misc/chomens-bot-java
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fix: support Shift-JIS encoding for midi for japanese MIDIs

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This commit is contained in:
ChomeNS
2025-04-30 17:24:23 +07:00
parent a7f6cac49b
commit 96f5f66f01
2 changed files with 27 additions and 5 deletions
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30
src/main/java/me/chayapak1/chomens_bot/song/MidiConverter.java
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@@ -5,7 +5,8 @@ import me.chayapak1.chomens_bot.Bot;
import javax.sound.midi.*;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.ByteBuffer;
import java.nio.charset.*;
import java.util.*;
import static javax.sound.midi.ShortMessage.SYSTEM_RESET;
@@ -51,7 +52,7 @@ public class MidiConverter implements Converter {
if (mm.getType() == SET_TEMPO) {
tempoEvents.add(event);
} else if (mm.getType() == TRACK_NAME) {
final String stringTitle = new String(mm.getData(), StandardCharsets.UTF_8);
final String stringTitle = decodeStringWithUTF8OrShiftJIS(mm.getData());
if (stringTitle.isBlank()) continue;
@@ -64,10 +65,10 @@ public class MidiConverter implements Converter {
isFirst = false;
}
} else if (mm.getType() == TEXT) {
text.append(new String(mm.getData(), StandardCharsets.UTF_8));
text.append(decodeStringWithUTF8OrShiftJIS(mm.getData()));
text.append('\n');
} else if (mm.getType() == LYRICS) {
final String lyric = new String(mm.getMessage(), StandardCharsets.UTF_8);
final String lyric = decodeStringWithUTF8OrShiftJIS(mm.getMessage());
lyrics.put(event.getTick(), lyric);
}
@@ -452,4 +453,25 @@ public class MidiConverter implements Converter {
percussionMap.put(86, 14 + 25 * Instrument.BASEDRUM.id);
percussionMap.put(87, 7 + 25 * Instrument.BASEDRUM.id);
}
// this is needed for japanese MIDIs like night of nights, which uses shift jis encoded string as its title
// here is the bytes of it
// [-125, 105, -125, 67, -125, 103, -127, 69, -125, 73, -125, 117, -127, 69, -125, 105, -125, 67, -125, 99]
//
// jshell> new String(bytes, java.nio.charset.StandardCharsets.UTF_8)
// $5 ==> "<22>i<EFBFBD>C<EFBFBD>g<EFBFBD>E<EFBFBD>I<EFBFBD>u<EFBFBD>E<EFBFBD>i<EFBFBD>C<EFBFBD>c"
//
// jshell> new String(bytes, java.nio.charset.Charset.forName("Shift-JIS"))
// $4 ==> "ナイト・オブ・ナイツ"
private static String decodeStringWithUTF8OrShiftJIS (final byte[] bytes) {
final CharsetDecoder utf8Decoder = StandardCharsets.UTF_8.newDecoder();
utf8Decoder.onMalformedInput(CodingErrorAction.REPORT); // detect invalid bytes, so we can fall back
utf8Decoder.onUnmappableCharacter(CodingErrorAction.REPORT);
try {
return utf8Decoder.decode(ByteBuffer.wrap(bytes)).toString();
} catch (final CharacterCodingException e) {
return new String(bytes, Charset.forName("Shift_JIS"));
}
}
}