27be5bc728
be rewritten to fixed point. seems to compile cleanly for iriver. git-svn-id: svn://svn.rockbox.org/rockbox/trunk@6197 a1c6a512-1295-4272-9138-f99709370657
263 lines
13 KiB
Text
263 lines
13 KiB
Text
TO DO: add question regarding set_close_button_callback vs set_window_close_hook
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/* _______ ____ __ ___ ___
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* \ _ \ \ / \ / \ \ / / ' ' '
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* | | \ \ | | || | \/ | . .
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* | | | | | | || ||\ /| |
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* | | | | | | || || \/ | | ' ' '
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* | | | | | | || || | | . .
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* | |_/ / \ \__// || | |
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* /_______/ynamic \____/niversal /__\ /____\usic /| . . ibliotheque
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* / \
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* / . \
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* faq.txt - Frequently Asked Questions. / / \ \
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* | < / \_
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* This file covers some of the common problems | \/ /\ /
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* and misconceptions people have with DUMB. If \_ / > /
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* your problem is not covered here, please | \ / /
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* contact me. I'll do my best to help - but | ' /
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* don't be offended if I just direct you to the \__/
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* manual!
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*/
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*****************************************************************************
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* I get a lot of strange warnings and errors when I compile my projects *
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* with this release of DUMB. They work with older versions! What happened? *
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*****************************************************************************
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Some parts of DUMB's API have been deprecated. See docs/deprec.txt for
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full details, including an explanation as to why your compiler warnings
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and errors are so unfriendly, and information on how to fix each warning
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or error.
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*****************************************************************************
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* When I try to compile DUMB with Allegro, it complains that it cannot find *
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* 'internal/alconfig.h'! What's wrong? *
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*****************************************************************************
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In Allegro 4.0.1, and quite likely some other versions of Allegro, the
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msvcmake batch file does not install Allegro properly. I believe this was
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fixed in Allegro 4.0.2, but don't take my word for it. Some include files
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are neglected, including alconfig.h. The fix is quite easy; you need to
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copy all of Allegro's include files to your compiler's directory. The
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following should do this for you (alter it accordingly depending on where
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MSVC and Allegro are installed):
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cd\progra~1\msvc\include
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xcopy/s \allegro\include\*.*
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You can safely tell it to overwrite all files.
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*****************************************************************************
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* When I build a project that uses DUMB, I get an error that it doesn't *
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* find -laldmbd! What's wrong? *
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*****************************************************************************
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See the notes for DUMB v0.8 in release.txt; the existence of libaldmbd.a
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in DUMB v0.7 was due to a mistake in the makefiles. It should be
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libaldmd.a, in order to maintain DOS compatibility. All subsequent
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releases get it right, but you will have to change your project files to
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allow for the change. If this is someone else's project, please let them
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know that it needs changing.
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*****************************************************************************
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* When I build a project that uses DUMB, I get some linker errors about *
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* _free, _malloc, etc. already being defined in LIBC.lib! What's wrong? *
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*****************************************************************************
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MSVC offers three different implementations of the standard libraries.
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When you link statically with a library, you have to use the same
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implementation that the library uses. You need the multithreaded DLL
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implementation, which you can select by passing /MD when you compile (not
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when you link). See howto.txt for details.
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*****************************************************************************
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* I created an IT file with Impulse Tracker, but DUMB won't play it! Why? *
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*****************************************************************************
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You probably created some patterns but didn't give any information on the
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order in which they should be played. Impulse Tracker will also fail to
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play your music if you press F5. Press F11 and you will have an
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opportunity to create an order list, required for playback.
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*****************************************************************************
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* I created an IT file with ModPlug Tracker and I have it fading out at the *
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* end. Why won't it loop when I play it with DUMB? *
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*****************************************************************************
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It loops at zero volume. This is what Impulse Tracker itself does. Fix the
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IT file by setting the global volume explicitly (Vxx in the effects
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column), either at the start, or right at the end before looping. Also see
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the next two questions.
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*****************************************************************************
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* My module plays too loud and distorts badly with DUMB! What can I do? *
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*****************************************************************************
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This problem is most often caused by ModPlug Tracker, which has a complete
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lack of regard for the playback volume of the original tracker. See the
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next question for DUMB's official position with regard to ModPlug Tracker.
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If you wrote your module with ModPlug Tracker, please try loading it with
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the original tracker and see if it distorts there too. If it does, reduce
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the volume. If not, then it's a problem with DUMB; please let me know.
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If for whatever reason you cannot modify the module file itself, you can
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make it sound better by reducing the volume passed to al_start_duh().
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*****************************************************************************
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* I created a music module with ModPlug Tracker, and DUMB doesn't play it *
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* right! *
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*****************************************************************************
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DUMB cannot and will not support ModPlug Tracker. Please see
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docs/modplug.txt for details. The original trackers, which DUMB is
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designed to mimic as closely as possible, are listed in readme.txt.
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If you find DUMB plays your module differently from the original tracker,
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then please contact me.
