ASF to MTS Converter

Convert ASF to MTS: What This Tutorial Covers

This is a narrow, specific job. You have Windows Media clips — .asf or .wmv, Microsoft's Advanced Systems Format — and something downstream wants .mts, the file name AVCHD camcorders write. Nine times out of ten that "something" is a video editor whose project was built around camcorder footage. This walk-through covers the two settings that decide whether the result is a real AVCHD-shaped file or just an MPEG transport stream wearing an .mts name, what quality you can honestly expect from the re-encode, and when the right answer is ASF to MP4 instead.

How to Convert ASF to MTS

1. Upload Your ASF File: Drag and drop the .asf or .wmv onto the page, or click "+ Add Files" to browse. Queue several clips and they all run with the same settings.
2. Confirm Video Codec Is H.264: Video Codec defaults to H.264 — the codec AVCHD is built on — with H.265, MPEG-1, MPEG-2, MPEG-4, Xvid, and DivX also offered. Leave it on H.264 unless a tool has explicitly asked for something else.
3. Set Audio Codec, Quality, Resolution, or Trim: AVCHD's own audio codec is Dolby AC-3, so pick Audio Codec → AC3 when the file has to behave like camcorder footage; AAC, MP2, MP3, EAC3, and DTS (DCA) are also available for general playback. Under File Compression, "Very High (Recommended)" is the starting Quality Preset, and Constant Quality exposes the 16–51 H.264 CRF slider where lower means better. Use Video resolution and Trim → Time Range only if you need to rescale or cut.
4. Convert and Download: Click Convert and save the .mts. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours — no sign-up, no watermark, never shared.

Walk-through: Getting an MTS an AVCHD Editor Will Accept

AVCHD was introduced by Sony and Panasonic in 2006 for consumer HD camcorders. Its rules are tight: H.264/MPEG-4 AVC video (Main or High profile, Level 4.1 or 4.2), audio as Dolby AC-3 or uncompressed linear PCM, everything multiplexed into an MPEG transport stream, at 1920×1080, 1440×1080, or 1280×720. .mts is what the camcorder writes on its own card; .m2ts is the same stream after import to a computer or onto Blu-ray-style media. An importer that only knows AVCHD is checking for those properties — not for the file extension.

That gives you a short checklist for this page:

• Keep Video Codec on H.264. The other choices in the dropdown produce a valid transport stream, but MPEG-2, Xvid, DivX, or H.265 inside a .mts is not AVCHD, and a strict AVCHD import path can refuse it.
• Choose AC3 for audio when the destination is an AVCHD project. AC-3 is one of only two audio codecs the AVCHD specification allows. AAC will play in VLC, mpv, and most editors, but it is not what a camcorder would have recorded.
• Do not raise the resolution. If the source .asf is standard definition, leave Video resolution on Keep original. Upscaling SD to 1080p produces a bigger file containing exactly the same detail.
• Start from a high Quality Preset. This is a second generation of lossy compression on top of whatever WMV already did, so give the H.264 pass room — "Very High (Recommended)", or Constant Quality in the high teens on the 16–51 CRF scale.

AVCHD Specification vs What This Page Produces

MTS vs M2TS vs MP4 as a Target

Common Errors and How to Fix Them

• "My editor still rejects the .mts" — check that Video Codec was left on H.264 and audio set to AC3. If a strict AVCHD importer still refuses it, the project probably wants plain MP4; use ASF to MP4.
• "The output looks no sharper than the source" — expected. WMV is already lossy and most .asf files are standard definition; a second encode cannot invent detail, and upscaling only stretches what is there.
• "Audio is missing or wrong after import" — the WMA track is re-encoded, not carried over. If the project expects Dolby Digital, set Audio Codec to AC3 and convert again.
• "The file is enormous" — AVCHD-class bitrates are large by design. Pin a ceiling with Constant Bitrate, drop the Preset Resolution, or switch targets to MP4.
• "Conversion fails, or the result is black or silent" — the source may be DRM-protected Windows Media, or a partially downloaded .asf with no decodable stream at that point.
• "My camcorder won't play the .mts I copied back to its card" — a camcorder plays what its AVCHD index and playlist files describe, not loose files dropped into a folder. Play converted clips on a computer instead.

