different method had to be
  
     implemented, but should provide equivalent protection.
  
   - Move the decision logic closer to the method specified in
  
     ISO-IEC/13818:7-2003, Appendix C Section 6.1. Specifically,
  
     make sure M/S needs less bits than dual stereo.
  
   - Don’t apply M/S in bands that are using I/S
  Now, this of course needed adjustments in the compare targets and
  
  fuzz factors of the AAC encoder’s fate tests, but if wondering why
  
  the targets go up (more distortion), consider the previous coder
  
  was using too many bits on LF content (far more than required by
  
  psy), and thus those signals will now be more distorted, not less.
  The extra distortion isn’t audible though, I carried extensive
  
  ABX testing to make sure.
  A very similar patch was also extensively tested by Kamendo2 in
  
  the context of #2686.
  

  • [DH] Changelog
  • [DH] libavcodec/aac.h
  • [DH] libavcodec/aaccoder.c
  • [DH] libavcodec/aaccoder_trellis.h
  • [DH] libavcodec/aaccoder_twoloop.h
  • [DH] libavcodec/aacenc.c
  • [DH] libavcodec/aacenc.h
  • [DH] libavcodec/aacenc_is.c
  • [DH] libavcodec/aacenc_is.h
  • [DH] libavcodec/aacenc_pred.c
  • [DH] libavcodec/aacenc_quantization.h
  • [DH] libavcodec/aacenc_utils.h
  • [DH] libavcodec/aacpsy.c
  • [DH] libavcodec/mathops.h
  • [DH] libavcodec/mips/aaccoder_mips.c
  • [DH] libavcodec/psymodel.c
  • [DH] libavcodec/psymodel.h
  • [DH] tests/fate/aac.mak

• French CNIL recommends Piwik : the only analytics tool that does not require Cookie Consent

  29 octobre 2014, par Matthieu Aubry — Press Releases

  There has been recent and important changes in France regarding data privacy and the use of cookies. This blog post will introduce you to these changes and explain how you make your website compliant.

  Cookie Consent in the data freedom law

  Since the adoption of the EU Directive 2009/136/EC “Telecom Package”, Internet users must be informed and provide their prior consent to the storage of cookies on their computer. The use of cookies for advertising, analytics and social share buttons require the user’s consent :

  It is necessary to inform users of the presence, purpose and duration of the cookies placed in their browsers, and the means at their disposal to oppose it.

  What is a cookie ?

  Cookies are tracers placed on Internet users’ hard drives by the web hosts of the visited website. They allow the website to identify a single user across multiple visits with a unique identifier. Cookies may be used for various purposes : building up a shopping cart, storing a website’s language settings, or targeting advertising by monitoring the user’s web-browsing.

  Which cookies are exempt from the Cookie Consent rule ?

  France has exempted certain cookies from the cookie consent rule : for those cookies that are strictly necessary to offer the service sought after by the user you do not need to ask consent to user. Examples of such cookies are :

  • the shopping cart cookie,
  • authentication cookies,
  • short lived session cookies,
  • load balancer cookies,
  • certain first party analytics (such as Piwik cookies),
  • persistent cookies for interface personalisation.

  Asking users for consent for Analytics (tracking) Cookies

  For all cookies that are not exempted from the Cookie Consent then you will need to :

  • obtain consent from web users before placing or reading cookies and similar technologies,
  • clearly inform web users of the different purposes for which the cookies and similar technologies will be used,
  • propose a real choice to web users between accepting or refusing cookies and similar technologies.

  You don’t need Cookie Consent with Piwik

  The excellent news is that there is a way to bypass the Cookie Consent banner on your website :

  If you are using another analytics solution other than Piwik then you will need to ask users for consent. If you do not want to ask for consent then download and install Piwik or signup to Piwik Cloud to get started.

  If you are already using Piwik you need to do two simple things : (1) anonymise visitor IP addresses (at least two bytes) and (2) include the opt-out iframe solution in your website (learn more).

  Note that these recommendations currently only apply in France, but because the law is European we can expect similar findings in other European countries.

  CNIL recommends Piwik

  We are proud that the CNIL has identified Piwik as the only tool that respects all privacy requirements set by the European Telecom law.

  

  About the CNIL

  The CNIL is an independent administrative body that operates in accordance with the French data protection legislation. The CNIL has been entrusted with the general duty to inform people of the rights that the data protection legislation allows them.

  The role and responsabilities of the CNIL are :

  • to protect citizens and their data
  • to regulate and control processing of personal data
  • to inspect the security of data processing systems and applications, and impose penalties

  Piwik and Privacy

  At Piwik we love Privacy – our open analytics platform comes with built-in Privacy.

  Future of Privacy at Piwik

  Piwik is already the leader when it comes to respecting user privacy but we plan to continue improving privacy within the open analytics platform. For more information and specific ideas see Privacy enhancing issues in our issue tracker.

  References

  Learn more in these articles in French [fr] or English :

  • [fr] Sites web, cookies et autres traceurs
  • [fr] Comment me mettre en conformité avec la recommandation “Cookies” de la CNIL ?
  • [fr] Recommandation sur les cookies : obligations pour les responsables de sites ?
  • CNIL Starts Controlling Cookie Settings in October 2014
  • CNIL recommends Piwik for compliance with data protection laws

  Contact

  To learn more about Piwik, please visit piwik.org,

  Get in touch with the Piwik team : Contact information,

  For professional support contact Piwik PRO.