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thiebaut
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--------
YORICK-Z
--------
This is a compiled add-on for yorick (an interpreted computer language
specialized for numerical and scientific problems). Yorick-z adds
support for zlib (the data compression system used by gzip), png (a
lossless image compression format), jpeg (a lossy image compression
format), and mpeg (mpeg1, a compressed video format). These are not
supported in the basic yorick distribution, because each relies on a
specialized library beyond what is required for basic yorick
functionality. (On Unix systems, yorick requires only libc, libm, and
libX11. On Windows systems, yorick requires only dlls which ship with
every Windows system.)
The specific dependencies for yorick-z are:
libz http://www.zlib.org or http://www.gzip.org/zlib/
- compression scheme used by gzip (.gz files)
libpng http://www.libpng.org/pub/png/
also ftp://ftp.uu.net/graphics/png
- .png image files, depends on libz
libjpeg http://www.ijg.org/
also ftp://ftp.uu.net/graphics/jpeg/
- .jpg image files
libavcodec http://ffmpeg.sourceforge.net/
- .mpg video files
The APIs for these packages are not completely stable. The yorick-z
package will work with the following versions:
zlib >= 1.1.4
libpng >= 1.2.8 (>=1.2.2 on little endian machines, eg pentium)
libjpeg >= 6b
ffmpeg = 0.4.8 or 0.4.9-pre1 (particularly unstable API)
The yorick-z package supports zlib compression and decompression, both
reading and writing of png and jpeg images, and only writing of mpeg1
video movies. You can configure yorick-z to build any one or all of
these packages, so you do not need to have, for example, libz, libpng,
or libavcodec to build a version of yorick with jpeg support.
Ordinarily, any of these libraries would be present on a system as a
shared library, which will be dynamically linked to yorick at runtime.
However, you are free to link any of them statically. The libz,
libpng, and libjpeg shared libraries are tolerably widespread, since
most web browsers use those libraries.
However, at this writing, libavcodec (ffmpeg) is relatively rare, that
is, you will likely need to make a special effort to acquire and
install it on your system if you want the yorick-z mpeg1 support. In
recognition of this fact, yorick-z allows you a third option for
libavcodec, in addition to either a static link, or a build-time link
to a shared library: Namely, you can configure yorick-z to dlopen
libavcodec at the first reference to any of the mpeg1 functionality.
That is, you can build yorick-z in such a way that the mpeg1
functionality becomes available when you install libavcodec, but the
other parts of yorick-z all work properly if you don't have
libavcodec. (Note: This does not work under MacOS X.)
-----------------
BUILDING YORICK-Z
-----------------
To build yorick-z, unpack it, cd into the top-level directory, and type:
./configure
make
To test the package, type:
make check
To install the package, type (as root):
make install
Before you do any of this, you need a working yorick that is on your
PATH (e.i.- so that when you type "yorick" at a command shell prompt,
the code starts). You also need to have installed zlib (the libz
library), libpng, and libjpeg. If libavcodec (part of ffmpeg) is not
installed, then yorick-z mpeg support will not work until it is
installed. The absence of either the headers or libraries for the
other packages will result in them being omitted entirely during the
build. See the LIBAVCODEC (mpeg1) section below for detailed description
of the configuration options for that library.
If the libraries or headers are not installed in a standard place
($prefix/include for headers and $prefix/lib for libraries, where
$prefix is /usr, /usr/local, or /sw), then you can use the --zlib,
--png, --jpeg, or --avcodec options to ./configure to point the script
to the directories where you built those libraries:
Usage: ./configure [options]
Options are one or more of:
--yorick=/path/to/yorick
set path to yorick executable (if not on your PATH)
--zlib=/path/to/zlib-version
set path to directory containing zlib.h and libz.a
--png=/path/to/png-version
set path to directory containing png.h and libpng.a
--jpeg=/path/to/jpeg-version
set path to directory containing jpeglib.h and libjpeg.a
--avcodec=/path/to/ffmpeg-version/libavcodec
set path to directory containing avcodec.h and libavcodec.a
--dl-avcodec
use dlopen to link to libavcodec at runtime
--no-avcodec
skip libavcodec (mpeg1) support entirely
--a
generate /path/to/pkg/libpkg.a on load line instead of
the default -L/path/to/pkg -lpkg
This is the only way to force a particular static library
to be loaded on some platforms (e.g.- MacOS X).
Note that the --zlib, --png, --jpeg, and --avcodec options presume
that you have built, but NOT installed those packages. That is, the
paths are the names of the directories in your source tree. Of
course, if you install them in a standard place like /usr/lib or
/usr/local/lib, you don't need these options at all.
If you need even finer control than this (for example, to separately
specify directory paths for header and library files), you can set
environment variables before running configure (read the configure
script for details), or edit Makeyorz by hand after running configure.
---------------------------------
LIBAVCODEC (mpeg1) dlopen support
---------------------------------
The configure script will assume you want dlopen support for
libavcodec, which does not require any headers at build time, will
work at runtime if libavcodec.so is installed, and fail gracefully
only when you attempt to actually create an mpeg movie, if
libavcodec.so has not been installed.
If you later install the libavcodec shared library in a non-standard
place (not /usr/lib, /usr/local/lib, nor /sw/lib), you may place the
library in Y_HOME/lib (type Y_HOME in yorick to discover that
directory path). If you are unable to do that, as a last resort, you
may place the path name of the libavcodec shared library, minus its
file extension (.so, .sl, or .dylib) in the Y_LIBAVCODEC environment
variable.
You can also force the configure script to try to link libavcodec at
build time, as it does for libz, libpng, and libjpeg. To do this,
use any one of the following configure options:
--avcodec=/path/to/ffmpeg-version/libavcodec
link to specified libavcodec at build time
--dl-avcodec
link to installed libavcodec at runtime
--no-avcodec
omit libavcodec (mpeg1) support, even if libavcodec present