faq

SDL_mixer 是一个基于 SDL 的混音器

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    TiMidity -- Experimental MIDI to WAVE converter
    Copyright (C) 1995 Tuukka Toivonen <[e-mail]>

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   Frequently Asked Questions with answers:

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Q: What is it?

A: Where?  Well Chris, TiMidity is a software-only synthesizer, MIDI
   renderer, MIDI to WAVE converter, realtime MIDI player for UNIX machines,
   even (I've heard) a Netscape helper application.  It takes a MIDI file
   and writes a WAVE or raw PCM data or plays it on your digital audio
   device.  It sounds much more realistic than FM synthesis, but you need a
   ~100Mhz processor to listen to 32kHz stereo music in the background while
   you work.  11kHz mono can be played on a low-end 486, and, to some, it
   still sounds better than FM.

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Q: I don't have a GUS, can I use TiMidity?

A: Yes.  That's the point.  You don't need a Gravis Ultrasound to use
   TiMidity, you just need GUS-compatible patches, which are freely
   available on the Internet.  See below for pointers.

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Q: I have a GUS, can I use TiMidity?

A: The DOS port doesn't have GUS support, and TiMidity won't be taking
   advantage of the board's internal synthesizer under other operating
   systems either.  So it kind of defeats the purpose.  But you can use it.

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Q: I tried playing a MIDI file I got off the Net but all I got was a
   dozen warnings saying "No instrument mapped to tone bank 0, program
   xx - this instrument will not be heard". What's wrong?

A: The General MIDI standard specifies 128 melodic instruments and
   some sixty percussion sounds. If you wish to play arbitrary General
   MIDI files, you'll need to get more patch files.

   There's a program called Midia for SGI's, which also plays MIDI
   files and has a lot more bells and whistles than TiMidity. It uses
   GUS-compatible patches, too -- so you can get the 8 MB set at
   ftp://archive.cs.umbc.edu/pub/midia for pretty good GM compatibility.

   There are also many excellent patches on the Ultrasound FTP sites.
   I can recommend Dustin McCartney's collections gsdrum*.zip and
   wow*.zip in the "[.../]sound/patches/files" directory. The huge
   ProPats series (pp3-*.zip) contains good patches as well. General
   MIDI files can also be found on these sites.

   This site list is from the GUS FAQ:

>                        FTP Sites                     Archive Directories
>                        ---------                     -------------------
> Main N.American Site:  archive.orst.edu              pub/packages/gravis
>                        wuarchive.wustl.edu           systems/ibmpc/ultrasound
> Main Asian Site:       nctuccca.edu.tw               PC/ultrasound
> Main European Site:    src.doc.ic.ac.uk              packages/ultrasound
> Main Australian Site:  ftp.mpx.com.au                /ultrasound/general
>                                                      /ultrasound/submit
> South African Site:    ftp.sun.ac.za                 /pub/packages/ultrasound
> Submissions:           archive.epas.utoronto.ca      pub/pc/ultrasound/submit
> Newly Validated Files: archive.epas.utoronto.ca      pub/pc/ultrasound
> 
> Mirrors:               garbo.uwasa.fi                mirror/ultrasound
>                        ftp.st.nepean.uws.edu.au      pc/ultrasound
>                        ftp.luth.se                   pub/msdos/ultrasound

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Q: Some files have awful clicks and pops.

A: Find out which patch is responsible for the clicking (try "timidity
   -P<patch> <midi/test-decay|midi/test-panning>".  Add "strip=tail" in
   the config file after its name.  If this doesn't fix it, mail me the
   patch.

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Q: I'm playing Fantasie Impromptu in the background. When I run Netscape,
   the sound gets choppy and it takes ten minutes to load. What can I do?

A: Here are some things to try:

   - Use a lower sampling rate.

   - Use mono output. This can improve performance by 10-30%.
     (Using 8-bit instead of 16-bit output makes no difference.)

   - Use a smaller number of simultaneous voices.

   - Make sure you compiled with FAST_DECAY and PRECALC_LOOPS enabled
     in config.h

   - If you don't have hardware to compute sines, recompile with
     LOOKUP_SINE enabled in config.h

   - Recompile with LOOKUP_HACK enabled in config.h.

   - Recompile with LINEAR_INTERPOLATION disabled in config.h.

   - Recompile with DANGEROUS_RENICE enabled in config.h, and make
     TiMidity setuid root. This will help only if you frequently play
     music while other processes are running.

   - Recompile with an Intel-optimized gcc for a 5-15%
     performance increase.

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