Convert FLAC to MKV — Free Online Converter
Convert Free Lossless Audio Codec (.flac) to Matroska Video (.mkv) online for free. Fast, secure audio conversion with no watermarks or registration....
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変換方法
Upload your .flac file by dragging it into the upload area or clicking to browse.
Choose your output settings. The default settings work great for most files.
Click Convert and download your .mkv file when it's ready.
About FLAC to MKV Conversion
MKV (Matroska Video) is an open-standard container that can hold virtually any audio, video, or subtitle track. Unlike most video containers, MKV natively supports FLAC audio without re-encoding — the FLAC bitstream can be copied directly into the Matroska container. This makes FLAC to MKV conversion nearly instant and completely lossless. The primary use case is packaging lossless audio alongside video tracks, subtitles, or metadata in a single Matroska file.
Why Convert FLAC to MKV?
MKV is the preferred container for archiving high-quality video with lossless audio. Blu-ray rips, remuxes, and high-bitrate encodes frequently use FLAC audio inside MKV because it provides better compression than PCM while remaining lossless. MKV also supports multiple audio tracks, so FLAC can sit alongside a lossy AAC track for devices that do not decode FLAC. Additionally, MKV's chapter and attachment support allows embedding cover art, fonts, and navigation metadata.
Common Use Cases
- Muxing FLAC audio into an MKV video file for archival-quality Blu-ray remuxes
- Creating MKV files with multiple audio tracks (FLAC lossless + AAC compatibility track)
- Packaging concert recordings or music videos with lossless audio and synchronized lyrics
- Storing multi-channel FLAC (5.1 or 7.1) in MKV for home theater media servers
- Building media libraries for Plex, Jellyfin, or Kodi which handle MKV with FLAC natively
How It Works
FFmpeg uses stream copy (-c:a copy) to remux FLAC audio into an MKV container without re-encoding. The FLAC codec is natively supported by Matroska (codec ID A_FLAC). MKV's EBML (Extensible Binary Meta Language) structure allows arbitrary numbers of audio, video, and subtitle tracks with per-track language tags. Chapter markers use the Matroska Chapters specification. The muxing operation is near-instant since no transcoding occurs.
Quality & Performance
Zero quality loss when using stream copy mode. The FLAC audio data is transferred bit-for-bit from the FLAC container to the MKV container. The same PCM samples are preserved exactly.
Device Compatibility
| Device | FLAC | MKV |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Partial | Partial |
| iPhone/iPad | Partial | Partial |
| Android | Native | Partial |
| Linux | Partial | Partial |
| Web Browser | No | No |
Recommended Settings by Platform
Spotify
Resolution: N/A
Bitrate: 320 kbps
OGG Vorbis preferred
Apple Music
Resolution: N/A
Bitrate: 256 kbps
AAC format required
SoundCloud
Resolution: N/A
Bitrate: 128 kbps
Lossless FLAC/WAV for best quality
Podcast
Resolution: N/A
Bitrate: 128 kbps
MP3 mono for spoken word
Tips for Best Results
- 1Use stream copy (-c:a copy) to preserve the exact FLAC bitstream without re-encoding
- 2Add chapter markers for long recordings, concerts, or audiobook-style content
- 3Include a secondary AAC audio track for playback on devices that do not decode FLAC
- 4Use MKVToolNix (mkvmerge) as an alternative to FFmpeg for muxing tasks with a GUI
Related Conversions
FLAC to MKV conversion is ideal for media archivists and home theater enthusiasts who want lossless audio in a flexible multimedia container. The conversion is instant and lossless when using stream copy.