作者vivimice (麦斯◎我的奶酪在哪里﹖)
看板Visual_Basic
标题[API] The Channel Map
时间Wed Jul 27 15:17:05 2005
来源﹕mk:@MSITStore:E:\Microsoft%20Visual%20Studio\MSDN98\98VS\2052\
MultiMed.chm::/devdoc/live/pdgrmm/images/mmap_a05.gif
翻译﹕vivimice 智慧权所有
原载﹕缥缈水云间 (bbs.freecity.cn)
The Channel Map
The channel map affects all MIDI channel messages. MIDI channel messages
include note-on, note-off, polyphonic-key-aftertouch, control-change,
program-change, channel-aftertouch, and pitch-bend-change messages. The
MIDI Mapper uses a single channel map with an entry for each of the 16 MIDI
channels. Each channel-map entry specifies the following:
‧A destination channel for the MIDI message
‧A destination output device for the MIDI message
‧An optional patch map specifying other possible modifications for the
MIDI message
The destination channel is set to one of the 16 MIDI channels. MIDI messages
are modified to reflect each new channel assignment. For example, if the
destination channel entry for MIDI channel 4 is set to 6, all MIDI messages
sent to channel 4 will be mapped to channel 6, as shown in the following
illustration.
┌────────┐
│ MIDI Mapper │
├────────┤
0x93, 0x60, 0x7F →│ Channel Mapper │→ 0x95, 0x60, 0x7F
﹉﹉﹉﹉﹉﹉﹉﹉ └────────┘ ﹉﹉﹉﹉﹉﹉﹉﹉
Value Value
Before Mapping After Mapping
In this example, the MIDI status byte 0x93 is mapped to 0x95. The low-order
of a MIDI status byte specifies the channel number. Source channels are set
to either active or inactive. Messages sent to inactive source channels are
ignored, so an inactive channel is in effect muted or turned off.
The destination output device is set to one of the available MIDI output
devices. A MIDI output device can be an internal synthesizer or a physical
MIDI output port.
MIDI system messages are MIDI messages (with status bytes) from 0xF0 to 0xFF.
There is no channel associated with MIDI system messages, so they cannot be
mapped. MIDI system messages are sent to all MIDI output devices listed in a
channel map.
参考译文﹕
通道表影响所有的MIDI通道消息。MIDI通道消息包含音符开启、音符关闭、复音键触後
响应、控制器变更、程序码变更、通道触後响应和弯音轮消息。MIDI映射表使用带有对
应於16个MIDI通道的16个入口的单个MIDI映射表。每个入口指定一下信息﹕
‧MIDI消息的目标通道
‧MIDI消息的目标输出设备
‧一个可选的乐器表﹐该乐器表指定了对MIDI消息的其它可能的变更。
目标通道被设置为16个MIDI通道之一﹐MIDI消息被变更以便於重定向到每个新分配的通
道。例如﹐如果4号MIDI通道的目标通道入口被设置为6的话﹐那麽所有送往4号通道的
都会被映射到6号通道﹐如图所示。（见上图）
在这个例子中﹐MIDI状态字节0x93被映射成为0x95。MIDI状态字节的低位（译者注﹕准
确地说应该是低四位）指定了通道号码。源通道被设置成为活动的或者非活动的。送往
非活动状态源通道的消息将会被忽略掉﹐所以非活动状态通道在效果上相当於被静音的
或者被关闭的通道。
目标输出设备设置成可用的MIDI输出设备。一个MIDI输出设备可以是一个内部的合成器
或者一个物理MIDI输出端口。
MIDI系统消息是指标志位为0xF0～0xFF的MIDI消息。系统消息是没有对应的通道与之相
联系的﹐所以它们不能被映射。MIDI系统消息会被送往通道列表中列出的所有MIDI输出
设备。
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