Free online M2V to MTS converter

What the M2V format is

M2V is an MPEG-2 elementary video stream, usually containing video only and no audio, subtitles, or container metadata. DVD authoring applications, MPEG encoders, and video editors can create M2V files when video and audio are exported as separate streams. You may encounter M2V files alongside an .ac3, .mpa, or .wav audio file in DVD production workflows.

What the MTS format is

MTS is an MPEG transport stream commonly used for AVCHD recordings from Sony, Panasonic, and other HD camcorders. It can hold video, audio, subtitles, timestamps, and stream metadata in one file. AVCHD-compatible MTS files commonly use H.264/AVC video with AC-3 or LPCM audio, although the MPEG transport-stream container can also carry MPEG-2 video.

MTS is useful for camera workflows, Blu-ray-related production, and software that expects transport-stream input. Changing an extension to .mts does not perform a conversion; the file must be remultiplexed or re-encoded.

How to actually convert M2V to MTS

FFmpeg is the most direct desktop method. First check the source streams:

ffprobe input.m2v

If the destination accepts MPEG-2 video inside a transport stream, remux the video without re-encoding:

ffmpeg -i input.m2v -map 0:v:0 -c:v copy -an -f mpegts output.mts

This is fast and preserves the original picture quality. The -an option explicitly creates a video-only output. If the target requires typical AVCHD H.264 video, encode the M2V stream instead:

ffmpeg -i input.m2v -map 0:v:0 -c:v libx264 -preset medium -crf 18 -pix_fmt yuv420p -an -f mpegts output.mts

Use a higher -crf value, such as 21 or 23, for a smaller file with more quality loss. The M2V source cannot supply audio; mux a separate track only if you have one:

ffmpeg -i input.m2v -i audio.ac3 -map 0:v:0 -map 1:a:0 -c:v copy -c:a copy -f mpegts output.mts

For an H.264 AVCHD-style output with separate AC-3 audio, replace the video options with -c:v libx264 -profile:v high -level 4.1 -pix_fmt yuv420p and retain -c:a ac3 -b:a 256k. Exact AVCHD acceptance depends on resolution, frame rate, H.264 level, audio codec, and transport-stream metadata.

For conversion without installing software, upload the file to the free converter on 101convert.com and choose MTS as the output format.

Quality, compatibility, and limitations

Remuxing with -c:v copy does not reduce quality, but some camera editors and hardware players reject MPEG-2 video in an MTS container because they expect H.264 AVCHD parameters. Re-encoding to H.264 improves compatibility but introduces generation loss and takes longer.

Standard M2V files have no audio, so an MTS made from only that file will also be silent. If the original project has separate audio, mux it during conversion and verify synchronization and codec support in the target application. Test the resulting file with ffprobe output.mts and play it in the intended editor or device rather than relying on the filename extension.