27.Jan.2001
Fun Time World
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SoftCinema and How to Get New Codecs
Sebastian Brylka from Fun Time World did a summary of a Polish article
(see title link) which we review here by his agreement.
«Jacek Cybularczyk, author of SoftCinema, released an article about the origin
of new codecs for the video player on Amiga.com.pl.
This article was written in Polish, thus here only the most important details.
Meantime the program SoftCinema can read the two formats OpenDivX and
soon 3ivX, too. Still missing e.g. is MPEG-4 support and several other not
quite legal codecs. The problem about those is that sources of the formats are
not free available. But there are some possibilities to fix this problem, too.
Though there are codecs for MPEG-4 and DivX on Macintosh, but due to missing
documentations of the Macintosh resources and extensions this all might be
difficult, somehow. The authors also don't seem to have a PowerMac for disassembling.
In case of the second possibility the author wrote that many might think this to be
moronic, but the thing works. You take the Windows dll's for help. Work started about
two month ago. The technic used is called "binary translation". First the x86 code
gets prepared for the C preprocessor in form of a macro instruction. Much of the
work takes the program TX86 which can read the dll's (comparable to Amiga libraries)
and convert them to C code. This isn't done total automatically, so you still have to
correct much yourself. The this way created code is compiled and can be executed under
a Windows emulated environment called WIN32ENV. In this a part of Win32 and some
important libraries are emulated. This all works on a PowerPC native only. Though all
possible codecs run, but speed is at flabby 1 FPS.
To get things somehow faster the code, which contains about 17,000 lines of macro
instructions, must get optimized. Unfortunately without optimization 72 MB are not enough
to compile, thus the rest of the work were done under APUS with a 200 MB SWAP file. For
an optimized compilation a 1 GB SWAP file was needed. The procedure took about 13 hours.
But the effort was worth while, meantime everything runs much faster. Next the dll's
will be converted to assembler to gain even better speed. This is possible after
analysing the C codes and using what GCC has generated. Later on everything will get
optimized once more. After profiling often used program parts either will be re-written
or more heavy optimized.
[News message: 27. Jan. 2001, 14:18] [Comments: 0]
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