MyMediaTools

Convert WMV to M2TS — Free Online Tool

Convert WMV files to M2TS format, re-encoding the MPEG-4 Part 2 video stream (msmpeg4) into H.264 (libx264) and the WMA audio into AAC — producing a BDAV-compatible MPEG-2 Transport Stream suitable for Blu-ray authoring, AVCHD playback, and broadcast workflows.

FFmpeg Command

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Estimated output:

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How It Works

WMV files use Microsoft's proprietary ASF container with MPEG-4 Part 2 video (msmpeg4 or msmpeg4v2) and WMA audio (wmav2) — neither of which is compatible with M2TS. This means the conversion is a full transcode, not a remux: the video stream is decoded from msmpeg4 and re-encoded as H.264 using libx264, and the WMA audio is decoded and re-encoded as AAC. The output is wrapped in an MPEG-2 Transport Stream container, which is the standard used by Blu-ray Disc (BDAV) and AVCHD camcorders. Because both the WMV and M2TS formats are lossy at their respective quality settings, you will experience a second generation of compression — keeping the CRF value low (e.g., 18 or lower) minimizes additional quality loss from the video re-encoding stage.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg binary — the open-source multimedia processing engine that powers this conversion entirely in your browser via WebAssembly (FFmpeg.wasm), with no server upload required.
-i input.wmv Specifies the input file in WMV format — an ASF container holding Microsoft MPEG-4 Part 2 video (msmpeg4) and WMA audio (wmav2), both of which will be fully decoded before re-encoding begins.
-c:v libx264 Sets the video encoder to libx264, re-encoding the source msmpeg4 video stream into H.264 (AVC) — the video codec required by the BDAV/M2TS specification and supported by Blu-ray players, AVCHD devices, and broadcast systems.
-c:a aac Sets the audio encoder to AAC, transcoding the WMA (wmav2) audio from the source WMV into Advanced Audio Coding — a widely compatible lossy format that is natively supported by the M2TS container and Blu-ray playback systems.
-crf 23 Sets the Constant Rate Factor for the H.264 encode to 23, which is libx264's default balanced quality setting. Lower values (e.g., 18) produce higher quality and larger files, which is worth considering since the WMV source was already lossy and a second transcode will compound compression artifacts.
-b:a 128k Sets the AAC audio output bitrate to 128 kbps. This matches a typical mid-quality WMA2 stream from a standard WMV file; if the source WMV has higher-bitrate WMA audio, increase this value (e.g., -b:a 192k) to better preserve audio fidelity through the transcode.
output.m2ts Specifies the output filename with the .m2ts extension, which tells FFmpeg to wrap the encoded H.264 video and AAC audio into an MPEG-2 Transport Stream container formatted for BDAV (Blu-ray Disc Audio-Video) compatibility.

Common Use Cases

  • Authoring a Blu-ray disc from old WMV home videos or presentations captured on Windows Media Encoder, where the Blu-ray authoring software requires an MPEG-2 Transport Stream with H.264 video.
  • Importing WMV footage into AVCHD-compatible editing workflows where the NLE or device expects M2TS files organized in a BDMV folder structure.
  • Archiving Windows Media Video recordings from corporate or broadcast environments into a more broadcast-compatible M2TS format that supports multiple audio tracks and subtitles.
  • Preparing WMV content captured from legacy Windows-based recording systems for playback on Blu-ray players or set-top boxes that do not support the ASF/WMV container.
  • Converting WMV training videos or conference recordings into M2TS so subtitle tracks can be added, leveraging M2TS's subtitle support that WMV lacks.
  • Migrating a library of WMV streams originally encoded for Windows Media Player into a more universally compatible high-definition container for long-term preservation.

Frequently Asked Questions

Yes, some quality loss is unavoidable because this conversion requires a full transcode — your WMV's msmpeg4 video and WMA audio must both be decoded and re-encoded from scratch. WMV is already a lossy format, so re-encoding introduces a second generation of compression artifacts. To minimize this, use a lower CRF value in the FFmpeg command (e.g., -crf 18 instead of -crf 23), which increases H.264 quality at the cost of a larger output file.
The M2TS (BDAV) container is part of the Blu-ray specification, which mandates specific codecs: H.264 (AVC), H.265 (HEVC), or VC-1 for video, and AAC, AC-3, or DTS for audio. WMV's native video codec — Microsoft's MPEG-4 Part 2 variant (msmpeg4) — is not an allowed codec in the M2TS/BDAV specification, so a stream copy is not possible and full re-encoding to H.264 is required.
Adjust the -crf value in the command: lower numbers mean higher quality and larger files, higher numbers mean lower quality and smaller files. The default -crf 23 is a balanced midpoint for H.264. For near-lossless output from a WMV source, try -crf 15 or -crf 18. For a smaller file where some visible quality loss is acceptable, -crf 28 or -crf 30 is reasonable. The full command would look like: ffmpeg -i input.wmv -c:v libx264 -c:a aac -crf 18 -b:a 128k output.m2ts
No. M2TS uses its own separate Blu-ray content protection system (AACS), and WMV's Microsoft DRM (PlayReady/Windows Media DRM) is specific to the ASF container and cannot be transferred to M2TS. If your WMV file is DRM-protected, FFmpeg will not be able to decode it, and the conversion will fail. Only unprotected WMV files can be converted with this tool.
Not automatically — the output quality is bounded by the quality of the source WMA audio in the WMV. The default -b:a 128k AAC setting is comparable to a mid-quality WMA2 stream. If your source WMV has high-bitrate WMA audio (e.g., 192k or 256k), you should raise the -b:a value to match: for example, replace -b:a 128k with -b:a 192k in the command to better preserve the original fidelity during the WMA-to-AAC transcode.
Yes. On Linux or macOS, you can run a shell loop in your terminal: for f in *.wmv; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "${f%.wmv}.m2ts"; done. On Windows Command Prompt, use: for %f in (*.wmv) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "%~nf.m2ts". This browser-based tool processes one file at a time, so the FFmpeg command displayed on this page is especially valuable for batch processing large WMV libraries locally.

Technical Notes

WMV's ASF container stores video using Microsoft's proprietary MPEG-4 Part 2 derivatives (msmpeg4v2 or msmpeg4), which are distinct from the ISO-standard MPEG-4 Part 2 used in formats like DivX or Xvid. Neither variant is valid in an M2TS/BDAV stream, necessitating a full re-encode to H.264. The output M2TS file uses the MPEG-2 Transport Stream multiplexing layer, which packetizes audio and video into 188-byte TS packets — a structure designed for error-resilient broadcast and disc delivery rather than simple progressive download. WMV supports multiple audio tracks (via ASF stream selection), and M2TS also supports multiple audio tracks, but FFmpeg's default command maps only the first audio stream; add -map 0:a to include all audio tracks if your source WMV has multiple. WMV's DRM support and Windows Media Player-specific metadata (WM/* tags) will not be carried over to M2TS, as those are ASF-specific features. Chapter and subtitle data are also not present in WMV, so no information is lost in that regard. If the source WMV was encoded at a low bitrate (e.g., 500k video), increasing the H.264 CRF will not recover lost detail — the output quality ceiling is always set by the source.

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