Add your MTS file
Drop one or more .mts files onto the converter above, or browse for them. They load into browser memory only — nothing is uploaded, so there is no size-based pricing and no server queue.
MTS to FLAC
Pulling the soundtrack out of a .mts video into .flac audio keeps what you can hear and drops the picture entirely. Free, private, and validated — the file never leaves your browser.
100% private for supported formats
Runs on your deviceConvert supported files
Drop MTS files here
Batch files can each use a different output. Nothing uploads for local conversions.
Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.About converting AVCHD video to FLAC audio
Pulling the soundtrack out of a .mts video into .flac audio keeps what you can hear and drops the picture entirely. An .mts file is AVCHD footage as written to a camcorder's memory card, containing H.264 video inside an MPEG transport stream. Sony and Panasonic camcorders from the late 2000s onward filled SD cards with .mts clips, so the extension is familiar to anyone importing family or event video.
A .flac file contains audio compressed with the Free Lossless Audio Codec, which shrinks recordings without discarding a single sample. Decoded .flac output is bit-identical to the source, so the format has become the standard for music archiving and high-resolution downloads. For this route the practical draw is genuinely lossless while roughly halving storage and open specification with no royalties anywhere in the chain — balanced against still several times larger than a good lossy encode, which is worth knowing before you commit a large batch.
Why convert MTS to FLAC?
The usual reason to take .flac audio out of a .mts file is that only the sound matters — a talk, interview, song, or podcast segment. Keeping the video stream would waste storage, and a dedicated audio file is easier to trim, tag, and play. On the source side, transport-stream packet overhead makes files larger than the same video in MP4; on the target side, the payoff is genuinely lossless while roughly halving storage, which is exactly what you want for ripping CD collections for permanent archival.
MTS vs FLAC at a glance
| Aspect | AVCHD video (.mts) | FLAC audio (.flac) |
|---|---|---|
| Format type | Container — quality depends on the codecs and settings inside | Lossless — every pixel or sample is preserved exactly |
| How it stores data | uses 192-byte transport packets, standard 188-byte packets plus a 4-byte arrival timestamp, matching Blu-ray's BDAV layout | linear prediction followed by Rice coding typically yields files 40 to 60 percent the size of raw PCM |
| Strongest at | importing camcorder footage into Premiere, Resolve, or Final Cut | ripping CD collections for permanent archival |
| Weak spot | transport-stream packet overhead makes files larger than the same video in MP4 | still several times larger than a good lossy encode |
| Metadata | recording date, camera settings, and GPS coordinates on some models are stored in the AVCHD folder's clip-info files rather than in the .mts stream itself | vorbis comments for tags plus a dedicated PICTURE block for cover art; cue sheets can be embedded for whole-disc rips |
Pick FLAC as the output
Select .flac in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if FLAC is selectable, the route is real and validated.
Convert on your device
Press Convert. A WebAssembly FFmpeg build demuxes the audio track and re-encodes it locally; the video stream is simply discarded.
Verify and download
Each result is signature-checked before the download unlocks, so a failed encode can never masquerade as a valid FLAC file. Outputs keep the original filename with the .flac extension.
MTS to FLAC questions, answered
Will converting MTS to FLAC lose quality?
Since mts is container-oriented and flac is lossless-oriented, the conversion preserves the source content exactly as stored; no additional compression pass is applied beyond what .flac itself requires.
Is it private to convert MTS files here?
Yes — the .mts file is processed inside your browser tab and never uploaded. A WebAssembly FFmpeg build demuxes the audio track and re-encodes it locally; the video stream is simply discarded. Close the tab and the file is gone from memory.
Where will the FLAC file work?
All major browsers decode .flac, Windows 10 and later plus Android play it natively, and virtually every dedicated audio player supports it. The persistent gap is Apple's Music ecosystem, where converting to ALAC delivers the same audio in a supported wrapper.
Will the FLAC file be bigger or smaller than my MTS?
Much smaller — the video stream is usually 80–95% of a .mts file's weight, and it is discarded entirely. The remaining audio is re-encoded at the bitrate implied by your quality setting.
What happens to the metadata in my MTS file?
This converter strips container metadata deliberately (the FFmpeg command runs with metadata mapping disabled) so exported files do not leak recording details. In the source, recording date, camera settings, and GPS coordinates on some models are stored in the AVCHD folder's clip-info files rather than in the .mts stream itself; none of it is transmitted anywhere because the file never leaves your browser.