64075c9b01
The denoiser function was modified to reduce the computational
complexity.
1. The denoiser c function modification:
The original implementation calculated pixel's filter_coefficient
based on the pixel value difference between current raw frame and last
denoised raw frame, and stored them in lookup tables. For each pixel c,
find its coefficient using
filter_coefficient[c] = LUT[abs_diff[c]];
and then apply filtering operation for the pixel.
The denoising filter costed about 12% of encoding time when it was
turned on, and half of the time was spent on finding coefficients in
lookup tables. In order to simplify the process, a short cut was taken.
The pixel adjustments vs. pixel diff value were calculated ahead of time.
adjustment = filtered_value - current_raw
= (filter_coefficient * diff + 128) >> 8
The adjustment vs. diff curve becomes flat very quick when diff increases.
This allowed us to use only several levels to get a close approximation
of the curve. Following the denoiser algorithm, the adjustments are
further modified according to how big the motion magnitude is.
2. The sse2 function was rewritten.
This change made denoiser filter function 3x faster, and improved the
encoder performance by 7% ~ 10% with the denoiser on.
Change-Id: I93a4308963b8e80c7307f96ffa8b8c667425bf50
vpx Multi-Format Codec SDK
README - 21 June 2012
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.
* Downloading the data for the unit tests requires curl[5] and sha1sum.
sha1sum is provided via the GNU coreutils, installed by default on
many *nix platforms, as well as MinGW and Cygwin. If coreutils is not
available, a compatible version of sha1sum can be built from
source[6]. These requirements are optional if not running the unit
tests.
[1]: http://www.tortall.net/projects/yasm
[2]: http://www.cygwin.com
[3]: http://php.net
[4]: http://www.doxygen.org
[5]: http://curl.haxx.se
[6]: http://www.microbrew.org/tools/md5sha1sum/
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-android-gcc
armv5te-linux-rvct
armv5te-linux-gcc
armv6-darwin-gcc
armv6-linux-rvct
armv6-linux-gcc
armv7-android-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-discuss@webmproject.org for help.