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*****************************************************************************
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* My program crashes as soon as I try to load anything with DUMB! *
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*****************************************************************************
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Please take my advice and use the debugging build of DUMB, not the
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optimised build. Then you'll probably find it aborts instead of crashing.
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In this case you probably forgot to register a DUMBFILE system; this is
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necessary for loading stand-alone files, though not for loading Allegro
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datafiles with embedded music. Follow the instructions in docs/howto.txt
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carefully and you shouldn't have this problem.
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If DUMB crashes with a specific music module, please let me know.
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*****************************************************************************
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* I want to use the stdio file access functions to load stand-alone music *
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* files, but I also want to load datafiles containing music files. The docs *
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* say I shouldn't call both dumb_register_stdfiles() and *
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* dumb_register_packfiles(). What shall I do? *
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*****************************************************************************
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When you register a DUMBFILE system, it only applies to files opened with
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dumbfile_open(), i.e. separate files. When a file is embedded in a
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datafile, dumbfile_open_ex() is used to read it, enabling it to use
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PACKFILEs regardless of which DUMBFILE system is registered. In short, you
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do not need to call dumb_register_packfiles() in order to load datafiles
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with embedded music. See the section on "Sequential File Input" in
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docs/dumb.txt if you're interested in how all this works.
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*****************************************************************************
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* I want to read a specific object in a datafile using Allegro's *
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* "demo.dat#MY_MUSIC" syntax. Why won't it work? *
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*****************************************************************************
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Did you call dumb_register_packfiles(), or did you call
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dumb_register_stdfiles()? It will only work if you use the former.
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*****************************************************************************
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* My program runs, but no music plays! What am I doing wrong? *
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*****************************************************************************
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There are a number of possible causes for this. The most likely reason is
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that you aren't calling al_poll_duh(); see docs/howto.txt for further
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information.
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Other possible causes are as follows:
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- The speakers are turned down (duh)
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- The volume of some system mixer is turned down
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- Another program is using the sound card (not a problem for most modern
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systems)
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- You didn't initialise Allegro's sound system; see install_sound() in
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Allegro's docs
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- Allegro's drivers don't work on your system and chosen platform
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In order to narrow down the cause, consider the following:
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- Do you get any other sound from your program?
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- Do other Allegro+DUMB programs generate sound?
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- Do other Allegro programs generate sound?
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- Do other non-Allegro programs generate sound?
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- Does your program fail only on a specific platform (e.g. DOS but not
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Windows)?
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This problem is highly system-specific; please try hard to solve it by
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yourself before contacting me. However, if you think this problem could
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affect other people, please let me know what the problem is and how you
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fixed it, if you did. Be as specific as possible.
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*****************************************************************************
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* The music stutters! What can I do? *
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*****************************************************************************
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If you have an older computer, it may not be able to cope with the load.
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Try reducing quality options; look up dumb_resampling_quality and
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dumb_it_max_to_mix in docs/dumb.txt, and consider changing the frequency
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you pass to al_start_duh().
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Stuttering may not be caused by excessive load. To find out, try
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increasing the buffer size passed to al_start_duh(). Beware of making it
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too big though; older systems will freeze periodically if it's too big,
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because they render larger chunks less frequently. The timing of callbacks
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will also be less accurate, if you are using those.
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If you're using the 'dumbplay' example, you can control these parameters
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by editing dumb.ini.
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*****************************************************************************
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* Why does DUMB use so much processor time compared with other players? *
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*****************************************************************************
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This should be less so in this release than in previous releases; the
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resampling and filtering algorithms have been optimised.
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By default, DUMB uses the most expensive resampling quality option. I've
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found on an AthlonXP 1800+ and on a Pentium 233 that it typically uses
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about twice as much processor time as the least expensive option.
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Try setting dumb_resampling_quality to DUMB_RQ_ALIASING or DUMB_RQ_LINEAR.
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See dumb.txt for more information. If you're using the example programs,
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you can control this variable by editing dumb.ini.
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DUMB uses 32-bit ints for mixing. Some players use 16-bit ints, and are
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therefore marginally faster (not much!) and lower quality. So you can't
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expect DUMB to beat these players. Furthermore, DUMB is currently written
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entirely in C. GCC does an impressive job on the C code, but that's not to
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say some custom-written assembly language couldn't beat it ...
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*****************************************************************************
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* Why does DUMB generate so much background noise? *
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*****************************************************************************
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You're probably using the DOS build on a system with bad Sound Blaster
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compatibility (most Windows XP systems fall in this category). This would
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mean DUMB could only access an 8-bit driver. The Windows build will almost
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certainly give better results. Your DOS binary will still give good
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results on systems with better compatibility (like my Windows 98 system).
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*****************************************************************************
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* I e-mailed you and you replied with "RTFM"! What does that mean? *
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*****************************************************************************
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Read The Manual. If it's a specific problem, I'll probably be kind and
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tell you where to look in the manual. However, if I get the impression you
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haven't even looked for a solution in the manual, expect no mercy ...
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Ben Davis
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entheh@users.sf.net
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IRC EFnet #dumb
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See readme.txt for details on using IRC.
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