readme.djgpp

MP3编码程序和资料

               Compiling LAME with DJGPP
                       by S.T.L.               

(LAME's homepage is http://www.sulaco.org/mp3, and LAME is distributed
under the LGPL. More information is in the README file)

============================================================================

(Note: S.T.L. doesn't know C programming (...yet) but he has learned
how to compile things with DJGPP. He's not providing his E-mail address
here because he wouldn't know how to answer any questions even if you
asked him!)

Compiling LAME with DJGPP is actually somewhat easy, though not as easy
as you might expect at first glance. Here are step-by-step instructions
on how to compile LAME with the latest version of DJGPP. S.T.L. runs a
Pentium III 600Mhz system using Windows 98 SE. These instructions should
work on any Windows 9x system and probably Windows 2000 as well, and for
all true Intel Pentium III, Pentium II, Celeron, or Pentium Pro processors.
The instructions can be made to work (with less optimization) on other
processors including Pentium (MMX or not), 486, 386, and K6. Also this
might work under DOS, but I haven't tried it. S.T.L. takes no responsibility
for what you do with these instructions. Now, let's get compiling!

1) Find and install DJGPP.  It's at www.delorie.com. They have a Zip Picker
there that makes the process easy and painless.

2) Download the LAME sourcecode, preferably the latest version. Extract it
to a directory using WinZip or another decompressor set to preserve the
directory structure. Hopefully you already have done this, as you're reading
this file!

3) Create a new directory wherever. I called mine Crud.

4) In the directory with all the .c and .h files (and the README, INSTALL, etc
files), copy all the *.c and *.h files to the Crud directory.

5) Go into the Crud directory and delete the following files and no others:
debugscalefac.c
mp3rtp.c
mp3x.c
rtp.c

6) The command (don't type this!)
GCC -o LAME_BAD.EXE -DNDEBUG -DLAMESNDFILE -DLAMEPARSE *.c
should now create a terribly unoptimized but working LAME_BAD.EXE. Don't type
it, because optimizations are a good thing and are what you want. I only
provide the command so you can use it as a last resort. Here's how to execute
the optimized command:

7) In the Crud directory, create a new file. I called mine FILE. (In the DOS
prompt, typing EDIT FILE will create such a file with no extension). Make its
text consist of:

-s -O2 -march=i686 -fomit-frame-pointer -ffast-math -funroll-loops 
-funroll-all-loops -malign-double -fstrict-aliasing -o LAME.EXE -DNDEBUG 
-DLAMESNDFILE -DLAMEPARSE *.c

That should be one line in FILE even if it doesn't look like it in NotePad
or whereever you're reading this. It is case sensitive.  If you're curious,
you're making this file instead of typing a commandline directly
because DOS will scream at such a long commandline.

***ONLY FOR PENTIUM III, PENTIUM II, CELERON, OR PENTIUM PRO USERS***
8) Now, save FILE and go back to the Crud directory. Typing GCC @FILE will
now compile LAME.EXE. It will be heavily optimized - on my machine, it can
encode a .WAV file using the -h -b256 -ms options at 5.73X, while the
official binary I downloaded and ran using those same options only achieved
5.32X.

9) Have fun!

***FOR OTHER PROCESSORS***
8a) Using the commandline in (7) won't work for non-P6-core processors.
Therefore you must use another commandline. The key is the -march=i686
option. If you are running a Pentium (MMX or not), use -march=i586. For
the 386 and 486, the option should now be self-explanatory! For a K6
processor, use -march=k6 . For any other type of processor, you'll just
have to not use the -march option at all, which will cost you some
optimization. If you'd like to create an executable that runs fast on
[modern computer X], say a Pentium III, but you still want it to be
able to run on any i386 or later computer, use the -mcpu=[CPU TYPE
HERE], using the same cpu types as -march= accepts.  The
mcpu option gives less optimization, though.

9a) Have fun!