MIDI

MIDI Mapper (Windows 3.1)

Windows applications address hardware devices such as MIDI interfaces or synthesizers through the use of drivers. The drivers provide applications software with a common interface through which hardware may be accessed, and this simplifies the hardware compatibility issue. Synthesizer drivers must be installed using the Windows Driver applet within the Control Panel.

指定如MIDI界面或合成器等硬件设备使用驱动的Windows applications。用于使驱动提供应用软件一个公用的界面（硬件通过其被访问），而这解决了硬件兼容问题。合成器的驱动必须使用控制面板内的Windows Driver applet进行安装。

When a MIDI interface or synthesizer is installed in the PC and a suitable device driver has been loaded, the Windows MIDI Mapper applet will then appear within the Control Panel (under multimedia devices if using Windows 95/98). MIDI messages are sent from an application to the MIDI Mapper, which then routes the messages to the appropriate device driver. The MIDI Mapper may be set to perform some filtering or translations of the MIDI messages in route from the application to the driver.

MIDI Mapper Setups are used to assign MIDI channels to device drivers. For instance, If you have an MPU-401 interface with a General MIDI synthesizer and you also have a Creative Labs Sound Blaster card in your system, you might wish to assign channels 13 to 16 to the Ad Lib driver (which will drive the Base-level FM synthesizer on the Sound Blaster), and assign channels 1 - 10 to the MPU-401 driver. In this case, MPC compatible MIDI files will play on both the General MIDI synthesizer and the FM synthesizer at the same time. The General MIDI synthesizer will play the Extended arrangement on MIDI channels 1 - 10, and the FM synthesizer will play the Base arrangement on channels 13-16.

The MIDI Mapper Setups can also be used to change the Channel number of MIDI messages. If you have MIDI files which were composed for a General MIDI instrument, and you are playing them on a Base Multitimbral Synthesizer, you would probably want to take the MIDI percussion data coming from your application on Channel 10 and send this information to the device driver on Channel 16.

The MIDI Mapper patch maps are used to translate patch numbers when playing MPC or General MIDI files on synthesizers which do not use the General MIDI patch numbers. Patch maps can also be used to play MIDI files which were arranged for non-GM synthesizers on GM synthesizers. For example, the Windows-supplied MT-32 patch map can be used when playing GM-compatible .MID files on the Roland MT-32 sound module or LAPC-1 sound card. The MIDI Mapper key maps perform a similar function, translating the key numbers contained in MIDI Note On and Note Off messages. This capability is useful for translating GM-compatible percussion parts for playback on non-GM synthesizers or vice-versa. The Windows-supplied MT-32 key map changes the key-to-drum sound assignments used for General MIDI to those used by the MT-32 and LAPC-1.