ios - 获取使用 Logic 生成的 midi 序列 (MusicSequence) 标记
<p><p>我正在开发一个应用程序，它可以播放带有音频单元的 midi 序列 (.mid)。
midi 文件是使用 Logic 创建的，它提供了在时间线上添加标记的可能性。</p>
<p>在代码中，我使用 MusicSequence MusicPlayer 读取文件，并使用 MIDIClientCreate MIDIDestinationCreate 解析 MIDI 数据包。</p>
<p><strong>主要方法</strong></p>
<pre><code> OSStatus result = noErr;
// Initialise the music sequence
NewMusicSequence(&_s);
// Get a string to the path of the MIDI file which
// should be located in the Resources folder
NSString *midiFilePath = [
pathForResource:@"mymidifile"
ofType:@"mid"];
// Create a new URL which points to the MIDI file
NSURL * midiFileURL = ;
// Load the file
MusicSequenceFileLoad(_s, (__bridge CFURLRef) midiFileURL, 0, 0);
// Initialise the music player
NewMusicPlayer(&_p);
// Load the sound from EXS file
;
//Load Click
;
//Assign channel to tracks
MusicTrack track = NULL;
MusicTrack track2 = NULL;
MusicSequenceGetIndTrack(_s, 1, &track);
MusicSequenceGetIndTrack(_s, 2, &track2);
//Assign tracks to audio units
MusicTrackSetDestNode(track, _samplerNode);
MusicTrackSetDestNode(track2, _samplerNode2);
// Create a client
result = MIDIClientCreate(CFSTR("Virtual Client"),MyMIDINotifyProc,(__bridge void *)(self),&_virtualMidi);
NSAssert( result == noErr, @"MIDIClientCreate failed. Error code: %d '%.4s'", (int) result, (const char *)&result);
// Create an endpoint
result = MIDIDestinationCreate(_virtualMidi, (CFStringRef)@"Virtual Destination", MyMIDIReadProc, (__bridge void *)(self), &_virtualEndPoint);
NSAssert( result == noErr, @"MIDIDestinationCreate failed. Error code: %d '%.4s'", (int) result, (const char *)&result);
// ************* Set the endpoint of the sequence to be our virtual endpoint
MusicSequenceSetMIDIEndpoint(_s, _virtualEndPoint);
// Load the sequence into the music player
MusicPlayerSetSequence(_p, _s);
// Called to do some MusicPlayer setup. This just
// reduces latency when MusicPlayerStart is called
MusicPlayerPreroll(_p);
// Starts the music playing
MusicPlayerStart(_p);
</code></pre>
<p><strong>还有我的 readProc 函数</strong></p>
<pre><code>void MyMIDIReadProc(const MIDIPacketList *pktlist,
AudioProcessor *refCon,
void *connRefCon) {
AudioUnit *player = nil;
MIDIPacket *packet = (MIDIPacket *)pktlist->packet;
NSString *messageType;
for (int i=0; i < pktlist->numPackets; i++) {
Byte midiStatus = packet->data;
Byte midiCommand = midiStatus >> 4;// mask off all but top 4 bits
Byte note = packet->data & 0x7F;
Byte velocity = packet->data & 0x7F;
// find the channel by masking off all but the low 4 bits
NSInteger midiChannel = midiStatus & 0x0F;
switch (midiStatus & 0xF0) {
case 0x80:
messageType = @"Note Off";
break;
case 0x90:
messageType = @"Note On";
break;
case 0xA0:
messageType = @"Aftertouch";
break;
case 0xB0:
messageType = @"Control change";
break;
case 0xC0:
messageType = @"Program Change";
break;
case 0xD0:
messageType = @"Channel Pressure";
break;
case 0xE0:
messageType = @"Pitch Wheel";
break;
default:
messageType = @"Unk";
break;
}
NSLog(@"%@",messageType);
int noteNumber = ((int) note) % 12;
NSString *noteType;
switch (noteNumber) {
case 0:
noteType = @"C";
break;
case 1:
noteType = @"C#/Db";
break;
case 2:
noteType = @"D";
break;
case 3:
noteType = @"D#/Eb";
break;
case 4:
noteType = @"E";
break;
case 5:
noteType = @"F";
break;
case 6:
noteType = @"F#/Gb";
break;
case 7:
noteType = @"G";
break;
case 8:
noteType = @"G#/Ab";
break;
case 9:
noteType = @"A";
break;
case 10:
noteType = @"A#/Bb";
break;
case 11:
noteType = @"B";
break;
default:
break;
}
if( velocity == 0 ){
UInt32 noteOff = kMIDIMessage_NoteOff << 4 | 0;
if( midiChannel == 0 ){
MusicDeviceMIDIEvent (refCon.samplerUnit, noteOff, note, 0, 0);
}else if( midiChannel == 1 ){
MusicDeviceMIDIEvent (refCon.samplerUnit2, noteOff, note, 0, 0);
}
}else{
if( midiChannel == 0 ){
MusicDeviceMIDIEvent (refCon.samplerUnit, midiStatus, note, velocity, 0);
}else if( midiChannel == 1 ){
MusicDeviceMIDIEvent (refCon.samplerUnit2, midiStatus, note, velocity, 0);
}
}
packet = MIDIPacketNext(packet);
}
</code></pre>
<p>}</p>
<p>使用我的 readProc 函数，我可以看到所有的 midi 消息，但看不到标记...</p>
<p>如果我在 Logic 中重新打开 midi 文件，标记在文件中，但在哪里...我如何在代码中获取它？</p></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>标记作为标记元事件包含在 MIDI 文件中。所以你需要扩展你的解析来支持元事件。元事件的状态为 0xFF。对于标记，下一个字节是 0x06，然后是长度和字符数。</p></p>
<p style="font-size: 20px;">关于ios - 获取使用 Logic 生成的 midi 序列 (MusicSequence) 标记，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/18275924/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/18275924/
</a>
</p>
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