Free online MTS to FLAC converter

Source format: MTS

MTS is a video container format commonly used by AVCHD camcorders and some other consumer video devices. It usually contains H.264/AVC video with AC-3 or LPCM audio, and it is mainly used for recording high-definition footage from cameras. Because it is a video format, an MTS file is not just audio; to convert it to FLAC, you typically extract the audio track from the video.

Target format: FLAC

FLAC stands for Free Lossless Audio Codec. It is a widely supported lossless audio format that preserves the original audio quality while compressing the file size more efficiently than uncompressed WAV. FLAC is popular for music archiving, editing, and playback on many desktop and portable devices.

How to perform the conversion

The best approach is to use a tool that can read the video container and export only the audio stream. FFmpeg is the most reliable option for this conversion because it handles MTS files well and can encode directly to FLAC.

1. Install FFmpeg on your computer if it is not already available.
2. Open a terminal or command prompt in the folder containing the MTS file.
3. Run a command such as ffmpeg -i input.mts -vn -c:a flac output.flac
4. If the source audio is already lossless or you want to avoid re-encoding when possible, you can first inspect the streams with ffprobe input.mts.
5. Check the resulting output.flac in an audio player or editor to confirm the conversion succeeded.

If you prefer a graphical workflow, some media converters and editors can open MTS files and export audio as FLAC. In many cases, the steps are similar: open the file, choose File → Export or Save as, select FLAC as the output format, and export only the audio track. You can also convert the file on 101convert.com for free, without installing any software.

Notes on quality and compatibility

Because MTS is a video format, converting it to FLAC means you are keeping only the audio and discarding the video. If the original MTS audio is lossy (for example, AC-3), converting it to FLAC will not restore lost detail; it only preserves the audio in a lossless container from that point onward. If the source audio is already uncompressed or high quality, FLAC is an excellent archival choice.

Some MTS files contain multiple audio tracks, and you may need to choose the correct one during conversion. Also, FLAC supports metadata well, but chapter markers and video-related data from the MTS file will not carry over. For best compatibility, keep the original MTS file as a backup in case you later need the video or original audio streams.