Skip to main content

Documentation Index

Fetch the complete documentation index at: https://mintlify.com/6xingyv/accompanist-lyrics-core/llms.txt

Use this file to discover all available pages before exploring further.

KRC is the lyrics format used by Kugou Music. It extends the familiar LRC line-timestamp syntax with per-word timing encoded in angle brackets, a base64-encoded [language:…] metadata block for embedded translations and phonetics, background vocal lines, and colon-role markers for dual-singer alignment. KugouKrcParser is a Kotlin object (singleton) that decodes all of these features into KaraokeLine instances.

​
Format

​
Line and word timing

Every lyric line opens with [lineStartMs,lineDurationMs]. Each word inside the line is preceded by <wordOffsetMs,wordDurationMs,0> where the offset is relative to the line start: 
[lineStartMs,lineDurationMs]<offset,duration,0>word<offset,duration,0>text
For example: 
[3463,720]<0,352,0>How <352,368,0>long
[4527,1352]<0,207,0>Can <207,225,0>we <432,328,0>stay <760,592,0>awake
The absolute start time of each word is calculated as lineStartMs + offset.

​
Background vocal lines

A background line uses the [bg:…] prefix instead of a timestamp. The syllable timing format inside is identical to a main line. Background lines are parsed and attached to the accompanimentLines list of the immediately preceding MainKaraokeLine: 
[12000,2000]<0,300,0>Main<300,400,0> vocal
[bg:<0,300,0>Back<300,400,0>ground]

​
Colon role markers

A line whose text starts or ends with : (full-width ： is also supported) acts as an alignment toggle. The parser tracks the current alignment state and flips it each time it encounters a colon marker:
  • The first colon marker switches from KaraokeAlignment.Start → KaraokeAlignment.End.
  • The next colon marker switches back to KaraokeAlignment.Start.
This convention is how Kugou KRC files encode dual-singer lines without a separate agent-metadata block. The colon character is kept in the syllable text rather than being removed.

​
Embedded phonetics and translations

The [language:…] tag holds a base64-encoded JSON structure decoded by KugouKrcMetadataDecoder. After decoding it yields:
  • phonetics: A List<List<String>> where each inner list holds per-syllable phonetic readings for one lyric line.
  • translations: A List<String> where each entry is the translation for the corresponding lyric line.
Phonetics are injected into KaraokeSyllable.phonetic only when the number of decoded phonetic tokens exactly matches the number of syllables on that line. Translations are stored in KaraokeLine.MainKaraokeLine.translation.

​
Detection

KugouKrcParser identifies KRC content by requiring both patterns on the same line: 
^\[\d+,\d+\]          // Line-level time tag
<\d+,\d+,\d+>.{1}    // Word-level time tag with at least one character of text
This two-part check avoids false positives from plain LRC files, which have line timestamps but no angle-bracket word timing.

​
Usage

KugouKrcParser is a Kotlin object—no instantiation required: 
val lyrics = KugouKrcParser.parse(krcContent)

// Or from a pre-split list of lines
val lyrics = KugouKrcParser.parse(krcLines)

​
Working with the result

SyncedLyrics.lines contains KaraokeLine.MainKaraokeLine entries. Background lines are nested inside accompanimentLines on the main line they follow. There are no SyncedLine entries—KRC always produces syllable-level output: 
val lyrics = KugouKrcParser.parse(krcContent)

for (line in lyrics.lines) {
    val main = line as KaraokeLine.MainKaraokeLine

    println("[${main.alignment}] ${main.start}ms–${main.end}ms")

    for (syllable in main.syllables) {
        val phonetic = syllable.phonetic?.let { " ($it)" } ?: ""
        println("  ${syllable.start}ms '${syllable.content}'$phonetic")
    }

    main.translation?.let { println("  → $it") }

    main.accompanimentLines?.forEach { bg ->
        println("  [BG] ${bg.syllables.joinToString("") { it.content }}")
    }
}

​
Minimal example

val krc = """
    [3463,720]<0,352,0>How <352,368,0>long
    [4527,1352]<0,207,0>Can <207,225,0>we <432,328,0>stay <760,592,0>awake
""".trimIndent()

val lyrics = KugouKrcParser.parse(krc)

println(lyrics.lines.size)          // 2

val first = lyrics.lines[0] as KaraokeLine.MainKaraokeLine
println(first.syllables[0].content) // "How "
println(first.syllables[0].start)   // 3463  (3463 + 0)
println(first.syllables[1].content) // "long"
println(first.syllables[1].start)   // 3815  (3463 + 352)

​
Timing deduplication

The parser tracks lastLineStartTime and advances any line whose declared start time is less than or equal to the previous line’s start time by at least 3 ms. This guards against malformed KRC files where duplicate or out-of-order timestamps would otherwise confuse binary-search playback helpers.
KRC files distributed by Kugou Music are typically compressed and encrypted. KugouKrcParser operates on the decoded plaintext form of the file. Decryption and decompression are outside the scope of this library and must be handled by the application before calling parse.
KugouKrcParser is a Kotlin object (singleton). Call it directly as KugouKrcParser.parse(content) without instantiation, just like EnhancedLrcParser and LyricifySyllableParser.

Build docs developers (and LLMs) love

Get started for freeTalk to us