I got some mp3s with cyrillic id3 tags that didn't decode properly on my machine. I decided to ask DeepSeek to write a script to fix that, and it just worked on the first try. Around a 100 lines of code.
here it is:
npm install iconv-lite node-id3
const iconv = require('iconv-lite');
const NodeID3 = require('node-id3');
const fs = require('fs').promises;
async function decodeMP3Tags(filePath) {
try {
// Read both ID3v2 and ID3v1.1 tags
const tags = {
v2: NodeID3.read(filePath),
v1: await readID3v1(filePath)
};
// Merge tags with priority to ID3v2
const mergedTags = {
title: tags.v2.title || tags.v1?.title,
artist: tags.v2.artist || tags.v1?.artist,
album: tags.v2.album || tags.v1?.album,
year: tags.v2.year || tags.v1?.year,
comment: tags.v2.comment?.text || tags.v1?.comment,
trackNumber: tags.v2.trackNumber || tags.v1?.track
};
// Decode all fields
const decodedTags = {};
for (const [field, value] of Object.entries(mergedTags)) {
if (value) decodedTags[field] = decodeCyrillic(value);
}
// Write back as ID3v2.4 tags with UTF-8 encoding
NodeID3.update(decodedTags, filePath);
// Remove ID3v1.1 tags if present
await removeID3v1(filePath);
console.log('Successfully updated tags:', decodedTags);
} catch (error) {
console.error('Error processing file:', error);
}
}
// ID3v1.1 Reader (128 bytes at end of file)
async function readID3v1(filePath) {
try {
const buffer = Buffer.alloc(128);
const handle = await fs.open(filePath, 'r');
const stats = await handle.stat();
if (stats.size < 128) return null;
await handle.read(buffer, 0, 128, stats.size - 128);
await handle.close();
if (buffer.toString('ascii', 0, 3) !== 'TAG') return null;
return {
title: buffer.toString('binary', 3, 33),
artist: buffer.toString('binary', 33, 63),
album: buffer.toString('binary', 63, 93),
year: buffer.toString('binary', 93, 97),
comment: buffer.toString('binary', 97, 127),
track: buffer[125]
};
} catch (e) {
return null;
}
}
// ID3v1.1 Remover
async function removeID3v1(filePath) {
try {
const handle = await fs.open(filePath, 'r+');
const stats = await handle.stat();
if (stats.size < 128) return;
const endBuffer = Buffer.alloc(128);
await handle.read(endBuffer, 0, 128, stats.size - 128);
if (endBuffer.toString('ascii', 0, 3) === 'TAG') {
await handle.truncate(stats.size - 128);
}
await handle.close();
} catch (e) {
console.error('Error removing ID3v1:', e);
}
}
// Cyrillic decoding (same as previous)
function decodeCyrillic(text) {
const bytes = Buffer.from(text, 'latin1');
const encodings = ['windows-1251', 'koi8-r', 'iso-8859-5', 'cp866'];
let best = { decoded: text, count: 0 };
for (const encoding of encodings) {
try {
const decoded = iconv.decode(bytes, encoding);
const count = [...decoded].filter(c => {
const cp = c.codePointAt(0);
return (cp >= 0x0400 && cp <= 0x04FF) || (cp >= 0x0500 && cp <= 0x052F);
}).length;
if (count > best.count) best = { decoded, count };
} catch (e) {}
}
return best.decoded;
}
// Usage
const filePath = process.argv[2];
if (!filePath) {
console.log('Usage: node decode-mp3.js path/to/file.mp3');
process.exit(1);
}
decodeMP3Tags(filePath);