Fixed MIDI generation

Author: lemcoder

core/src/commonMain/kotlin/pl/lemanski/mikroSoundFont/io/midi/MidiFile.kt

@@ -1,6 +1,7 @@
 package pl.lemanski.mikroSoundFont.io.midi
 
 import pl.lemanski.mikroSoundFont.midi.MidiMessage
+import pl.lemanski.mikroSoundFont.midi.MidiMetaMessage
 import pl.lemanski.mikroSoundFont.midi.MidiTrack
 import pl.lemanski.mikroSoundFont.midi.UnsupportedMidiMessage
 
@@ -28,14 +29,11 @@ data class MidiFile(
 
                 val millis = trackTicks * ticks2time
                 msg.time = millis.toInt()
-// TODO
-
-//                if (msg is MidiMetaMessage.SetTempo) {
-//                    val tempo = msg.tempo
-//                    ticks2time = tempo / (1000.0 * division)
-//                    tempoTicks = trackTicks
-//                    tempoMsec = millis
-//                }
+
+                if (msg is MidiMetaMessage.SetTempo) {
+                    val tempo = msg.tempo
+                    ticks2time = tempo / (1000.0 * division)
+                }
 
                 allMessages.add(msg)
             }

core/src/commonMain/kotlin/pl/lemanski/mikroSoundFont/io/midi/message/read/MidiMetaMessageParser.kt

@@ -1,6 +1,7 @@
 package pl.lemanski.mikroSoundFont.io.midi.message.read
 
 import kotlinx.io.Buffer
+import kotlinx.io.readUByte
 import pl.lemanski.mikroSoundFont.InvalidMidiDataException
 import pl.lemanski.mikroSoundFont.io.midi.message.readVarLen
 import pl.lemanski.mikroSoundFont.midi.MidiMessage
@@ -49,7 +50,7 @@ internal class MidiMetaMessageParser(
 
         var tempoValue = 0
         repeat(dataSize) {
-            tempoValue = tempoValue shl 8 or buffer.readByte().toInt()
+            tempoValue = tempoValue shl 8 or buffer.readUByte().toInt()
         }
 
         return MidiMetaMessage.SetTempo(

core/src/commonMain/kotlin/pl/lemanski/mikroSoundFont/midi/MidiSequencer.kt

@@ -1,15 +1,12 @@
 package pl.lemanski.mikroSoundFont.midi
 
 import pl.lemanski.mikroSoundFont.SoundFont
-import pl.lemanski.mikroSoundFont.getLogger
 
 class MidiSequencer(
     private val soundFont: SoundFont,
     private val sampleRate: Int,
 ) {
     private val sampleBlockSize: Int = 512
-    private val logger = getLogger()
-    private var currentTime = 0L
     private val messages = mutableListOf<MidiMessage>()
 
     fun loadMidiEvents(midiMessages: List<MidiMessage>) {
@@ -18,15 +15,15 @@ class MidiSequencer(
     }
 
     fun generate(): FloatArray {
-        var currentTime = 0.0
+        var currentTime = 0
         var audioBuffer = FloatArray(0)
 
-        for (msg in messages) {
-            msg.process()
-            val targetTime = msg.time.toDouble()
+        for (i in 0..<messages.size) {
+            messages[i].process()
+            val targetTime = messages.getOrNull(i + 1)?.time ?: currentTime
 
-            while (targetTime >= currentTime) {
-                currentTime += sampleBlockSize * (1000.0 / sampleRate)
+            while (targetTime > currentTime) {
+                currentTime += (sampleBlockSize * (1000.0 / sampleRate)).toInt()
                 audioBuffer += soundFont.renderFloat(sampleBlockSize, false)
             }
         }
@@ -36,10 +33,10 @@ class MidiSequencer(
 
     private fun MidiMessage.process() = when (this) {
         is MidiVoiceMessage.NoteOff       -> soundFont.channels[channel].noteOff(key)
-        is MidiVoiceMessage.NoteOn        -> soundFont.channels[channel].noteOn(key, velocity / 127.0f)
+        is MidiVoiceMessage.NoteOn        -> soundFont.channels[channel].noteOn(key, if (velocity == 0) 0f else 1f)
         is MidiVoiceMessage.PitchBend     -> soundFont.channels[channel].setPitchWheel(pitchBend)
         is MidiVoiceMessage.ProgramChange -> soundFont.channels[channel].setPresetNumber(program, channel == 9)
         is MidiVoiceMessage.ControlChange -> soundFont.channels[channel].setMidiControl(control, controlValue)
-        else                              -> { }
+        else                              -> {}
     }
 }

core/src/commonTest/kotlin/pl/lemanski/mikroSoundFont/midi/MidiTest.kt

@@ -14,7 +14,7 @@ class MidiTest {
 
     @Test
     fun testMidi() {
-        val midiFileBuffer = loadFile("$dir\\hbd.mid")
+        val midiFileBuffer = loadFile("$dir\\under.mid")
         val midiFile = MidiFileParser(midiFileBuffer).parse()
         val messages = midiFile.getMessagesOverTime()