FLAC
Free Lossless Audio CodecUsed for lossless music archiving.
- Family
- Audio
- MIME
- audio/flac
Convert FLAC to MKV online
To convert FLAC to MKV, upload the FLAC file, start the conversion and download the result: Converter.now writes an MKV with H.264 video (CRF 23) and Opus audio at 160 kbps. Because FLAC has no picture, a still black 1280x720 frame is added so the MKV is a real video that video sites accept. MKV is a lossy format, so the file is usually much smaller but some fine detail is discarded; keep your FLAC original.
◈ Encrypted transfer◷ Short retention⊘ No watermark◎ Works on every device
FLAC to MKV at a glance
- Converts
- Free Lossless Audio Codec → Matroska video
- Output
- An MKV with H.264 video (CRF 23) and Opus audio at 160 kbps
- Compression
- FLAC: lossless → MKV: lossy
- Engine
- FFmpeg
- Privacy
- Private download link; files are deleted after 6 hours. No account needed.
Audio-only container delivery: How FLAC becomes MKV
FLAC audio is what actually exists here, and it gets encoded straight into a MKV media container. No artwork or motion is invented, so the resulting MKV file can carry no meaningful video stream at all. FLAC frames decode to lossless samples, but the stream can still carry unusual channel assignments, sample rates, cuesheets, and Vorbis-comment metadata. Matroska delivery can retain multiple timed tracks, languages, subtitles, chapters, and attachments, though simplified writers and browser players may use only a subset.
Decoded media - Losslessly compressed audio that preserves decoded samples and supports rich tags. Encoded delivery profile - A flexible Matroska container capable of multiple audio, video, subtitle, and attachment streams.
Need a different output? See all FLAC conversion options, or check which other files convert to MKV.
Before converting a whole batch, read why the same extension can hold different codecs; it explains why a familiar extension can still fail to play.
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MKV
Matroska videoDesigned for flexible multi-track video storage.
- Family
- Video
- MIME
- video/x-matroska
FLAC source facts versus MKV output requirements
What can fail when Free Lossless Audio Codec is interpreted
FLAC does not make a lossy source lossless again, and some basic players reject less common sample rates or channel layouts.
What Matroska video cannot safely promise
A simplified conversion may keep only primary streams, and many browsers do not play MKV directly.
How the MKV writer handles this route
The verified MKV profile uses H.264 video and Opus audio when those streams are present.
Checking the MKV result before you trust it
Record the FLAC evidence before conversion
Compare duration, sample rate, channels, peak levels, and tags with the decoded source.
Test the MKV file in its receiving workflow
Inspect the stream list, subtitles, language labels, chapters, seeking, and sync.
When to actually choose FLAC to MKV
Use this route only when the receiving workflow specifically accepts audio inside MKV. It is not a music-visualizer or slideshow generator.
What changes between the FLAC model and the MKV deliverable
- Because FLAC has no picture, a still black 1280x720 frame is added so the MKV is a real video that video sites accept.
- MKV is a lossy format, so the file is usually much smaller but some fine detail is discarded; keep your FLAC original.
- Treat FLAC-specific metadata fields as optional in the MKV result until you have actually confirmed they survived.