BREAKING CHANGE: *.umpx now stores track size in bytes, not # of UMPs.

This addresses #23

docs/MIDI2_FORMATS.md

@@ -17,18 +17,18 @@ We provide two options for UMP-based music files:
 
 ```
 // Data Format:
-//   identifier: 0xAAAAAAAAAAAAAAAA (16 bytes)
-//   i32 deltaTimeSpec
-//   i32 numTracks
-//   tracks - each track contains:
-//       identifier: 0xEEEEEEEEEEEEEEEE (16 bytes)
-//       i32 numUMPs
-//       umps (i32, i64 or i128) in BIG endian
+//   - identifier 0xAAAAAAAAAAAAAAAA (16 bytes)
+//   - i32 deltaTimeSpec
+//   - i32 numTracks
+//   - tracks - each track contains these items in order:
+//       - identifier 0xEEEEEEEEEEEEEEEE (16 bytes)
+//       - i32 sizeInBytes
+//       - UMPs (i32, i64 or i128) in BIG endian
 ```
 
-If `deltaTimeSpec` is a positive integer, it works like the value in SMF header chunk. There is no "format" specifier in this format - if "numTracks" is 1 then it is obviously compatible with FORMAT 0.
+If `deltaTimeSpec` is a positive integer, it works like the `division` field value in SMF header chunk. There is no "format" specifier in this format - if "numTracks" is 1 then it is obviously compatible with FORMAT 0.
 
-All the UMPs are serialized in BIG endian for persistant stability across platforms.
+All the UMPs are serialized in BIG endian per 32-bit integer for persistant stability across platforms and better binary readability.
 
 ## META events
 

ktmidi/src/commonMain/kotlin/dev/atsushieno/ktmidi/Midi2ReaderWriter.kt

@@ -27,13 +27,16 @@ internal class Midi2MusicWriter(val stream: MutableList<Byte>) {
         ret.add(music.tracks.size)
         for (track in music.tracks) {
             (0..3).forEach { _ -> ret.add(0xEEEEEEEE.toInt()) }
-            ret.add(track.messages.size)
-            for (message in track.messages)
+            ret.add(0) // stub for `size` field, to be replaced later
+            val trackStartOffset = ret.size
+            for (message in track.messages) {
                 when (message.messageType) {
                     5 -> ret.addAll(sequenceOf(message.int1, message.int2, message.int3, message.int4))
                     3, 4 -> ret.addAll(sequenceOf(message.int1, message.int2))
                     else -> ret.add(message.int1)
                 }
+            }
+            ret[trackStartOffset - 1] = (ret.size - trackStartOffset) * 4 // sizeof(Int)
         }
         return ret
     }
@@ -89,9 +92,13 @@ internal class Midi2MusicReader(val music: Midi2Music, stream: List<Byte>) {
     private fun readTrack(): Midi2Track {
         val ret = Midi2Track()
         expectIdentifier16(0xEE.toByte())
-        val numUMPs = reader.readInt32()
-        for (t in 0 until numUMPs)
-            ret.messages.add(reader.readUmp())
+        val numBytes = reader.readInt32()
+        var readSize = 0
+        while (readSize < numBytes) {
+            val ump = reader.readUmp()
+            readSize += ump.sizeInBytes
+            ret.messages.add(ump)
+        }
         return ret
     }
 }

ktmidi/src/commonTest/kotlin/dev/atsushieno/ktmidi/Midi2MusicTest.kt

@@ -39,6 +39,6 @@ class Midi2MusicTest {
         // Note that "stream id" also counts in the packet size in sysex8 (hence 12, not 11).
         // Note that umpx is always serialized in BIG endian.
         assertContentEquals(musicFileIdentifier + listOf(0, 0, 0, 0) + listOf(0, 0, 0, 1) +musicTrackIdentifier +
-            listOf(0, 0, 0, 1) + listOf(0x50, 12, 0, 0, 0, 0, 0, ff, ff, ff, 3, 7, 0xA1.toByte(), 0x20, 0, 0), bytes, "umpx")
+            listOf(0, 0, 0, 16) + listOf(0x50, 12, 0, 0, 0, 0, 0, ff, ff, ff, 3, 7, 0xA1.toByte(), 0x20, 0, 0), bytes, "umpx")
     }
 }