MTS to ASF Converter

MTS to ASF Converter

MTS is the AVCHD recording format from Sony, Panasonic, and Canon HD camcorders; ASF (Advanced Systems Format) is Microsoft's streaming container, better known by its .wmv cousin. This conversion exists for one specific reason: feeding modern camcorder footage into legacy Windows tooling — Windows Movie Maker, old Windows Media Player workflows, or a streaming server that only accepts .asf/.wmv. If you just want a file that plays everywhere, convert MTS to MP4 instead — it is smaller, more compatible, and not tied to a discontinued ecosystem.

MTS (AVCHD) Format at a Glance

ASF (Windows Media) Format at a Glance

How to Convert MTS to ASF

1. Upload Your MTS File: Drag and drop your .mts clip or click "+ Add Files". Batch upload is supported, and files are sent over an encrypted connection.
2. Pick a Video Codec: Open Advanced Options and set Video Codec. The default is H.264; for true Windows Media Player and Movie Maker compatibility, switch it to WMV 2 (or WMV 1) — see the note below on why this matters.
3. Set Audio Codec and Quality (Optional): Audio Codec defaults to WMA v2 (the Windows-native audio); adjust the Preset (default "Very High") or set a Specific file size, and use Video resolution or Trim to downscale or shorten the clip.
4. Convert and Download: Click "Convert" and download your .asf file. No sign-up, no watermark.

A Note on Codec Choice: H.264 vs WMV Inside ASF

The default keeps your camcorder's H.264 stream and wraps it in the ASF container. That is valid, but Windows Media Player looks for a WMV/VC-1 decoder when it opens an .asf file and will usually report a missing codec for H.264-in-ASF — so the default does not reliably play in the very tools people choose ASF for. If your goal is legacy Windows compatibility, set Video Codec to WMV 2. Be aware of the trade-off: WMV 2 is an older, less efficient codec than H.264, so you are re-encoding lossy H.264 into a lossy, lower-efficiency codec — expect a larger file at equal quality, or some quality loss at equal size. Audio follows the same pattern: AC-3 or PCM is re-encoded to WMA, which is lossy. If neither legacy playback nor .asf is a hard requirement, MTS to MP4 avoids both downgrades.

Frequently Asked Questions

Why does my converted ASF file not play in Windows Media Player?

Most likely the Video Codec was left on the default H.264. Windows Media Player opens .asf files expecting a WMV or VC-1 stream and reports a missing codec when it finds H.264 inside the ASF container. Re-run the conversion with Video Codec set to WMV 2 (or WMV 1) and the file will play in Windows Media Player, Movie Maker, and other native Windows tools.

Should I convert MTS to ASF or to WMV?

There is effectively no difference in the file — ASF, WMV, and WMA are the same Microsoft container with different extensions; .wmv simply signals that the file holds video. Pick ASF if a specific tool or streaming server demands the .asf extension; pick MTS to WMV if your software expects .wmv. Either way, choose a WMV codec for native Windows playback.

Will I lose quality converting MTS to ASF?

If you keep the default H.264 codec, quality is essentially preserved because the video stream is re-wrapped rather than re-encoded; only the audio is converted to WMA. If you switch to a WMV codec for compatibility, the H.264 video is re-encoded into a less efficient codec, so expect either a larger file or visible quality loss compared with the source. There is no setting that makes WMV match H.264 byte-for-byte at the same size.

Does ASF preserve the AVCHD timecode and interlacing from my camcorder?

ASF does not carry the AVCHD-specific metadata and recording flags from the original transport stream. Interlaced 1080i footage is converted field-for-field, but the camcorder timecode track and AVCHD chapter markers are not transferred to the Windows Media container. For editing that depends on that metadata, keep an .mts/.m2ts master and convert a copy.

Is the ASF format still maintained?

No. Microsoft last revised the Advanced Systems Format specification (version 01.20.03) in December 2004, and it is now treated as a legacy format. It remains readable by Windows Media Player and older Windows applications, but it is not a modern delivery format — MP4 with H.264 or H.265 has long since replaced it for general use and web streaming.

Can I convert the ASF back to MTS later?

Yes, but with a caveat: converting ASF to MTS re-encodes the WMV/WMA streams back to H.264 and AC-3, and you cannot recover detail lost in the first re-encode. If you might need the AVCHD original again, archive the source .mts file rather than relying on a round trip through ASF.

Are my files kept after the conversion?

No. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically a few hours after conversion — there is no sign-up, no watermark, and files are never shared or made public. In our testing, a 60-second 1080i AVCHD clip re-encoded to WMV 2 in ASF produced a noticeably larger file than the same clip in H.264 MP4, which is expected given WMV 2's lower coding efficiency.