When This Doesn't Work

MTS is a narrow target, and most people who land here would be better served by something else. It is a large, HD-oriented camcorder format with patchy support outside dedicated editing and camcorder software — no browser plays it, no phone opens it by default, and no social platform wants it. Convert to MTS when an AVCHD-based editing project genuinely demands it; convert to ASF to MP4 when the goal is "make this old Windows Media clip play and share everywhere". If you already have .mts files and need them portable, MTS to MP4 goes the other way. And no converter can process a DRM-locked or truncated .asf — that needs an unprotected copy from the original source.

Frequently Asked Questions

Why would I convert ASF to MTS instead of MP4?

Realistically, only for an editing workflow built around AVCHD footage. MTS is the on-camcorder name for AVCHD — H.264 video with AC-3 or LPCM audio in an MPEG transport stream — so some non-linear editors and AVCHD import paths take .mts cleanly while balking at a Windows Media .asf. Outside that case MTS has no advantage over MP4 and several disadvantages: bigger files, no browser or phone playback, and no social-platform support.

Will converting to MTS make my video look better?

No. ASF almost always carries Windows Media Video, which is lossy, and a great many .asf files are standard definition. Re-encoding into H.264 inside a transport stream is a second lossy pass: it changes the packaging, not the picture. Nothing the original WMV encoder discarded comes back, and choosing a 1080p preset for an SD source produces a larger file with the same amount of real detail. The reason to do this conversion is compatibility, not quality.

Which codecs should I pick for a file an AVCHD editor will accept?

H.264 for video and AC3 for audio. Those are the AVCHD specification's own choices — the format allows only H.264/AVC video, and only Dolby AC-3 or linear PCM audio. Video Codec already defaults to H.264 here; set Audio Codec to AC3 yourself if the destination is an AVCHD project. The other codecs in those dropdowns produce a perfectly valid transport stream that plays in VLC or mpv, but they are not AVCHD and a strict importer may say so.

What is the difference between .mts and .m2ts?

They hold the same thing. AVCHD camcorders write .mts files onto their own storage; the same stream is named .m2ts after it is imported to a computer or written to Blu-ray-style media. Both are MPEG transport streams carrying H.264 video. If your tool specifically wants the longer name, convert here and rename, or use the ASF to M2TS endpoint instead.

Can I copy the converted .mts back onto my camcorder and play it?

Almost certainly not. An AVCHD camcorder does not browse loose files: it reads an index and playlist structure that ships alongside the clips in the AVCHD folder tree, and a file that structure does not describe simply will not appear in the camera's playback menu. Some models also reject clips whose resolution, frame rate, or bitrate falls outside what that model records. Play converted files on a computer or a media player instead.

Should I upscale a standard-definition ASF to 1080p while I am at it?

No. Leave Video resolution on Keep original, or choose a preset at or below the source frame size. AVCHD supports 720p and 1080i/1080p, but only footage that was HD when it was shot benefits from an HD setting — scaling a 640×480 WMV up to 1920×1080 multiplies the pixel count without adding information, and costs you file size and encode time for nothing.

Why does my DRM-protected ASF or WMV fail to convert?

ASF has a digital-rights-management framework built into the container, and files from older Windows Media stores and subscription services use it. The audio and video streams are encrypted and only a licence bound to the original account or machine can unlock them, so no converter can decode the picture in order to re-encode it. The job fails, or produces a black or silent file. Only an unprotected copy of the source can be converted.

How are my uploaded ASF files handled, and is there a size limit?

Encoding happens on our servers rather than on your own hardware, so the practical limit is how large a file you can upload and how long you want to wait rather than anything about your machine. Uploads travel over an encrypted (TLS) connection, are processed on our servers, and are deleted automatically after a few hours. Nothing is shared or made public, no watermark is added, and no account is required.