vpx Multi-Format Codec SDK README - 19 May 2010 Welcome to the WebM VP8 Codec SDK! COMPILING THE APPLICATIONS/LIBRARIES: The build system used is similar to autotools. Building generally consists of "configuring" with your desired build options, then using GNU make to build the application. 1. Prerequisites * All x86 targets require the Yasm[1] assembler be installed. * All Windows builds require that Cygwin[2] be installed. * Building the documentation requires PHP[3] and Doxygen[4]. If you do not have these packages, you must pass --disable-install-docs to the configure script. [1]: http://www.tortall.net/projects/yasm [2]: http://www.cygwin.com [3]: http://php.net [4]: http://www.doxygen.org 2. Out-of-tree builds Out of tree builds are a supported method of building the application. For an out of tree build, the source tree is kept separate from the object files produced during compilation. For instance: $ mkdir build $ cd build $ ../libvpx/configure <options> $ make 3. Configuration options The 'configure' script supports a number of options. The --help option can be used to get a list of supported options: $ ../libvpx/configure --help 4. Cross development For cross development, the most notable option is the --target option. The most up-to-date list of supported targets can be found at the bottom of the --help output of the configure script. As of this writing, the list of available targets is: armv5te-linux-rvct armv5te-linux-gcc armv5te-symbian-gcc armv6-darwin-gcc armv6-linux-rvct armv6-linux-gcc armv6-symbian-gcc iwmmxt-linux-rvct iwmmxt-linux-gcc iwmmxt2-linux-rvct iwmmxt2-linux-gcc armv7-linux-rvct armv7-linux-gcc mips32-linux-gcc ppc32-darwin8-gcc ppc32-darwin9-gcc ppc64-darwin8-gcc ppc64-darwin9-gcc ppc64-linux-gcc x86-darwin8-gcc x86-darwin8-icc x86-darwin9-gcc x86-darwin9-icc x86-linux-gcc x86-linux-icc x86-solaris-gcc x86-win32-vs7 x86-win32-vs8 x86_64-darwin9-gcc x86_64-linux-gcc x86_64-solaris-gcc x86_64-win64-vs8 universal-darwin8-gcc universal-darwin9-gcc generic-gnu The generic-gnu target, in conjunction with the CROSS environment variable, can be used to cross compile architectures that aren't explicitly listed, if the toolchain is a cross GNU (gcc/binutils) toolchain. Other POSIX toolchains will likely work as well. For instance, to build using the mipsel-linux-uclibc toolchain, the following command could be used (note, POSIX SH syntax, adapt to your shell as necessary): $ CROSS=mipsel-linux-uclibc- ../libvpx/configure In addition, the executables to be invoked can be overridden by specifying the environment variables: CC, AR, LD, AS, STRIP, NM. Additional flags can be passed to these executables with CFLAGS, LDFLAGS, and ASFLAGS. 5. Configuration errors If the configuration step fails, the first step is to look in the error log. This defaults to config.err. This should give a good indication of what went wrong. If not, contact us for support. SUPPORT This library is an open source project supported by its community. Please please email webm-users@webmproject.org for help.
Ronald S. Bultje
authored
This patch introduces the concept of dual inter16x16 prediction. A 16x16 inter-predicted macroblock can use 2 references instead of 1, where both references use the same mvmode (new, near/est, zero). In the case of newmv, this means that two MVs are coded instead of one. The frame can be encoded in 3 ways: all MBs single-prediction, all MBs dual prediction, or per-MB single/dual prediction selection ("hybrid"), in which case a single bit is coded per-MB to indicate whether the MB uses single or dual inter prediction. In the future, we can (maybe?) get further gains by mixing this with Adrian's 32x32 work, per-segment dual prediction settings, or adding support for dual splitmv/8x8mv inter prediction. Gain (on derf-set, CQ mode) is ~2.8% (SSIM) or ~3.6% (glb PSNR). Most gain is at medium/high bitrates, but there's minor gains at low bitrates also. Output was confirmed to match between encoder and decoder. Note for optimization people: this patch introduces a 2nd version of 16x16/8x8 sixtap/bilin functions, which does an avg instead of a store. They may want to look and make sure this is implemented to their satisfaction so we can optimize it best in the future. Change-ID: I59dc84b07cbb3ccf073ac0f756d03d294cb19281