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1993-10-27
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DVPEG C Source Code README file (Feb. 28, 1993)
-------------------------------
This is the readme file for my modifications/additions to the IJG JPEG source
code. This was compiled using Borland C/C++ 3.1 and the project files are
for Borland C. The JPEG conversion code was from IJG, the SVGA drivers were
originally from vgakit41.zip and everything else is my creation (mainly
jvmain.c, jvutils.c, jvdraw.c, all of the videosetup stuff.
For an explanation of the programs operation get the executable files
(dvpgXX.zip) and look at their readme files (XX is the version number).
Recently the video routines were redone to better support the 15 and 24 bit
video cards. The program is at the point where it could easily be changed to
read VPic configuration files.
For a list of modifications done between versions check the text at the
start of jvmain.c
*******************************************************
Note: This is probably the last version of DVPEG. The SVGAkit will probably
be used for its much better graphics routines in future versions. This
will allow me to support more video cards and automatically detect what
video modes are supported. If you are doing graphics programming you
_must_ have this tool.
********************************************************
I have also included a document file from the IJG JPEG source so that you
can get new versions etc from their archive sites.
The main viewer module is jvmain.c (with jvutil.c providing utilities).
There are 3 project files. DVPEG is the viewer, DVPEG286 is the 286 viewer
and VIDSETUP is the video setup program. The dvpeg-re project and files
are for a "REduced viewer". It is a JPEG as grayscale only and does not
support any quantizing for JPEG images. It was done to create a smaller
executable without some features for reduced memory, grayscale GIF, JPEG
viewing.
If you are going to compile the 286 version and/or switch between that and
the 386 version you must recompile all modules because the 386 version uses
386 assembler while the 286 version will use the C code (slower). But you
must ensure that the appropiate .obj files get replaced (currently jrevdct.*,
jquant2.*).
The compiler flag small_viewer is used to compile a version of the viewer
for 386 machines that only supports grayscale JPEGs, does not quantize. It
will show color JPEGs but only as grayscale, undithered, unquantized. This
is for people who require a small viewer for JPEG, GIF, ... in grayscale.
The differences between the 386 and 286 versions are in the 386 flag of
Borland C. I no longer use assembler files since BC 3.1 seems to generate
fairly good code.
This program is getting really messy as I push it for speed. The merging
of the IJG JPEG code with my own (jdcolor.c) gave me a 25% speed boost for
15 & 16 bit graphics modes but the output is growing very complex.
Documentation is still sparce but I am working on it. The main to-do is now
going to be improvment in the hi_color viewing code.
- Eric
praetzel@sunee.uwaterloo.ca
DVPEG is always at @ sunee in pub/jpeg/viewers