The MTS file format stores data in the MTS format. Converting to FLAC produces a audio file that applies lossless compression to PCM audio, preserving the original waveform exactly while reducing file size by 40-60% versus WAV. This extracts the audio stream from the video container, discarding the video track. The audio track is decoded and re-encoded (or stream-copied if the codec matches) while the video frames are discarded. This makes FLAC the practical choice when the destination system requires it or when the original format is not supported by the target application. 1converter runs this conversion on the server: your file is uploaded encrypted over HTTPS, converted using trusted open-source libraries, and the output is held for 24 hours before automatic deletion.