Free online M2T to ASF converter

What the M2T format is

M2T is an MPEG-2 Transport Stream file commonly used by HDV camcorders and capture applications. HDV recordings often use MPEG-2 video at 1440×1080 or 1280×720, interlaced scanning, and an MPEG-1 Layer II audio track. The extension may appear as .m2t, .m2ts, or .ts depending on the camera and capture software, although M2T specifically usually refers to HDV transport-stream output.

Older Sony, Canon, and JVC HDV workflows, along with tools such as HDVSplit and some nonlinear editors, commonly create or export M2T files. VLC, MPC-HC, FFmpeg, and many professional video editors can generally open them.

What the ASF format is

ASF, or Advanced Systems Format, is a Microsoft container designed for streaming and storing Windows Media audio and video. Files commonly use the .asf extension; WMV files are also based on ASF but normally use the .wmv extension.

ASF is useful for legacy Windows Media Player workflows, older Microsoft software, and devices that expect Windows Media codecs. It can carry compressed video, audio, metadata, indexes, and streaming information, but modern players and editors generally provide better support for MP4, MOV, or Matroska.

How to convert M2T to ASF

Using FFmpeg

FFmpeg provides predictable control over the codecs, bitrate, frame size, and interlacing settings. Install a current FFmpeg build, place the source file in a convenient folder, and run:

ffmpeg -i input.m2t -c:v wmv2 -b:v 5M -c:a wmav2 -b:a 192k output.asf

This encodes the video with WMV2 and the audio with Windows Media Audio, a combination supported by many ASF-capable Windows applications. Replace input.m2t with the actual filename and adjust 5M to control video quality and file size.

For an interlaced 1080 HDV source, preserve interlacing explicitly when required by the target device:

ffmpeg -i input.m2t -c:v wmv2 -b:v 8M -flags +ilme+ildct -top 1 -c:a wmav2 -b:a 192k output.asf

Use -top 1 only when the source has top-field-first ordering. HDV is commonly top-field-first, but verify the recording before applying this option. To inspect streams without converting, run ffprobe input.m2t.

For a smaller file, reduce the bitrate or resolution, for example:

ffmpeg -i input.m2t -vf scale=1280:-2 -c:v wmv2 -b:v 3M -c:a wmav2 -b:a 128k output.asf

On 101convert.com, use the built-in free online converter: select the M2T file, choose ASF as the output format, start the conversion, and download the resulting file. Online conversion is unsuitable for confidential footage or very large camera recordings because the source must be uploaded and processing depends on connection and file limits.

Quality and compatibility limitations

Changing .m2t to .asf does not convert the file; it only changes its name and usually produces an unreadable or misleading result. Re-encoding is normally necessary because M2T uses an MPEG-2 transport stream while ASF workflows typically expect Windows Media codecs.

WMV2 encoding is lossy, so the ASF file will not retain the exact quality of the original HDV footage. Keep the M2T master and use a higher video bitrate when the ASF file is intended for editing or archival reference. If the destination accepts MPEG-2 inside ASF, a stream copy may be possible, but compatibility is inconsistent and a normal WMV2 re-encode is safer for legacy Windows applications.

Check the finished file in the exact target program or device. ASF support does not guarantee support for 1440×1080 video, interlaced playback, WMV2, WMA, or files larger than the device's size limit.