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John Koleszar 36be4f7f06 Fix drastic undershoot in long form content 
When the modified_error_left accumulator exceeds INT_MAX, an incorrect
cast to int resulted in a negative value, causing the rate control to
allocate no bits to that keyframe group, leading to severe undershoot
and subsequent poor quality.

This error was exposed by the recent change to the rolling target and
actual spend accumulators in commit 305be4e4 which fixed them to
actually calculate the average value rather than be re-initialized
on every frame to the average per-frame bitrate. When this bug was
triggered, the target bitrate could be 0, so the rolling target
becomes small, which causes the undershoot. The code prior to 305be4e4
did not exhibit this behavior because the rolling target was always
set to a reasonable value and was independent of the actual target
bitrate. With this patch, the actual target bitrate is calculated
correctly, and the rate control tracks as expected.

This cast was likely added to silence a compiler warning on a comparison
between a double (modified_error_left) and an int (0). Instead, this
patch removes the cast and changes the comparison to be against 0.0,
which should prevent the warning from reoccuring.

This fixes issue #289. Special thanks to gnafu for his efforts in
reporting and debugging this fix.

Change-Id: Ie5cc1a7b516c578a76c3a50c892a6f04a11621fe
2011-03-02 22:52:27 -05:00
build Fix crash on Sparc Solaris. 2011-02-25 10:14:10 -05:00
examples vp8_set_maps: remove hard-coded width/height 2010-11-17 09:24:05 -05:00
libmkv Eliminate more warnings. 2010-10-28 08:26:03 -04:00
nestegg ivfdec: webm reader support 2010-10-25 22:01:40 -04:00
tools Generate AUTHORS file with a script 2010-06-16 15:43:09 -04:00
vp8 Fix drastic undershoot in long form content 2011-03-02 22:52:27 -05:00
vpx documentation: minor cosmetics 2011-02-16 17:59:33 -08:00
vpx_mem clean up unused files 2011-02-18 09:09:49 -05:00
vpx_ports documentation: minor cosmetics 2011-02-16 17:59:33 -08:00
vpx_scale clean up unused files 2011-02-18 09:09:49 -05:00
.gitattributes Initial WebM release 2010-05-18 11:58:33 -04:00
.gitignore update gitignore 2010-09-28 10:09:01 -04:00
.mailmap Update AUTHORS 2010-09-02 13:41:03 -04:00
args.c Add psnr/ssim tuning option 2010-12-17 10:01:05 -05:00
args.h Add psnr/ssim tuning option 2010-12-17 10:01:05 -05:00
AUTHORS Update AUTHORS 2010-10-26 16:10:22 -04:00
CHANGELOG CHANGELOG: correct date 2010-10-28 09:14:14 -04:00
configure purge wince configuration 2011-02-22 14:42:00 -05:00
docs.mk Remove examples.doxy dep w/--disable-examples 2011-02-24 15:11:05 -08:00
example_xma.c Use WebM in copyright notice for consistency 2010-09-09 10:01:21 -04:00
examples.mk Adds "armvX-none-rvct" targets 2011-01-28 12:47:39 +02:00
keywords.dox Initial WebM release 2010-05-18 11:58:33 -04:00
libs.doxy_template Use WebM in copyright notice for consistency 2010-09-09 10:01:21 -04:00
libs.mk purge wince configuration 2011-02-22 14:42:00 -05:00
LICENSE LICENSE: update with latest text 2010-06-04 16:19:40 -04:00
mainpage.dox documentation: minor cosmetics 2011-02-16 17:59:33 -08:00
md5_utils.c Adds "armvX-none-rvct" targets 2011-01-28 12:47:39 +02:00
md5_utils.h Use public domain implementation for MD5 algorithm 2010-06-14 08:48:22 -04:00
PATENTS LICENSE: update with latest text 2010-06-04 16:19:40 -04:00
README purge wince configuration 2011-02-22 14:42:00 -05:00
solution.mk purge wince configuration 2011-02-22 14:42:00 -05:00
tools_common.c fix pipe support on windows 2010-11-02 09:14:24 -04:00
tools_common.h fix pipe support on windows 2010-11-02 09:14:24 -04:00
usage_cx.dox Initial WebM release 2010-05-18 11:58:33 -04:00
usage_dx.dox Initial WebM release 2010-05-18 11:58:33 -04:00
usage.dox documentation: minor cosmetics 2011-02-16 17:59:33 -08:00
vp8_api1_migration.txt Initial WebM release 2010-05-18 11:58:33 -04:00
vpxdec.c Adds "armvX-none-rvct" targets 2011-01-28 12:47:39 +02:00
vpxenc.c Adds "armvX-none-rvct" targets 2011-01-28 12:47:39 +02:00
y4minput.c Eliminate more warnings. 2010-10-28 08:26:03 -04:00
y4minput.h Use WebM in copyright notice for consistency 2010-09-09 10:01:21 -04:00

README 

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.