JSON3 vs LRC: YouTube Caption vs Lyrics Format
JSON3 vs LRC: compare structure, timing precision, and use cases. Free JSON3 to LRC converter to turn YouTube captions into synced lyrics.
JSON3 and LRC solve two completely different problems. JSON3 is YouTube's internal caption format, built for storing every detail of a video's captions with millisecond and word-level timing. LRC is a lightweight lyrics format built for one job: showing time-synced text alongside music. Converting JSON3 to LRC is how you turn a music video's YouTube captions into karaoke-style lyrics a media player can follow.
JSON3 vs LRC at a Glance
| Feature | JSON3 (YouTube) | LRC (Lyrics) |
|---|---|---|
| File extension | .json3 or .json | .lrc |
| Format type | Structured JSON objects | Plain text, one line per cue |
| Timestamp format | Milliseconds as integers (tStartMs) | [mm:ss.xx] bracket tags, centisecond precision |
| Time precision | Millisecond, plus word-level offsets (tOffsetMs) | Centisecond (2 digits) |
| Word-level timing | Yes, via tOffsetMs within each event | No, one timestamp per line |
| End times | Yes, via dDurationMs | No, only start times |
| Multi-line cues | Yes, multiple text segments per event | No, single line per timestamp |
| Metadata | Styling hints and JSON metadata | Optional ID tags: [ti:], [ar:], [al:] |
| Created for | YouTube's caption delivery system | Early MP3 lyrics plugins |
| Primary use case | Storing YouTube captions with maximum fidelity | Displaying synced lyrics with music |
Key Differences Explained
Timestamps and Timing
JSON3 records timing as millisecond integers and supports word-level offsets inside each event, giving it the finest-grained timing of any subtitle format. LRC uses [mm:ss.xx] bracket timestamps with only centisecond (hundredth-of-a-second) precision and no end times. When converting JSON3 to LRC, millisecond values are rounded to centiseconds, end times are dropped, and each event becomes a single timestamped line.
Structure and Line Handling
A JSON3 event can hold several text segments and represent a multi-line caption cue. LRC has no concept of multi-line cues: every lyric line carries one bracket timestamp at the start, followed by the text on the same line. Converting means flattening multi-segment events into single-line lyric entries, which fits music lyrics naturally but loses the ability to stack two lines at once.
Purpose and Ecosystem
JSON3 exists only inside YouTube. No music player, karaoke app, or media tool reads it. LRC is the de facto standard for synced lyrics in apps like foobar2000, Winamp plugins, MiniLyrics, and many phone music players. The two formats never overlap in their native ecosystems, so conversion is the bridge that moves caption text from YouTube into a lyrics workflow.
When to Use JSON3
JSON3 matters only when you are pulling captions out of YouTube, especially from a music video where the captions track the vocals. It preserves maximum timing data, including word-level offsets that can be useful for karaoke-style alignment. Treat JSON3 as an intermediate format: download it for fidelity, then convert to LRC for the lyrics app that will actually play it.
When to Use LRC
Choose LRC whenever the goal is synchronized lyrics for music playback. A music video's captions become a valid LRC file that scrolls line by line in time with the audio. LRC is small, simple, and supported by most lyrics plugins and karaoke software. Its limitations, no end times and centisecond precision only, are rarely a problem for lyrics where each line simply hands off to the next.
Converting JSON3 to LRC
Our free JSON3 to LRC converter handles the structural and timing differences automatically. It parses JSON3 events, rounds millisecond start times to centisecond [mm:ss.xx] tags, flattens multi-segment events into single lyric lines, and produces valid LRC output with optional metadata tags. All text is preserved, including Unicode, CJK characters, and emoji.
Frequently Asked Questions
Can I use JSON3 directly as lyrics?
No. JSON3 is YouTube's internal format and no lyrics app reads it. You must convert JSON3 to LRC before any music player or karaoke tool can display it as synced lyrics.
Does converting JSON3 to LRC lose timing?
Some precision is rounded down: JSON3 milliseconds become LRC centiseconds, and JSON3 word-level offsets are dropped because LRC supports only one timestamp per line. End times are not represented in LRC either. For lyrics, the start-time-per-line model is almost always sufficient.
How do I download YouTube captions as JSON3?
Use yt-dlp with the --write-auto-sub --sub-format json3 flags, or YouTube's timedtext API with fmt=json3. Music videos with captioned vocals are the best source for LRC conversion.
Is LRC better than JSON3?
They are built for different things. JSON3 holds far richer timing data but works only inside YouTube. LRC is the right format the moment you want those captions to display as synced lyrics in a music player.